Merge "Unregister pthread_atfork handlers on dlclose()"

13 files changed, 270 insertions, 47 deletions

diff --git a/libc/Android.mk b/libc/Android.mk
index 2175dc4..a9fed2c 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -63,6 +63,7 @@ libc_common_src_files := \
     stdio/sprintf.c \
     stdio/stdio.c \
     stdio/stdio_ext.cpp \
+    stdlib/atexit.c \
     stdlib/exit.c \
 
 # Fortify implementations of libc functions.
@@ -482,7 +483,6 @@ libc_upstream_openbsd_ndk_src_files := \
     upstream-openbsd/lib/libc/stdio/wprintf.c \
     upstream-openbsd/lib/libc/stdio/wscanf.c \
     upstream-openbsd/lib/libc/stdio/wsetup.c \
-    upstream-openbsd/lib/libc/stdlib/atexit.c \
     upstream-openbsd/lib/libc/stdlib/atoi.c \
     upstream-openbsd/lib/libc/stdlib/atol.c \
     upstream-openbsd/lib/libc/stdlib/atoll.c \
@@ -1340,10 +1340,13 @@ LOCAL_CPPFLAGS := $(libc_common_cppflags)
 
 LOCAL_C_INCLUDES := $(libc_common_c_includes)
 LOCAL_SRC_FILES := \
+    arch-common/bionic/crtbegin_so.c \
+    arch-common/bionic/crtbrand.S \
     $(libc_arch_dynamic_src_files) \
     bionic/malloc_debug_common.cpp \
     bionic/libc_init_dynamic.cpp \
     bionic/NetdClient.cpp \
+    arch-common/bionic/crtend_so.S \
 
 LOCAL_MODULE := libc
 LOCAL_CLANG := $(use_clang)
@@ -1388,15 +1391,15 @@ LOCAL_LDFLAGS_arm := -Wl,--hash-style=sysv
 
 $(eval $(call patch-up-arch-specific-flags,LOCAL_CFLAGS,libc_common_cflags))
 $(eval $(call patch-up-arch-specific-flags,LOCAL_SRC_FILES,libc_arch_dynamic_src_files))
+
+LOCAL_NO_CRT := true
+LOCAL_ASFLAGS += $(libc_crt_target_cflags)
+
 # special for arm
-LOCAL_NO_CRT_arm := true
 LOCAL_CFLAGS_arm += -DCRT_LEGACY_WORKAROUND
-LOCAL_ASFLAGS_arm += $(libc_crt_target_cflags)
 LOCAL_SRC_FILES_arm += \
-    arch-common/bionic/crtbegin_so.c \
-    arch-common/bionic/crtbrand.S \
-    arch-arm/bionic/atexit_legacy.c \
-    arch-common/bionic/crtend_so.S
+    arch-arm/bionic/atexit_legacy.c
+
 LOCAL_ADDRESS_SANITIZER := false
 LOCAL_NATIVE_COVERAGE := $(bionic_coverage)
 
diff --git a/libc/arch-arm64/bionic/crtbegin.c b/libc/arch-arm64/bionic/crtbegin.c
index fec0b11..7e2c5d7 100644
--- a/libc/arch-arm64/bionic/crtbegin.c
+++ b/libc/arch-arm64/bionic/crtbegin.c
@@ -67,3 +67,4 @@ __asm__ (
 
 #include "../../arch-common/bionic/__dso_handle.h"
 #include "../../arch-common/bionic/atexit.h"
+#include "../../arch-common/bionic/pthread_atfork.h"
diff --git a/libc/arch-common/bionic/crtbegin.c b/libc/arch-common/bionic/crtbegin.c
index fa9f3f3..c46405c 100644
--- a/libc/arch-common/bionic/crtbegin.c
+++ b/libc/arch-common/bionic/crtbegin.c
@@ -59,6 +59,7 @@ void _start() {
 
