From f8ad850f11e11d10e7de1a16ca53cb193afc9313 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 6 Jun 2010 23:49:18 -0400 Subject: try to get rid of races in hostfs open() In case of mode mismatch, do *not* blindly close the descriptor another openers might be using right now. Open the underlying file with currently sufficient mode, then * if current mode has grown so that it's sufficient for us now, just close our new fd * if current mode has grown and our fd is *not* enough to cover it, close and repeat. * otherwise, install our fd if the file hadn't been opened at all or dup2() our fd over the current one (and close our fd). Critical section is protected by mutex; yes, system-wide. All we do under it is a bunch of comparison and maybe an overwriting dup2() on host. Signed-off-by: Al Viro --- fs/hostfs/hostfs_user.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'fs/hostfs/hostfs_user.c') diff --git a/fs/hostfs/hostfs_user.c b/fs/hostfs/hostfs_user.c index 91ebfce..6777aa0 100644 --- a/fs/hostfs/hostfs_user.c +++ b/fs/hostfs/hostfs_user.c @@ -160,6 +160,11 @@ int fsync_file(int fd, int datasync) return 0; } +int replace_file(int oldfd, int fd) +{ + return dup2(oldfd, fd); +} + void close_file(void *stream) { close(*((int *) stream)); -- cgit v1.1