112 lines
3.4 KiB
Go
112 lines
3.4 KiB
Go
// Package syscallcompat wraps Linux-specific syscalls.
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package syscallcompat
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import (
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"sync"
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"syscall"
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"unsafe"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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const _FALLOC_FL_KEEP_SIZE = 0x01
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var preallocWarn sync.Once
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// EnospcPrealloc preallocates ciphertext space without changing the file
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// size. This guarantees that we don't run out of space while writing a
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// ciphertext block (that would corrupt the block).
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func EnospcPrealloc(fd int, off int64, len int64) (err error) {
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for {
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err = syscall.Fallocate(fd, _FALLOC_FL_KEEP_SIZE, off, len)
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if err == syscall.EINTR {
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// fallocate, like many syscalls, can return EINTR. This is not an
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// error and just signifies that the operation was interrupted by a
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// signal and we should try again.
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continue
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}
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if err == syscall.EOPNOTSUPP {
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// ZFS and ext3 do not support fallocate. Warn but continue anyway.
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// https://github.com/rfjakob/gocryptfs/issues/22
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preallocWarn.Do(func() {
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tlog.Warn.Printf("Warning: The underlying filesystem " +
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"does not support fallocate(2). gocryptfs will continue working " +
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"but is no longer resistant against out-of-space errors.\n")
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})
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return nil
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}
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return err
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}
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}
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// Fallocate wraps the Fallocate syscall.
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func Fallocate(fd int, mode uint32, off int64, len int64) (err error) {
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return syscall.Fallocate(fd, mode, off, len)
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}
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// Openat wraps the Openat syscall.
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func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
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return syscall.Openat(dirfd, path, flags, mode)
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}
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// Renameat wraps the Renameat syscall.
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func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error) {
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return syscall.Renameat(olddirfd, oldpath, newdirfd, newpath)
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}
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// Unlinkat syscall. In old versions the 'flags' argument was missing, so
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// manually call it by using the corresponding syscall number.
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func Unlinkat(dirfd int, path string, flags int) (err error) {
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var _p0 *byte
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_p0, err = syscall.BytePtrFromString(path)
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if err != nil {
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return
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}
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_, _, e1 := syscall.Syscall(syscall.SYS_UNLINKAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(flags))
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if e1 != 0 {
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err = e1
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}
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return
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}
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// Mknodat wraps the Mknodat syscall.
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func Mknodat(dirfd int, path string, mode uint32, dev int) (err error) {
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return syscall.Mknodat(dirfd, path, mode, dev)
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}
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// Dup3 wraps the Dup3 syscall. We want to use Dup3 rather than Dup2 because Dup2
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// is not implemented on arm64.
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func Dup3(oldfd int, newfd int, flags int) (err error) {
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return syscall.Dup3(oldfd, newfd, flags)
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}
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// Fchmodat syscall.
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func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
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return syscall.Fchmodat(dirfd, path, mode, flags)
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}
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// Fchownat syscall.
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func Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error) {
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return syscall.Fchownat(dirfd, path, uid, gid, flags)
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}
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// Symlinkat syscall. Unfortunately this function is not exported directly, so
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// manually call it by using the corresponding syscall number.
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func Symlinkat(oldpath string, newdirfd int, newpath string) (err error) {
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var _p0 *byte
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_p0, err = syscall.BytePtrFromString(oldpath)
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if err != nil {
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return
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}
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var _p1 *byte
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_p1, err = syscall.BytePtrFromString(newpath)
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if err != nil {
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return
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}
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_, _, e1 := syscall.Syscall(syscall.SYS_SYMLINKAT, uintptr(unsafe.Pointer(_p0)), uintptr(newdirfd), uintptr(unsafe.Pointer(_p1)))
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if e1 != 0 {
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err = e1
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}
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return
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}
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