/*
 * Copyright (c) 2009-2020, Redis Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "server.h"
#include "util.h"
#include "sha1.h" /* SHA1 is used for DEBUG DIGEST */
#include "crc64.h"
#include "bio.h"
#include "quicklist.h"
#include "fpconv_dtoa.h"
#include "cluster.h"
#include "threads_mngr.h"
#include "io_threads.h"
#include "sds.h"
#include "module.h"

#include <arpa/inet.h>
#include <signal.h>
#include <dlfcn.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>

#include "valkey_strtod.h"

#ifdef HAVE_BACKTRACE
#include <execinfo.h>
#ifndef __OpenBSD__
#include <ucontext.h>
#else
typedef ucontext_t sigcontext_t;
#endif
#endif /* HAVE_BACKTRACE */

#ifdef USE_LIBBACKTRACE
#include <backtrace.h>
#include <sys/wait.h>
#endif

#ifdef __CYGWIN__
#ifndef SA_ONSTACK
#define SA_ONSTACK 0x08000000
#endif
#endif

#if defined(__APPLE__) && defined(__arm64__)
#include <mach/mach.h>
#endif

/* Globals */
static int bug_report_start = 0; /* True if bug report header was already logged. */
static pthread_mutex_t bug_report_start_mutex = PTHREAD_MUTEX_INITIALIZER;
/* Mutex for a case when two threads crash at the same time. */
static pthread_mutex_t signal_handler_lock;
static pthread_mutexattr_t signal_handler_lock_attr;
static volatile int signal_handler_lock_initialized = 0;
/* Forward declarations */
int bugReportStart(void);
void printCrashReport(void);
void bugReportEnd(int killViaSignal, int sig);
void logStackTrace(void *eip, int uplevel, int current_thread);
void sigalrmSignalHandler(int sig, siginfo_t *info, void *secret);

/* ================================= Debugging ============================== */

/* Compute the sha1 of string at 's' with 'len' bytes long.
 * The SHA1 is then xored against the string pointed by digest.
 * Since xor is commutative, this operation is used in order to
 * "add" digests relative to unordered elements.
 *
 * So digest(a,b,c,d) will be the same of digest(b,a,c,d) */
void xorDigest(unsigned char *digest, const void *ptr, size_t len) {
    SHA1_CTX ctx;
    unsigned char hash[20];
    int j;

    SHA1Init(&ctx);
    SHA1Update(&ctx, ptr, len);
    SHA1Final(hash, &ctx);

    for (j = 0; j < 20; j++) digest[j] ^= hash[j];
}

void xorStringObjectDigest(unsigned char *digest, robj *o) {
    o = getDecodedObject(o);
    xorDigest(digest, objectGetVal(o), sdslen(objectGetVal(o)));
    decrRefCount(o);
}

/* This function instead of just computing the SHA1 and xoring it
 * against digest, also perform the digest of "digest" itself and
 * replace the old value with the new one.
 *
 * So the final digest will be:
 *
 * digest = SHA1(digest xor SHA1(data))
 *
 * This function is used every time we want to preserve the order so
 * that digest(a,b,c,d) will be different than digest(b,c,d,a)
 *
 * Also note that mixdigest("foo") followed by mixdigest("bar")
 * will lead to a different digest compared to "fo", "obar".
 */
void mixDigest(unsigned char *digest, const void *ptr, size_t len) {
    SHA1_CTX ctx;

    xorDigest(digest, ptr, len);
    SHA1Init(&ctx);
    SHA1Update(&ctx, digest, 20);
    SHA1Final(digest, &ctx);
}

void mixStringObjectDigest(unsigned char *digest, robj *o) {
    o = getDecodedObject(o);
    mixDigest(digest, objectGetVal(o), sdslen(objectGetVal(o)));
    decrRefCount(o);
}

/* This function computes the digest of a data structure stored in the
 * object 'o'. It is the core of the DEBUG DIGEST command: when taking the
 * digest of a whole dataset, we take the digest of the key and the value
 * pair, and xor all those together.
 *
 * Note that this function does not reset the initial 'digest' passed, it
 * will continue mixing this object digest to anything that was already
 * present. */
void xorObjectDigest(serverDb *db, robj *keyobj, unsigned char *digest, robj *o) {
    uint32_t aux = htonl(o->type);
    mixDigest(digest, &aux, sizeof(aux));
    long long expiretime = objectGetExpire(o);
    char buf[128];

    /* Save the key and associated value */
    if (o->type == OBJ_STRING) {
        mixStringObjectDigest(digest, o);
    } else if (o->type == OBJ_LIST) {
        listTypeIterator *li = listTypeInitIterator(o, 0, LIST_TAIL);
        listTypeEntry entry;
        while (listTypeNext(li, &entry)) {
            robj *eleobj = listTypeGet(&entry);
            mixStringObjectDigest(digest, eleobj);
            decrRefCount(eleobj);
        }
        listTypeReleaseIterator(li);
    } else if (o->type == OBJ_SET) {
        setTypeIterator *si = setTypeInitIterator(o);
        sds sdsele;
        while ((sdsele = setTypeNextObject(si)) != NULL) {
            xorDigest(digest, sdsele, sdslen(sdsele));
            sdsfree(sdsele);
        }
        setTypeReleaseIterator(si);
    } else if (o->type == OBJ_ZSET) {
        unsigned char eledigest[20];

        if (o->encoding == OBJ_ENCODING_LISTPACK) {
            unsigned char *zl = objectGetVal(o);
            unsigned char *eptr, *sptr;
            unsigned char *vstr;
            unsigned int vlen;
            long long vll;
            double score;

            eptr = lpSeek(zl, 0);
            serverAssert(eptr != NULL);
            sptr = lpNext(zl, eptr);
            serverAssert(sptr != NULL);

            while (eptr != NULL) {
                vstr = lpGetValue(eptr, &vlen, &vll);
                score = zzlGetScore(sptr);

                memset(eledigest, 0, 20);
                if (vstr != NULL) {
                    mixDigest(eledigest, vstr, vlen);
                } else {
                    ll2string(buf, sizeof(buf), vll);
                    mixDigest(eledigest, buf, strlen(buf));
                }
                const int len = fpconv_dtoa(score, buf);
                buf[len] = '\0';
                mixDigest(eledigest, buf, strlen(buf));
                xorDigest(digest, eledigest, 20);
                zzlNext(zl, &eptr, &sptr);
            }
        } else if (o->encoding == OBJ_ENCODING_SKIPLIST) {
            zset *zs = objectGetVal(o);
            hashtableIterator iter;
            hashtableInitIterator(&iter, zs->ht, 0);

            void *next;
            while (hashtableNext(&iter, &next)) {
                zskiplistNode *node = next;
                const int len = fpconv_dtoa(node->score, buf);
                buf[len] = '\0';
                memset(eledigest, 0, 20);
                sds ele = zslGetNodeElement(node);
                mixDigest(eledigest, ele, sdslen(ele));
                mixDigest(eledigest, buf, strlen(buf));
                xorDigest(digest, eledigest, 20);
            }
            hashtableCleanupIterator(&iter);
        } else {
            serverPanic("Unknown sorted set encoding");
        }
    } else if (o->type == OBJ_HASH) {
        hashTypeIterator hi;
        hashTypeInitIterator(o, &hi);
        while (hashTypeNext(&hi) != C_ERR) {
            unsigned char eledigest[20];
            sds sdsele;

            memset(eledigest, 0, 20);
            sdsele = hashTypeCurrentObjectNewSds(&hi, OBJ_HASH_FIELD);
            mixDigest(eledigest, sdsele, sdslen(sdsele));
            sdsfree(sdsele);
            sdsele = hashTypeCurrentObjectNewSds(&hi, OBJ_HASH_VALUE);
            mixDigest(eledigest, sdsele, sdslen(sdsele));
            sdsfree(sdsele);
            xorDigest(digest, eledigest, 20);
        }
        hashTypeResetIterator(&hi);
    } else if (o->type == OBJ_STREAM) {
        streamIterator si;
        streamIteratorStart(&si, objectGetVal(o), NULL, NULL, 0);
        streamID id;
        int64_t numfields;

        while (streamIteratorGetID(&si, &id, &numfields)) {
            sds itemid = sdscatfmt(sdsempty(), "%U.%U", id.ms, id.seq);
            mixDigest(digest, itemid, sdslen(itemid));
            sdsfree(itemid);

            while (numfields--) {
                unsigned char *field, *value;
                int64_t field_len, value_len;
                streamIteratorGetField(&si, &field, &value, &field_len, &value_len);
                mixDigest(digest, field, field_len);
                mixDigest(digest, value, value_len);
            }
        }
        streamIteratorStop(&si);
    } else if (o->type == OBJ_MODULE) {
        ValkeyModuleDigest md = {{0}, {0}, keyobj, db->id};
        moduleValue *mv = objectGetVal(o);
        moduleType *mt = mv->type;
        moduleInitDigestContext(&md);
        if (mt->digest) {
            mt->digest(&md, mv->value);
            xorDigest(digest, md.x, sizeof(md.x));
        }
    } else {
        serverPanic("Unknown object type");
    }
    /* If the key has an expire, add it to the mix */
    if (expiretime != -1) xorDigest(digest, "!!expire!!", 10);
}

/* Compute the dataset digest. Since keys, sets elements, hashes elements
 * are not ordered, we use a trick: every aggregate digest is the xor
 * of the digests of their elements. This way the order will not change
 * the result. For list instead we use a feedback entering the output digest
 * as input in order to ensure that a different ordered list will result in
 * a different digest. */
void computeDatasetDigest(unsigned char *final) {
    unsigned char digest[20];
    uint32_t aux;

    memset(final, 0, 20); /* Start with a clean result */

    for (int j = 0; j < server.dbnum; j++) {
        serverDb *db = server.db[j];
        if (db == NULL || kvstoreSize(db->keys) == 0) continue;
        kvstoreIterator *kvs_it = kvstoreIteratorInit(db->keys, HASHTABLE_ITER_SAFE | HASHTABLE_ITER_PREFETCH_VALUES);

        /* hash the DB id, so the same dataset moved in a different DB will lead to a different digest */
        aux = htonl(j);
        mixDigest(final, &aux, sizeof(aux));

        /* Iterate this DB writing every entry */
        void *next;
        while (kvstoreIteratorNext(kvs_it, &next)) {
            robj *o = next;
            sds key;
            robj *keyobj;

            memset(digest, 0, 20); /* This key-val digest */
            key = objectGetKey(o);
            keyobj = createStringObject(key, sdslen(key));

            mixDigest(digest, key, sdslen(key));

            xorObjectDigest(db, keyobj, digest, o);

            /* We can finally xor the key-val digest to the final digest */
            xorDigest(final, digest, 20);
            decrRefCount(keyobj);
        }
        kvstoreIteratorRelease(kvs_it);
    }
}

#ifdef USE_JEMALLOC
void mallctl_int(client *c, robj **argv, int argc) {
    int ret;
    /* start with the biggest size (int64), and if that fails, try smaller sizes (int32, bool) */
    int64_t old = 0, val;
    if (argc > 1) {
        long long ll;
        if (getLongLongFromObjectOrReply(c, argv[1], &ll, NULL) != C_OK) return;
        val = ll;
    }
    size_t sz = sizeof(old);
    while (sz > 0) {
        size_t zz = sz;
        if ((ret = je_mallctl(objectGetVal(argv[0]), &old, &zz, argc > 1 ? &val : NULL, argc > 1 ? sz : 0))) {
            if (ret == EPERM && argc > 1) {
                /* if this option is write only, try just writing to it. */
                if (!(ret = je_mallctl(objectGetVal(argv[0]), NULL, 0, &val, sz))) {
                    addReply(c, shared.ok);
                    return;
                }
            }
            if (ret == EINVAL) {
                /* size might be wrong, try a smaller one */
                sz /= 2;
#if BYTE_ORDER == BIG_ENDIAN
                val <<= 8 * sz;
#endif
                continue;
            }
            addReplyErrorFormat(c, "%s", strerror(ret));
            return;
        } else {
#if BYTE_ORDER == BIG_ENDIAN
            old >>= 64 - 8 * sz;
#endif
            addReplyLongLong(c, old);
            return;
        }
    }
    addReplyErrorFormat(c, "%s", strerror(EINVAL));
}

void mallctl_string(client *c, robj **argv, int argc) {
    int rret, wret;
    char *old;
    size_t sz = sizeof(old);
    /* for strings, it seems we need to first get the old value, before overriding it. */
    if ((rret = je_mallctl(objectGetVal(argv[0]), &old, &sz, NULL, 0))) {
        /* return error unless this option is write only. */
        if (!(rret == EPERM && argc > 1)) {
            addReplyErrorFormat(c, "%s", strerror(rret));
            return;
        }
    }
    if (argc > 1) {
        char *val = objectGetVal(argv[1]);
        char **valref = &val;
        if ((!strcmp(val, "VOID"))) valref = NULL, sz = 0;
        wret = je_mallctl(objectGetVal(argv[0]), NULL, 0, valref, sz);
    }
    if (!rret)
        addReplyBulkCString(c, old);
    else if (wret)
        addReplyErrorFormat(c, "%s", strerror(wret));
    else
        addReply(c, shared.ok);
}
#endif

