From f93729f20da4a7416ec387d9d10a8776dba67c29 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher <jakobunt@gmail.com>
Date: Thu, 7 Jan 2016 21:39:41 +0100
Subject: [PATCH] Disable fallocate on OSX (not available and causes a build
 failure)

---
 pathfs_frontend/compat_darwin.go | 13 +++++++++++++
 pathfs_frontend/compat_linux.go  | 18 ++++++++++++++++++
 pathfs_frontend/file.go          | 15 ++-------------
 3 files changed, 33 insertions(+), 13 deletions(-)
 create mode 100644 pathfs_frontend/compat_darwin.go
 create mode 100644 pathfs_frontend/compat_linux.go

diff --git a/pathfs_frontend/compat_darwin.go b/pathfs_frontend/compat_darwin.go
new file mode 100644
index 0000000..816ba88
--- /dev/null
+++ b/pathfs_frontend/compat_darwin.go
@@ -0,0 +1,13 @@
+package pathfs_frontend
+
+import "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) {
+	//
+	// 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.
+}
diff --git a/pathfs_frontend/compat_linux.go b/pathfs_frontend/compat_linux.go
new file mode 100644
index 0000000..7ed3c74
--- /dev/null
+++ b/pathfs_frontend/compat_linux.go
@@ -0,0 +1,18 @@
+package pathfs_frontend
+
+import "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) {
+	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
+		}
+		return err
+	}
+}
diff --git a/pathfs_frontend/file.go b/pathfs_frontend/file.go
index d38a37b..911546d 100644
--- a/pathfs_frontend/file.go
+++ b/pathfs_frontend/file.go
@@ -99,7 +99,7 @@ func (f *file) createHeader() error {
 	// Prevent partially written (=corrupt) header by preallocating the space beforehand
 	f.fdLock.Lock()
 	defer f.fdLock.Unlock()
-	err := fallocateRetry(int(f.fd.Fd()), FALLOC_FL_KEEP_SIZE, 0, cryptfs.HEADER_LEN)
+	err := prealloc(int(f.fd.Fd()), 0, cryptfs.HEADER_LEN)
 	if err != nil {
 		cryptfs.Warn.Printf("createHeader: fallocateRetry failed: %s\n", err.Error())
 		return err
@@ -207,17 +207,6 @@ func (f *file) Read(buf []byte, off int64) (resultData fuse.ReadResult, code fus
 	return fuse.ReadResultData(out), status
 }
 
-// fallocateRetry - syscall.Fallocate() with retry for EINTR.
-func fallocateRetry(fd int, mode uint32, off int64, len int64) (err error) {
-	for {
-		err = syscall.Fallocate(fd, mode, off, len)
-		if err == syscall.EINTR {
-			continue
-		}
-		return err
-	}
-}
-
 const FALLOC_FL_KEEP_SIZE = 0x01
 
 // doWrite - encrypt "data" and write it to plaintext offset "off"
@@ -270,7 +259,7 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
 
 		// Prevent partially written (=corrupt) blocks by preallocating the space beforehand
 		f.fdLock.Lock()
-		err := fallocateRetry(int(f.fd.Fd()), FALLOC_FL_KEEP_SIZE, int64(blockOffset), int64(blockLen))
+		err := prealloc(int(f.fd.Fd()), int64(blockOffset), int64(blockLen))
 		f.fdLock.Unlock()
 		if err != nil {
 			cryptfs.Warn.Printf("doWrite: fallocateRetry failed: %s\n", err.Error())