 #include "__dso_handle.h"
 #include "atexit.h"
+#include "pthread_atfork.h"
 #ifdef __i386__
 # include "../../arch-x86/bionic/__stack_chk_fail_local.h"
 #endif
diff --git a/libc/arch-common/bionic/crtbegin_so.c b/libc/arch-common/bionic/crtbegin_so.c
index 641e45a..3754363 100644
--- a/libc/arch-common/bionic/crtbegin_so.c
+++ b/libc/arch-common/bionic/crtbegin_so.c
@@ -56,6 +56,7 @@ void __on_dlclose() {
 # include "__dso_handle_so.h"
 # include "atexit.h"
 #endif
+#include "pthread_atfork.h"
 #ifdef __i386__
 # include "../../arch-x86/bionic/__stack_chk_fail_local.h"
 #endif
diff --git a/libc/arch-common/bionic/pthread_atfork.h b/libc/arch-common/bionic/pthread_atfork.h
new file mode 100644
index 0000000..0c48a12
--- /dev/null
+++ b/libc/arch-common/bionic/pthread_atfork.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+extern void* __dso_handle;
+
+extern int __register_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void), void* dso);
+
+#ifndef _LIBC
+// Libc used to export this in previous versions, therefore it needs
+// to remain global for binary compatibility.
+__attribute__ ((visibility ("hidden")))
+#endif
+int pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void)) {
+  return __register_atfork(prepare, parent, child, &__dso_handle);
+}
+
diff --git a/libc/arch-mips/bionic/crtbegin.c b/libc/arch-mips/bionic/crtbegin.c
index 50e9eeb..d72ec7b 100644
--- a/libc/arch-mips/bionic/crtbegin.c
+++ b/libc/arch-mips/bionic/crtbegin.c
@@ -92,3 +92,4 @@ __asm__ (
 
 #include "../../arch-common/bionic/__dso_handle.h"
 #include "../../arch-common/bionic/atexit.h"
+#include "../../arch-common/bionic/pthread_atfork.h"
diff --git a/libc/bionic/pthread_atfork.cpp b/libc/bionic/pthread_atfork.cpp
index d1c4ad0..093ffd2 100644
--- a/libc/bionic/pthread_atfork.cpp
+++ b/libc/bionic/pthread_atfork.cpp
@@ -30,6 +30,8 @@
 #include <pthread.h>
 #include <stdlib.h>
 
+#include "private/bionic_macros.h"
+
 struct atfork_t {
   atfork_t* next;
   atfork_t* prev;
@@ -37,79 +39,143 @@ struct atfork_t {
   void (*prepare)(void);
   void (*child)(void);
   void (*parent)(void);
+
+  void* dso_handle;
 };
 
-struct atfork_list_t {
-  atfork_t* first;
-  atfork_t* last;
+class atfork_list_t {
+ public:
+  atfork_list_t() : first_(nullptr), last_(nullptr) {}
+
+  template<typename F>
+  void walk_forward(F f) {
+    for (atfork_t* it = first_; it != nullptr; it = it->next) {
+      f(it);
+    }
+  }
+
+  template<typename F>
+  void walk_backwards(F f) {
+    for (atfork_t* it = last_; it != nullptr; it = it->prev) {
+      f(it);
+    }
+  }
+
+  void push_back(atfork_t* entry) {
+    entry->next = nullptr;
+    entry->prev = last_;
+    if (entry->prev != nullptr) {
+      entry->prev->next = entry;
+    }
+    if (first_ == nullptr) {
+      first_ = entry;
+    }
+    last_ = entry;
+  }
+
+  template<typename F>
+  void remove_if(F predicate) {
+    atfork_t* it = first_;
+    while (it != nullptr) {
+      if (predicate(it)) {
+        atfork_t* entry = it;
+        it = it->next;
+        remove(entry);
+      } else {
+        it = it->next;
+      }
+    }
+  }
+
+ private:
+  void remove(atfork_t* entry) {
+    if (entry->prev != nullptr) {
+      entry->prev->next = entry->next;
+    } else {
+      first_ = entry->next;
+    }
+
+    if (entry->next != nullptr) {
+      entry->next->prev = entry->prev;
+    } else {
+      last_ = entry->prev;
+    }
+
+    free(entry);
+  }
+
+  atfork_t* first_;
+  atfork_t* last_;
+
+  DISALLOW_COPY_AND_ASSIGN(atfork_list_t);
 };
 
 static pthread_mutex_t g_atfork_list_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
-static atfork_list_t g_atfork_list = { NULL, NULL };
+static atfork_list_t g_atfork_list;
 
 void __bionic_atfork_run_prepare() {
   // We lock the atfork list here, unlock it in the parent, and reset it in the child.
   // This ensures that nobody can modify the handler array between the calls
   // to the prepare and parent/child handlers.
-  //
-  // TODO: If a handler tries to mutate the list, they'll block. We should probably copy
-  // the list before forking, and have prepare, parent, and child all work on the consistent copy.
   pthread_mutex_lock(&g_atfork_list_mutex);
 