void debugCommand(client *c) {
    if (c->argc == 2 && !strcasecmp(objectGetVal(c->argv[1]), "help")) {
        const char *help[] = {
            "AOF-FLUSH-SLEEP <microsec>",
            "    Server will sleep before flushing the AOF, this is used for testing.",
            "ASSERT",
            "    Crash by assertion failed.",
            "CHANGE-REPL-ID",
            "    Change the replication IDs of the instance.",
            "    Dangerous: should be used only for testing the replication subsystem.",
            "CONFIG-REWRITE-FORCE-ALL",
            "    Like CONFIG REWRITE but writes all configuration options, including",
            "    keywords not listed in original configuration file or default values.",
            "CRASH-AND-RECOVER [<milliseconds>]",
            "    Hard crash and restart after a <milliseconds> delay (default 0).",
            "DIGEST",
            "    Output a hex signature representing the current DB content.",
            "DIGEST-VALUE <key> [<key> ...]",
            "    Output a hex signature of the values of all the specified keys.",
            "ERROR <string>",
            "    Return a RESP protocol error with <string> as message. Useful for clients",
            "    unit tests to simulate error replies.",
            "LEAK <string>",
            "    Create a memory leak of the input string.",
            "LOG <message>",
            "    Write <message> to the server log.",
            "HTSTATS <dbid> [full]",
            "    Return hash table statistics of the specified database.",
            "HTSTATS-KEY <key> [full]",
            "    Like HTSTATS but for the hash table stored at <key>'s value.",
            "LOADAOF",
            "    Flush the AOF buffers on disk and reload the AOF in memory.",
            "REPLICATE <string>",
            "    Replicates the provided string to replicas, allowing data divergence.",
#ifdef USE_JEMALLOC
            "MALLCTL <key> [<val>]",
            "    Get or set a malloc tuning integer.",
            "MALLCTL-STR <key> [<val>]",
            "    Get or set a malloc tuning string.",
#endif
            "OBJECT <key> [fast]",
            "    Show low level info about `key` and associated value.",
            "    Some fields of the default behavior may be time consuming to fetch,",
            "    and `fast` can be passed to avoid fetching them.",
            "DROP-CLUSTER-PACKET-FILTER <packet-type>",
            "    Drop all packets that match the filtered type. Set to -1 allow all packets or -2 to drop all packets.",
            "CLOSE-CLUSTER-LINK-ON-PACKET-DROP <0|1>",
            "    This is valid only when DROP-CLUSTER-PACKET-FILTER is set to a valid packet type.",
            "    When set to 1, the cluster link is closed after dropping a packet based on the filter.",
            "DISABLE-CLUSTER-RANDOM-PING <0|1>",
            "    Disable sending cluster ping to a random node every second.",
            "DISABLE-CLUSTER-RECONNECTION <0|1>",
            "    Disable cluster reconnection of cluster nodes.",
            "OOM",
            "    Crash the server simulating an out-of-memory error.",
            "PANIC",
            "    Crash the server simulating a panic.",
            "POPULATE <count> [<prefix>] [<size>]",
            "    Create <count> string keys named key:<num>. If <prefix> is specified then",
            "    it is used instead of the 'key' prefix. These are not propagated to",
            "    replicas. Cluster slots are not respected so keys not belonging to the",
            "    current node can be created in cluster mode.",
            "PROTOCOL <type>",
            "    Reply with a test value of the specified type. <type> can be: string,",
            "    integer, double, bignum, null, array, set, map, attrib, push, verbatim,",
            "    true, false.",
            "RELOAD [option ...]",
            "    Save the RDB on disk and reload it back to memory. Valid <option> values:",
            "    * MERGE: conflicting keys will be loaded from RDB.",
            "    * NOFLUSH: the existing database will not be removed before load, but",
            "      conflicting keys will generate an exception and kill the server.",
            "    * NOSAVE: the database will be loaded from an existing RDB file.",
            "    Examples:",
            "    * DEBUG RELOAD: verify that the server is able to persist, flush and reload",
            "      the database.",
            "    * DEBUG RELOAD NOSAVE: replace the current database with the contents of an",
            "      existing RDB file.",
            "    * DEBUG RELOAD NOSAVE NOFLUSH MERGE: add the contents of an existing RDB",
            "      file to the database.",
            "RESTART [<milliseconds>]",
            "    Graceful restart: save config, db, restart after a <milliseconds> delay (default 0).",
            "SDSLEN <key>",
            "    Show low level SDS string info representing `key` and value.",
            "SEGFAULT",
            "    Crash the server with sigsegv.",
            "SET-ACTIVE-EXPIRE <0|1>",
            "    Setting it to 0 disables expiring keys in background when they are not",
            "    accessed (otherwise the behavior). Setting it to 1 reenables back the",
            "    default.",
            "QUICKLIST-PACKED-THRESHOLD <size>",
            "    Sets the threshold for elements to be inserted as plain vs packed nodes",
            "    Default value is 1GB, allows values up to 4GB. Setting to 0 restores to default.",
            "SET-SKIP-CHECKSUM-VALIDATION <0|1>",
            "    Enables or disables checksum checks for RDB files and RESTORE's payload.",
            "SLEEP <seconds>",
            "    Stop the server for <seconds>. Decimals allowed.",
            "STRINGMATCH-TEST",
            "    Run a fuzz tester against the stringmatchlen() function.",
            "STRUCTSIZE",
            "    Return the size of different core C structures.",
            "LISTPACK <key>",
            "    Show low level info about the listpack encoding of <key>.",
            "QUICKLIST <key> [<0|1>]",
            "    Show low level info about the quicklist encoding of <key>.",
            "    The optional argument (0 by default) sets the level of detail",
            "CLIENT-EVICTION",
            "    Show low level client eviction pools info (maxmemory-clients).",
            "PAUSE-CRON <0|1>",
            "    Stop periodic cron job processing.",
            "REPLYBUFFER PEAK-RESET-TIME <NEVER||RESET|time>",
            "    Sets the time (in milliseconds) to wait between client reply buffer peak resets.",
            "    In case NEVER is provided the last observed peak will never be reset",
            "    In case RESET is provided the peak reset time will be restored to the default value",
            "REPLYBUFFER RESIZING <0|1>",
            "    Enable or disable the reply buffer resize cron job",
            "PAUSE-AFTER-FORK <0|1>",
            "    Stop the server's main process after fork.",
            "DELAY-RDB-CLIENT-FREE-SECOND <seconds>",
            "    Grace period in seconds for replica main channel to establish psync.",
            "DICT-RESIZING <0|1>",
            "    Enable or disable the main dict and expire dict resizing.",
            "HASHTABLE-CAN-ABORT-SHRINK <0|1>",
            "    Enable or disable the hashtable shrink abort.",
            "CLIENT-ENFORCE-REPLY-LIST <0|1>",
            "    When set to 1, it enforces the use of the client reply list directly",
            "    and avoids using the client's static buffer.",
            "SLOTMIGRATION PREVENT-PAUSE <0|1>",
            "    When set to 1, slot migrations will be prevented from pausing on the source node.",
            "SLOTMIGRATION PREVENT-FAILOVER <0|1>",
            "    When set to 1, slot migrations will be prevented from performing the slot-level failover on the target node.",
            NULL};
        addExtendedReplyHelp(c, help, clusterDebugCommandExtendedHelp());
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "segfault")) {
        /* Compiler gives warnings about writing to a random address
         * e.g "*((char*)-1) = 'x';". As a workaround, we map a read-only area
         * and try to write there to trigger segmentation fault. */
        char *p = mmap(NULL, 4096, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
        *p = 'x';
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "panic")) {
        serverPanic("DEBUG PANIC called at Unix time %lld", (long long)time(NULL));
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "restart") || !strcasecmp(objectGetVal(c->argv[1]), "crash-and-recover")) {
        long long delay = 0;
        if (c->argc >= 3) {
            if (getLongLongFromObjectOrReply(c, c->argv[2], &delay, NULL) != C_OK) return;
            if (delay < 0) delay = 0;
        }
        int flags = !strcasecmp(objectGetVal(c->argv[1]), "restart")
                        ? (RESTART_SERVER_GRACEFULLY | RESTART_SERVER_CONFIG_REWRITE)
                        : RESTART_SERVER_NONE;
        restartServer(c, flags, delay);
        addReplyError(c, "failed to restart the server. Check server logs.");
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "oom")) {
        void *ptr = zmalloc(SIZE_MAX / 2); /* Should trigger an out of memory. */
        zfree(ptr);
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "assert")) {
        serverAssertWithInfo(c, c->argv[0], 1 == 2);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "log") && c->argc == 3) {
        serverLog(LL_WARNING, "DEBUG LOG: %s", (char *)objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "leak") && c->argc == 3) {
        sdsdup(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "reload")) {
        int flush = 1, save = 1;
        int flags = RDBFLAGS_NONE;

        /* Parse the additional options that modify the RELOAD
         * behavior. */
        for (int j = 2; j < c->argc; j++) {
            char *opt = objectGetVal(c->argv[j]);
            if (!strcasecmp(opt, "MERGE")) {
                flags |= RDBFLAGS_ALLOW_DUP;
            } else if (!strcasecmp(opt, "NOFLUSH")) {
                flush = 0;
            } else if (!strcasecmp(opt, "NOSAVE")) {
                save = 0;
            } else {
                addReplyError(c, "DEBUG RELOAD only supports the "
                                 "MERGE, NOFLUSH and NOSAVE options.");
                return;
            }
        }

        /* The default behavior is to save the RDB file before loading
         * it back. */
        if (save) {
            rdbSaveInfo rsi, *rsiptr;
            rsiptr = rdbPopulateSaveInfo(&rsi);
            if (rdbSave(REPLICA_REQ_NONE, server.rdb_filename, rsiptr, RDBFLAGS_NONE) != C_OK) {
                addReplyErrorObject(c, shared.err);
                return;
            }
        }

        /* The default behavior is to remove the current dataset from
         * memory before loading the RDB file, however when MERGE is
         * used together with NOFLUSH, we are able to merge two datasets. */
        if (flush) flags |= RDBFLAGS_EMPTY_DATA;

        protectClient(c);
        int ret = rdbLoad(server.rdb_filename, NULL, flags);
        unprotectClient(c);
        if (ret != RDB_OK) {
            addReplyError(c, "Error trying to load the RDB dump, check server logs.");
            return;
        }
        serverLog(LL_NOTICE, "DB reloaded by DEBUG RELOAD");
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "loadaof")) {
        if (server.aof_state != AOF_OFF) flushAppendOnlyFile(1);
        emptyData(-1, EMPTYDB_NO_FLAGS, NULL);
        protectClient(c);
        if (server.aof_manifest) aofManifestFree(server.aof_manifest);
        aofLoadManifestFromDisk();
        aofDelHistoryFiles();
        int ret = loadAppendOnlyFiles(server.aof_manifest);
        unprotectClient(c);
        if (ret != AOF_OK && ret != AOF_EMPTY) {
            addReplyError(c, "Error trying to load the AOF files, check server logs.");
            return;
        }
        server.dirty = 0; /* Prevent AOF / replication */
        serverLog(LL_NOTICE, "Append Only File loaded by DEBUG LOADAOF");
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "drop-cluster-packet-filter") && c->argc == 3) {
        long packet_type;
        if (getLongFromObjectOrReply(c, c->argv[2], &packet_type, NULL) != C_OK) return;
        server.cluster_drop_packet_filter = packet_type;
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "close-cluster-link-on-packet-drop") && c->argc == 3) {
        server.debug_cluster_close_link_on_packet_drop = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "disable-cluster-random-ping") && c->argc == 3) {
        server.debug_cluster_disable_random_ping = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "disable-cluster-reconnection") && c->argc == 3) {
        server.debug_cluster_disable_reconnection = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "slotmigration")) {
        if (!strcasecmp(objectGetVal(c->argv[2]), "prevent-pause")) {
            server.debug_slot_migration_prevent_pause = atoi(objectGetVal(c->argv[3]));
        } else if (!strcasecmp(objectGetVal(c->argv[2]), "prevent-failover")) {
            server.debug_slot_migration_prevent_failover = atoi(objectGetVal(c->argv[3]));
        } else {
            addReplySubcommandSyntaxError(c);
            return;
        }
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "object") && (c->argc == 3 || c->argc == 4)) {
        robj *val;
        char *strenc;

        int fast = 0;
        if (c->argc == 4 && !strcasecmp(objectGetVal(c->argv[3]), "fast")) fast = 1;

        if ((val = dbFind(c->db, objectGetVal(c->argv[2]))) == NULL) {
            addReplyErrorObject(c, shared.nokeyerr);
            return;
        }
        strenc = strEncoding(val->encoding);

        char extra[138] = {0};
        if (val->encoding == OBJ_ENCODING_QUICKLIST) {
            char *nextra = extra;
            int remaining = sizeof(extra);
            quicklist *ql = objectGetVal(val);
            /* Add number of quicklist nodes */
            int used = snprintf(nextra, remaining, " ql_nodes:%lu", ql->len);
            nextra += used;
            remaining -= used;
            /* Add average quicklist fill factor */
            double avg = (double)ql->count / ql->len;
            used = snprintf(nextra, remaining, " ql_avg_node:%.2f", avg);
            nextra += used;
            remaining -= used;
            /* Add quicklist fill level / max listpack size */
            used = snprintf(nextra, remaining, " ql_listpack_max:%d", ql->fill);
            nextra += used;
            remaining -= used;
            /* Add isCompressed? */
            int compressed = ql->compress != 0;
            used = snprintf(nextra, remaining, " ql_compressed:%d", compressed);
            nextra += used;
            remaining -= used;
            if (!fast) {
                /* Add total uncompressed size */
                unsigned long sz = 0;
                for (quicklistNode *node = ql->head; node; node = node->next) {
                    sz += node->sz;
                }
                used = snprintf(nextra, remaining, " ql_uncompressed_size:%lu", sz);
                nextra += used;
                remaining -= used;
            }
        }

        sds s = sdsempty();
        s = sdscatprintf(s, "Value at:%p refcount:%d encoding:%s", (void *)val, val->refcount, strenc);
        if (!fast) s = sdscatprintf(s, " serializedlength:%zu", rdbSavedObjectLen(val, c->argv[2], c->db->id));
        /* Either lru or lfu field could work correctly which depends on server.maxmemory_policy. */
        if (lrulfu_isUsingLFU()) {
            s = sdscatprintf(s, " lfu_freq:%u lfu_access_time_minutes:%u", objectGetLFUFrequency(val), val->lru >> 8);
        } else {
            s = sdscatprintf(s, " lru:%d lru_seconds_idle:%u", val->lru, lru_getIdleSecs(val->lru));
        }
        s = sdscatprintf(s, "%s", extra);
        addReplyStatusLength(c, s, sdslen(s));
        sdsfree(s);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "sdslen") && c->argc == 3) {
        robj *val;
        sds key;

        if ((val = dbFind(c->db, objectGetVal(c->argv[2]))) == NULL) {
            addReplyErrorObject(c, shared.nokeyerr);
            return;
        }
        key = objectGetKey(val);

        if (val->type != OBJ_STRING || !sdsEncodedObject(val)) {
            addReplyError(c, "Not an sds encoded string.");
        } else {
            /* Report the complete robj allocation size as the key's allocation
             * size. Report 0 as allocation size for embedded values. */
            size_t obj_alloc = zmalloc_usable_size(val);
            size_t val_alloc = val->encoding == OBJ_ENCODING_RAW ? sdsAllocSize(objectGetVal(val)) : 0;
            addReplyStatusFormat(c,
                                 "key_sds_len:%lld key_sds_avail:%lld obj_alloc:%lld "
                                 "val_sds_len:%lld val_sds_avail:%lld val_alloc:%lld",
                                 (long long)sdslen(key), (long long)sdsavail(key), (long long)obj_alloc,
                                 (long long)sdslen(objectGetVal(val)), (long long)sdsavail(objectGetVal(val)),
                                 (long long)val_alloc);
        }
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "listpack") && c->argc == 3) {
        robj *o;

        if ((o = objectCommandLookupOrReply(c, c->argv[2], shared.nokeyerr)) == NULL) return;

        if (o->encoding != OBJ_ENCODING_LISTPACK) {
            addReplyError(c, "Not a listpack encoded object.");
        } else {
            lpRepr(objectGetVal(o));
            addReplyStatus(c, "Listpack structure printed on stdout");
        }
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "quicklist") && (c->argc == 3 || c->argc == 4)) {
        robj *o;

        if ((o = objectCommandLookupOrReply(c, c->argv[2], shared.nokeyerr)) == NULL) return;

        int full = 0;
        if (c->argc == 4) full = atoi(objectGetVal(c->argv[3]));
        if (o->encoding != OBJ_ENCODING_QUICKLIST) {
            addReplyError(c, "Not a quicklist encoded object.");
        } else {
            quicklistRepr(objectGetVal(o), full);
            addReplyStatus(c, "Quicklist structure printed on stdout");
        }
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "populate") && c->argc >= 3 && c->argc <= 5) {
        long keys, j;
        robj *key, *val;
        char buf[128];

        if (getPositiveLongFromObjectOrReply(c, c->argv[2], &keys, NULL) != C_OK) return;

        if (server.loading || server.async_loading) {
            addReplyErrorObject(c, shared.loadingerr);
            return;
        }

        if (dbExpand(c->db, keys, 1) == C_ERR) {
            addReplyError(c, "OOM in dbExpand");
            return;
        }
        long valsize = 0;
        if (c->argc == 5 && getPositiveLongFromObjectOrReply(c, c->argv[4], &valsize, NULL) != C_OK) return;

        for (j = 0; j < keys; j++) {
            snprintf(buf, sizeof(buf), "%s:%lu", (c->argc == 3) ? "key" : (char *)objectGetVal(c->argv[3]), j);
            key = createStringObject(buf, strlen(buf));
            if (lookupKeyWrite(c->db, key) != NULL) {
                decrRefCount(key);
                continue;
            }
            snprintf(buf, sizeof(buf), "value:%lu", j);
            if (valsize == 0)
                val = createStringObject(buf, strlen(buf));
            else {
                int buflen = strlen(buf);
                val = createStringObject(NULL, valsize);
                memcpy(objectGetVal(val), buf, valsize <= buflen ? valsize : buflen);
            }
            dbAdd(c->db, key, &val);
            signalModifiedKey(c, c->db, key);
            decrRefCount(key);
        }
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "digest") && c->argc == 2) {
        /* DEBUG DIGEST (form without keys specified) */
        unsigned char digest[20];
        sds d = sdsempty();

        computeDatasetDigest(digest);
        for (int i = 0; i < 20; i++) d = sdscatprintf(d, "%02x", digest[i]);
        addReplyStatus(c, d);
        sdsfree(d);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "digest-value") && c->argc >= 2) {
        /* DEBUG DIGEST-VALUE key key key ... key. */
        addReplyArrayLen(c, c->argc - 2);
        for (int j = 2; j < c->argc; j++) {
            unsigned char digest[20];
            memset(digest, 0, 20); /* Start with a clean result */

