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[Bug libc/11741] New: printf doesn't return a negative value in case of output error
- From: "vincent+libc at vinc17 dot org" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: 23 Jun 2010 08:44:41 -0000
- Subject: [Bug libc/11741] New: printf doesn't return a negative value in case of output error
- Reply-to: sourceware-bugzilla at sourceware dot org
For fprintf (thus printf), the C standard says:
The fprintf function returns the number of characters transmitted,
or a negative value if an output or encoding error occurred.
But printf doesn't return a negative value in case of output error (at least not
in some cases). For instance:
#include <stdio.h>
int main (void)
{
int r;
r = printf ("%10000s\n", "foo");
fprintf (stderr, "%d\n", r);
return 0;
}
Then I get:
$ ./out > /dev/null
10001
$ ./out >&-
8196
The first case is correct (anything can be written to /dev/null), but in the
second case (where the fd is closed), there's obviously an output error (the
return value is not 10001), but in such a case, r should have been negative.
Tested with glibc 2.11.2 on a Debian/unstable machine and on Fedora release 12
machine.
This bug looks like bug 1146, but that one was fixed 5 years ago.
--
Summary: printf doesn't return a negative value in case of output
error
Product: glibc
Version: 2.11
Status: NEW
Severity: normal
Priority: P2
Component: libc
AssignedTo: drepper at redhat dot com
ReportedBy: vincent+libc at vinc17 dot org
CC: glibc-bugs at sources dot redhat dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=11741
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