   // 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 = g_atfork_list.last; it != NULL; it = it->prev) {
-    if (it->prepare != NULL) {
+  g_atfork_list.walk_backwards([](atfork_t* it) {
+    if (it->prepare != nullptr) {
       it->prepare();
     }
-  }
+  });
 }
 
 void __bionic_atfork_run_child() {
-  for (atfork_t* it = g_atfork_list.first; it != NULL; it = it->next) {
-    if (it->child != NULL) {
+  g_atfork_list.walk_forward([](atfork_t* it) {
+    if (it->child != nullptr) {
       it->child();
     }
-  }
+  });
 
   g_atfork_list_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
 }
 
 void __bionic_atfork_run_parent() {
-  for (atfork_t* it = g_atfork_list.first; it != NULL; it = it->next) {
-    if (it->parent != NULL) {
+  g_atfork_list.walk_forward([](atfork_t* it) {
+    if (it->parent != nullptr) {
       it->parent();
     }
-  }
+  });
 
   pthread_mutex_unlock(&g_atfork_list_mutex);
 }
 
-int pthread_atfork(void (*prepare)(void), void (*parent)(void), void(*child)(void)) {
+// __register_atfork is the name used by glibc
+extern "C" int __register_atfork(void (*prepare)(void), void (*parent)(void),
+                                 void(*child)(void), void* dso) {
   atfork_t* entry = reinterpret_cast<atfork_t*>(malloc(sizeof(atfork_t)));
-  if (entry == NULL) {
+  if (entry == nullptr) {
     return ENOMEM;
   }
 
   entry->prepare = prepare;
   entry->parent = parent;
   entry->child = child;
+  entry->dso_handle = dso;
 
   pthread_mutex_lock(&g_atfork_list_mutex);
 
-  // Append 'entry' to the list.
-  entry->next = NULL;
-  entry->prev = g_atfork_list.last;
-  if (entry->prev != NULL) {
-    entry->prev->next = entry;
-  }
-  if (g_atfork_list.first == NULL) {
-    g_atfork_list.first = entry;
-  }
-  g_atfork_list.last = entry;
+  g_atfork_list.push_back(entry);
 
   pthread_mutex_unlock(&g_atfork_list_mutex);
 
   return 0;
 }
+
+extern "C" __LIBC_HIDDEN__ void __unregister_atfork(void* dso) {
+  pthread_mutex_lock(&g_atfork_list_mutex);
+  g_atfork_list.remove_if([&](const atfork_t* entry) {
+    return entry->dso_handle == dso;
+  });
+  pthread_mutex_unlock(&g_atfork_list_mutex);
+}
+
diff --git a/libc/upstream-openbsd/lib/libc/stdlib/atexit.c b/libc/stdlib/atexit.c
index 6532b38..df2b1b5 100644
--- a/libc/upstream-openbsd/lib/libc/stdlib/atexit.c
+++ b/libc/stdlib/atexit.c
@@ -35,11 +35,15 @@
 #include <string.h>
 #include <unistd.h>
 #include "atexit.h"
-#include "thread_private.h"
+#include "private/thread_private.h"
 
 struct atexit *__atexit;
 static int restartloop;
 
+/* BEGIN android-changed: __unregister_atfork is used by __cxa_finalize */
+extern void __unregister_atfork(void* dso);
+/* END android-changed */
+
 /*
  * Function pointers are stored in a linked list of pages. The list
  * is initially empty, and pages are allocated on demand. The first
@@ -62,7 +66,7 @@ __cxa_atexit(void (*func)(void *), void *arg, void *dso)
 {
 	struct atexit *p = __atexit;
 	struct atexit_fn *fnp;
-	int pgsize = getpagesize();
+	size_t pgsize = getpagesize();
 	int ret = -1;
 
 	if (pgsize < sizeof(*p))
@@ -161,6 +165,12 @@ restart:
 		__atexit = NULL;
 	}
 	_ATEXIT_UNLOCK();
+
+  /* BEGIN android-changed: call __unregister_atfork if dso is not null */
+  if (dso != NULL) {
+    __unregister_atfork(dso);
+  }
+  /* END android-changed */
 }
 