            /* We don't use lookupKey because a debug command should
             * work on logically expired keys */
            robj *o = dbFind(c->db, objectGetVal(c->argv[j]));
            if (o) xorObjectDigest(c->db, c->argv[j], digest, o);

            sds d = sdsempty();
            for (int i = 0; i < 20; i++) d = sdscatprintf(d, "%02x", digest[i]);
            addReplyStatus(c, d);
            sdsfree(d);
        }
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "protocol") && c->argc == 3) {
        /* DEBUG PROTOCOL [string|integer|double|bignum|null|array|set|map|
         *                 attrib|push|verbatim|true|false] */
        char *name = objectGetVal(c->argv[2]);
        if (!strcasecmp(name, "string")) {
            addReplyBulkCString(c, "Hello World");
        } else if (!strcasecmp(name, "integer")) {
            addReplyLongLong(c, 12345);
        } else if (!strcasecmp(name, "double")) {
            addReplyDouble(c, 3.141);
        } else if (!strcasecmp(name, "bignum")) {
            addReplyBigNum(c, "1234567999999999999999999999999999999", 37);
        } else if (!strcasecmp(name, "null")) {
            addReplyNull(c);
        } else if (!strcasecmp(name, "array")) {
            addReplyArrayLen(c, 3);
            for (int j = 0; j < 3; j++) addReplyLongLong(c, j);
        } else if (!strcasecmp(name, "set")) {
            addReplySetLen(c, 3);
            for (int j = 0; j < 3; j++) addReplyLongLong(c, j);
        } else if (!strcasecmp(name, "map")) {
            addReplyMapLen(c, 3);
            for (int j = 0; j < 3; j++) {
                addReplyLongLong(c, j);
                addReplyBool(c, j == 1);
            }
        } else if (!strcasecmp(name, "attrib")) {
            if (c->resp >= 3) {
                addReplyAttributeLen(c, 1);
                addReplyBulkCString(c, "key-popularity");
                addReplyArrayLen(c, 2);
                addReplyBulkCString(c, "key:123");
                addReplyLongLong(c, 90);
            }
            /* Attributes are not real replies, so a well formed reply should
             * also have a normal reply type after the attribute. */
            addReplyBulkCString(c, "Some real reply following the attribute");
        } else if (!strcasecmp(name, "push")) {
            if (c->resp < 3) {
                addReplyError(c, "RESP2 is not supported by this command");
                return;
            }
            struct ClientFlags old_flags = c->flag;
            c->flag.pushing = 1;
            addReplyPushLen(c, 2);
            addReplyBulkCString(c, "server-cpu-usage");
            addReplyLongLong(c, 42);
            if (!old_flags.pushing) c->flag.pushing = 0;
            /* Push replies are not synchronous replies, so we emit also a
             * normal reply in order for blocking clients just discarding the
             * push reply, to actually consume the reply and continue. */
            addReplyBulkCString(c, "Some real reply following the push reply");
        } else if (!strcasecmp(name, "true")) {
            addReplyBool(c, 1);
        } else if (!strcasecmp(name, "false")) {
            addReplyBool(c, 0);
        } else if (!strcasecmp(name, "verbatim")) {
            addReplyVerbatim(c, "This is a verbatim\nstring", 25, "txt");
        } else {
            addReplyError(c, "Wrong protocol type name. Please use one of the following: "
                             "string|integer|double|bignum|null|array|set|map|attrib|push|verbatim|true|false");
        }
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "sleep") && c->argc == 3) {
        double dtime = valkey_strtod_sds(objectGetVal(c->argv[2]), NULL);
        long long utime = dtime * 1000000;
        struct timespec tv;

        tv.tv_sec = utime / 1000000;
        tv.tv_nsec = (utime % 1000000) * 1000;
        nanosleep(&tv, NULL);
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "set-active-expire") && c->argc == 3) {
        server.active_expire_enabled = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "quicklist-packed-threshold") && c->argc == 3) {
        int memerr;
        unsigned long long sz = memtoull((const char *)objectGetVal(c->argv[2]), &memerr);
        if (memerr || !quicklistSetPackedThreshold(sz)) {
            addReplyError(c, "argument must be a memory value bigger than 1 and smaller than 4gb");
        } else {
            addReply(c, shared.ok);
        }
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "set-skip-checksum-validation") && c->argc == 3) {
        server.skip_checksum_validation = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "aof-flush-sleep") && c->argc == 3) {
        server.aof_flush_sleep = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "replicate") && c->argc >= 3) {
        replicationFeedReplicas(-1, c->argv + 2, c->argc - 2);
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "error") && c->argc == 3) {
        sds errstr = sdsnewlen("-", 1);

        errstr = sdscatsds(errstr, objectGetVal(c->argv[2]));
        errstr = sdsmapchars(errstr, "\n\r", "  ", 2); /* no newlines in errors. */
        errstr = sdscatlen(errstr, "\r\n", 2);
        addReplySds(c, errstr);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "structsize") && c->argc == 2) {
        sds sizes = sdsempty();
        sizes = sdscatprintf(sizes, "bits:%d ", (sizeof(void *) == 8) ? 64 : 32);
        sizes = sdscatprintf(sizes, "robj:%d ", (int)sizeof(robj));
        sizes = sdscatprintf(sizes, "dictentry:%d ", (int)dictEntryMemUsage(NULL));
        sizes = sdscatprintf(sizes, "sdshdr5:%d ", (int)sizeof(struct sdshdr5));
        sizes = sdscatprintf(sizes, "sdshdr8:%d ", (int)sizeof(struct sdshdr8));
        sizes = sdscatprintf(sizes, "sdshdr16:%d ", (int)sizeof(struct sdshdr16));
        sizes = sdscatprintf(sizes, "sdshdr32:%d ", (int)sizeof(struct sdshdr32));
        sizes = sdscatprintf(sizes, "sdshdr64:%d ", (int)sizeof(struct sdshdr64));
        addReplyBulkSds(c, sizes);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "htstats") && c->argc >= 3) {
        long dbid;
        sds stats = sdsempty();
        char buf[4096];
        int full = 0;

        if (getLongFromObjectOrReply(c, c->argv[2], &dbid, NULL) != C_OK) {
            sdsfree(stats);
            return;
        }
        if (dbid < 0 || dbid >= server.dbnum) {
            sdsfree(stats);
            addReplyError(c, "Out of range database");
            return;
        }
        if (c->argc >= 4 && !strcasecmp(objectGetVal(c->argv[3]), "full")) full = 1;

        stats = sdscatprintf(stats, "[Dictionary HT]\n");
        serverDb *db = server.db[dbid];
        if (db) {
            kvstoreGetStats(db->keys, buf, sizeof(buf), full);
            stats = sdscat(stats, buf);
        }

        stats = sdscatprintf(stats, "[Expires HT]\n");
        if (db) {
            kvstoreGetStats(db->expires, buf, sizeof(buf), full);
            stats = sdscat(stats, buf);
        }

        addReplyVerbatim(c, stats, sdslen(stats), "txt");

        sdsfree(stats);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "htstats-key") && c->argc >= 3) {
        int full = 0;
        if (c->argc >= 4 && !strcasecmp(objectGetVal(c->argv[3]), "full")) full = 1;

        robj *o = objectCommandLookupOrReply(c, c->argv[2], shared.nokeyerr);
        if (o == NULL) return;

        /* Get the hashtable reference from the object, if possible. */
        hashtable *ht = NULL;
        switch (o->encoding) {
        case OBJ_ENCODING_SKIPLIST: {
            zset *zs = objectGetVal(o);
            ht = zs->ht;
        } break;
        case OBJ_ENCODING_HASHTABLE: ht = objectGetVal(o); break;
        }

        if (ht != NULL) {
            char buf[4096];
            hashtableGetStats(buf, sizeof(buf), ht, full);
            addReplyVerbatim(c, buf, strlen(buf), "txt");
        } else {
            addReplyError(c, "The value stored at the specified key is not "
                             "represented using an hash table");
        }
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "change-repl-id") && c->argc == 2) {
        serverLog(LL_NOTICE, "Changing replication IDs after receiving DEBUG change-repl-id");
        changeReplicationId();
        clearReplicationId2();
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "stringmatch-test") && c->argc == 2) {
        stringmatchlen_fuzz_test();
        addReplyStatus(c, "Apparently the server did not crash: test passed");
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "set-disable-deny-scripts") && c->argc == 3) {
        server.script_disable_deny_script = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "config-rewrite-force-all") && c->argc == 2) {
        if (rewriteConfig(server.configfile, 1) == -1)
            addReplyErrorFormat(c, "CONFIG-REWRITE-FORCE-ALL failed: %s", strerror(errno));
        else
            addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "client-eviction") && c->argc == 2) {
        if (!server.client_mem_usage_buckets) {
            addReplyError(c, "maxmemory-clients is disabled.");
            return;
        }
        sds bucket_info = sdsempty();
        for (int j = 0; j < CLIENT_MEM_USAGE_BUCKETS; j++) {
            if (j == 0)
                bucket_info = sdscatprintf(bucket_info, "bucket          0");
            else
                bucket_info =
                    sdscatprintf(bucket_info, "bucket %10zu", (size_t)1 << (j - 1 + CLIENT_MEM_USAGE_BUCKET_MIN_LOG));
            if (j == CLIENT_MEM_USAGE_BUCKETS - 1)
                bucket_info = sdscatprintf(bucket_info, "+            : ");
            else
                bucket_info =
                    sdscatprintf(bucket_info, " - %10zu: ", ((size_t)1 << (j + CLIENT_MEM_USAGE_BUCKET_MIN_LOG)) - 1);
            bucket_info = sdscatprintf(bucket_info, "tot-mem: %10zu, clients: %lu\n",
                                       server.client_mem_usage_buckets[j].mem_usage_sum,
                                       server.client_mem_usage_buckets[j].clients->len);
        }
        addReplyVerbatim(c, bucket_info, sdslen(bucket_info), "txt");
        sdsfree(bucket_info);
#ifdef USE_JEMALLOC
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "mallctl") && c->argc >= 3) {
        mallctl_int(c, c->argv + 2, c->argc - 2);
        return;
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "mallctl-str") && c->argc >= 3) {
        mallctl_string(c, c->argv + 2, c->argc - 2);
        return;
#endif
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "pause-cron") && c->argc == 3) {
        server.pause_cron = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "replybuffer") && c->argc == 4) {
        if (!strcasecmp(objectGetVal(c->argv[2]), "peak-reset-time")) {
            if (!strcasecmp(objectGetVal(c->argv[3]), "never")) {
                server.reply_buffer_peak_reset_time = -1;
            } else if (!strcasecmp(objectGetVal(c->argv[3]), "reset")) {
                server.reply_buffer_peak_reset_time = REPLY_BUFFER_DEFAULT_PEAK_RESET_TIME;
            } else {
                if (getLongFromObjectOrReply(c, c->argv[3], &server.reply_buffer_peak_reset_time, NULL) != C_OK) return;
            }
        } else if (!strcasecmp(objectGetVal(c->argv[2]), "resizing")) {
            server.reply_buffer_resizing_enabled = atoi(objectGetVal(c->argv[3]));
        } else {
            addReplySubcommandSyntaxError(c);
            return;
        }
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "pause-after-fork") && c->argc == 3) {
        server.debug_pause_after_fork = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "delay-rdb-client-free-seconds") && c->argc == 3) {
        server.wait_before_rdb_client_free = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "dict-resizing") && c->argc == 3) {
        server.dict_resizing = atoi(objectGetVal(c->argv[2]));
        updateDictResizePolicy();
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "hashtable-can-abort-shrink") && c->argc == 3) {
        hashtableSetCanAbortShrink(atoi(objectGetVal(c->argv[2])));
        addReply(c, shared.ok);
    } else if (!strcasecmp(objectGetVal(c->argv[1]), "client-enforce-reply-list") && c->argc == 3) {
        server.debug_client_enforce_reply_list = atoi(objectGetVal(c->argv[2]));
        addReply(c, shared.ok);
    } else if (!handleDebugClusterCommand(c)) {
        addReplySubcommandSyntaxError(c);
        return;
    }
}

/* =========================== Crash handling  ============================== */

__attribute__((noinline, weak)) void _serverAssert(const char *estr, const char *file, int line) {
    int new_report = bugReportStart();
    serverLog(LL_WARNING, "=== %sASSERTION FAILED ===", new_report ? "" : "RECURSIVE ");
    serverLog(LL_WARNING, "==> %s:%d '%s' is not true", file, line, estr);

    if (server.crashlog_enabled) {
#ifdef HAVE_BACKTRACE
        logStackTrace(NULL, 1, 0);
#endif
        /* If this was a recursive assertion, it what most likely generated
         * from printCrashReport. */
        if (new_report) printCrashReport();
    }

    // remove the signal handler so on abort() we will output the crash report.
    removeSigSegvHandlers();
    bugReportEnd(0, 0);
}

