mirror of
https://github.com/chromium/crashpad.git
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Revert "posix: Replace DoubleForkAndExec() with ForkAndSpawn()"
This reverts commit 460943dd9a71dc76f68182a8ede766d5543e5341.
Reason for revert: This fails to compile in Chromium Android.
posix_spawn and posix_spawnp are available in Android NDK 28, but
Chromium is building with version 23.
https://ci.chromium.org/ui/p/chromium/builders/try/android_compile_dbg/1179765/overview
Original change's description:
> posix: Replace DoubleForkAndExec() with ForkAndSpawn()
>
> The DoubleForkAndExec() function was taking over 622 milliseconds to run
> on macOS 11 (BigSur) on Intel i5-1038NG7. I did some debugging by adding
> some custom traces and found that the fork() syscall is the bottleneck
> here, i.e., the first fork() takes around 359 milliseconds and the
> nested fork() takes around 263 milliseconds. Replacing the nested fork()
> and exec() with posix_spawn() reduces the time consumption to 257
> milliseconds!
>
> See https://github.com/libuv/libuv/pull/3064 to know why fork() is so
> slow on macOS and why posix_spawn() is a better replacement.
>
> Another point to note is that even base::LaunchProcess() from Chromium
> calls posix_spawnp() on macOS -
> 8f8d82dea0
:base/process/launch_mac.cc;l=295-296
>
> Change-Id: I25c6ee9629a1ae5d0c32b361b56a1ce0b4b0fd26
> Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/3641386
> Reviewed-by: Mark Mentovai <mark@chromium.org>
> Commit-Queue: Mark Mentovai <mark@chromium.org>
Change-Id: I7f6161bc4734c50308438cdde1e193023ee9bfb8
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/3719439
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
This commit is contained in:
parent
23cefd0417
commit
6e946c4af8
1
AUTHORS
1
AUTHORS
@ -12,4 +12,3 @@ Opera Software ASA
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Vewd Software AS
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Vewd Software AS
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LG Electronics, Inc.
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LG Electronics, Inc.
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MIPS Technologies, Inc.
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MIPS Technologies, Inc.
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Darshan Sen <raisinten@gmail.com>
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@ -45,7 +45,7 @@
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#include "util/linux/socket.h"
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#include "util/linux/socket.h"
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#include "util/misc/address_sanitizer.h"
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#include "util/misc/address_sanitizer.h"
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#include "util/misc/from_pointer_cast.h"
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#include "util/misc/from_pointer_cast.h"
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#include "util/posix/fork_and_spawn.h"
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#include "util/posix/double_fork_and_exec.h"
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#include "util/posix/scoped_mmap.h"
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#include "util/posix/scoped_mmap.h"
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#include "util/posix/signals.h"
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#include "util/posix/signals.h"
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@ -459,7 +459,7 @@ bool CrashpadClient::StartHandler(
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argv.push_back(FormatArgumentInt("initial-client-fd", handler_sock.get()));
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argv.push_back(FormatArgumentInt("initial-client-fd", handler_sock.get()));
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argv.push_back("--shared-client-connection");
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argv.push_back("--shared-client-connection");
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if (!ForkAndSpawn(argv, nullptr, handler_sock.get(), false, nullptr)) {
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if (!DoubleForkAndExec(argv, nullptr, handler_sock.get(), false, nullptr)) {
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return false;
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return false;
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}
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}
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@ -614,7 +614,7 @@ bool CrashpadClient::StartJavaHandlerForClient(
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int socket) {
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int socket) {
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std::vector<std::string> argv = BuildAppProcessArgs(
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std::vector<std::string> argv = BuildAppProcessArgs(
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class_name, database, metrics_dir, url, annotations, arguments, socket);
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class_name, database, metrics_dir, url, annotations, arguments, socket);
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return ForkAndSpawn(argv, env, socket, false, nullptr);
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return DoubleForkAndExec(argv, env, socket, false, nullptr);
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}
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}
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bool CrashpadClient::StartHandlerWithLinkerAtCrash(
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bool CrashpadClient::StartHandlerWithLinkerAtCrash(
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@ -663,7 +663,7 @@ bool CrashpadClient::StartHandlerWithLinkerForClient(
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annotations,
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annotations,
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arguments,
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arguments,
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socket);
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socket);
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return ForkAndSpawn(argv, env, socket, false, nullptr);
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return DoubleForkAndExec(argv, env, socket, false, nullptr);
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}
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}
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#endif
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#endif
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@ -697,7 +697,7 @@ bool CrashpadClient::StartHandlerForClient(
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argv.push_back(FormatArgumentInt("initial-client-fd", socket));
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argv.push_back(FormatArgumentInt("initial-client-fd", socket));
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return ForkAndSpawn(argv, nullptr, socket, true, nullptr);
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return DoubleForkAndExec(argv, nullptr, socket, true, nullptr);
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}
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}
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// static
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// static
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@ -36,7 +36,7 @@
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#include "util/mach/notify_server.h"
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#include "util/mach/notify_server.h"
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#include "util/misc/clock.h"
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#include "util/misc/clock.h"
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#include "util/misc/implicit_cast.h"
