v2rayA/v2rayA · warning

getProcessInfo: %w

Error message

getProcessInfo: %w

What it means

getProcessInfo reads /proc/<pid>/stat to extract the process name and PPID; if the read fails it wraps the OS error as 'getProcessInfo: %w' and returns zero values. Because the function returns named values, callers may silently receive empty pn/ppid — the error is created but NOT returned to callers, so it mostly shows up as lost error information plus empty process names.

Source

Thrown at service/common/netTools/netstat/netstat_unix.go:214

func getProcName(s string) string {
	i := strings.Index(s, "(")
	if i < 0 {
		return ""
	}
	s = s[i+1:]
	j := strings.LastIndex(s, ")")
	if j < 0 {
		return ""
	}
	return s[:j]
}

func getProcessInfo(pid string) (pn string, ppid string) {
	p := filepath.Join(pathProc, pid, "stat")
	b, err := os.ReadFile(p)
	if err != nil {
		err = fmt.Errorf("getProcessInfo: %w", err)
		return
	}
	sp := bytes.Fields(b)
	pn = string(sp[1])
	return getProcName(pn), string(sp[3])
}

func isProcessSocket(pid string, socketInode map[string]struct{}) string {
	// link name is of the form socket:[5860846]
	p := filepath.Join(pathProc, pid, "fd")
	f, err := os.Open(p)
	fns, err := f.Readdirnames(-1)
	f.Close()
	if err != nil {
		return ""
	}
	for _, fn := range fns {
		lk, err := os.Readlink(filepath.Join(p, fn))

View on GitHub (pinned to 71e5442fc5)

Solutions

1. Accept empty results for vanished PIDs — rescan; transient races are the most common cause.
2. Run with privileges or relax hidepid so /proc/<pid>/stat of other users is readable.
3. Note the library bug: getProcessInfo assigns err but never returns it, so callers can't distinguish 'no such process' from 'not matched'; patch it to return an error if you need fidelity.
4. Verify with 'cat /proc/<pid>/stat' as the service user to confirm accessibility.

Example fix

// before (library code): error swallowed
b, err := os.ReadFile(p)
if err != nil {
    err = fmt.Errorf("getProcessInfo: %w", err)
    return // err assigned but never propagated
}
// after: propagate properly
func getProcessInfo(pid string) (pn, ppid string, err error) {
    b, err := os.ReadFile(filepath.Join(pathProc, pid, "stat"))
    if err != nil { return "", "", fmt.Errorf("getProcessInfo: %w", err) }
    ...
}

func statReadable(pid string) bool {
    f, err := os.Open(filepath.Join("/proc", pid, "stat"))
    if err != nil { return false }
    f.Close()
    return true
}

func processInfoValid(pn, ppid string) bool { return pn != "" && ppid != "" }

pn, ppid := getProcessInfo(pid) // note: error is swallowed by the library
if pn == "" {
    time.Sleep(50 * time.Millisecond)
    pn, ppid = getProcessInfo(pid) // retry once: PID may have raced away
}

When it happens

Trigger: A PID directory listed by findProcessID/FillProcesses/Process disappears (process exits) between ReadDir and the stat read; permission denied on /proc/<pid>/stat for other users' processes (hidepid); kernel threads or zombie entries with unreadable stat.

Common situations: Race-heavy scans on busy systems where PIDs churn; unprivileged user scanning root-owned processes under hidepid=2; PID namespaces mismatch in containers; short-lived processes exiting during the scan.

Related errors

• process not found, correspond socket was freed
• parseAddr: Bad formatted string
• parseAddr: %w
• cannot open the directory /proc
• process not found

AI-assisted analysis of v2rayA/v2rayA@71e5442fc5 (2026-09-05). Data as JSON: /api/errors/1b64ab61ef18411c. Report an issue: GitHub.