/* Returns the argv argument in binary representation, limited to length 128. */
sds getArgvReprString(robj *argv) {
    robj *decoded = getDecodedObject(argv);
    sds repr = sdscatrepr(sdsempty(), objectGetVal(decoded), min(sdslen(objectGetVal(decoded)), 128));
    decrRefCount(decoded);
    return repr;
}

/* Checks if the argument at the given index should be redacted from logs. */
int shouldRedactArg(const client *c, int idx) {
    serverAssert(idx < c->argc);
    /* Don't redact if the config is disabled */
    if (!server.hide_user_data_from_log) return 0;
    /* first_sensitive_arg_idx value should be changed based on the command type. */
    int first_sensitive_arg_idx = 1;
    return idx >= first_sensitive_arg_idx;
}

void _serverAssertPrintClientInfo(const client *c) {
    int j;
    char conninfo[CONN_INFO_LEN];

    bugReportStart();
    serverLog(LL_WARNING, "=== ASSERTION FAILED CLIENT CONTEXT ===");
    serverLog(LL_WARNING, "client->flags = %llu", (unsigned long long)c->raw_flag);
    serverLog(LL_WARNING, "client->conn = %s", connGetInfo(c->conn, conninfo, sizeof(conninfo)));
    serverLog(LL_WARNING, "client->argc = %d", c->argc);
    for (j = 0; j < c->argc; j++) {
        if (shouldRedactArg(c, j)) {
            serverLog(LL_WARNING, "client->argv[%d]: %zu bytes", j, sdslen((sds)objectGetVal(c->argv[j])));
            continue;
        }
        sds repr = getArgvReprString(c->argv[j]);
        serverLog(LL_WARNING, "client->argv[%d] = %s (refcount: %d)", j, repr, c->argv[j]->refcount);
        sdsfree(repr);
        if (!strcasecmp(objectGetVal(c->argv[j]), "auth") || !strcasecmp(objectGetVal(c->argv[j]), "auth2")) {
            break;
        }
    }
}

void serverLogObjectDebugInfo(const robj *o) {
    serverLog(LL_WARNING, "Object type: %u", o->type);
    serverLog(LL_WARNING, "Object encoding: %u", o->encoding);
    serverLog(LL_WARNING, "Object refcount: %d", o->refcount);
#if defined(UNSAFE_CRASH_REPORT) && UNSAFE_CRASH_REPORT
    /* This code is now disabled. o->ptr may be unreliable to print. in some
     * cases a ziplist could have already been freed by realloc, but not yet
     * updated to o->ptr. in other cases the call to ziplistLen may need to
     * iterate on all the items in the list (and possibly crash again).
     * For some cases it may be ok to crash here again, but these could cause
     * invalid memory access which will bother valgrind and also possibly cause
     * random memory portion to be "leaked" into the logfile. */
    if (o->type == OBJ_STRING && sdsEncodedObject(o)) {
        serverLog(LL_WARNING, "Object raw string len: %zu", sdslen(o->ptr));
        if (sdslen(o->ptr) < 4096) {
            sds repr = sdscatrepr(sdsempty(), o->ptr, sdslen(o->ptr));
            serverLog(LL_WARNING, "Object raw string content: %s", repr);
            sdsfree(repr);
        }
    } else if (o->type == OBJ_LIST) {
        serverLog(LL_WARNING, "List length: %d", (int)listTypeLength(o));
    } else if (o->type == OBJ_SET) {
        serverLog(LL_WARNING, "Set size: %d", (int)setTypeSize(o));
    } else if (o->type == OBJ_HASH) {
        serverLog(LL_WARNING, "Hash size: %d", (int)hashTypeLength(o));
    } else if (o->type == OBJ_ZSET) {
        serverLog(LL_WARNING, "Sorted set size: %d", (int)zsetLength(o));
        if (o->encoding == OBJ_ENCODING_SKIPLIST)
            serverLog(LL_WARNING, "Skiplist level: %d", (int)((const zset *)o->ptr)->zsl->level);
    } else if (o->type == OBJ_STREAM) {
        serverLog(LL_WARNING, "Stream size: %d", (int)streamLength(o));
    }
#endif
}

void _serverAssertPrintObject(const robj *o) {
    bugReportStart();
    serverLog(LL_WARNING, "=== ASSERTION FAILED OBJECT CONTEXT ===");
    serverLogObjectDebugInfo(o);
}

void _serverAssertWithInfo(const client *c, const robj *o, const char *estr, const char *file, int line) {
    if (c) _serverAssertPrintClientInfo(c);
    if (o) _serverAssertPrintObject(o);
    _serverAssert(estr, file, line);
}

__attribute__((noinline)) void _serverPanic(const char *file, int line, const char *msg, ...) {
    va_list ap;
    va_start(ap, msg);
    char fmtmsg[256];
    vsnprintf(fmtmsg, sizeof(fmtmsg), msg, ap);
    va_end(ap);

    int new_report = bugReportStart();
    serverLog(LL_WARNING, "------------------------------------------------");
    serverLog(LL_WARNING, "!!! Software Failure. Press left mouse button to continue");
    serverLog(LL_WARNING, "Guru Meditation: %s #%s:%d", fmtmsg, file, line);

    if (server.crashlog_enabled) {
#ifdef HAVE_BACKTRACE
        logStackTrace(NULL, 1, 0);
#endif
        /* If this was a recursive panic, it what most likely generated
         * from printCrashReport. */
        if (new_report) printCrashReport();
    }

    // remove the signal handler so on abort() we will output the crash report.
    removeSigSegvHandlers();
    bugReportEnd(0, 0);
}

/* Start a bug report, returning 1 if this is the first time this function was called, 0 otherwise. */
int bugReportStart(void) {
    pthread_mutex_lock(&bug_report_start_mutex);
    if (bug_report_start == 0) {
        serverLog(LL_WARNING | LL_RAW, "\n\n=== %s BUG REPORT START: Cut & paste starting from here ===\n",
                  server.extended_redis_compat ? "REDIS" : "VALKEY");
        bug_report_start = 1;
        pthread_mutex_unlock(&bug_report_start_mutex);
        return 1;
    }
    pthread_mutex_unlock(&bug_report_start_mutex);
    return 0;
}

#ifdef HAVE_BACKTRACE

/* Returns the current eip and set it to the given new value (if its not NULL) */
static void *getAndSetMcontextEip(ucontext_t *uc, void *eip) {
#define NOT_SUPPORTED() \
    do {                \
        UNUSED(uc);     \
        UNUSED(eip);    \
        return NULL;    \
    } while (0)
#define GET_SET_RETURN(target_var, new_val)     \
    do {                                        \
        void *old_val = (void *)target_var;     \
        if (new_val) {                          \
            void **temp = (void **)&target_var; \
            *temp = new_val;                    \
        }                                       \
        return old_val;                         \
    } while (0)
#if defined(__APPLE__) && !defined(MAC_OS_10_6_DETECTED)
/* Mac OS X < 10.6 */
#if defined(__x86_64__)
    GET_SET_RETURN(uc->uc_mcontext->__ss.__rip, eip);
#elif defined(__i386__)
    GET_SET_RETURN(uc->uc_mcontext->__ss.__eip, eip);
#else
    /* Mac OS X PowerPC */
    GET_SET_RETURN(uc->uc_mcontext->__ss.__srr0, eip);
#endif
#elif defined(__APPLE__) && defined(MAC_OS_10_6_DETECTED)
/* Mac OS X >= 10.6 */
#if defined(_STRUCT_X86_THREAD_STATE64) && !defined(__i386__)
    GET_SET_RETURN(uc->uc_mcontext->__ss.__rip, eip);
#elif defined(__i386__)
    GET_SET_RETURN(uc->uc_mcontext->__ss.__eip, eip);
#elif defined(__ppc__)
    GET_SET_RETURN(uc->uc_mcontext->__ss.__srr0, eip);
#else
    /* macOS ARM64 */
    void *old_val = (void *)arm_thread_state64_get_pc(uc->uc_mcontext->__ss);
    if (eip) {
        arm_thread_state64_set_pc_fptr(uc->uc_mcontext->__ss, eip);
    }
    return old_val;
#endif
#elif defined(__linux__)
/* Linux */
#if defined(__i386__) || ((defined(__X86_64__) || defined(__x86_64__)) && defined(__ILP32__))
    GET_SET_RETURN(uc->uc_mcontext.gregs[14], eip);
#elif defined(__X86_64__) || defined(__x86_64__)
    GET_SET_RETURN(uc->uc_mcontext.gregs[16], eip);
#elif defined(__ia64__)    /* Linux IA64 */
    GET_SET_RETURN(uc->uc_mcontext.sc_ip, eip);
#elif defined(__riscv)     /* Linux RISC-V */
    GET_SET_RETURN(uc->uc_mcontext.__gregs[REG_PC], eip);
#elif defined(__arm__)     /* Linux ARM */
    GET_SET_RETURN(uc->uc_mcontext.arm_pc, eip);
#elif defined(__aarch64__) /* Linux AArch64 */
    GET_SET_RETURN(uc->uc_mcontext.pc, eip);
#else
    NOT_SUPPORTED();
#endif
#elif defined(__FreeBSD__)
/* FreeBSD */
#if defined(__i386__)
    GET_SET_RETURN(uc->uc_mcontext.mc_eip, eip);
#elif defined(__x86_64__)
    GET_SET_RETURN(uc->uc_mcontext.mc_rip, eip);
#else
    NOT_SUPPORTED();
#endif
#elif defined(__OpenBSD__)
/* OpenBSD */
#if defined(__i386__)
    GET_SET_RETURN(uc->sc_eip, eip);
#elif defined(__x86_64__)
    GET_SET_RETURN(uc->sc_rip, eip);
#else
    NOT_SUPPORTED();
#endif
#elif defined(__NetBSD__)
#if defined(__i386__)
    GET_SET_RETURN(uc->uc_mcontext.__gregs[_REG_EIP], eip);
#elif defined(__x86_64__)
    GET_SET_RETURN(uc->uc_mcontext.__gregs[_REG_RIP], eip);
#else
    NOT_SUPPORTED();
#endif
#elif defined(__DragonFly__)
    GET_SET_RETURN(uc->uc_mcontext.mc_rip, eip);
#elif defined(__sun) && defined(__x86_64__)
    GET_SET_RETURN(uc->uc_mcontext.gregs[REG_RIP], eip);
#else
    NOT_SUPPORTED();
#endif
#undef NOT_SUPPORTED
}

VALKEY_NO_SANITIZE("address")
void logStackContent(void **sp) {
    if (server.hide_user_data_from_log) {
        serverLog(LL_NOTICE, "hide-user-data-from-log is on, skip logging stack content to avoid spilling user data.");
        return;
    }
    int i;
    for (i = 15; i >= 0; i--) {
        unsigned long addr = (unsigned long)sp + i;
        unsigned long val = (unsigned long)sp[i];

        if (sizeof(long) == 4)
            serverLog(LL_WARNING, "(%08lx) -> %08lx", addr, val);
        else
            serverLog(LL_WARNING, "(%016lx) -> %016lx", addr, val);
    }
}

/* Log dump of processor registers */
void logRegisters(ucontext_t *uc) {
    serverLog(LL_WARNING | LL_RAW, "\n------ REGISTERS ------\n");
#define NOT_SUPPORTED()                                                                 \
    do {                                                                                \
        UNUSED(uc);                                                                     \
        serverLog(LL_WARNING, "  Dumping of registers not supported for this OS/arch"); \
    } while (0)

