[Bug libc/11319] New: dprintf doesn't handle errors proprerly

["kirill at shutemov dot name" <sourceware-bugzilla@sourceware.org>]

According to manpage dprintf(3) (actually return value described in manpage for
printf(3)) should return a negative value, if an output error is encountered.
But dprintf(3) return positive value, if underlying write(2) returns -1 and sets
errno=EINVAL.

$ cat dprintf_test.c 
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/eventfd.h>

int main(int argc, char **argv)
{
        int ret;
        int fd = eventfd(0, 0);

        /*
         * man 2 eventfd:
         *
         * A write(2) will fail with the error EINVAL if the size of the supplied
         * buffer is less than 8 bytes...
         */
        ret = dprintf(fd, "%d", 0);

        printf("%d: %s\n", ret, strerror(errno));

        return 0;
}
$ gcc -o dprintf_test dprintf_test.c 
$ ./dprintf_test
1: Invalid argument

$ strace ./dprintf_test
...
eventfd2(0, 0)                          = 3
...
write(3, "0", 1)                        = -1 EINVAL (Invalid argument)
...

-- 
           Summary: dprintf doesn't handle errors proprerly
           Product: glibc
           Version: 2.11
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: kirill at shutemov dot name
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=11319

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