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The lock test creates a lock and checks that it is not stale. This also tests whether the corresponding process still exists. However, it is possible that the lock is refreshed concurrently, which updates the lock timestamp. Calling `processExists()` with a value receiver, however, creates an unsynchronized copy of this field. Thus call the method using a pointer receiver.
50 lines
1.1 KiB
Go
50 lines
1.1 KiB
Go
//go:build !windows
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// +build !windows
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package restic
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import (
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"os"
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"os/user"
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"strconv"
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"syscall"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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)
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// uidGidInt returns uid, gid of the user as a number.
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func uidGidInt(u *user.User) (uid, gid uint32, err error) {
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ui, err := strconv.ParseUint(u.Uid, 10, 32)
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if err != nil {
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return 0, 0, errors.Errorf("invalid UID %q", u.Uid)
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}
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gi, err := strconv.ParseUint(u.Gid, 10, 32)
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if err != nil {
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return 0, 0, errors.Errorf("invalid GID %q", u.Gid)
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}
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return uint32(ui), uint32(gi), nil
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}
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// checkProcess will check if the process retaining the lock
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// exists and responds to SIGHUP signal.
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// Returns true if the process exists and responds.
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func (l *Lock) processExists() bool {
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proc, err := os.FindProcess(l.PID)
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if err != nil {
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debug.Log("error searching for process %d: %v\n", l.PID, err)
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return false
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}
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defer func() {
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_ = proc.Release()
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}()
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debug.Log("sending SIGHUP to process %d\n", l.PID)
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err = proc.Signal(syscall.SIGHUP)
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if err != nil {
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debug.Log("signal error: %v, lock is probably stale\n", err)
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return false
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}
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return true
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}
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