os: handle EINTR from open(2).

The man page for sigaction(2) on OS X doesn't guarantee that SA_RESTART
will work for open(2) on regular files:

    The affected system calls include open(2), read(2), write(2),
    sendto(2), recvfrom(2), sendmsg(2) and recvmsg(2) on a
    communications channel or a slow device (such as a terminal, but not
    a regular file) and during a wait(2) or ioctl(2).

I've never observed EINTR from open(2) for a traditional file system
such as HFS+, but it's easy to observe with a fuse file system that is
slightly slow (cf. https://goo.gl/UxsVgB). After this change, the
problem can no longer be reproduced when calling os.OpenFile.

Fixes #11180.

Change-Id: I967247430e20a7d29a285b3d76bf3498dc4773db
Reviewed-on: https://go-review.googlesource.com/14484
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/os/file_unix.go b/src/os/file_unix.go
index 0677707ee074c05fba37a9b2fff62e517cd236ba..36b2a608ff8021a95cd86deab4217b044bfa6944 100644 (file)
--- a/src/os/file_unix.go
+++ b/src/os/file_unix.go
@@ -90,8 +90,16 @@ func OpenFile(name string, flag int, perm FileMode) (*File, error) {
                }
        }
 
+retry:
        r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, syscallMode(perm))
        if e != nil {
+               // On OS X, sigaction(2) doesn't guarantee that SA_RESTART will cause
+               // open(2) to be restarted for regular files. This is easy to reproduce on
+               // fuse file systems (see http://golang.org/issue/11180).
+               if e == syscall.EINTR {
+                       goto retry
+               }
+
                return nil, &PathError{"open", name, e}
        }