[Android] [PATCH] Add pthread_once function from AOSP

[Edward Wang]

See:
http://www.compdigitec.com/labs/2012/06/25/fclose-freezes-when-run-inside-pthread-on-android-2-1/
http://code.google.com/p/android/issues/detail?id=5116

Summary:
Android 2.1/2.2's pthread implementation has a bug where fclose() hangs inside pthread. This commit imports a working version of pthread_once that makes VLC for Android work on Android 2.1 and 2.2.
---
 Version 4

 vlc-android/jni/Android.mk     |    5 ++-
 vlc-android/jni/pthread-once.c |   92 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+), 1 deletions(-)
 create mode 100644 vlc-android/jni/pthread-once.c

diff --git a/vlc-android/jni/Android.mk b/vlc-android/jni/Android.mk
index fbead7c..b613554 100644
--- a/vlc-android/jni/Android.mk
+++ b/vlc-android/jni/Android.mk
@@ -3,7 +3,7 @@ include $(CLEAR_VARS)
 
 LOCAL_MODULE    := libvlcjni
 
-LOCAL_SRC_FILES := libvlcjni.c aout.c thumbnailer.c pthread-condattr.c pthread-rwlocks.c eventfd.c sem.c
+LOCAL_SRC_FILES := libvlcjni.c aout.c thumbnailer.c pthread-condattr.c pthread-rwlocks.c pthread-once.c eventfd.c sem.c
 
 LOCAL_C_INCLUDES := $(VLC_SRC_DIR)/include
 
@@ -14,6 +14,9 @@ CPP_STATIC=$(ANDROID_NDK)/sources/cxx-stl/gnu-libstdc++/libs/$(ARCH)/libgnustl_s
 LOCAL_CFLAGS := -std=gnu99
 ifeq ($(ARCH), armeabi)
 	LOCAL_CFLAGS += -DHAVE_ARMEABI
+	# Needed by ARMv6 (the System Control coprocessor/CP15 is mandatory on ARMv6)
+	# On newer ARM architectures we can use Thumb2
+	LOCAL_ARM_MODE := arm
 endif
 ifeq ($(ARCH), armeabi-v7a)
 	LOCAL_CFLAGS += -DHAVE_ARMEABI_V7A
diff --git a/vlc-android/jni/pthread-once.c b/vlc-android/jni/pthread-once.c
new file mode 100644
index 0000000..8a6fa5b
--- /dev/null
+++ b/vlc-android/jni/pthread-once.c
@@ -0,0 +1,92 @@
+/*
+ * 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.
+ */
+#include <errno.h>
+#include <pthread.h>
+#include <unistd.h>
+
+#include <machine/cpu-features.h>
+
+/* Adapted from bionic_atomic_inline.h */
+static inline void ANDROID_MEMBAR_FULL() {
+    /* SMP */
+#ifdef __arm__
+    #if __ARM_ARCH__ >= 7
+    do { __asm__ __volatile__ ("dmb" ::: "memory"); } while (0);
+    #elif __ARM_ARCH__ == 6
+    /*
+     * For ARMv6 we need to issue a specific MCR instead of the DMB, since
+     * that wasn't added until v7.
+     *
+     * From: https://casper.berkeley.edu/svn/trunk/roach/sw/linux/include/asm-arm/system.h
+     */
+    do { __asm__ __volatile__ ("mcr p15, 0, %0, c7, c10, 5" :: "r" (0) : "memory"); } while (0);
+    #elif __ARM_ARCH__ < 6
+    /*
+     * For anything older, SMP isn't relevant.
+     */
+    #endif
+#elif (defined(__i386__) || defined(__x86_64__)) && defined(__SSE2__)
+    /*
+     * For recent x86, we can use the SSE2 mfence instruction.
+     */
+    do { __asm__ __volatile__ ("mfence" ::: "memory"); } while (0);
+#else
+    /*
+     * Implementation not defined for this platform.  Hopefully we're building
+     * in uniprocessor mode.
+     *
+     * For example: MIPS, PowerPC, etc
+     */
+#endif
+    /* Non-SMP fallback */
+    do { __asm__ __volatile__ ("" ::: "memory"); } while (0);
+}
+
+/* NOTE: this implementation doesn't support a init function that throws a C++ exception
+ *       or calls fork()
+ */
+int pthread_once( pthread_once_t*  once_control,  void (*init_routine)(void) )
+{
+    if( once_control == NULL || init_routine == NULL )
+        return EINVAL;
+    static pthread_mutex_t   once_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER;
+    volatile pthread_once_t* ocptr = once_control;
+
+    pthread_once_t tmp = *ocptr;
+    ANDROID_MEMBAR_FULL();
+    if (tmp == PTHREAD_ONCE_INIT) {
+        pthread_mutex_lock( &once_lock );
+        if (*ocptr == PTHREAD_ONCE_INIT) {
+            (*init_routine)();
+            ANDROID_MEMBAR_FULL();
+            *ocptr = ~PTHREAD_ONCE_INIT;
+        }
+        pthread_mutex_unlock( &once_lock );
+    }
+    return 0;
+}
-- 
1.7.5.4