From: Keyhan Vakil <kvakil@berkeley.edu>
To: musl@lists.openwall.com
Subject: Bug in gets function?
Date: Mon, 11 Feb 2019 18:55:24 -0800 [thread overview]
Message-ID: <CABU-nVQmDvX2v_3V2ZJhvkBGrKgjBK0XRkejGVsKDU8ooYJ30A@mail.gmail.com> (raw)
Hi. It seems that the gets function does not follow the C99 spec. In
particular, if the input contains a null byte in the middle of the
input, then the new-line character is not discarded.
For reference, here's the relevant part in the C99 standard
(7.19.7.7):
> The gets function reads characters from the input stream pointed to
> by stdin, into the array pointed to by s, until end-of-file is
> encountered or a new-line character is read. Any new-line character
> is discarded, and a null character is written immediately after the
> last character read into the array.
Here is an example:
#include <stdio.h>
char s[8];
int main() {
gets(s);
for (int i = 0; i < sizeof s; i++) {
printf("%02x ", s[i]);
}
printf("\n");
return 0;
}
When compiled against gcc:
$ echo -e 'A\x00B' | ./a.out
41 00 42 00 00 00 00 00
When compiled against musl:
$ echo -e 'A\x00B' | ./a.out
41 00 42 0a 00 00 00 00
Note the terminating newline, which contradicts the spec.
Thanks,
Keyhan
next reply other threads:[~2019-02-12 2:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 2:55 Keyhan Vakil [this message]
2019-02-12 3:48 ` Rich Felker
2019-02-12 3:51 ` Rich Felker
2019-02-12 14:41 ` James Larrowe
2019-02-12 14:55 ` Ponnuvel Palaniyappan
2019-02-12 16:30 ` Rich Felker
2019-02-13 21:39 ` Alexey Izbyshev
2019-02-13 22:13 ` Rich Felker
2019-02-13 23:19 ` Alexey Izbyshev
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