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#include "util/misc/implicit_cast.h"
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#include "util/posix/fork_and_spawn.h"
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#include "util/posix/double_fork_and_exec.h"
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namespace crashpad {
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namespace crashpad {
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@ -343,7 +343,7 @@ class HandlerStarter final : public NotifyServer::DefaultInterface {
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// this parent process, which was probably using the exception server now
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// this parent process, which was probably using the exception server now
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// being restarted. The handler can’t monitor itself for its own crashes via
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// being restarted. The handler can’t monitor itself for its own crashes via
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// this interface.
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// this interface.
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if (!ForkAndSpawn(
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if (!DoubleForkAndExec(
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argv,
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argv,
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nullptr,
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nullptr,
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server_write_fd.get(),
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server_write_fd.get(),
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@ -29,7 +29,7 @@
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#include "util/linux/ptrace_client.h"
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#include "util/linux/ptrace_client.h"
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#include "util/misc/metrics.h"
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#include "util/misc/metrics.h"
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#include "util/misc/uuid.h"
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#include "util/misc/uuid.h"
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#include "util/posix/fork_and_spawn.h"
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#include "util/posix/double_fork_and_exec.h"
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namespace crashpad {
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namespace crashpad {
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@ -266,11 +266,12 @@ bool CrosCrashReportExceptionHandler::HandleExceptionWithConnection(
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argv.push_back("--always_allow_feedback");
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argv.push_back("--always_allow_feedback");
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}
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}
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if (!ForkAndSpawn(argv,
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if (!DoubleForkAndExec(argv,
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nullptr /* envp */,
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nullptr /* envp */,
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file_writer.fd() /* preserve_fd */,
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file_writer.fd() /* preserve_fd */,
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false /* use_path */,
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false /* use_path */,
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nullptr /* child_function */)) {
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nullptr /* child_function */)) {
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LOG(ERROR) << "DoubleForkAndExec failed";
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Metrics::ExceptionCaptureResult(
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Metrics::ExceptionCaptureResult(
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Metrics::CaptureResult::kFinishedWritingCrashReportFailed);
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Metrics::CaptureResult::kFinishedWritingCrashReportFailed);
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return false;
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return false;
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@ -288,10 +288,10 @@ crashpad_static_library("util") {
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sources += [
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sources += [
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"posix/close_multiple.cc",
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"posix/close_multiple.cc",
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"posix/close_multiple.h",
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"posix/close_multiple.h",
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"posix/double_fork_and_exec.cc",
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"posix/double_fork_and_exec.h",
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"posix/drop_privileges.cc",
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"posix/drop_privileges.cc",
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"posix/drop_privileges.h",
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"posix/drop_privileges.h",
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"posix/fork_and_spawn.cc",
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"posix/fork_and_spawn.h",
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"posix/process_info.h",
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"posix/process_info.h",
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# These map signals to and from strings. While Fuchsia defines some of
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# These map signals to and from strings. While Fuchsia defines some of
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166
util/posix/double_fork_and_exec.cc
Normal file
166
util/posix/double_fork_and_exec.cc
Normal file
@ -0,0 +1,166 @@
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// Copyright 2017 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "util/posix/double_fork_and_exec.h"
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#include <stdlib.h>
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#include <string.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include "base/check_op.h"
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#include "base/logging.h"
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#include "base/posix/eintr_wrapper.h"
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#include "base/strings/stringprintf.h"
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#include "util/posix/close_multiple.h"
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namespace crashpad {
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bool DoubleForkAndExec(const std::vector<std::string>& argv,
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const std::vector<std::string>* envp,
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int preserve_fd,
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bool use_path,
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void (*child_function)()) {
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DCHECK(!envp || !use_path);
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// argv_c contains const char* pointers and is terminated by nullptr. This is
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// suitable for passing to execv(). Although argv_c is not used in the parent
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// process, it must be built in the parent process because it’s unsafe to do
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// so in the child or grandchild process.
