[COMMITTED] libio: Update internal fmemopen position after write (BZ #20005)
Commit Message
Current GLIBC fmemopen fails with a simple testcase:
char buffer[500] = "x";
FILE *stream;
stream = fmemopen(buffer, 500, "r+");
fwrite("fish",sizeof(char),5,stream);
printf("pos-1:%ld\n",ftell(stream));
fflush(stream);
printf("pos-2:%ld\n",ftell(stream));
It returns:
pos-1:5
pos-2:0
Where it should return:
pos-1:5
pos-2:5
This is due the internal write function does not correctly update the internal
object position state and then the seek operation returns a wrong value. This
patch fixes it.
It fixes both BZ #20005 and BZ #19230 (marked as duplicated). A new test is
added to check for such case.
Tested on x86_64 and i686.
* libio/fmemopen.c (fmemopen_write): Update internal position after
write.
* stdio-common/Makefile (tests): Add tst-fmemopen4.c.
* stdio-common/tst-fmemopen4.c: New file..
---
ChangeLog | 8 +++++
libio/fmemopen.c | 6 ++--
stdio-common/Makefile | 2 +-
stdio-common/tst-fmemopen4.c | 71 ++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 83 insertions(+), 4 deletions(-)
create mode 100644 stdio-common/tst-fmemopen4.c
Comments
Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:
> diff --git a/libio/fmemopen.c b/libio/fmemopen.c
> index 23b5c5f..9264b72 100644
> --- a/libio/fmemopen.c
> +++ b/libio/fmemopen.c
> @@ -86,10 +86,10 @@ fmemopen_write (void *cookie, const char *b, size_t s)
>
> memcpy (&(c->buffer[pos]), b, s);
>
> - pos += s;
> - if ((size_t) pos > c->maxpos)
> + c->pos += s;
> + if ((size_t) c->pos > c->maxpos)
> {
> - c->maxpos = pos;
> + c->maxpos = c->pos;
What happens if pos != c->pos in an append stream?
Andreas.
On 26/04/2016 18:07, Andreas Schwab wrote:
> Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:
>
>> diff --git a/libio/fmemopen.c b/libio/fmemopen.c
>> index 23b5c5f..9264b72 100644
>> --- a/libio/fmemopen.c
>> +++ b/libio/fmemopen.c
>> @@ -86,10 +86,10 @@ fmemopen_write (void *cookie, const char *b, size_t s)
>>
>> memcpy (&(c->buffer[pos]), b, s);
>>
>> - pos += s;
>> - if ((size_t) pos > c->maxpos)
>> + c->pos += s;
>> + if ((size_t) c->pos > c->maxpos)
>> {
>> - c->maxpos = pos;
>> + c->maxpos = c->pos;
>
> What happens if pos != c->pos in an append stream?
>
> Andreas.
>
I am trying to come up with a scenario where it will lead to failure.
Do you have some in mind?
Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:
> I am trying to come up with a scenario where it will lead to failure.
> Do you have some in mind?
You get a different value of c->maxpos.
Andreas.
@@ -1,3 +1,11 @@
+2016-04-26 Adhemerval Zanella <adhemerval.zanella@linaro.org>
+
+ [BZ #20005]
+ * libio/fmemopen.c (fmemopen_write): Update internal position after
+ write.
+ * stdio-common/Makefile (tests): Add tst-fmemopen4.c.
+ * stdio-common/tst-fmemopen4.c: New file..
+
2016-04-26 Joseph Myers <joseph@codesourcery.com>
[BZ #19996]
@@ -86,10 +86,10 @@ fmemopen_write (void *cookie, const char *b, size_t s)
memcpy (&(c->buffer[pos]), b, s);
- pos += s;
- if ((size_t) pos > c->maxpos)
+ c->pos += s;
+ if ((size_t) c->pos > c->maxpos)
{
- c->maxpos = pos;
+ c->maxpos = c->pos;
if (addnullc)
c->buffer[c->maxpos] = '\0';
}
@@ -58,7 +58,7 @@ tests := tstscanf test_rdwr test-popen tstgetln test-fseek \
scanf16 scanf17 tst-setvbuf1 tst-grouping bug23 bug24 \
bug-vfprintf-nargs tst-long-dbl-fphex tst-fphex-wide tst-sprintf3 \
bug25 tst-printf-round bug23-2 bug23-3 bug23-4 bug26 tst-fmemopen3 \
- tst-printf-bz18872 tst-vfprintf-width-prec
+ tst-printf-bz18872 tst-vfprintf-width-prec tst-fmemopen4
test-srcs = tst-unbputc tst-printf
new file mode 100644
@@ -0,0 +1,71 @@
+/* fmemopen tests for BZ#1930 and BZ#20005.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+
+
+/* Check if fflush does not reset the file position. */
+static int
+do_test (void)
+{
+ char buffer[500] = "x";
+
+ FILE *stream = fmemopen (buffer, sizeof (buffer), "r+");
+ if (stream == NULL)
+ {
+ printf ("error: fmemopen could not open stream\n");
+ return 1;
+ }
+
+ const char test[] = "test";
+
+ size_t r = fwrite (test, sizeof (char), sizeof (test), stream);
+ if (r != sizeof (test))
+ {
+ printf ("error: fwrite returned %zu, expected %zu\n", r, sizeof(test));
+ return 1;
+ }
+
+ r = ftell (stream);
+ if (r != sizeof (test))
+ {
+ printf ("error: ftell return %zu, expected %zu\n", r, sizeof(test));
+ return 1;
+ }
+
+ if (fflush (stream) != 0)
+ {
+ printf ("error: fflush failed\n");
+ return 1;
+ }
+
+ r = ftell (stream);
+ if (r != sizeof (test))
+ {
+ printf ("error: ftell return %zu, expected %zu\n", r, sizeof(test));
+ return 1;
+ }
+
+ return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"