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package syscallcompat
import (
"sync"
"syscall"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
const FALLOC_FL_KEEP_SIZE = 0x01
var preallocWarn sync.Once
// EnospcPrealloc preallocates ciphertext space without changing the file
// size. This guarantees that we don't run out of space while writing a
// ciphertext block (that would corrupt the block).
func EnospcPrealloc(fd int, off int64, len int64) (err error) {
for {
err = syscall.Fallocate(fd, FALLOC_FL_KEEP_SIZE, off, len)
if err == syscall.EINTR {
// fallocate, like many syscalls, can return EINTR. This is not an
// error and just signifies that the operation was interrupted by a
// signal and we should try again.
continue
}
if err == syscall.EOPNOTSUPP {
// ZFS and ext3 do not support fallocate. Warn but continue anyway.
// https://github.com/rfjakob/gocryptfs/issues/22
preallocWarn.Do(func() {
tlog.Warn.Printf("Warning: The underlying filesystem " +
"does not support fallocate(2). gocryptfs will continue working " +
"but is no longer resistant against out-of-space errors.\n")
})
return nil
}
return err
}
}
func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
return syscall.Openat(dirfd, path, flags, mode)
}
func Fallocate(fd int, mode uint32, off int64, len int64) (err error) {
return syscall.Fallocate(fd, mode, off, len)
}
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