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std::vector<const char*> argv_c;
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argv_c.reserve(argv.size() + 1);
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for (const std::string& argument : argv) {
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argv_c.push_back(argument.c_str());
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}
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argv_c.push_back(nullptr);
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std::vector<const char*> envp_c;
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if (envp) {
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envp_c.reserve(envp->size() + 1);
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for (const std::string& variable : *envp) {
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envp_c.push_back(variable.c_str());
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}
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envp_c.push_back(nullptr);
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}
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// Double-fork(). The three processes involved are parent, child, and
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// grandchild. The grandchild will call execv(). The child exits immediately
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// after spawning the grandchild, so the grandchild becomes an orphan and its
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// parent process ID becomes 1. This relieves the parent and child of the
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// responsibility to reap the grandchild with waitpid() or similar. The
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// grandchild is expected to outlive the parent process, so the parent
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// shouldn’t be concerned with reaping it. This approach means that accidental
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// early termination of the handler process will not result in a zombie
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// process.
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pid_t pid = fork();
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if (pid < 0) {
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PLOG(ERROR) << "fork";
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return false;
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}
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if (pid == 0) {
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// Child process.
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if (child_function) {
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child_function();
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}
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// Call setsid(), creating a new process group and a new session, both led
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// by this process. The new process group has no controlling terminal. This
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// disconnects it from signals generated by the parent process’ terminal.
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//
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// setsid() is done in the child instead of the grandchild so that the
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// grandchild will not be a session leader. If it were a session leader, an
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// accidental open() of a terminal device without O_NOCTTY would make that
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// terminal the controlling terminal.
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//
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// It’s not desirable for the grandchild to have a controlling terminal. The
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// grandchild manages its own lifetime, such as by monitoring clients on its
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// own and exiting when it loses all clients and when it deems it
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// appropraite to do so. It may serve clients in different process groups or
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// sessions than its original client, and receiving signals intended for its
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// original client’s process group could be harmful in that case.
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PCHECK(setsid() != -1) << "setsid";
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pid = fork();
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if (pid < 0) {
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PLOG(FATAL) << "fork";
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}
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if (pid > 0) {
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// Child process.
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// _exit() instead of exit(), because fork() was called.
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_exit(EXIT_SUCCESS);
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}
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// Grandchild process.
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CloseMultipleNowOrOnExec(STDERR_FILENO + 1, preserve_fd);
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// &argv_c[0] is a pointer to a pointer to const char data, but because of
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// how C (not C++) works, execvp() wants a pointer to a const pointer to
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// char data. It modifies neither the data nor the pointers, so the
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// const_cast is safe.
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char* const* argv_for_execv = const_cast<char* const*>(&argv_c[0]);
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if (envp) {
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// This cast is safe for the same reason that the argv_for_execv cast is.
