[PATCH] blkdiscard: check that the file is a block device before opening

We need to enforce that the opened file is a block device, as opening a file with the O_EXCL flag on and the O_CREATE flag off has undefined behavior unless the file is a block device. Signed-off-by: Ari Sundholm --- util-linux/blkdiscard.c | 14 +- 1 file changed,

[PATCH v2] blkdiscard: check that the file is a block device before opening

We need to enforce that the opened file is a block device, as opening a file with the O_EXCL flag on and the O_CREAT flag off has undefined behavior unless the file is a block device. v2: Fix typo: O_CREAT, not O_CREATE. Signed-off-by: Ari Sundholm --- util-linux/blkdiscard.c

Re: [PATCH] blkdiscard: check that the file is a block device before opening

This patch just trades one undefined behaviour for another. I'd open first and then do fstat. Otherwise change your comment, because it isn't really enforcing anything with a race condition between the stat and the open. Sam On Tue, Jan 5, 2016 at 11:50 AM, Ari Sundholm wrote:

[PATCH v3] blkdiscard: check that the file is a block device before opening

Opening a file with the O_EXCL flag on and the O_CREAT flag off has undefined behavior unless the file is a block device. Let's try and avoid this case on a best-effort basis. The undefined behavior can still be hit if the block device is replaced with something else inbetween. v2: Fix typo:

Re: [PATCH] blkdiscard: check that the file is a block device before opening

Hi! Thanks for your comments. On Tue, 2016-01-05 at 11:54 +, Sam Liddicott wrote: > This patch just trades one undefined behaviour for another. I'd rather think of it as reducing the number of cases where we would get undefined behavior, while not completely eliminating them. > > I'd open