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authorJakob Unterwurzacher2016-07-03 17:51:40 +0200
committerJakob Unterwurzacher2016-07-03 17:51:40 +0200
commitc9a472c12ff08a6481c086c791f3005e81dbbcf1 (patch)
treeb2a18a1482f15564ad91fec117b4b7953af218d4 /internal/syscallcompat
parent0d5d6fc99bf84ff583e7ebf0283c4d0efe4245be (diff)
syscallcompat: move syscall wrapper to their own package
We will get more of them as OSX also lacks support for openat.
Diffstat (limited to 'internal/syscallcompat')
-rw-r--r--internal/syscallcompat/sys_darwin.go12
-rw-r--r--internal/syscallcompat/sys_linux.go37
2 files changed, 49 insertions, 0 deletions
diff --git a/internal/syscallcompat/sys_darwin.go b/internal/syscallcompat/sys_darwin.go
new file mode 100644
index 0000000..d437170
--- /dev/null
+++ b/internal/syscallcompat/sys_darwin.go
@@ -0,0 +1,12 @@
+package syscallcompat
+
+// 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) {
+ //
+ // Sorry, fallocate is not available on OSX at all and
+ // fcntl F_PREALLOCATE is not accessible from Go.
+ //
+ // See https://github.com/rfjakob/gocryptfs/issues/18 if you want to help.
+ return nil
+}
diff --git a/internal/syscallcompat/sys_linux.go b/internal/syscallcompat/sys_linux.go
new file mode 100644
index 0000000..9fe9da5
--- /dev/null
+++ b/internal/syscallcompat/sys_linux.go
@@ -0,0 +1,37 @@
+package syscallcompat
+
+import (
+ "sync"
+ "syscall"
+
+ "github.com/rfjakob/gocryptfs/internal/tlog"
+)
+
+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) {
+ 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 does not support fallocate which caused gocryptfs to abort
+ // every write operation: 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
+ }
+}