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Update fflush(3) to return success on a read-only stream.

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This has small changes to what Apple uses for compliance
with SUSv3. The changes cause no secondary effects in the
gnulib tests (we pass them).

Obtained from:	Apple Inc. (Libc 997.90.3 with changes)
Reviewed by:	bde
Phabric:	D440
This commit is contained in:
Pedro F. Giffuni 2014-07-20 20:05:39 +00:00
parent 26cf239814
commit 05c9304f58
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=268924
1 changed files with 16 additions and 9 deletions
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25
lib/libc/stdio/fflush.c
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@ -60,7 +60,7 @@ fflush(FILE *fp)
/*
* There is disagreement about the correct behaviour of fflush()
* when passed a file which is not open for reading. According to
* when passed a file which is not open for writing. According to
* the ISO C standard, the behaviour is undefined.
* Under linux, such an fflush returns success and has no effect;
* under Windows, such an fflush is documented as behaving instead
@ -68,11 +68,13 @@ fflush(FILE *fp)
* Given that applications may be written with the expectation of
* either of these two behaviours, the only safe (non-astonishing)
* option is to return EBADF and ask that applications be fixed.
* SUSv3 now requires that fflush() returns success on a read-only
* stream.
*
*/
if ((fp->_flags & (__SWR | __SRW)) == 0) {
errno = EBADF;
retval = EOF;
} else
if ((fp->_flags & (__SWR | __SRW)) == 0)
retval = 0;
else
retval = __sflush(fp);
FUNLOCKFILE(fp);
return (retval);
@ -89,10 +91,9 @@ __fflush(FILE *fp)
if (fp == NULL)
return (_fwalk(sflush_locked));
if ((fp->_flags & (__SWR | __SRW)) == 0) {
errno = EBADF;
retval = EOF;
} else
if ((fp->_flags & (__SWR | __SRW)) == 0)
retval = 0;
else
retval = __sflush(fp);
return (retval);
}
@ -122,6 +123,12 @@ __sflush(FILE *fp)
for (; n > 0; n -= t, p += t) {
t = _swrite(fp, (char *)p, n);
if (t <= 0) {
/* Reset _p and _w. */
if (p > fp->_p) /* Some was written. */
memmove(fp->_p, p, n);
fp->_p += n;
if ((fp->_flags & (__SLBF | __SNBF)) == 0)
fp->_w -= n;
fp->_flags |= __SERR;
return (EOF);
}