From 6e5801f728a121cc002d7f6912dab2d9b60a3743 Mon Sep 17 00:00:00 2001
From: Roland McGrath <roland@gnu.org>
Date: Mon, 27 Mar 2000 18:19:46 +0000
Subject: 2000-03-27  Roland McGrath  <roland@baalperazim.frob.com>

	Locking support for stdio streams with glibc-2.2 libio.  EXPERIMENTAL!
	* lockfile.c: New file.
	* libthreads.map: New file.
	* Makefile (SRCS): Add lockfile.c.
	[$(VERSIONING) = yes] ($(libname).so.$(hurd-version)): Depend
	on $(srcdir)/$(libname).map to get version script into the link.
---
 libthreads/lockfile.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 libthreads/lockfile.c

(limited to 'libthreads/lockfile.c')

diff --git a/libthreads/lockfile.c b/libthreads/lockfile.c
new file mode 100644
index 00000000..b0b019de
--- /dev/null
+++ b/libthreads/lockfile.c
@@ -0,0 +1,101 @@
+/* lockfile - Handle locking and unlocking of stream.  Hurd cthreads version.
+   Copyright (C) 2000 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 Library General Public License as
+   published by the Free Software Foundation; either version 2 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <cthreads.h>		/* Must come before <stdio.h>! */
+
+#define _IO_MTSAFE_IO
+#include <stdio.h>
+
+#include <assert.h>
+
+
+#ifdef _STDIO_USES_IOSTREAM
+
+#undef _IO_flockfile
+#undef _IO_funlockfile
+#undef _IO_ftrylockfile
+
+void
+_cthreads_flockfile (_IO_FILE *fp)
+{
+  cthread_t self = cthread_self ();
+
+  if (fp->_lock->owner == self)
+    {
+      assert (fp->_lock->count != 0);
+      ++fp->_lock->count;
+    }
+  else
+    {
+      __mutex_lock (&fp->_lock->mutex);
+      assert (fp->_lock->owner == 0);
+      fp->_lock->owner = self;
+      assert (fp->_lock->count == 0);
+      fp->_lock->count = 1;
+    }
+}
+
+void
+_cthreads_funlockfile (_IO_FILE *fp)
+{
+  if (--fp->_lock->count == 0)
+    {
+      assert (fp->_lock->owner == cthread_self ());
+      fp->_lock->owner = 0;
+      __mutex_unlock (&fp->_lock->mutex);
+    }
+}
+
+int
+_cthreads_ftrylockfile (_IO_FILE *fp)
+{
+  cthread_t self = cthread_self ();
+
+  if (fp->_lock->owner == self)
+    {
+      assert (fp->_lock->count != 0);
+      ++fp->_lock->count;
+    }
+  else if (__mutex_try_lock (&fp->_lock->mutex))
+    {
+      assert (fp->_lock->owner == 0);
+      fp->_lock->owner = self;
+      assert (fp->_lock->count == 0);
+      fp->_lock->count = 1;
+    }
+  else
+    return 0;			/* No lock for us.  */
+
+  /* We got the lock. */
+  return 1;
+}
+
+#define strong_alias(src, dst)	asm (".globl " #dst "; " #dst " = " #src)
+#define weak_alias(src, dst)	asm (".weak " #dst  "; " #dst " = " #src)
+
+weak_alias (_cthreads_flockfile, _IO_flockfile);
+weak_alias (_cthreads_funlockfile, _IO_funlockfile);
+weak_alias (_cthreads_ftrylockfile, _IO_ftrylockfile);
+
+weak_alias (_cthreads_flockfile, flockfile);
+weak_alias (_cthreads_funlockfile, funlockfile);
+weak_alias (_cthreads_ftrylockfile, ftrylockfile);
+
+
+#endif /* _STDIO_USES_IOSTREAM */
-- 
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