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Unregister pthread_atfork handlers on dlclose()

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Change-Id: I326fdf6bb06bed12743f08980b5c69d849c015b8
This commit is contained in:
Dmitriy Ivanov 2014-11-20 20:47:02 -08:00
parent ff18108981
commit 6df122f852
13 changed files with 261 additions and 41 deletions
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2
libc/Android.mk
View file

@ -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.
@ -481,7 +482,6 @@ 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 \

1
libc/arch-arm64/bionic/crtbegin.c
View file

@ -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"

1
libc/arch-common/bionic/crtbegin.c
View file

@ -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

1
libc/arch-common/bionic/crtbegin_so.c
View file

@ -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

29
libc/arch-common/bionic/pthread_atfork.h Normal file
View file

@ -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);
}

1
libc/arch-mips/bionic/crtbegin.c
View file

@ -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"

122
libc/bionic/pthread_atfork.cpp
View file

@ -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);
}

16
libc/upstream-openbsd/lib/libc/stdlib/atexit.c → libc/stdlib/atexit.c
View file

@ -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;

0
libc/upstream-openbsd/lib/libc/stdlib/atexit.h → libc/stdlib/atexit.h
View file

25
tests/libs/Android.build.pthread_atfork.mk Normal file
View file

@ -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

6
tests/libs/Android.mk
View file

@ -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
@ -203,6 +204,11 @@ 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
#

21
tests/libs/pthread_atfork.cpp Normal file
View file

@ -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);
}

77
tests/pthread_test.cpp
View file

@ -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) {