syscallcompat: move syscall wrapper to their own package

We will get more of them as OSX also lacks support for openat.

3 files changed, 3 insertions, 49 deletions

diff --git a/internal/fusefrontend/compat_darwin.go b/internal/fusefrontend/compat_darwin.go
deleted file mode 100644
index 445fb45..0000000
--- a/internal/fusefrontend/compat_darwin.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package fusefrontend
-
-// 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/fusefrontend/compat_linux.go b/internal/fusefrontend/compat_linux.go
deleted file mode 100644
index 9a8684f..0000000
--- a/internal/fusefrontend/compat_linux.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package fusefrontend
-
-import (
-	"sync"
-	"syscall"
-)
-
-import "github.com/rfjakob/gocryptfs/internal/tlog"
-
-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
-	}
-}
diff --git a/internal/fusefrontend/file.go b/internal/fusefrontend/file.go
index ead253f..f0e0c41 100644
--- a/internal/fusefrontend/file.go
+++ b/internal/fusefrontend/file.go
@@ -16,6 +16,7 @@ import (
 	"github.com/hanwen/go-fuse/fuse/nodefs"
 
 	"github.com/rfjakob/gocryptfs/internal/contentenc"
+	"github.com/rfjakob/gocryptfs/internal/syscallcompat"
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
 
@@ -100,7 +101,7 @@ func (f *file) createHeader() error {
 	buf := h.Pack()
 
 	// Prevent partially written (=corrupt) header by preallocating the space beforehand
-	err := prealloc(int(f.fd.Fd()), 0, contentenc.HEADER_LEN)
+	err := syscallcompat.Prealloc(int(f.fd.Fd()), 0, contentenc.HEADER_LEN)
 	if err != nil {
 		tlog.Warn.Printf("ino%d: createHeader: prealloc failed: %s\n", f.ino, err.Error())
 		return err
@@ -261,7 +262,7 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
 			f.ino, uint64(len(blockData))-f.contentEnc.BlockOverhead(), b.BlockNo)
 
 		// Prevent partially written (=corrupt) blocks by preallocating the space beforehand
-		err := prealloc(int(f.fd.Fd()), int64(blockOffset), int64(len(blockData)))
+		err := syscallcompat.Prealloc(int(f.fd.Fd()), int64(blockOffset), int64(len(blockData)))
 		if err != nil {
 			tlog.Warn.Printf("ino%d fh%d: doWrite: prealloc failed: %s", f.ino, f.intFd(), err.Error())
 			status = fuse.ToStatus(err)