On 08/24/2016 06:40 PM, Martin Sebor wrote:
On 08/23/2016 05:00 PM, Joseph Myers wrote:
Some observations:
* Does -fprintf-return-value allow for the possibility of snprintf
failing
because of a memory allocation failure and so returning -1 when GCC
computed bounds on what it could return if successful?
No. I recall having seen Glibc fail with ENOMEM years ago when
formatting a floating point number to a very large precision but
I haven't seen any implementation fail. I haven't yet looked to
see if the Glibc failure can still happen. My reading of C and
POSIX is that snprintf is only allowed to fail due to an encoding
error, not because it runs out of memory, so such a failure would
seem like a bug.
It can still happen, and not just for floating point.
#include <stdio.h>
int
main()
{
printf("%0999999d\n", 5);
}
valgrind reports:
total heap usage: 1 allocs, 1 frees, 1,000,031 bytes allocated
We are certainly not proud of this state of affairs, but it is unlikely
to change anytime soon.
Florian
