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package pidpicker
import (
"bytes"
"cmp"
"fmt"
"io/fs"
"os"
"path/filepath"
"slices"
"strconv"
"strings"
"sync"
)
// ProcessInfo is the metadata shown in the PID picker list.
type ProcessInfo struct {
Pid int
ParentPID int
Comm string
Cmdline string
}
// ScanProcesses returns process metadata from /proc.
func ScanProcesses() ([]ProcessInfo, error) {
return scanProcessesFrom("/proc")
}
// ScanThreads returns thread metadata from /proc/<pid>/task for one process.
func ScanThreads(pid int) ([]ProcessInfo, error) {
return scanThreadsFrom("/proc", pid)
}
// ScanAllThreads returns thread metadata from /proc/*/task.
func ScanAllThreads() ([]ProcessInfo, error) {
return scanAllThreadsFrom("/proc")
}
func scanProcessesFrom(procRoot string) ([]ProcessInfo, error) {
entries, err := os.ReadDir(procRoot)
if err != nil {
return nil, fmt.Errorf("read proc root %q: %w", procRoot, err)
}
processes := make([]ProcessInfo, 0, len(entries))
for _, entry := range entries {
process, ok := readProcessInfo(procRoot, entry)
if !ok {
continue
}
processes = append(processes, process)
}
slices.SortFunc(processes, func(a, b ProcessInfo) int {
return cmp.Compare(a.Pid, b.Pid)
})
return processes, nil
}
func readProcessInfo(procRoot string, entry fs.DirEntry) (ProcessInfo, bool) {
if !entry.IsDir() {
return ProcessInfo{}, false
}
pid, err := strconv.Atoi(entry.Name())
if err != nil {
return ProcessInfo{}, false
}
statPath := filepath.Join(procRoot, entry.Name(), "stat")
statData, err := os.ReadFile(statPath)
if err != nil {
return ProcessInfo{}, false
}
comm, err := parseCommFromStat(string(statData))
if err != nil {
return ProcessInfo{}, false
}
cmdlinePath := filepath.Join(procRoot, entry.Name(), "cmdline")
cmdlineData, err := os.ReadFile(cmdlinePath)
if err != nil {
cmdlineData = nil
}
return ProcessInfo{
Pid: pid,
ParentPID: pid,
Comm: comm,
Cmdline: normalizeCmdline(cmdlineData),
}, true
}
func parseCommFromStat(statLine string) (string, error) {
open := strings.IndexByte(statLine, '(')
close := strings.LastIndexByte(statLine, ')')
if open < 0 || close < 0 || close <= open+1 {
return "", fmt.Errorf("invalid stat line")
}
comm := statLine[open+1 : close]
if strings.TrimSpace(comm) == "" {
return "", fmt.Errorf("empty comm in stat line")
}
return comm, nil
}
func normalizeCmdline(raw []byte) string {
if len(raw) == 0 {
return ""
}
trimmed := bytes.TrimRight(raw, "\x00")
if len(trimmed) == 0 {
return ""
}
parts := bytes.Split(trimmed, []byte{0})
out := make([]string, 0, len(parts))
for _, part := range parts {
if len(part) == 0 {
continue
}
out = append(out, string(part))
}
return strings.Join(out, " ")
}
func scanThreadsFrom(procRoot string, pid int) ([]ProcessInfo, error) {
taskRoot := filepath.Join(procRoot, strconv.Itoa(pid), "task")
entries, err := os.ReadDir(taskRoot)
if err != nil {
return nil, fmt.Errorf("read task root %q: %w", taskRoot, err)
}
cmdlineData, _ := os.ReadFile(filepath.Join(procRoot, strconv.Itoa(pid), "cmdline"))
cmdline := normalizeCmdline(cmdlineData)
threads := make([]ProcessInfo, 0, len(entries))
for _, entry := range entries {
thread, ok := readThreadInfo(taskRoot, entry, cmdline)
if !ok {
continue
}
threads = append(threads, thread)
}
slices.SortFunc(threads, func(a, b ProcessInfo) int {
return cmp.Compare(a.Pid, b.Pid)
})
return threads, nil
}
func readThreadInfo(taskRoot string, entry fs.DirEntry, cmdline string) (ProcessInfo, bool) {
if !entry.IsDir() {
return ProcessInfo{}, false
}
tid, err := strconv.Atoi(entry.Name())
if err != nil {
return ProcessInfo{}, false
}
commPath := filepath.Join(taskRoot, entry.Name(), "comm")
commData, err := os.ReadFile(commPath)
if err != nil {
return ProcessInfo{}, false
}
comm := strings.TrimSpace(string(commData))
if comm == "" {
return ProcessInfo{}, false
}
return ProcessInfo{
Pid: tid,
ParentPID: extractPIDFromPath(taskRoot),
Comm: comm,
Cmdline: cmdline,
}, true
}
func scanAllThreadsFrom(procRoot string) ([]ProcessInfo, error) {
processes, err := scanProcessesFrom(procRoot)
if err != nil {
return nil, err
}
threads := make([]ProcessInfo, 0, len(processes)*8)
var mu sync.Mutex
var wg sync.WaitGroup
sem := make(chan struct{}, 16)
for _, p := range processes {
pid := p.Pid
wg.Add(1)
go func() {
defer wg.Done()
sem <- struct{}{}
defer func() { <-sem }()
perProc, err := scanThreadsFrom(procRoot, pid)
if err != nil {
return
}
mu.Lock()
threads = append(threads, perProc...)
mu.Unlock()
}()
}
wg.Wait()
slices.SortFunc(threads, func(a, b ProcessInfo) int {
if a.Pid != b.Pid {
return cmp.Compare(a.Pid, b.Pid)
}
return cmp.Compare(a.ParentPID, b.ParentPID)
})
return threads, nil
}
func extractPIDFromPath(taskRoot string) int {
parts := strings.Split(filepath.Clean(taskRoot), string(os.PathSeparator))
if len(parts) < 2 {
return -1
}
pid, err := strconv.Atoi(parts[len(parts)-2])
if err != nil {
return -1
}
return pid
}
|
