Use private futexes for semaphores, unless they are initialized with pshared != 0.

Change-Id: I534e36a7171cd37037ae03b910ba71ea6968286d
Note: previously, sem_init() would return an error if pshared != 0.

1 files changed, 57 insertions, 0 deletions

diff --git a/libc/private/bionic_futex.h b/libc/private/bionic_futex.h
new file mode 100644
index 0000000..eb49fb7
--- /dev/null
+++ b/libc/private/bionic_futex.h
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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.
+ */
+#ifndef _BIONIC_FUTEX_H
+#define _BIONIC_FUTEX_H
+
+#include <linux/futex.h>
+
+extern int __futex_wait(volatile void *ftx, int val, const struct timespec *timeout);
+extern int __futex_wake(volatile void *ftx, int count);
+
+extern int __futex_syscall3(volatile void *ftx, int op, int val);
+extern int __futex_syscall4(volatile void *ftx, int op, int val, const struct timespec *timeout);
+
+#ifndef FUTEX_PRIVATE_FLAG
+#define FUTEX_PRIVATE_FLAG  128
+#endif
+
+#ifndef FUTEX_WAIT_PRIVATE
+#define FUTEX_WAIT_PRIVATE  (FUTEX_WAIT|FUTEX_PRIVATE_FLAG)
+#endif
+
+#ifndef FUTEX_WAKE_PRIVATE
+#define FUTEX_WAKE_PRIVATE  (FUTEX_WAKE|FUTEX_PRIVATE_FLAG)
+#endif
+
+/* Like __futex_wait/wake, but take an additionnal 'pshared' argument.
+ * when non-0, this will use normal futexes. Otherwise, private futexes.
+ */
+extern int  __futex_wake_ex(volatile void *ftx, int pshared, int val);
+extern int  __futex_wait_ex(volatile void *ftx, int pshared, int val, const struct timespec *timeout);
+
+#endif /* _BIONIC_FUTEX_H */