wip: migrate to mono-repo. SPN has already been moved to spn/

service/network/proc/pids_by_user.go

@@ -0,0 +1,81 @@
+//go:build linux
+
+package proc
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"strconv"
+	"sync"
+	"syscall"
+	"time"
+
+	"github.com/safing/portbase/log"
+	"github.com/safing/portbase/utils"
+)
+
+var (
+	// pidsByUserLock is also used for locking the socketInfo.PID on all socket.*Info structs.
+	pidsByUser      = make(map[int][]int)
+	pidsByUserLock  sync.RWMutex
+	fetchPidsByUser = utils.NewCallLimiter(10 * time.Millisecond)
+)
+
+// getPidsByUser returns the cached PIDs for the given UID.
+func getPidsByUser(uid int) (pids []int, ok bool) {
+	pidsByUserLock.RLock()
+	defer pidsByUserLock.RUnlock()
+
+	pids, ok = pidsByUser[uid]
+	return
+}
+
+// updatePids fetches and creates a new pidsByUser map using a call limiter.
+func updatePids() {
+	fetchPidsByUser.Do(func() {
+		newPidsByUser := make(map[int][]int)
+		pidCnt := 0
+
+		entries := readDirNames("/proc")
+		if len(entries) == 0 {
+			log.Warning("proc: found no PIDs in /proc")
+			return
+		}
+
+	entryLoop:
+		for _, entry := range entries {
+			pid, err := strconv.ParseInt(entry, 10, 32)
+			if err != nil {
+				continue entryLoop
+			}
+
+			statData, err := os.Stat("/proc/" + strconv.FormatInt(pid, 10))
+			if err != nil {
+				if !errors.Is(err, fs.ErrNotExist) {
+					log.Warningf("proc: could not stat /proc/%d: %s", pid, err)
+				}
+				continue entryLoop
+			}
+			sys, ok := statData.Sys().(*syscall.Stat_t)
+			if !ok {
+				log.Warningf("proc: unable to parse /proc/%d: wrong type", pid)
+				continue entryLoop
+			}
+
+			pids, ok := newPidsByUser[int(sys.Uid)]
+			if ok {
+				newPidsByUser[int(sys.Uid)] = append(pids, int(pid))
+			} else {
+				newPidsByUser[int(sys.Uid)] = []int{int(pid)}
+			}
+			pidCnt++
+		}
+
+		// log.Tracef("proc: updated PID table with %d entries", pidCnt)
+
+		pidsByUserLock.Lock()
+		defer pidsByUserLock.Unlock()
+		pidsByUser = newPidsByUser
+	})
+}