libc MT-safety, part 2.

Add a lock to FILE.  flockfile and friends are now implemented
(for the most part) in libc.  flockfile_debug is implemented in
libc_r; I suppose it's about time to kill it but will do it in
a future commit.

Fix a potential deadlock in _fwalk in a threaded environment.
A file flag (__SIGN) was added to stdio.h that, when set, tells
_fwalk to ignore it in its walk.  This seemed to be needed in
refill.c because each file needs to be locked when flushing.

Add a stub for pthread_self in libc.  This is needed by flockfile
which is allowed by POSIX to be recursive.

Make fgetpos() error return value (-1) match man page.

Remove recursive calls to locked functions (stdio); I think I've
got them all, but I may have missed a couple.

A few K&R -> ANSI conversions along with removal of a few instances
of "register".

$Id$ -> $FreeBSD$ in libc/stdio/rget.c

Not objected to:	-arch, a few months ago

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/libc/stdio/fwalk.c b/lib/libc/stdio/fwalk.c
index 17cb5ce..b943be4 100644
--- a/lib/libc/stdio/fwalk.c
+++ b/lib/libc/stdio/fwalk.c
@@ -61,10 +61,13 @@ _fwalk(function)
 	 * It should be safe to walk the list without locking it;
 	 * new nodes are only added to the end and none are ever
 	 * removed.
+	 *
+	 * Avoid locking this list while walking it or else you will
+	 * introduce a potential deadlock in [at least] refill.c.
 	 */
 	for (g = &__sglue; g != NULL; g = g->next)
 		for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
-			if (fp->_flags != 0)
+			if ((fp->_flags != 0) && ((fp->_flags & __SIGN) == 0))
 				ret |= (*function)(fp);
 	return (ret);
 }