Libc-320.tar.gz

[apple/libc.git] / stdio / FreeBSD / _flock_stub.c

diff --git a/stdio/FreeBSD/_flock_stub.c b/stdio/FreeBSD/_flock_stub.c
new file mode 100644 (file)
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+++ b/stdio/FreeBSD/_flock_stub.c
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+/*
+ * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *     This product includes software developed by John Birrell.
+ * 4. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * POSIX stdio FILE locking functions. These assume that the locking
+ * is only required at FILE structure level, not at file descriptor
+ * level too.
+ *
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD: src/lib/libc/stdio/_flock_stub.c,v 1.12 2002/03/22 21:53:04 obrien Exp $");
+
+#include "namespace.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <pthread.h>
+#include "un-namespace.h"
+
+#include "local.h"
+
+
+/*
+ * Weak symbols for externally visible functions in this file:
+ */
+__weak_reference(_flockfile, flockfile);
+__weak_reference(_flockfile_debug_stub, _flockfile_debug);
+__weak_reference(_ftrylockfile, ftrylockfile);
+__weak_reference(_funlockfile, funlockfile);
+
+/*
+ * We need to retain binary compatibility for a while.  So pretend
+ * that _lock is part of FILE * even though it is dereferenced off
+ * _extra now.  When we stop encoding the size of FILE into binaries
+ * this can be changed in stdio.h.  This will reduce the amount of
+ * code that has to change in the future (just remove this comment
+ * and #define).
+ */
+#define _lock _extra
+
+void
+_flockfile(FILE *fp)
+{
+       pthread_t curthread = _pthread_self();
+
+       if (fp->_lock->fl_owner == curthread)
+               fp->_lock->fl_count++;
+       else {
+               /*
+                * Make sure this mutex is treated as a private
+                * internal mutex:
+                */
+               _pthread_mutex_lock(&fp->_lock->fl_mutex);
+               fp->_lock->fl_owner = curthread;
+               fp->_lock->fl_count = 1;
+       }
+}
+
+/*
+ * This can be overriden by the threads library if it is linked in.
+ */
+void
+_flockfile_debug_stub(FILE *fp, char *fname, int lineno)
+{
+       _flockfile(fp);
+}
+
+int
+_ftrylockfile(FILE *fp)
+{
+       pthread_t curthread = _pthread_self();
+       int     ret = 0;
+
+       if (fp->_lock->fl_owner == curthread)
+               fp->_lock->fl_count++;
+       /*
+        * Make sure this mutex is treated as a private
+        * internal mutex:
+        */
+       else if (_pthread_mutex_trylock(&fp->_lock->fl_mutex) == 0) {
+               fp->_lock->fl_owner = curthread;
+               fp->_lock->fl_count = 1;
+       }
+       else
+               ret = -1;
+       return (ret);
+}
+
+void 
+_funlockfile(FILE *fp)
+{
+       pthread_t       curthread = _pthread_self();
+
+       /*
+        * Check if this file is owned by the current thread:
+        */
+       if (fp->_lock->fl_owner == curthread) {
+               /*
+                * Check if this thread has locked the FILE
+                * more than once:
+                */
+               if (fp->_lock->fl_count > 1)
+                       /*
+                        * Decrement the count of the number of
+                        * times the running thread has locked this
+                        * file:
+                        */
+                       fp->_lock->fl_count--;
+               else {
+                       /*
+                        * The running thread will release the
+                        * lock now:
+                        */
+                       fp->_lock->fl_count = 0;
+                       fp->_lock->fl_owner = NULL;
+                       _pthread_mutex_unlock(&fp->_lock->fl_mutex);
+               }
+       }
+}