1 files changed, 120 insertions, 0 deletions
diff --git a/libc/bionic/pthread_atfork.cpp b/libc/bionic/pthread_atfork.cpp
new file mode 100644
index 0000000..5bf63fb
--- /dev/null
+++ b/libc/bionic/pthread_atfork.cpp
@@ -0,0 +1,120 @@
+/*
+ * 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>
+
+static pthread_mutex_t gAtForkListMutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER;
+
+struct atfork_t {
+  atfork_t* next;
+  atfork_t* prev;
+
+  void (*prepare)(void);
+  void (*child)(void);
+  void (*parent)(void);
+};
+
+struct atfork_list_t {
+  atfork_t* first;
+  atfork_t* last;
+};
+
+static atfork_list_t gAtForkList = { NULL, NULL };
+
+void __bionic_atfork_run_prepare() {
+  // We will lock this here, and unlock it in the parent and child functions.
+  // This ensures that nobody can modify the handler array between the calls
+  // to the prepare and parent/child handlers.
+  //
+  // TODO: If a handler mucks with the list, it could cause problems.  Right
+  //       now it's ok because all they can do is add new items to the end
+  //       of the list, but if/when we implement cleanup in dlclose() things
+  //       will get more interesting...
+  pthread_mutex_lock(&gAtForkListMutex);
+
+  // Call pthread_atfork() prepare handlers. POSIX states that the prepare
+  // handlers should be called in the reverse order of the parent/child
+  // handlers, so we iterate backwards.
+  for (atfork_t* it = gAtForkList.last; it != NULL; it = it->prev) {
+    if (it->prepare != NULL) {
+      it->prepare();
+    }
+  }
+}
+
+void __bionic_atfork_run_child() {
+  for (atfork_t* it = gAtForkList.first; it != NULL; it = it->next) {
+    if (it->child != NULL) {
+      it->child();
+    }
+  }
+
+  pthread_mutexattr_t attr;
+  pthread_mutexattr_init(&attr);
+  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+  pthread_mutex_init(&gAtForkListMutex, &attr);
+}
+
+void __bionic_atfork_run_parent() {
+  for (atfork_t* it = gAtForkList.first; it != NULL; it = it->next) {
+    if (it->parent != NULL) {
+      it->parent();
+    }
+  }
+
+  pthread_mutex_unlock(&gAtForkListMutex);
+}
+
+int pthread_atfork(void (*prepare)(void), void (*parent)(void), void(*child)(void)) {
+  atfork_t* entry = reinterpret_cast<atfork_t*>(malloc(sizeof(atfork_t)));
+  if (entry == NULL) {
+    return ENOMEM;
+  }
+
+  entry->prepare = prepare;
+  entry->parent = parent;
+  entry->child = child;
+
+  pthread_mutex_lock(&gAtForkListMutex);
+
+  // Append 'entry' to the list.
+  entry->next = NULL;
+  entry->prev = gAtForkList.last;
+  if (entry->prev != NULL) {
+    entry->prev->next = entry;
+  }
+  if (gAtForkList.first == NULL) {
+    gAtForkList.first = entry;
+  }
+  gAtForkList.last = entry;
+
+  pthread_mutex_unlock(&gAtForkListMutex);
+
+  return 0;
+}