process: Refactor and create ProcessInformation::from_pid()

src/uu/pgrep/src/process.rs

@@ -485,15 +485,17 @@ impl ProcessInformation {
         })
     }
 
-    pub fn current_process_info() -> Result<ProcessInformation, io::Error> {
-        use std::str::FromStr;
+    pub fn from_pid(pid: usize) -> Result<Self, io::Error> {
+        Self::try_new(PathBuf::from(format!("/proc/{}", pid)))
+    }
 
+    pub fn current_process_info() -> Result<ProcessInformation, io::Error> {
         #[cfg(target_os = "linux")]
         let pid = uucore::process::getpid();
         #[cfg(not(target_os = "linux"))]
         let pid = 0; // dummy
 
-        ProcessInformation::try_new(PathBuf::from_str(&format!("/proc/{pid}")).unwrap())
+        Self::from_pid(pid as usize)
     }
 
     pub fn proc_status(&self) -> &str {
@@ -967,7 +969,7 @@ unknown              /dev/tty        4 1-63 console"#;
     #[test]
     #[cfg(target_os = "linux")]
     fn test_cgroups() {
-        let mut pid_entry = ProcessInformation::try_new("/proc/1".into()).unwrap();
+        let mut pid_entry = ProcessInformation::from_pid(1).unwrap();
         if pid_entry.name().unwrap() == "systemd" {
             let cgroups = pid_entry.cgroups().unwrap();
             if let Some(membership) = cgroups.iter().find(|cg| cg.hierarchy_id == 0) {

src/uu/pidwait/src/wait.rs

@@ -30,16 +30,9 @@ pub(crate) fn wait(procs: &[ProcessInformation]) {
 }
 #[cfg(target_os = "linux")]
 fn is_running(pid: usize) -> bool {
-    use std::{path::PathBuf, str::FromStr};
     use uu_pgrep::process::RunState;
 
-    let proc = PathBuf::from_str(&format!("/proc/{pid}")).unwrap();
-
-    if !proc.exists() {
-        return false;
-    }
-
-    match ProcessInformation::try_new(proc) {
+    match ProcessInformation::from_pid(pid) {
         Ok(mut proc) => proc
             .run_state()
             .map(|it| it != RunState::Stopped)

src/uu/ps/src/process_selection.rs

@@ -116,9 +116,7 @@ impl ProcessSelectionSettings {
         if let Some(ref quick_pids) = self.quick_pids {
             let mut selected = Vec::new();
             for &pid in quick_pids {
-                if let Ok(process) =
-                    ProcessInformation::try_new(std::path::PathBuf::from(format!("/proc/{}", pid)))
-                {
+                if let Ok(process) = ProcessInformation::from_pid(pid) {
                     selected.push(process);
                 }
             }

src/uu/snice/src/action.rs

@@ -52,7 +52,6 @@ impl SelectedTarget {
 
     #[cfg(target_os = "linux")]
     fn from_tty(tty: &Teletype) -> Vec<u32> {
-        use std::{path::PathBuf, str::FromStr};
         use uu_pgrep::process::ProcessInformation;
 
         process_snapshot()
@@ -60,9 +59,8 @@ impl SelectedTarget {
             .iter()
             .filter(|(pid, _)| {
                 let pid = pid.as_u32();
-                let path = PathBuf::from_str(&format!("/proc/{pid}/")).unwrap();
 
-                ProcessInformation::try_new(path).unwrap().tty() == *tty
+                ProcessInformation::from_pid(pid as usize).unwrap().tty() == *tty
             })
             .map(|(pid, _)| pid.as_u32())
             .collect()

src/uu/snice/src/snice.rs

@@ -10,8 +10,8 @@ use clap::{crate_version, Arg, Command};
 use prettytable::{format::consts::FORMAT_CLEAN, row, Table};
 pub use process_matcher::clap_args;
 use process_matcher::*;
+use std::collections::HashSet;
 use std::io::Write;
-use std::{collections::HashSet, path::PathBuf, str::FromStr};
 use sysinfo::Pid;
 use uu_pgrep::process::ProcessInformation;
 #[cfg(target_family = "unix")]
@@ -128,7 +128,7 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
 pub fn ask_user(pid: u32) -> bool {
     let process = process_snapshot().process(Pid::from_u32(pid)).unwrap();
 
-    let tty = ProcessInformation::try_new(PathBuf::from_str(&format!("/proc/{pid}")).unwrap())
+    let tty = ProcessInformation::from_pid(pid as usize)
         .map(|mut v| v.tty().to_string())
         .unwrap_or(String::from("?"));
 
@@ -187,9 +187,7 @@ pub fn construct_verbose_result(
 
             let process = process_snapshot().process(Pid::from_u32(pid)).unwrap();
 
-            let tty =
-                ProcessInformation::try_new(PathBuf::from_str(&format!("/proc/{pid}")).unwrap())
-                    .map(|mut v| v.tty().to_string());
+            let tty = ProcessInformation::from_pid(pid as usize).map(|mut v| v.tty().to_string());
 
             let user = process
                 .user_id()