Privatae
133 lines
3.6 KiB
Go
133 lines
3.6 KiB
Go
//go:build linux
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package main
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import (
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"os"
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"strconv"
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"strings"
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"sync"
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"time"
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)
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// Linux facts for the origin walk, all from /proc: comm, ppid and tty_nr
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// from /proc/<pid>/stat, the cgroup's leaf unit from /proc/<pid>/cgroup, the
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// executable from /proc/<pid>/exe. Read per pid on demand and memoised for
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// one scan by the closure procFactsReader returns.
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// parseProcStatFacts reads comm, ppid and tty_nr out of a stat line. The
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// comm is parenthesised and may hold spaces; fields are counted from the
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// LAST ')': state(0) ppid(1) pgrp(2) session(3) tty_nr(4).
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func parseProcStatFacts(stat string) (comm string, ppid int, tty int, ok bool) {
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i := strings.LastIndex(stat, ")")
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j := strings.Index(stat, "(")
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if i < 0 || j < 0 || j > i {
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return "", 0, 0, false
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}
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comm = stat[j+1 : i]
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f := strings.Fields(stat[i+1:])
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if len(f) < 5 {
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return comm, 0, 0, false
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}
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ppid, _ = strconv.Atoi(f[1])
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tty, _ = strconv.Atoi(f[4])
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return comm, ppid, tty, true
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}
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// cgroupUnit returns the systemd unit a cgroup path ends in (a .service or a
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// user@N.service child), or "" for a login session scope and everything
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// else. "0::/system.slice/cron.service" -> "cron.service".
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func cgroupUnit(cgroup string) string {
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for _, line := range strings.Split(cgroup, "\n") {
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// v2: "0::/path"; v1: "N:controllers:/path" — the path is after the last ':'
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k := strings.LastIndex(line, ":")
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if k < 0 {
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continue
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}
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path := line[k+1:]
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leaf := path[strings.LastIndex(path, "/")+1:]
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if strings.HasSuffix(leaf, ".service") {
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return leaf
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}
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}
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return ""
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}
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func procFactsReader() func(int) (procFacts, bool) {
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memo := map[int]procFacts{}
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miss := map[int]bool{}
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return func(pid int) (procFacts, bool) {
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if f, ok := memo[pid]; ok {
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return f, true
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}
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if miss[pid] {
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return procFacts{}, false
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}
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p := "/proc/" + strconv.Itoa(pid)
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stat, err := os.ReadFile(p + "/stat")
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if err != nil {
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miss[pid] = true
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return procFacts{}, false
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}
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comm, ppid, tty, ok := parseProcStatFacts(string(stat))
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if !ok {
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miss[pid] = true
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return procFacts{}, false
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}
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f := procFacts{PID: pid, PPID: ppid, Comm: binBase(comm), Interactive: tty != 0}
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if tty != 0 {
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f.Detail = "tty " + ttyName(tty)
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}
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if cg, err := os.ReadFile(p + "/cgroup"); err == nil {
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f.Unit = cgroupUnit(string(cg))
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}
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if exe, err := os.Readlink(p + "/exe"); err == nil {
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f.Exe = strings.TrimSuffix(exe, " (deleted)")
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if f.Comm == "" {
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f.Comm = binBase(f.Exe)
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}
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}
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memo[pid] = f
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return f, true
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}
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}
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// ttyName renders a tty_nr the way `ps` does for the common cases: pts/N and
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// ttyN. Anything else is shown as the raw number — a fact, not a guess.
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func ttyName(n int) string {
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major, minor := (n>>8)&0xfff, (n&0xff)|((n>>12)&0xfff00)
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switch major {
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case 136, 137, 138, 139, 140, 141, 142, 143:
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return "pts/" + strconv.Itoa((major-136)*256+minor)
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case 4:
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return "tty" + strconv.Itoa(minor)
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}
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return strconv.Itoa(n)
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}
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// systemd timers, read once per scan window and shared with the scheduler
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// inventory. `systemctl` absent (a non-systemd box) yields an empty map.
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var timerCache = struct {
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sync.Mutex
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at time.Time
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m map[string]string
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}{}
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func systemdTimerUnits() map[string]string {
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timerCache.Lock()
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defer timerCache.Unlock()
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if timerCache.m != nil && time.Since(timerCache.at) < schedCacheFor {
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return timerCache.m
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}
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m := map[string]string{}
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if out, err := runTimed("systemctl", "list-timers", "--all", "--no-legend", "--plain"); err == nil {
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m = parseSystemdTimers(string(out))
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}
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timerCache.at, timerCache.m = time.Now(), m
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return m
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}
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func originExtras() originExtra {
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return originExtra{TimerUnits: systemdTimerUnits()}
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}
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