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Fix the handle locking in stdio

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Fix the handle locking in stdio to use flockfile/funlockfile
internally when and where required.  Macros in <stdio.h> are updated
to automatically call the underlying functions when the process is
threaded to obtain the necessary locking.  A private mutex is added
to protect __sglue, the internal list of FILE handles, and another
to protect the one-time initialization.  Some routines in libc that
use getc() change to use getc_unlocked() as they're either protected
by their own lock or aren't thread-safe routines anyway.

Based on OpenBSD change by guenther@openbsd.org
http://www.mail-archive.com/source-changes@cvs.openbsd.org/msg01015.html

Bug: 3446659
Change-Id: Ie82116e358c541718d6709ec45ca6796be5a007b
This commit is contained in:
Kenny Root
2011-02-12 07:13:44 -08:00
parent 72f9a5c374
commit f582340a6a
36 changed files with 239 additions and 92 deletions
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13
libc/stdio/refill.c
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@@ -39,9 +39,8 @@
static int
lflush(FILE *fp)
{
if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
return (__sflush(fp));
return (__sflush_locked(fp)); /* ignored... */
return (0);
}
@@ -103,8 +102,16 @@ __srefill(FILE *fp)
* flush all line buffered output files, per the ANSI C
* standard.
*/
if (fp->_flags & (__SLBF|__SNBF))
if (fp->_flags & (__SLBF|__SNBF)) {
/* Ignore this file in _fwalk to avoid potential deadlock. */
fp->_flags |= __SIGN;
(void) _fwalk(lflush);
fp->_flags &= ~__SIGN;
/* Now flush this file without locking it. */
if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
__sflush(fp);
}
fp->_p = fp->_bf._base;
fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
fp->_flags &= ~__SMOD; /* buffer contents are again pristine */