Andy Dixon
5aa60d7bc7
Commands that change the vault hold an exclusive lock on DIR/.lock and readers hold a shared one, taken after the passphrase prompt. A blocked process says it is waiting. Unix uses fcntl locks and Windows uses LockFileEx, both released by the OS if the process dies. Plan 9 and WebAssembly fall back to an exclusive lock file. build.sh cross-compiles static binaries for every Go target that builds without cgo (43 today, armv6 and armv7 for 32-bit ARM Linux) and writes SHA256SUMS.
40 lines
902 B
Go
40 lines
902 B
Go
// Copyright 2026 The vault Authors.
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// SPDX-License-Identifier: GPL-3.0-or-later
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//go:build unix
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package main
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import (
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"errors"
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"io"
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"os"
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"golang.org/x/sys/unix"
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)
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// acquireLock uses fcntl record locks, which the kernel releases if the
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// process dies, and which also work on NFS.
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func acquireLock(path string, exclusive bool, waiting func()) (func(), error) {
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f, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE, 0o600)
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if err != nil {
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return nil, err
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}
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lk := unix.Flock_t{Type: unix.F_RDLCK, Whence: io.SeekStart}
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if exclusive {
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lk.Type = unix.F_WRLCK
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}
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err = unix.FcntlFlock(f.Fd(), unix.F_SETLK, &lk)
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if errors.Is(err, unix.EAGAIN) || errors.Is(err, unix.EACCES) {
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waiting()
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for err = unix.EINTR; errors.Is(err, unix.EINTR); {
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err = unix.FcntlFlock(f.Fd(), unix.F_SETLKW, &lk)
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}
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}
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if err != nil {
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f.Close()
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return nil, err
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}
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return func() { f.Close() }, nil
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}
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