/* Mac OS X */
#if defined(__APPLE__) && defined(MAC_OS_10_6_DETECTED)
    /* Mac OS X AMD64 */
#if defined(_STRUCT_X86_THREAD_STATE64) && !defined(__i386__)
    serverLog(LL_WARNING,
              "\n"
              "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
              "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
              "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
              "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
              "RIP:%016lx EFL:%016lx\nCS :%016lx FS:%016lx  GS:%016lx",
              (unsigned long)uc->uc_mcontext->__ss.__rax, (unsigned long)uc->uc_mcontext->__ss.__rbx,
              (unsigned long)uc->uc_mcontext->__ss.__rcx, (unsigned long)uc->uc_mcontext->__ss.__rdx,
              (unsigned long)uc->uc_mcontext->__ss.__rdi, (unsigned long)uc->uc_mcontext->__ss.__rsi,
              (unsigned long)uc->uc_mcontext->__ss.__rbp, (unsigned long)uc->uc_mcontext->__ss.__rsp,
              (unsigned long)uc->uc_mcontext->__ss.__r8, (unsigned long)uc->uc_mcontext->__ss.__r9,
              (unsigned long)uc->uc_mcontext->__ss.__r10, (unsigned long)uc->uc_mcontext->__ss.__r11,
              (unsigned long)uc->uc_mcontext->__ss.__r12, (unsigned long)uc->uc_mcontext->__ss.__r13,
              (unsigned long)uc->uc_mcontext->__ss.__r14, (unsigned long)uc->uc_mcontext->__ss.__r15,
              (unsigned long)uc->uc_mcontext->__ss.__rip, (unsigned long)uc->uc_mcontext->__ss.__rflags,
              (unsigned long)uc->uc_mcontext->__ss.__cs, (unsigned long)uc->uc_mcontext->__ss.__fs,
              (unsigned long)uc->uc_mcontext->__ss.__gs);
    logStackContent((void **)uc->uc_mcontext->__ss.__rsp);
#elif defined(__i386__)
    /* Mac OS X x86 */
    serverLog(LL_WARNING,
              "\n"
              "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
              "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
              "SS:%08lx  EFL:%08lx EIP:%08lx CS :%08lx\n"
              "DS:%08lx  ES:%08lx  FS :%08lx GS :%08lx",
              (unsigned long)uc->uc_mcontext->__ss.__eax, (unsigned long)uc->uc_mcontext->__ss.__ebx,
              (unsigned long)uc->uc_mcontext->__ss.__ecx, (unsigned long)uc->uc_mcontext->__ss.__edx,
              (unsigned long)uc->uc_mcontext->__ss.__edi, (unsigned long)uc->uc_mcontext->__ss.__esi,
              (unsigned long)uc->uc_mcontext->__ss.__ebp, (unsigned long)uc->uc_mcontext->__ss.__esp,
              (unsigned long)uc->uc_mcontext->__ss.__ss, (unsigned long)uc->uc_mcontext->__ss.__eflags,
              (unsigned long)uc->uc_mcontext->__ss.__eip, (unsigned long)uc->uc_mcontext->__ss.__cs,
              (unsigned long)uc->uc_mcontext->__ss.__ds, (unsigned long)uc->uc_mcontext->__ss.__es,
              (unsigned long)uc->uc_mcontext->__ss.__fs, (unsigned long)uc->uc_mcontext->__ss.__gs);
    logStackContent((void **)uc->uc_mcontext->__ss.__esp);
#elif defined(__arm64__)
    /* macOS ARM64 */
    serverLog(
        LL_WARNING,
        "\n"
        "x0:%016lx x1:%016lx x2:%016lx x3:%016lx\n"
        "x4:%016lx x5:%016lx x6:%016lx x7:%016lx\n"
        "x8:%016lx x9:%016lx x10:%016lx x11:%016lx\n"
        "x12:%016lx x13:%016lx x14:%016lx x15:%016lx\n"
        "x16:%016lx x17:%016lx x18:%016lx x19:%016lx\n"
        "x20:%016lx x21:%016lx x22:%016lx x23:%016lx\n"
        "x24:%016lx x25:%016lx x26:%016lx x27:%016lx\n"
        "x28:%016lx fp:%016lx lr:%016lx\n"
        "sp:%016lx pc:%016lx cpsr:%08lx\n",
        (unsigned long)uc->uc_mcontext->__ss.__x[0], (unsigned long)uc->uc_mcontext->__ss.__x[1],
        (unsigned long)uc->uc_mcontext->__ss.__x[2], (unsigned long)uc->uc_mcontext->__ss.__x[3],
        (unsigned long)uc->uc_mcontext->__ss.__x[4], (unsigned long)uc->uc_mcontext->__ss.__x[5],
        (unsigned long)uc->uc_mcontext->__ss.__x[6], (unsigned long)uc->uc_mcontext->__ss.__x[7],
        (unsigned long)uc->uc_mcontext->__ss.__x[8], (unsigned long)uc->uc_mcontext->__ss.__x[9],
        (unsigned long)uc->uc_mcontext->__ss.__x[10], (unsigned long)uc->uc_mcontext->__ss.__x[11],
        (unsigned long)uc->uc_mcontext->__ss.__x[12], (unsigned long)uc->uc_mcontext->__ss.__x[13],
        (unsigned long)uc->uc_mcontext->__ss.__x[14], (unsigned long)uc->uc_mcontext->__ss.__x[15],
        (unsigned long)uc->uc_mcontext->__ss.__x[16], (unsigned long)uc->uc_mcontext->__ss.__x[17],
        (unsigned long)uc->uc_mcontext->__ss.__x[18], (unsigned long)uc->uc_mcontext->__ss.__x[19],
        (unsigned long)uc->uc_mcontext->__ss.__x[20], (unsigned long)uc->uc_mcontext->__ss.__x[21],
        (unsigned long)uc->uc_mcontext->__ss.__x[22], (unsigned long)uc->uc_mcontext->__ss.__x[23],
        (unsigned long)uc->uc_mcontext->__ss.__x[24], (unsigned long)uc->uc_mcontext->__ss.__x[25],
        (unsigned long)uc->uc_mcontext->__ss.__x[26], (unsigned long)uc->uc_mcontext->__ss.__x[27],
        (unsigned long)uc->uc_mcontext->__ss.__x[28], (unsigned long)arm_thread_state64_get_fp(uc->uc_mcontext->__ss),
        (unsigned long)arm_thread_state64_get_lr(uc->uc_mcontext->__ss),
        (unsigned long)arm_thread_state64_get_sp(uc->uc_mcontext->__ss),
        (unsigned long)arm_thread_state64_get_pc(uc->uc_mcontext->__ss), (unsigned long)uc->uc_mcontext->__ss.__cpsr);
    logStackContent((void **)arm_thread_state64_get_sp(uc->uc_mcontext->__ss));
#else
    /* At the moment we do not implement this for PowerPC */
    NOT_SUPPORTED();
#endif
/* Linux */
#elif defined(__linux__)
/* Linux x86 */
#if defined(__i386__) || ((defined(__X86_64__) || defined(__x86_64__)) && defined(__ILP32__))
    serverLog(LL_WARNING,
              "\n"
              "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
              "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
              "SS :%08lx EFL:%08lx EIP:%08lx CS:%08lx\n"
              "DS :%08lx ES :%08lx FS :%08lx GS:%08lx",
              (unsigned long)uc->uc_mcontext.gregs[11], (unsigned long)uc->uc_mcontext.gregs[8],
              (unsigned long)uc->uc_mcontext.gregs[10], (unsigned long)uc->uc_mcontext.gregs[9],
              (unsigned long)uc->uc_mcontext.gregs[4], (unsigned long)uc->uc_mcontext.gregs[5],
              (unsigned long)uc->uc_mcontext.gregs[6], (unsigned long)uc->uc_mcontext.gregs[7],
              (unsigned long)uc->uc_mcontext.gregs[18], (unsigned long)uc->uc_mcontext.gregs[17],
              (unsigned long)uc->uc_mcontext.gregs[14], (unsigned long)uc->uc_mcontext.gregs[15],
              (unsigned long)uc->uc_mcontext.gregs[3], (unsigned long)uc->uc_mcontext.gregs[2],
              (unsigned long)uc->uc_mcontext.gregs[1], (unsigned long)uc->uc_mcontext.gregs[0]);
    logStackContent((void **)uc->uc_mcontext.gregs[7]);
#elif defined(__X86_64__) || defined(__x86_64__)
    /* Linux AMD64 */
    serverLog(LL_WARNING,
              "\n"
              "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
              "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
              "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
              "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
              "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
              (unsigned long)uc->uc_mcontext.gregs[13], (unsigned long)uc->uc_mcontext.gregs[11],
              (unsigned long)uc->uc_mcontext.gregs[14], (unsigned long)uc->uc_mcontext.gregs[12],
              (unsigned long)uc->uc_mcontext.gregs[8], (unsigned long)uc->uc_mcontext.gregs[9],
              (unsigned long)uc->uc_mcontext.gregs[10], (unsigned long)uc->uc_mcontext.gregs[15],
              (unsigned long)uc->uc_mcontext.gregs[0], (unsigned long)uc->uc_mcontext.gregs[1],
              (unsigned long)uc->uc_mcontext.gregs[2], (unsigned long)uc->uc_mcontext.gregs[3],
              (unsigned long)uc->uc_mcontext.gregs[4], (unsigned long)uc->uc_mcontext.gregs[5],
              (unsigned long)uc->uc_mcontext.gregs[6], (unsigned long)uc->uc_mcontext.gregs[7],
              (unsigned long)uc->uc_mcontext.gregs[16], (unsigned long)uc->uc_mcontext.gregs[17],
              (unsigned long)uc->uc_mcontext.gregs[18]);
    logStackContent((void **)uc->uc_mcontext.gregs[15]);
#elif defined(__riscv)     /* Linux RISC-V */
    serverLog(LL_WARNING,
              "\n"
              "ra:%016lx gp:%016lx\ntp:%016lx t0:%016lx\n"
              "t1:%016lx t2:%016lx\ns0:%016lx s1:%016lx\n"
              "a0:%016lx a1:%016lx\na2:%016lx a3:%016lx\n"
              "a4:%016lx a5:%016lx\na6:%016lx a7:%016lx\n"
              "s2:%016lx s3:%016lx\ns4:%016lx s5:%016lx\n"
              "s6:%016lx s7:%016lx\ns8:%016lx s9:%016lx\n"
              "s10:%016lx s11:%016lx\nt3:%016lx t4:%016lx\n"
              "t5:%016lx t6:%016lx\n",
              (unsigned long)uc->uc_mcontext.__gregs[1], (unsigned long)uc->uc_mcontext.__gregs[3],
              (unsigned long)uc->uc_mcontext.__gregs[4], (unsigned long)uc->uc_mcontext.__gregs[5],
              (unsigned long)uc->uc_mcontext.__gregs[6], (unsigned long)uc->uc_mcontext.__gregs[7],
              (unsigned long)uc->uc_mcontext.__gregs[8], (unsigned long)uc->uc_mcontext.__gregs[9],
              (unsigned long)uc->uc_mcontext.__gregs[10], (unsigned long)uc->uc_mcontext.__gregs[11],
              (unsigned long)uc->uc_mcontext.__gregs[12], (unsigned long)uc->uc_mcontext.__gregs[13],
              (unsigned long)uc->uc_mcontext.__gregs[14], (unsigned long)uc->uc_mcontext.__gregs[15],
              (unsigned long)uc->uc_mcontext.__gregs[16], (unsigned long)uc->uc_mcontext.__gregs[17],
              (unsigned long)uc->uc_mcontext.__gregs[18], (unsigned long)uc->uc_mcontext.__gregs[19],
              (unsigned long)uc->uc_mcontext.__gregs[20], (unsigned long)uc->uc_mcontext.__gregs[21],
              (unsigned long)uc->uc_mcontext.__gregs[22], (unsigned long)uc->uc_mcontext.__gregs[23],
              (unsigned long)uc->uc_mcontext.__gregs[24], (unsigned long)uc->uc_mcontext.__gregs[25],
              (unsigned long)uc->uc_mcontext.__gregs[26], (unsigned long)uc->uc_mcontext.__gregs[27],
              (unsigned long)uc->uc_mcontext.__gregs[28], (unsigned long)uc->uc_mcontext.__gregs[29],
              (unsigned long)uc->uc_mcontext.__gregs[30], (unsigned long)uc->uc_mcontext.__gregs[31]);
    logStackContent((void **)uc->uc_mcontext.__gregs[REG_SP]);
#elif defined(__aarch64__) /* Linux AArch64 */
    serverLog(LL_WARNING,
              "\n"
              "X18:%016lx X19:%016lx\nX20:%016lx X21:%016lx\n"
              "X22:%016lx X23:%016lx\nX24:%016lx X25:%016lx\n"
              "X26:%016lx X27:%016lx\nX28:%016lx X29:%016lx\n"
              "X30:%016lx\n"
              "pc:%016lx sp:%016lx\npstate:%016lx fault_address:%016lx\n",
              (unsigned long)uc->uc_mcontext.regs[18], (unsigned long)uc->uc_mcontext.regs[19],
              (unsigned long)uc->uc_mcontext.regs[20], (unsigned long)uc->uc_mcontext.regs[21],
              (unsigned long)uc->uc_mcontext.regs[22], (unsigned long)uc->uc_mcontext.regs[23],
              (unsigned long)uc->uc_mcontext.regs[24], (unsigned long)uc->uc_mcontext.regs[25],
              (unsigned long)uc->uc_mcontext.regs[26], (unsigned long)uc->uc_mcontext.regs[27],
              (unsigned long)uc->uc_mcontext.regs[28], (unsigned long)uc->uc_mcontext.regs[29],
              (unsigned long)uc->uc_mcontext.regs[30], (unsigned long)uc->uc_mcontext.pc,
              (unsigned long)uc->uc_mcontext.sp, (unsigned long)uc->uc_mcontext.pstate,
              (unsigned long)uc->uc_mcontext.fault_address);
    logStackContent((void **)uc->uc_mcontext.sp);
#elif defined(__arm__)     /* Linux ARM */
    serverLog(LL_WARNING,
              "\n"
              "R10:%016lx R9 :%016lx\nR8 :%016lx R7 :%016lx\n"
              "R6 :%016lx R5 :%016lx\nR4 :%016lx R3 :%016lx\n"
              "R2 :%016lx R1 :%016lx\nR0 :%016lx EC :%016lx\n"
              "fp: %016lx ip:%016lx\n"
              "pc:%016lx sp:%016lx\ncpsr:%016lx fault_address:%016lx\n",
              (unsigned long)uc->uc_mcontext.arm_r10, (unsigned long)uc->uc_mcontext.arm_r9,
              (unsigned long)uc->uc_mcontext.arm_r8, (unsigned long)uc->uc_mcontext.arm_r7,
              (unsigned long)uc->uc_mcontext.arm_r6, (unsigned long)uc->uc_mcontext.arm_r5,
              (unsigned long)uc->uc_mcontext.arm_r4, (unsigned long)uc->uc_mcontext.arm_r3,
              (unsigned long)uc->uc_mcontext.arm_r2, (unsigned long)uc->uc_mcontext.arm_r1,
              (unsigned long)uc->uc_mcontext.arm_r0, (unsigned long)uc->uc_mcontext.error_code,
              (unsigned long)uc->uc_mcontext.arm_fp, (unsigned long)uc->uc_mcontext.arm_ip,
              (unsigned long)uc->uc_mcontext.arm_pc, (unsigned long)uc->uc_mcontext.arm_sp,
              (unsigned long)uc->uc_mcontext.arm_cpsr, (unsigned long)uc->uc_mcontext.fault_address);
    logStackContent((void **)uc->uc_mcontext.arm_sp);
#else
    NOT_SUPPORTED();
#endif
#elif defined(__FreeBSD__)
#if defined(__x86_64__)
    serverLog(LL_WARNING,
              "\n"
              "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
              "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
              "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
              "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
              "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
              (unsigned long)uc->uc_mcontext.mc_rax, (unsigned long)uc->uc_mcontext.mc_rbx,
              (unsigned long)uc->uc_mcontext.mc_rcx, (unsigned long)uc->uc_mcontext.mc_rdx,
              (unsigned long)uc->uc_mcontext.mc_rdi, (unsigned long)uc->uc_mcontext.mc_rsi,
              (unsigned long)uc->uc_mcontext.mc_rbp, (unsigned long)uc->uc_mcontext.mc_rsp,
              (unsigned long)uc->uc_mcontext.mc_r8, (unsigned long)uc->uc_mcontext.mc_r9,
              (unsigned long)uc->uc_mcontext.mc_r10, (unsigned long)uc->uc_mcontext.mc_r11,
              (unsigned long)uc->uc_mcontext.mc_r12, (unsigned long)uc->uc_mcontext.mc_r13,
              (unsigned long)uc->uc_mcontext.mc_r14, (unsigned long)uc->uc_mcontext.mc_r15,
              (unsigned long)uc->uc_mcontext.mc_rip, (unsigned long)uc->uc_mcontext.mc_rflags,
              (unsigned long)uc->uc_mcontext.mc_cs);
    logStackContent((void **)uc->uc_mcontext.mc_rsp);
#elif defined(__i386__)
    serverLog(LL_WARNING,
              "\n"
              "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
              "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
              "SS :%08lx EFL:%08lx EIP:%08lx CS:%08lx\n"
              "DS :%08lx ES :%08lx FS :%08lx GS:%08lx",
              (unsigned long)uc->uc_mcontext.mc_eax, (unsigned long)uc->uc_mcontext.mc_ebx,
              (unsigned long)uc->uc_mcontext.mc_ebx, (unsigned long)uc->uc_mcontext.mc_edx,
              (unsigned long)uc->uc_mcontext.mc_edi, (unsigned long)uc->uc_mcontext.mc_esi,
              (unsigned long)uc->uc_mcontext.mc_ebp, (unsigned long)uc->uc_mcontext.mc_esp,
              (unsigned long)uc->uc_mcontext.mc_ss, (unsigned long)uc->uc_mcontext.mc_eflags,
              (unsigned long)uc->uc_mcontext.mc_eip, (unsigned long)uc->uc_mcontext.mc_cs,
              (unsigned long)uc->uc_mcontext.mc_es, (unsigned long)uc->uc_mcontext.mc_fs,
              (unsigned long)uc->uc_mcontext.mc_gs);
    logStackContent((void **)uc->uc_mcontext.mc_esp);
#else
    NOT_SUPPORTED();
#endif
#elif defined(__OpenBSD__)
#if defined(__x86_64__)
    serverLog(LL_WARNING,
              "\n"
              "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
              "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
              "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
              "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
              "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
              (unsigned long)uc->sc_rax, (unsigned long)uc->sc_rbx, (unsigned long)uc->sc_rcx,
              (unsigned long)uc->sc_rdx, (unsigned long)uc->sc_rdi, (unsigned long)uc->sc_rsi,
              (unsigned long)uc->sc_rbp, (unsigned long)uc->sc_rsp, (unsigned long)uc->sc_r8, (unsigned long)uc->sc_r9,
              (unsigned long)uc->sc_r10, (unsigned long)uc->sc_r11, (unsigned long)uc->sc_r12,
              (unsigned long)uc->sc_r13, (unsigned long)uc->sc_r14, (unsigned long)uc->sc_r15,
              (unsigned long)uc->sc_rip, (unsigned long)uc->sc_rflags, (unsigned long)uc->sc_cs);
    logStackContent((void **)uc->sc_rsp);
#elif defined(__i386__)
    serverLog(LL_WARNING,
              "\n"
              "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
              "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
              "SS :%08lx EFL:%08lx EIP:%08lx CS:%08lx\n"
              "DS :%08lx ES :%08lx FS :%08lx GS:%08lx",
              (unsigned long)uc->sc_eax, (unsigned long)uc->sc_ebx, (unsigned long)uc->sc_ebx,
              (unsigned long)uc->sc_edx, (unsigned long)uc->sc_edi, (unsigned long)uc->sc_esi,
              (unsigned long)uc->sc_ebp, (unsigned long)uc->sc_esp, (unsigned long)uc->sc_ss,
              (unsigned long)uc->sc_eflags, (unsigned long)uc->sc_eip, (unsigned long)uc->sc_cs,
              (unsigned long)uc->sc_es, (unsigned long)uc->sc_fs, (unsigned long)uc->sc_gs);
    logStackContent((void **)uc->sc_esp);
#else
    NOT_SUPPORTED();
#endif
#elif defined(__NetBSD__)
#if defined(__x86_64__)
    serverLog(LL_WARNING,
              "\n"
              "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
              "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
              "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
              "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
              "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
              (unsigned long)uc->uc_mcontext.__gregs[_REG_RAX], (unsigned long)uc->uc_mcontext.__gregs[_REG_RBX],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_RCX], (unsigned long)uc->uc_mcontext.__gregs[_REG_RDX],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_RDI], (unsigned long)uc->uc_mcontext.__gregs[_REG_RSI],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_RBP], (unsigned long)uc->uc_mcontext.__gregs[_REG_RSP],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_R8], (unsigned long)uc->uc_mcontext.__gregs[_REG_R9],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_R10], (unsigned long)uc->uc_mcontext.__gregs[_REG_R11],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_R12], (unsigned long)uc->uc_mcontext.__gregs[_REG_R13],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_R14], (unsigned long)uc->uc_mcontext.__gregs[_REG_R15],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_RIP], (unsigned long)uc->uc_mcontext.__gregs[_REG_RFLAGS],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_CS]);
    logStackContent((void **)uc->uc_mcontext.__gregs[_REG_RSP]);
#elif defined(__i386__)
    serverLog(LL_WARNING,
              "\n"
              "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
              "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
              "SS :%08lx EFL:%08lx EIP:%08lx CS:%08lx\n"
              "DS :%08lx ES :%08lx FS :%08lx GS:%08lx",
              (unsigned long)uc->uc_mcontext.__gregs[_REG_EAX], (unsigned long)uc->uc_mcontext.__gregs[_REG_EBX],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_EDX], (unsigned long)uc->uc_mcontext.__gregs[_REG_EDI],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_ESI], (unsigned long)uc->uc_mcontext.__gregs[_REG_EBP],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_ESP], (unsigned long)uc->uc_mcontext.__gregs[_REG_SS],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_EFLAGS], (unsigned long)uc->uc_mcontext.__gregs[_REG_EIP],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_CS], (unsigned long)uc->uc_mcontext.__gregs[_REG_ES],
              (unsigned long)uc->uc_mcontext.__gregs[_REG_FS], (unsigned long)uc->uc_mcontext.__gregs[_REG_GS]);
#else
    NOT_SUPPORTED();
#endif
#elif defined(__DragonFly__)
    serverLog(LL_WARNING,
              "\n"
              "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
              "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
              "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
              "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
              "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
              (unsigned long)uc->uc_mcontext.mc_rax, (unsigned long)uc->uc_mcontext.mc_rbx,
              (unsigned long)uc->uc_mcontext.mc_rcx, (unsigned long)uc->uc_mcontext.mc_rdx,
              (unsigned long)uc->uc_mcontext.mc_rdi, (unsigned long)uc->uc_mcontext.mc_rsi,
              (unsigned long)uc->uc_mcontext.mc_rbp, (unsigned long)uc->uc_mcontext.mc_rsp,
              (unsigned long)uc->uc_mcontext.mc_r8, (unsigned long)uc->uc_mcontext.mc_r9,
              (unsigned long)uc->uc_mcontext.mc_r10, (unsigned long)uc->uc_mcontext.mc_r11,
              (unsigned long)uc->uc_mcontext.mc_r12, (unsigned long)uc->uc_mcontext.mc_r13,
              (unsigned long)uc->uc_mcontext.mc_r14, (unsigned long)uc->uc_mcontext.mc_r15,
              (unsigned long)uc->uc_mcontext.mc_rip, (unsigned long)uc->uc_mcontext.mc_rflags,
              (unsigned long)uc->uc_mcontext.mc_cs);
    logStackContent((void **)uc->uc_mcontext.mc_rsp);
#elif defined(__sun)
#if defined(__x86_64__)
    serverLog(LL_WARNING,
              "\n"
              "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
              "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
              "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
              "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
              "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
              (unsigned long)uc->uc_mcontext.gregs[REG_RAX], (unsigned long)uc->uc_mcontext.gregs[REG_RBX],
              (unsigned long)uc->uc_mcontext.gregs[REG_RCX], (unsigned long)uc->uc_mcontext.gregs[REG_RDX],
              (unsigned long)uc->uc_mcontext.gregs[REG_RDI], (unsigned long)uc->uc_mcontext.gregs[REG_RSI],
              (unsigned long)uc->uc_mcontext.gregs[REG_RBP], (unsigned long)uc->uc_mcontext.gregs[REG_RSP],
              (unsigned long)uc->uc_mcontext.gregs[REG_R8], (unsigned long)uc->uc_mcontext.gregs[REG_R9],
              (unsigned long)uc->uc_mcontext.gregs[REG_R10], (unsigned long)uc->uc_mcontext.gregs[REG_R11],
              (unsigned long)uc->uc_mcontext.gregs[REG_R12], (unsigned long)uc->uc_mcontext.gregs[REG_R13],
              (unsigned long)uc->uc_mcontext.gregs[REG_R14], (unsigned long)uc->uc_mcontext.gregs[REG_R15],
              (unsigned long)uc->uc_mcontext.gregs[REG_RIP], (unsigned long)uc->uc_mcontext.gregs[REG_RFL],
              (unsigned long)uc->uc_mcontext.gregs[REG_CS]);
    logStackContent((void **)uc->uc_mcontext.gregs[REG_RSP]);
#endif
#else
    NOT_SUPPORTED();
#endif
#undef NOT_SUPPORTED
}

