Re: [PATCH 4/5 v2] set: check seek success

[Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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On Mon, Nov 10, 2014 at 09:31:55AM -0700, Stephen Warren wrote:
> On 11/10/2014 01:51 AM, Thierry Reding wrote:
> >On Sat, Nov 08, 2014 at 11:14:09PM +0100, Patrick Georgi wrote:
> >>This could silently fail which leads to surprising behaviour.
> >>
> >>Found-by: Coverity Scan
> >>Signed-off-by: Patrick Georgi <patrick-U1IrdZU7gScKt1dFYRw6Gg@public.gmane.org>
> >>---
> >>  src/set.c | 6 +++++-
> >>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>
> >>diff --git a/src/set.c b/src/set.c
> >>index ff32b53..907d640 100644
> >>--- a/src/set.c
> >>+++ b/src/set.c
> >>@@ -59,7 +59,11 @@ read_from_image(char	*filename,
> >>  		return result;
> >>  	}
> >>
> >>-	fseek(fp, offset, SEEK_SET);
> >>+	if (fseek(fp, offset, SEEK_SET) == -1) {
> >>+		printf("Error: Couldn't seek to %s(%d)\n", filename, offset);
> >
> >offset is unsigned, so the format specifier should be %u. I also wonder
> >whether it would be good to output errno along with the message (or the
> >string representation thereof) to increase the information content. But
> >given that none of the other error messages have that it could be a
> >separate patch.
> 
> Using perror() might be useful?

Indeed, that would also make these messages go to stderr instead of
stdout and be more idiomatic.

Thierry

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