 /*
@@ -170,7 +180,7 @@ void
 __atexit_register_cleanup(void (*func)(void))
 {
 	struct atexit *p;
-	int pgsize = getpagesize();
+	size_t pgsize = getpagesize();
 
 	if (pgsize < sizeof(*p))
 		return;
diff --git a/libc/upstream-openbsd/lib/libc/stdlib/atexit.h b/libc/stdlib/atexit.h
index 3de2aa3..3de2aa3 100644
--- a/libc/upstream-openbsd/lib/libc/stdlib/atexit.h
+++ b/libc/stdlib/atexit.h
diff --git a/tests/libs/Android.build.pthread_atfork.mk b/tests/libs/Android.build.pthread_atfork.mk
new file mode 100644
index 0000000..72ffec4
--- /dev/null
+++ b/tests/libs/Android.build.pthread_atfork.mk
@@ -0,0 +1,25 @@
+#
+# Copyright (C) 2014 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# -----------------------------------------------------------------------------
+# This library used to test phtread_atfork handler behaviour
+# during/after dlclose.
+# -----------------------------------------------------------------------------
+libtest_pthread_atfork_src_files := pthread_atfork.cpp
+
+module := libtest_pthread_atfork
+include $(LOCAL_PATH)/Android.build.testlib.mk
+
diff --git a/tests/libs/Android.mk b/tests/libs/Android.mk
index 8afe177..c432c2e 100644
--- a/tests/libs/Android.mk
+++ b/tests/libs/Android.mk
@@ -25,6 +25,7 @@ common_additional_dependencies := \
     $(LOCAL_PATH)/Android.build.dlopen_check_order_dlsym.mk \
     $(LOCAL_PATH)/Android.build.dlopen_check_order_reloc_siblings.mk \
     $(LOCAL_PATH)/Android.build.dlopen_check_order_reloc_main_executable.mk \
+    $(LOCAL_PATH)/Android.build.pthread_atfork.mk \
     $(LOCAL_PATH)/Android.build.testlib.mk \
     $(LOCAL_PATH)/Android.build.versioned_lib.mk \
     $(TEST_PATH)/Android.build.mk
@@ -204,6 +205,11 @@ include $(LOCAL_PATH)/Android.build.dlopen_check_order_reloc_main_executable.mk
 include $(LOCAL_PATH)/Android.build.versioned_lib.mk
 
 # -----------------------------------------------------------------------------
+# Build libraries needed by pthread_atfork tests
+# -----------------------------------------------------------------------------
+include $(LOCAL_PATH)/Android.build.pthread_atfork.mk
+
+# -----------------------------------------------------------------------------
 # Library with dependency loop used by dlfcn tests
 #
 # libtest_with_dependency_loop -> a -> b -> c -> a
diff --git a/tests/libs/pthread_atfork.cpp b/tests/libs/pthread_atfork.cpp
new file mode 100644
index 0000000..3a5aa4f
--- /dev/null
+++ b/tests/libs/pthread_atfork.cpp
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <pthread.h>
+
+extern "C" int proxy_pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void)) {
+  return pthread_atfork(prepare, parent, child);
+}
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index a299f02..b8cfd56 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -16,6 +16,7 @@
 
 #include <gtest/gtest.h>
 
+#include <dlfcn.h>
 #include <errno.h>
 #include <inttypes.h>
 #include <limits.h>
@@ -987,14 +988,14 @@ TEST(pthread, pthread_once_1934122) {
 }
 
 static int g_atfork_prepare_calls = 0;
-static void AtForkPrepare1() { g_atfork_prepare_calls = (g_atfork_prepare_calls << 4) | 1; }
-static void AtForkPrepare2() { g_atfork_prepare_calls = (g_atfork_prepare_calls << 4) | 2; }
+static void AtForkPrepare1() { g_atfork_prepare_calls = (g_atfork_prepare_calls * 10) + 1; }
+static void AtForkPrepare2() { g_atfork_prepare_calls = (g_atfork_prepare_calls * 10) + 2; }
 static int g_atfork_parent_calls = 0;
-static void AtForkParent1() { g_atfork_parent_calls = (g_atfork_parent_calls << 4) | 1; }
-static void AtForkParent2() { g_atfork_parent_calls = (g_atfork_parent_calls << 4) | 2; }
+static void AtForkParent1() { g_atfork_parent_calls = (g_atfork_parent_calls * 10) + 1; }
+static void AtForkParent2() { g_atfork_parent_calls = (g_atfork_parent_calls * 10) + 2; }
 static int g_atfork_child_calls = 0;
-static void AtForkChild1() { g_atfork_child_calls = (g_atfork_child_calls << 4) | 1; }
-static void AtForkChild2() { g_atfork_child_calls = (g_atfork_child_calls << 4) | 2; }
+static void AtForkChild1() { g_atfork_child_calls = (g_atfork_child_calls * 10) + 1; }
+static void AtForkChild2() { g_atfork_child_calls = (g_atfork_child_calls * 10) + 2; }
 