#endif /* HAVE_BACKTRACE */

/* Return a file descriptor to write directly to the server log with the
 * write(2) syscall, that can be used in critical sections of the code
 * where the rest of server can't be trusted (for example during the memory
 * test) or when an API call requires a raw fd.
 *
 * Close it with closeDirectLogFiledes(). */
int openDirectLogFiledes(void) {
    int log_to_stdout = server.logfile[0] == '\0';
    int fd = log_to_stdout ? STDOUT_FILENO : open(server.logfile, O_APPEND | O_CREAT | O_WRONLY, 0644);
    return fd;
}

/* Used to close what closeDirectLogFiledes() returns. */
void closeDirectLogFiledes(int fd) {
    int log_to_stdout = server.logfile[0] == '\0';
    if (!log_to_stdout) close(fd);
}

#if defined(HAVE_BACKTRACE) && defined(__linux__)
static int stacktrace_pipe[2] = {0};
static void setupStacktracePipe(void) {
    if (-1 == anetPipe(stacktrace_pipe, O_CLOEXEC | O_NONBLOCK, O_CLOEXEC | O_NONBLOCK)) {
        serverLog(LL_WARNING, "setupStacktracePipe failed: %s", strerror(errno));
    }
}
#else
static void setupStacktracePipe(void) { /* we don't need a pipe to write the stacktraces */
}
#endif
#ifdef HAVE_BACKTRACE
#define BACKTRACE_MAX_SIZE 100

#ifdef USE_LIBBACKTRACE
/* Callback data for libbacktrace */
typedef struct {
    int fd;
    int count;
    int found_symbols;
} backtrace_callback_data;

/* Error callback for libbacktrace */
static void libbacktrace_error_cb(void *data, const char *msg, int errnum) {
    int fd = data ? *(int *)data : STDERR_FILENO;
    char buf[256];
    int len = snprintf(buf, sizeof(buf), "libbacktrace error: %s (errno %d)\n", msg, errnum);
    if (len > 0 && write(fd, buf, len)) { /* Avoid warning. */
    }
}

/* Full callback for libbacktrace - called for each frame with symbol info */
static int libbacktrace_full_cb(void *data, uintptr_t pc, const char *filename, int lineno, const char *function) {
    backtrace_callback_data *cb_data = (backtrace_callback_data *)data;
    char buf[512];
    int len;

    if (function) {
        if (filename && lineno > 0) {
            len = snprintf(buf, sizeof(buf), "#%d 0x%lx %s at %s:%d\n",
                           cb_data->count, (unsigned long)pc, function, filename, lineno);
        } else {
            len = snprintf(buf, sizeof(buf), "#%d 0x%lx %s\n",
                           cb_data->count, (unsigned long)pc, function);
        }
        /* Mark that we found a real function name */
        cb_data->found_symbols = 1;
    } else {
        len = snprintf(buf, sizeof(buf), "#%d 0x%lx <unknown>\n",
                       cb_data->count, (unsigned long)pc);
    }

    if (len > 0 && write(cb_data->fd, buf, len) == -1) { /* Avoid warning. */
    }
    cb_data->count++;
    return 0;
}

/* Fork and symbolize using libbacktrace (signal-safe approach) */
static void symbolizeWithLibbacktrace(void **trace, int trace_size, int fd, int uplevel) {
    pid_t pid = fork();

    if (pid == 0) {
        /* Child process - safe to use libbacktrace here */
        struct backtrace_state *state = backtrace_create_state(
            NULL, 0, libbacktrace_error_cb, &fd);
        if (state) {
            backtrace_callback_data cb_data = {.fd = fd, .count = 0, .found_symbols = 0};
            for (int i = uplevel; i < trace_size; i++) {
                backtrace_pcinfo(state, (uintptr_t)trace[i], libbacktrace_full_cb,
                                 libbacktrace_error_cb, &cb_data);
            }
            /* If libbacktrace produced no frames or no useful function names, fall back to standard backtrace */
            if (cb_data.count == 0 || !cb_data.found_symbols) {
                char *msg = "\n(libbacktrace failed to resolve symbols, falling back to standard backtrace)\n";
                if (write(fd, msg, strlen(msg)) == -1) { /* Avoid warning. */
                }
                backtrace_symbols_fd(trace + uplevel, trace_size - uplevel, fd);
            }
        } else {
            /* Fallback if state creation fails */
            backtrace_symbols_fd(trace + uplevel, trace_size - uplevel, fd);
        }
        _exit(0);
    } else if (pid > 0) {
        /* Parent process - wait for child with timeout */
        int status;
        int waited = 0;
        pid_t ret;
        while (waited < 50) {
            ret = waitpid(pid, &status, WNOHANG);
            if (ret > 0) break;                     /* Child exited */
            if (ret == -1 && errno != EINTR) break; /* Real error */
            usleep(10000);                          /* 10ms */
            waited++;
        }
        if (ret == 0 || (ret == -1 && errno == EINTR)) {
            /* Timeout or still interrupted - kill child */
            kill(pid, SIGKILL);
            waitpid(pid, NULL, 0);
        }
    } else {
        /* Fork failed, fall back to backtrace_symbols_fd */
        backtrace_symbols_fd(trace + uplevel, trace_size - uplevel, fd);
    }
}
#endif /* USE_LIBBACKTRACE */

#ifdef __linux__
#if !defined(_GNU_SOURCE)
#define _GNU_SOURCE
#endif
#include <sys/prctl.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <dirent.h>

#define TIDS_MAX_SIZE 150
static size_t get_ready_to_signal_threads_tids(int sig_num, pid_t tids[TIDS_MAX_SIZE]);

typedef struct {
    char thread_name[16];
    int trace_size;
    pid_t tid;
    void *trace[BACKTRACE_MAX_SIZE];
} stacktrace_data;

__attribute__((noinline)) static void collect_stacktrace_data(void) {
    stacktrace_data trace_data = {{0}};

    /* Get the stack trace first! */
    trace_data.trace_size = backtrace(trace_data.trace, BACKTRACE_MAX_SIZE);

    /* get the thread name */
    prctl(PR_GET_NAME, trace_data.thread_name);

    /* get the thread id */
    trace_data.tid = syscall(SYS_gettid);

    /* Send the output to the main process*/
    if (write(stacktrace_pipe[1], &trace_data, sizeof(trace_data)) == -1) { /* Avoid warning. */
    };
}

__attribute__((noinline)) static void writeStacktraces(int fd, int uplevel) {
    /* get the list of all the process's threads that don't block or ignore the THREADS_SIGNAL */
    pid_t tids[TIDS_MAX_SIZE];
    size_t len_tids = get_ready_to_signal_threads_tids(THREADS_SIGNAL, tids);
    if (!len_tids) {
        serverLogRawFromHandler(LL_WARNING, "writeStacktraces(): Failed to get the process's threads.");
    }

    char buff[PIPE_BUF];
    /* Clear the stacktraces pipe */
    while (read(stacktrace_pipe[0], &buff, sizeof(buff)) > 0) {
    }

    /* ThreadsManager_runOnThreads returns 0 if it is already running */
    if (!ThreadsManager_runOnThreads(tids, len_tids, collect_stacktrace_data)) return;

    size_t collected = 0;

    pid_t calling_tid = syscall(SYS_gettid);

    /* Read the stacktrace_pipe until it's empty */
    stacktrace_data curr_stacktrace_data = {{0}};
    while (read(stacktrace_pipe[0], &curr_stacktrace_data, sizeof(curr_stacktrace_data)) > 0) {
        /* stacktrace header includes the tid and the thread's name */
        snprintf_async_signal_safe(buff, sizeof(buff), "\n%d %s", curr_stacktrace_data.tid,
                                   curr_stacktrace_data.thread_name);
        if (write(fd, buff, strlen(buff)) == -1) { /* Avoid warning. */
        };

