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authorJakob Unterwurzacher2016-07-03 19:14:12 +0200
committerJakob Unterwurzacher2016-07-03 19:18:34 +0200
commit9b725c15cf50cfb85ec6ec88c47843092775dedc (patch)
tree3fd5f651428e48cdd8485389c81de467d9e5d9a0 /internal/syscallcompat
parentc9a472c12ff08a6481c086c791f3005e81dbbcf1 (diff)
syscallcompat: OSX: add Fallocate and Openat wrappers
...and convert all calls to syscall.{Fallocate,Openat} to syscallcompat . Both syscalls are not available on OSX. We emulate Openat and just return EOPNOTSUPP for Fallocate.
Diffstat (limited to 'internal/syscallcompat')
-rw-r--r--internal/syscallcompat/sys_darwin.go33
-rw-r--r--internal/syscallcompat/sys_linux.go19
2 files changed, 47 insertions, 5 deletions
diff --git a/internal/syscallcompat/sys_darwin.go b/internal/syscallcompat/sys_darwin.go
index d437170..81e1b15 100644
--- a/internal/syscallcompat/sys_darwin.go
+++ b/internal/syscallcompat/sys_darwin.go
@@ -1,5 +1,11 @@
package syscallcompat
+import (
+ "os"
+ "sync"
+ "syscall"
+)
+
// prealloc - preallocate space without changing the file size. This prevents
// us from running out of space in the middle of an operation.
func Prealloc(fd int, off int64, len int64) (err error) {
@@ -10,3 +16,30 @@ func Prealloc(fd int, off int64, len int64) (err error) {
// See https://github.com/rfjakob/gocryptfs/issues/18 if you want to help.
return nil
}
+
+var openatLock sync.Mutex
+
+// Poor man's Openat:
+// 1) fchdir to the dirfd
+// 2) open the file
+// 3) chdir back.
+func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
+ openatLock.Lock()
+ defer openatLock.Unlock()
+
+ oldWd, err := os.Getwd()
+ if err != nil {
+ return -1, err
+ }
+ err = syscall.Fchdir(dirfd)
+ if err != nil {
+ return -1, err
+ }
+ defer os.Chdir(oldWd)
+
+ return syscall.Open(path, flags, mode)
+}
+
+func Fallocate(fd int, mode uint32, off int64, len int64) (err error) {
+ return syscall.EOPNOTSUPP
+}
diff --git a/internal/syscallcompat/sys_linux.go b/internal/syscallcompat/sys_linux.go
index 9fe9da5..ca6df95 100644
--- a/internal/syscallcompat/sys_linux.go
+++ b/internal/syscallcompat/sys_linux.go
@@ -11,9 +11,10 @@ const FALLOC_FL_KEEP_SIZE = 0x01
var preallocWarn sync.Once
-// prealloc - preallocate space without changing the file size. This prevents
-// us from running out of space in the middle of an operation.
-func Prealloc(fd int, off int64, len int64) (err error) {
+// 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 {
@@ -23,8 +24,8 @@ func Prealloc(fd int, off int64, len int64) (err error) {
continue
}
if err == syscall.EOPNOTSUPP {
- // ZFS does not support fallocate which caused gocryptfs to abort
- // every write operation: https://github.com/rfjakob/gocryptfs/issues/22
+ // 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 " +
@@ -35,3 +36,11 @@ func Prealloc(fd int, off int64, len int64) (err error) {
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)
+}