 TEST(pthread, pthread_atfork_smoke) {
   ASSERT_EQ(0, pthread_atfork(AtForkPrepare1, AtForkParent1, AtForkChild1));
@@ -1005,13 +1006,71 @@ TEST(pthread, pthread_atfork_smoke) {
 
   // Child and parent calls are made in the order they were registered.
   if (pid == 0) {
-    ASSERT_EQ(0x12, g_atfork_child_calls);
+    ASSERT_EQ(12, g_atfork_child_calls);
     _exit(0);
   }
-  ASSERT_EQ(0x12, g_atfork_parent_calls);
+  ASSERT_EQ(12, g_atfork_parent_calls);
 
   // Prepare calls are made in the reverse order.
-  ASSERT_EQ(0x21, g_atfork_prepare_calls);
+  ASSERT_EQ(21, g_atfork_prepare_calls);
+  int status;
+  ASSERT_EQ(pid, waitpid(pid, &status, 0));
+}
+
+static void AtForkPrepare3() { g_atfork_prepare_calls = (g_atfork_prepare_calls * 10) + 3; }
+static void AtForkPrepare4() { g_atfork_prepare_calls = (g_atfork_prepare_calls * 10) + 4; }
+
+static void AtForkParent3() { g_atfork_parent_calls = (g_atfork_parent_calls * 10) + 3; }
+static void AtForkParent4() { g_atfork_parent_calls = (g_atfork_parent_calls * 10) + 4; }
+
+static void AtForkChild3() { g_atfork_child_calls = (g_atfork_child_calls * 10) + 3; }
+static void AtForkChild4() { g_atfork_child_calls = (g_atfork_child_calls * 10) + 4; }
+
+TEST(pthread, pthread_atfork_with_dlclose) {
+  ASSERT_EQ(0, pthread_atfork(AtForkPrepare1, AtForkParent1, AtForkChild1));
+
+  void* handle = dlopen("libtest_pthread_atfork.so", RTLD_NOW | RTLD_LOCAL);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+  typedef int (*fn_t)(void (*)(void), void (*)(void), void (*)(void));
+  fn_t fn = reinterpret_cast<fn_t>(dlsym(handle, "proxy_pthread_atfork"));
+  ASSERT_TRUE(fn != nullptr) << dlerror();
+  // the library registers 2 additional atfork handlers in a constructor
+  ASSERT_EQ(0, fn(AtForkPrepare2, AtForkParent2, AtForkChild2));
+  ASSERT_EQ(0, fn(AtForkPrepare3, AtForkParent3, AtForkChild3));
+
+  ASSERT_EQ(0, pthread_atfork(AtForkPrepare4, AtForkParent4, AtForkChild4));
+
+  int pid = fork();
+
+  ASSERT_NE(-1, pid) << strerror(errno);
+
+  if (pid == 0) {
+    ASSERT_EQ(1234, g_atfork_child_calls);
+    _exit(0);
+  }
+
+  ASSERT_EQ(1234, g_atfork_parent_calls);
+  ASSERT_EQ(4321, g_atfork_prepare_calls);
+
+  EXPECT_EQ(0, dlclose(handle));
+  g_atfork_prepare_calls = g_atfork_parent_calls = g_atfork_child_calls = 0;
+
+  int status;
+  ASSERT_EQ(pid, waitpid(pid, &status, 0));
+
+  pid = fork();
+
+  ASSERT_NE(-1, pid) << strerror(errno);
+
+  if (pid == 0) {
+    ASSERT_EQ(14, g_atfork_child_calls);
+    _exit(0);
+  }
+
+  ASSERT_EQ(14, g_atfork_parent_calls);
+  ASSERT_EQ(41, g_atfork_prepare_calls);
+
+  ASSERT_EQ(pid, waitpid(pid, &status, 0));
 }
 
 TEST(pthread, pthread_attr_getscope) {