        /* skip kernel call to the signal handler, the signal handler and the callback addresses */
        int curr_uplevel = 3;

        if (curr_stacktrace_data.tid == calling_tid) {
            /* skip signal syscall and ThreadsManager_runOnThreads */
            curr_uplevel += uplevel + 2;
            /* Add an indication to header of the thread that is handling the log file */
            if (write(fd, " *\n", strlen(" *\n")) == -1) { /* Avoid warning. */
            };
        } else {
            /* just add a new line */
            if (write(fd, "\n", strlen("\n")) == -1) { /* Avoid warning. */
            };
        }

        /* add the stacktrace */
#ifdef USE_LIBBACKTRACE
        symbolizeWithLibbacktrace(curr_stacktrace_data.trace, curr_stacktrace_data.trace_size, fd, curr_uplevel);
#else
        backtrace_symbols_fd(curr_stacktrace_data.trace + curr_uplevel, curr_stacktrace_data.trace_size - curr_uplevel,
                             fd);
#endif

        ++collected;
    }

    snprintf_async_signal_safe(buff, sizeof(buff), "\n%lu/%lu expected stacktraces.\n", (long unsigned)(collected),
                               (long unsigned)len_tids);
    if (write(fd, buff, strlen(buff)) == -1) { /* Avoid warning. */
    };
}

#endif /* __linux__ */

__attribute__((noinline)) static void writeCurrentThreadsStackTrace(int fd, int uplevel) {
    void *trace[BACKTRACE_MAX_SIZE];

    int trace_size = backtrace(trace, BACKTRACE_MAX_SIZE);

    char *msg = "\nBacktrace:\n";
    if (write(fd, msg, strlen(msg)) == -1) { /* Avoid warning. */
    };
#ifdef USE_LIBBACKTRACE
    symbolizeWithLibbacktrace(trace, trace_size, fd, uplevel);
#else
    backtrace_symbols_fd(trace + uplevel, trace_size - uplevel, fd);
#endif
}

/* Logs the stack trace using the backtrace() call. This function is designed
 * to be called from signal handlers safely.
 * The eip argument is optional (can take NULL).
 * The uplevel argument indicates how many of the calling functions to skip.
 * Functions that are taken in consideration in "uplevel" should be declared with
 * __attribute__ ((noinline)) to make sure the compiler won't inline them.
 */
__attribute__((noinline)) void logStackTrace(void *eip, int uplevel, int current_thread) {
    int fd = openDirectLogFiledes();
    char *msg;
    uplevel++; /* skip this function */

    if (fd == -1) return; /* If we can't log there is anything to do. */

    msg = "\n------ STACK TRACE ------\n";
    if (write(fd, msg, strlen(msg)) == -1) { /* Avoid warning. */
    };

    if (eip) {
        /* Write EIP to the log file*/
        msg = "EIP:\n";
        if (write(fd, msg, strlen(msg)) == -1) { /* Avoid warning. */
        };
        backtrace_symbols_fd(&eip, 1, fd);
    }

    /* Write symbols to log file */
    ++uplevel;
#ifdef __linux__
    if (current_thread) {
        writeCurrentThreadsStackTrace(fd, uplevel);
    } else {
        writeStacktraces(fd, uplevel);
    }
#else
    /* Outside of linux, we only support writing the current thread. */
    UNUSED(current_thread);
    writeCurrentThreadsStackTrace(fd, uplevel);
#endif
    msg = "\n------ STACK TRACE DONE ------\n";
    if (write(fd, msg, strlen(msg)) == -1) { /* Avoid warning. */
    };


    /* Cleanup */
    closeDirectLogFiledes(fd);
}

#endif /* HAVE_BACKTRACE */

sds genClusterDebugString(sds infostring) {
    sds cluster_info = genClusterInfoString(sdsempty());
    sds cluster_nodes = clusterGenNodesDescription(NULL, 0, 0);

    infostring = sdscatprintf(infostring, "\r\n# Cluster info\r\n");
    infostring = sdscatsds(infostring, cluster_info);
    infostring = sdscatprintf(infostring, "\n------ CLUSTER NODES OUTPUT ------\n");
    infostring = sdscatsds(infostring, cluster_nodes);

    sdsfree(cluster_info);
    sdsfree(cluster_nodes);

    return infostring;
}

/* Log global server info */
void logServerInfo(void) {
    sds infostring, clients;
    serverLogRaw(LL_WARNING | LL_RAW, "\n------ INFO OUTPUT ------\n");
    int all = 0, everything = 0;
    robj *argv[1];
    argv[0] = createStringObject("all", strlen("all"));
    dict *section_dict = genInfoSectionDict(argv, 1, NULL, &all, &everything);
    infostring = genValkeyInfoString(section_dict, all, everything);
    if (server.cluster_enabled) {
        infostring = genClusterDebugString(infostring);
    }
    serverLogRaw(LL_WARNING | LL_RAW, infostring);
    serverLogRaw(LL_WARNING | LL_RAW, "\n------ CLIENT LIST OUTPUT ------\n");
    clients = getAllClientsInfoString(-1, server.hide_user_data_from_log);
    serverLogRaw(LL_WARNING | LL_RAW, clients);
    sdsfree(infostring);
    sdsfree(clients);
    releaseInfoSectionDict(section_dict);
    decrRefCount(argv[0]);
}

/* Log certain config values, which can be used for debugging */
void logConfigDebugInfo(void) {
    sds configstring;
    configstring = getConfigDebugInfo();
    serverLogRaw(LL_WARNING | LL_RAW, "\n------ CONFIG DEBUG OUTPUT ------\n");
    serverLogRaw(LL_WARNING | LL_RAW, configstring);
    sdsfree(configstring);
}

/* Log modules info. Something we wanna do last since we fear it may crash. */
void logModulesInfo(void) {
    serverLogRaw(LL_WARNING | LL_RAW, "\n------ MODULES INFO OUTPUT ------\n");
    sds infostring = modulesCollectInfo(sdsempty(), NULL, 1, 0);
    serverLogRaw(LL_WARNING | LL_RAW, infostring);
    sdsfree(infostring);
}

/* Log information about the "current" client, that is, the client that is
 * currently being served by the server. May be NULL if the server is not serving a
 * client right now. */
void logCurrentClient(client *cc, const char *title) {
    if (cc == NULL) return;

    sds client;
    int j;

    serverLog(LL_WARNING | LL_RAW, "\n------ %s CLIENT INFO ------\n", title);
    client = catClientInfoString(sdsempty(), cc, server.hide_user_data_from_log);
    serverLog(LL_WARNING | LL_RAW, "%s\n", client);
    sdsfree(client);
    serverLog(LL_WARNING | LL_RAW, "argc: %d\n", cc->argc);
    for (j = 0; j < cc->argc; j++) {
        if (shouldRedactArg(cc, j)) {
            serverLog(LL_WARNING | LL_RAW, "argv[%d]: %zu bytes\n", j, sdslen((sds)objectGetVal(cc->argv[j])));
            continue;
        }
        sds repr = getArgvReprString(cc->argv[j]);
        serverLog(LL_WARNING | LL_RAW, "argv[%d]: %s\n", j, repr);
        sdsfree(repr);
        if (!strcasecmp(objectGetVal(cc->argv[j]), "auth") || !strcasecmp(objectGetVal(cc->argv[j]), "auth2")) {
            break;
        }
    }
    /* Check if the first argument, usually a key, is found inside the
     * selected DB, and if so print info about the associated object. */
    if (cc->argc > 1) {
        robj *val, *key;

        key = getDecodedObject(cc->argv[1]);
        val = dbFind(cc->db, objectGetVal(key));
        if (val) {
            serverLog(LL_WARNING, "key '%s' found in DB containing the following object:", (char *)objectGetVal(key));
            serverLogObjectDebugInfo(val);
        }
        decrRefCount(key);
    }
}

#if defined(HAVE_PROC_MAPS)

#define MEMTEST_MAX_REGIONS 128

/* A non destructive memory test executed during segfault. */
int memtest_test_linux_anonymous_maps(void) {
    FILE *fp;
    char line[1024];
    char logbuf[1024];
    size_t start_addr, end_addr, size;
    size_t start_vect[MEMTEST_MAX_REGIONS];
    size_t size_vect[MEMTEST_MAX_REGIONS];
    int regions = 0, j;

    int fd = openDirectLogFiledes();
    if (fd == -1) return 0;

    fp = fopen("/proc/self/maps", "r");
    if (!fp) {
        closeDirectLogFiledes(fd);
        return 0;
    }
    while (fgets(line, sizeof(line), fp) != NULL) {
        char *start, *end, *p = line;

        start = p;
        p = strchr(p, '-');
        if (!p) continue;
        *p++ = '\0';
        end = p;
        p = strchr(p, ' ');
        if (!p) continue;
        *p++ = '\0';
        if (strstr(p, "stack") || strstr(p, "vdso") || strstr(p, "vsyscall")) continue;
        if (!strstr(p, "00:00")) continue;
        if (!strstr(p, "rw")) continue;

        start_addr = strtoul(start, NULL, 16);
        end_addr = strtoul(end, NULL, 16);
        size = end_addr - start_addr;

        start_vect[regions] = start_addr;
        size_vect[regions] = size;
        snprintf(logbuf, sizeof(logbuf), "*** Preparing to test memory region %lx (%lu bytes)\n",
                 (unsigned long)start_vect[regions], (unsigned long)size_vect[regions]);
        if (write(fd, logbuf, strlen(logbuf)) == -1) { /* Nothing to do. */
        }
        regions++;
    }

    int errors = 0;
    for (j = 0; j < regions; j++) {
        if (write(fd, ".", 1) == -1) { /* Nothing to do. */
        }
        errors += memtest_preserving_test((void *)start_vect[j], size_vect[j], 1);
        if (write(fd, errors ? "E" : "O", 1) == -1) { /* Nothing to do. */
        }
    }
    if (write(fd, "\n", 1) == -1) { /* Nothing to do. */
    }

    /* NOTE: It is very important to close the file descriptor only now
     * because closing it before may result into unmapping of some memory
     * region that we are testing. */
    fclose(fp);
    closeDirectLogFiledes(fd);
    return errors;
}
#endif /* HAVE_PROC_MAPS */

static void killMainThread(void) {
    int err;
    if (pthread_self() != server.main_thread_id && pthread_cancel(server.main_thread_id) == 0) {
        if ((err = pthread_join(server.main_thread_id, NULL)) != 0) {
            serverLog(LL_WARNING, "main thread can not be joined: %s", strerror(err));
        } else {
            serverLog(LL_WARNING, "main thread terminated");
        }
    }
}

/* Kill the running threads (other than current) in an unclean way. This function
 * should be used only when it's critical to stop the threads for some reason.
 * Currently the server does this only on crash (for instance on SIGSEGV) in order
 * to perform a fast memory check without other threads messing with memory. */
void killThreads(void) {
    killMainThread();
    bioKillThreads();
    killIOThreads();
}

void doFastMemoryTest(void) {
#if defined(HAVE_PROC_MAPS)
    if (server.memcheck_enabled) {
        /* Test memory */
        serverLogRaw(LL_WARNING | LL_RAW, "\n------ FAST MEMORY TEST ------\n");
        killThreads();
        if (memtest_test_linux_anonymous_maps()) {
            serverLogRaw(LL_WARNING | LL_RAW, "!!! MEMORY ERROR DETECTED! Check your memory ASAP !!!\n");
        } else {
            serverLogRaw(LL_WARNING | LL_RAW, "Fast memory test PASSED, however your memory can still be broken. "
                                              "Please run a memory test for several hours if possible.\n");
        }
    }
#endif /* HAVE_PROC_MAPS */
}

/* Scans the (assumed) x86 code starting at addr, for a max of `len`
 * bytes, searching for E8 (callq) opcodes, and dumping the symbols
 * and the call offset if they appear to be valid. */
void dumpX86Calls(void *addr, size_t len) {
    size_t j;
    unsigned char *p = addr;
    Dl_info info;
    /* Hash table to best-effort avoid printing the same symbol
     * multiple times. */
    unsigned long ht[256] = {0};

    if (len < 5) return;
    for (j = 0; j < len - 4; j++) {
        if (p[j] != 0xE8) continue; /* Not an E8 CALL opcode. */
        unsigned long target = (unsigned long)addr + j + 5;
        uint32_t tmp;
        memcpy(&tmp, p + j + 1, sizeof(tmp));
        target += tmp;
        if (dladdr((void *)target, &info) != 0 && info.dli_sname != NULL) {
            if (ht[target & 0xff] != target) {
                printf("Function at 0x%lx is %s\n", target, info.dli_sname);
                ht[target & 0xff] = target;
            }
            j += 4; /* Skip the 32 bit immediate. */
        }
    }
}

void dumpCodeAroundEIP(void *eip) {
    Dl_info info;
    if (dladdr(eip, &info) != 0) {
        serverLog(LL_WARNING | LL_RAW,
                  "\n------ DUMPING CODE AROUND EIP ------\n"
                  "Symbol: %s (base: %p)\n"
                  "Module: %s (base %p)\n"
                  "$ xxd -r -p /tmp/dump.hex /tmp/dump.bin\n"
                  "$ objdump --adjust-vma=%p -D -b binary -m i386:x86-64 /tmp/dump.bin\n"
                  "------\n",
                  info.dli_sname, info.dli_saddr, info.dli_fname, info.dli_fbase, info.dli_saddr);
        size_t len = (long)eip - (long)info.dli_saddr;
        unsigned long sz = sysconf(_SC_PAGESIZE);
        if (len < 1 << 13) { /* we don't have functions over 8k (verified) */
            /* Find the address of the next page, which is our "safety"
             * limit when dumping. Then try to dump just 128 bytes more
             * than EIP if there is room, or stop sooner. */
            void *base = (void *)info.dli_saddr;
            unsigned long next = ((unsigned long)eip + sz) & ~(sz - 1);
            unsigned long end = (unsigned long)eip + 128;
            if (end > next) end = next;
            len = end - (unsigned long)base;
            serverLogHexDump(LL_WARNING, "dump of function", base, len);
            dumpX86Calls(base, len);
        }
    }
}

void invalidFunctionWasCalled(void) {
}

typedef void (*invalidFunctionWasCalledType)(void);

__attribute__((noinline)) static void sigsegvHandler(int sig, siginfo_t *info, void *secret) {
    UNUSED(secret);
    UNUSED(info);
    int print_full_crash_info = 1;
    /* Check if it is safe to enter the signal handler. second thread crashing at the same time will deadlock. */
    if (pthread_mutex_lock(&signal_handler_lock) == EDEADLK) {
        /* If this thread already owns the lock (meaning we crashed during handling a signal) switch
         * to printing the minimal information about the crash. */
        serverLogRawFromHandler(LL_WARNING,
                                "Crashed running signal handler. Providing reduced version of recursive crash report.");
        print_full_crash_info = 0;
    }

    bugReportStart();
    serverLog(LL_WARNING, SERVER_NAME " %s crashed by signal: %d, si_code: %d", VALKEY_VERSION, sig, info->si_code);
    if (sig == SIGSEGV || sig == SIGBUS) {
        serverLog(LL_WARNING, "Accessing address: %p", (void *)info->si_addr);
    }
    if (info->si_code == SI_USER && info->si_pid != -1) {
        serverLog(LL_WARNING, "Killed by PID: %ld, UID: %d", (long)info->si_pid, info->si_uid);
    }

#ifdef HAVE_BACKTRACE
    ucontext_t *uc = (ucontext_t *)secret;
    void *eip = getAndSetMcontextEip(uc, NULL);
    if (eip != NULL) {
        serverLog(LL_WARNING, "Crashed running the instruction at: %p", eip);
    }

    if (eip == info->si_addr) {
        /* When eip matches the bad address, it's an indication that we crashed when calling a non-mapped
         * function pointer. In that case the call to backtrace will crash trying to access that address and we
         * won't get a crash report logged. Set it to a valid point to avoid that crash. */

        /* This trick allow to avoid compiler warning */
        void *ptr;
        invalidFunctionWasCalledType *ptr_ptr = (invalidFunctionWasCalledType *)&ptr;
        *ptr_ptr = invalidFunctionWasCalled;
        getAndSetMcontextEip(uc, ptr);
    }

    /* When printing the reduced crash info, just print the current thread
     * to avoid race conditions with the multi-threaded stack collector. */
    logStackTrace(eip, 1, !print_full_crash_info);

    if (eip == info->si_addr) {
        /* Restore old eip */
        getAndSetMcontextEip(uc, eip);
    }

    logRegisters(uc);
#endif

    if (print_full_crash_info) printCrashReport();

#ifdef HAVE_BACKTRACE
    if (eip != NULL) dumpCodeAroundEIP(eip);
#endif

    bugReportEnd(1, sig);
}

void setupDebugSigHandlers(void) {
    setupStacktracePipe();

    setupSigSegvHandler();

    struct sigaction act;

    sigemptyset(&act.sa_mask);
    act.sa_flags = SA_SIGINFO;
    act.sa_sigaction = sigalrmSignalHandler;
    sigaction(SIGALRM, &act, NULL);
}

void setupSigSegvHandler(void) {
    /* Initialize the signal handler lock.
    Attempting to initialize an already initialized mutex or mutexattr results in undefined behavior. */
    if (!signal_handler_lock_initialized) {
        /* Set signal handler with error checking attribute. re-lock within the same thread will error. */
        pthread_mutexattr_init(&signal_handler_lock_attr);
        pthread_mutexattr_settype(&signal_handler_lock_attr, PTHREAD_MUTEX_ERRORCHECK);
        pthread_mutex_init(&signal_handler_lock, &signal_handler_lock_attr);
        signal_handler_lock_initialized = 1;
    }

    struct sigaction act;

    sigemptyset(&act.sa_mask);
    /* SA_NODEFER to disables adding the signal to the signal mask of the
     * calling process on entry to the signal handler unless it is included in the sa_mask field. */
    /* SA_SIGINFO flag is set to raise the function defined in sa_sigaction.
     * Otherwise, sa_handler is used. */
    act.sa_flags = SA_NODEFER | SA_SIGINFO;
    act.sa_sigaction = sigsegvHandler;
    if (server.crashlog_enabled) {
        sigaction(SIGSEGV, &act, NULL);
        sigaction(SIGBUS, &act, NULL);
        sigaction(SIGFPE, &act, NULL);
        sigaction(SIGILL, &act, NULL);
        sigaction(SIGABRT, &act, NULL);
    }
}

void removeSigSegvHandlers(void) {
    struct sigaction act;
    sigemptyset(&act.sa_mask);
    act.sa_flags = SA_NODEFER | SA_RESETHAND;
    act.sa_handler = SIG_DFL;
    sigaction(SIGSEGV, &act, NULL);
    sigaction(SIGBUS, &act, NULL);
    sigaction(SIGFPE, &act, NULL);
    sigaction(SIGILL, &act, NULL);
    sigaction(SIGABRT, &act, NULL);
}

void printCrashReport(void) {
    server.crashed = 1;
    /* Log INFO and CLIENT LIST */
    logServerInfo();

    /* Log the current client */
    logCurrentClient(server.current_client, "CURRENT");
    logCurrentClient(server.executing_client, "EXECUTING");

    /* Log modules info. Something we wanna do last since we fear it may crash. */
    logModulesInfo();

    /* Log debug config information, which are some values
     * which may be useful for debugging crashes. */
    logConfigDebugInfo();

    /* Run memory test in case the crash was triggered by memory corruption. */
    doFastMemoryTest();
}

void bugReportEnd(int killViaSignal, int sig) {
    struct sigaction act;

    serverLogFromHandler(LL_WARNING | LL_RAW,
                         "\n=== %s BUG REPORT END. Make sure to include from START to END. ===\n\n"
                         "       Please report the crash by opening an issue on github:\n\n"
                         "           https://github.com/valkey-io/valkey/issues\n\n"
                         "  If a module was involved, please open in the module's repo instead.\n\n"
                         "  Suspect RAM error? Use valkey-server --test-memory to verify it.\n\n"
                         "  Some other issues could be detected by valkey-server --check-system\n",
                         server.extended_redis_compat ? "REDIS" : "VALKEY");

    /* free(messages); Don't call free() with possibly corrupted memory. */
    if (server.daemonize && server.supervised == 0 && server.pidfile) unlink(server.pidfile);

    if (!killViaSignal) {
        /* To avoid issues with valgrind, we may wanna exit rather than generate a signal */
        if (server.use_exit_on_panic) {
            /* Using _exit to bypass false leak reports by gcc ASAN */
            fflush(stdout);
            _exit(1);
        }
        abort();
    }

    /* Make sure we exit with the right signal at the end. So for instance
     * the core will be dumped if enabled. */
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    act.sa_handler = SIG_DFL;
    sigaction(sig, &act, NULL);
    kill(getpid(), sig);
}

/* ==================== Logging functions for debugging ===================== */

void serverLogHexDump(int level, char *descr, void *value, size_t len) {
    char buf[65], *b;
    unsigned char *v = value;
    char charset[] = "0123456789abcdef";

    serverLog(level, "%s (hexdump of %zu bytes):", descr, len);
    b = buf;
    while (len) {
        b[0] = charset[(*v) >> 4];
        b[1] = charset[(*v) & 0xf];
        b[2] = '\0';
        b += 2;
        len--;
        v++;
        if (b - buf == 64 || len == 0) {
            serverLogRaw(level | LL_RAW, buf);
            b = buf;
        }
    }
    serverLogRaw(level | LL_RAW, "\n");
}

/* =========================== Software Watchdog ============================ */
#include <sys/time.h>

void sigalrmSignalHandler(int sig, siginfo_t *info, void *secret) {
#ifdef HAVE_BACKTRACE
    ucontext_t *uc = (ucontext_t *)secret;
#else
    (void)secret;
#endif
    UNUSED(sig);

    /* SIGALRM can be sent explicitly to the process calling kill() to get the stacktraces,
       or every watchdog_period interval. In the last case, si_pid is not set */
    if (info->si_pid == 0) {
        serverLogRawFromHandler(LL_WARNING, "\n--- WATCHDOG TIMER EXPIRED ---");
    } else {
        serverLogRawFromHandler(LL_WARNING, "\nReceived SIGALRM");
    }
#ifdef HAVE_BACKTRACE
    logStackTrace(getAndSetMcontextEip(uc, NULL), 1, 0);
#else
    serverLogRawFromHandler(LL_WARNING, "Sorry: no support for backtrace().");
#endif
    serverLogRawFromHandler(LL_WARNING, "--------\n");
}

/* Schedule a SIGALRM delivery after the specified period in milliseconds.
 * If a timer is already scheduled, this function will re-schedule it to the
 * specified time. If period is 0 the current timer is disabled. */
void watchdogScheduleSignal(int period) {
    struct itimerval it;

    /* Will stop the timer if period is 0. */
    it.it_value.tv_sec = period / 1000;
    it.it_value.tv_usec = (period % 1000) * 1000;
    /* Don't automatically restart. */
    it.it_interval.tv_sec = 0;
    it.it_interval.tv_usec = 0;
    setitimer(ITIMER_REAL, &it, NULL);
}
void applyWatchdogPeriod(void) {
    /* Disable watchdog when period is 0 */
    if (server.watchdog_period == 0) {
        watchdogScheduleSignal(0); /* Stop the current timer. */
    } else {
        /* If the configured period is smaller than twice the timer period, it is
         * too short for the software watchdog to work reliably. Fix it now
         * if needed. */
        int min_period = (1000 / server.hz) * 2;
        if (server.watchdog_period < min_period) server.watchdog_period = min_period;
        watchdogScheduleSignal(server.watchdog_period); /* Adjust the current timer. */
    }
}

void debugPauseProcess(void) {
    serverLog(LL_NOTICE, "Process is about to stop.");
    raise(SIGSTOP);
    serverLog(LL_NOTICE, "Process has been continued.");
}

/* Positive input is sleep time in microseconds. Negative input is fractions
 * of microseconds, i.e. -10 means 100 nanoseconds. */
void debugDelay(int usec) {
    /* Since even the shortest sleep results in context switch and system call,
     * the way we achieve short sleeps is by statistically sleeping less often. */
    if (usec < 0) usec = (rand() % -usec) == 0 ? 1 : 0;
    if (usec) usleep(usec);
}

#ifdef HAVE_BACKTRACE
#ifdef __linux__

/* =========================== Stacktrace Utils ============================ */


/** If it doesn't block and doesn't ignore, return 1 (the thread will handle the signal)
 * If thread tid blocks or ignores sig_num returns 0 (thread is not ready to catch the signal).
 * also returns 0 if something is wrong and prints a warning message to the log file **/
static int is_thread_ready_to_signal(const char *proc_pid_task_path, const char *tid, int sig_num) {
    /* Open the threads status file path /proc/<pid>>/task/<tid>/status */
    char path_buff[PATH_MAX];
    snprintf_async_signal_safe(path_buff, PATH_MAX, "%s/%s/status", proc_pid_task_path, tid);

    int thread_status_file = open(path_buff, O_RDONLY);
    char buff[PATH_MAX];
    if (thread_status_file == -1) {
        serverLogFromHandler(LL_WARNING, "tid:%s: failed to open %s file", tid, path_buff);
        return 0;
    }

    int ret = 1;
    size_t field_name_len = strlen("SigBlk:\t"); /* SigIgn has the same length */
    char *line = NULL;
    size_t fields_count = 2;
    while ((line = fgets_async_signal_safe(buff, PATH_MAX, thread_status_file)) && fields_count) {
        /* iterate the file until we reach SigBlk or SigIgn field line */
        if (!strncmp(buff, "SigBlk:\t", field_name_len) || !strncmp(buff, "SigIgn:\t", field_name_len)) {
            line = buff + field_name_len;
            unsigned long sig_mask;
            if (-1 == string2ul_base16_async_signal_safe(line, sizeof(buff), &sig_mask)) {
                serverLogRawFromHandler(LL_WARNING, "Can't convert signal mask to an unsigned long due to an overflow");
                ret = 0;
                break;
            }

            /* The bit position in a signal mask aligns with the signal number. Since signal numbers start from 1
            we need to adjust the signal number by subtracting 1 to align it correctly with the zero-based indexing used
          */
            if (sig_mask & (1L << (sig_num - 1))) { /* if the signal is blocked/ignored return 0 */
                ret = 0;
                break;
            }
            --fields_count;
        }
    }

    close(thread_status_file);

    /* if we reached EOF, it means we haven't found SigBlk or/and SigIgn, something is wrong */
    if (line == NULL) {
        ret = 0;
        serverLogFromHandler(LL_WARNING, "tid:%s: failed to find SigBlk or/and SigIgn field(s) in %s/%s/status file",
                             tid, proc_pid_task_path, tid);
    }
    return ret;
}

/** We are using syscall(SYS_getdents64) to read directories, which unlike opendir(), is considered
 * async-signal-safe. This function wrapper getdents64() in glibc is supported as of glibc 2.30.
 * To support earlier versions of glibc, we use syscall(SYS_getdents64), which requires defining
 * linux_dirent64 ourselves. This structure is very old and stable: It will not change unless the kernel
 * chooses to break compatibility with all existing binaries. Highly Unlikely.
 */
struct linux_dirent64 {
    unsigned long long d_ino;
    long long d_off;
    unsigned short d_reclen; /* Length of this linux_dirent */
    unsigned char d_type;
    char d_name[256]; /* Filename (null-terminated) */
};

/** Returns the number of the process's threads that can receive signal sig_num.
 * Writes into tids the tids of these threads.
 * If it fails, returns 0.
 */
static size_t get_ready_to_signal_threads_tids(int sig_num, pid_t tids[TIDS_MAX_SIZE]) {
    /* Open /proc/<pid>/task file. */
    char path_buff[PATH_MAX];
    snprintf_async_signal_safe(path_buff, PATH_MAX, "/proc/%d/task", getpid());

    int dir;
    if (-1 == (dir = open(path_buff, O_RDONLY | O_DIRECTORY))) return 0;

    size_t tids_count = 0;
    pid_t calling_tid = syscall(SYS_gettid);
    int current_thread_index = -1;
    long nread;
    char buff[PATH_MAX];

    /* readdir() is not async-signal-safe (AS-safe).
    Hence, we read the file using SYS_getdents64, which is considered AS-sync*/
    while ((nread = syscall(SYS_getdents64, dir, buff, PATH_MAX))) {
        if (nread == -1) {
            close(dir);
            serverLogRawFromHandler(LL_WARNING,
                                    "get_ready_to_signal_threads_tids(): Failed to read the process's task directory");
            return 0;
        }
        /* Each thread is represented by a directory */
        for (long pos = 0; pos < nread;) {
            struct linux_dirent64 *entry = (struct linux_dirent64 *)(buff + pos);
            pos += entry->d_reclen;
            /* Skip irrelevant directories. */
            if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) continue;

            /* the thread's directory name is equivalent to its tid. */
            long tid;
            string2l(entry->d_name, strlen(entry->d_name), &tid);

            if (!is_thread_ready_to_signal(path_buff, entry->d_name, sig_num)) continue;

            if (tid == calling_tid) {
                current_thread_index = tids_count;
            }

            /* save the thread id */
            tids[tids_count++] = tid;

            /* Stop if we reached the maximum threads number. */
            if (tids_count == TIDS_MAX_SIZE) {
                serverLogRawFromHandler(LL_WARNING,
                                        "get_ready_to_signal_threads_tids(): Reached the limit of the tids buffer.");
                break;
            }
        }

        if (tids_count == TIDS_MAX_SIZE) break;
    }

    /* Swap the last tid with the current thread id */
    if (current_thread_index != -1) {
        pid_t last_tid = tids[tids_count - 1];

        tids[tids_count - 1] = calling_tid;
        tids[current_thread_index] = last_tid;
    }

    close(dir);

    return tids_count;
}
#endif /* __linux__ */
#endif /* HAVE_BACKTRACE */