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char* const* envp_for_execv = const_cast<char* const*>(&envp_c[0]);
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execve(argv_for_execv[0], argv_for_execv, envp_for_execv);
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PLOG(FATAL) << "execve " << argv_for_execv[0];
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}
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if (use_path) {
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execvp(argv_for_execv[0], argv_for_execv);
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PLOG(FATAL) << "execvp " << argv_for_execv[0];
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}
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execv(argv_for_execv[0], argv_for_execv);
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PLOG(FATAL) << "execv " << argv_for_execv[0];
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}
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|
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// waitpid() for the child, so that it does not become a zombie process. The
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// child normally exits quickly.
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//
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// Failures from this point on may result in the accumulation of a zombie, but
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// should not be considered fatal. Log only warnings, but don’t treat these
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// failures as a failure of the function overall.
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int status;
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pid_t wait_pid = HANDLE_EINTR(waitpid(pid, &status, 0));
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|
if (wait_pid == -1) {
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PLOG(WARNING) << "waitpid";
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return true;
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|
}
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DCHECK_EQ(wait_pid, pid);
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|
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|
if (WIFSIGNALED(status)) {
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|
int sig = WTERMSIG(status);
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LOG(WARNING) << base::StringPrintf(
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"intermediate process terminated by signal %d (%s)%s",
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|
sig,
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strsignal(sig),
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WCOREDUMP(status) ? " (core dumped)" : "");
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|
} else if (!WIFEXITED(status)) {
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|
LOG(WARNING) << base::StringPrintf(
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"intermediate process: unknown termination 0x%x", status);
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|
} else if (WEXITSTATUS(status) != EXIT_SUCCESS) {
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|
LOG(WARNING) << "intermediate process exited with code "
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|
<< WEXITSTATUS(status);
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|
}
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|
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|
return true;
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|
}
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|
|
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|
} // namespace crashpad
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@ -12,8 +12,8 @@
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// See the License for the specific language governing permissions and
|
// See the License for the specific language governing permissions and
|
||||||
// limitations under the License.
|
// limitations under the License.
|
||||||
|
|
||||||
#ifndef CRASHPAD_UTIL_POSIX_FORK_AND_SPAWN_H_
|
#ifndef CRASHPAD_UTIL_POSIX_DOUBLE_FORK_AND_EXEC_H_
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#define CRASHPAD_UTIL_POSIX_FORK_AND_SPAWN_H_
|
#define CRASHPAD_UTIL_POSIX_DOUBLE_FORK_AND_EXEC_H_
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|
|
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#include <string>
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#include <string>
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#include <vector>
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#include <vector>
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@ -23,7 +23,7 @@ namespace crashpad {
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//! \brief Executes a (grand-)child process.
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//! \brief Executes a (grand-)child process.
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//!
|
//!
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//! The grandchild process will be started through the
|
//! The grandchild process will be started through the
|
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//! `fork()`-and-`posix_spawn()` pattern. This allows the grandchild to fully
|
//! double-`fork()`-and-`execv()` pattern. This allows the grandchild to fully
|
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//! disassociate from the parent. The grandchild will not be a member of the
|
//! disassociate from the parent. The grandchild will not be a member of the
|
||||||
//! parent’s process group or session and will not have a controlling terminal,
|
//! parent’s process group or session and will not have a controlling terminal,
|
||||||
//! providing isolation from signals not intended for it. The grandchild’s
|
//! providing isolation from signals not intended for it. The grandchild’s
|
||||||
@ -37,7 +37,7 @@ namespace crashpad {
|
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//! \param[in] argv The argument vector to start the grandchild process with.
|
//! \param[in] argv The argument vector to start the grandchild process with.
|
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//! `argv[0]` is used as the path to the executable.
|
//! `argv[0]` is used as the path to the executable.
|
||||||
//! \param[in] envp A vector of environment variables of the form `var=value` to
|
//! \param[in] envp A vector of environment variables of the form `var=value` to
|
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//! be passed to `posix_spawn()`. If this value is `nullptr`, the current
|
//! be passed to `execve()`. If this value is `nullptr`, the current
|
||||||
//! environment is used.
|
//! environment is used.
|
||||||
//! \param[in] preserve_fd A file descriptor to be inherited by the grandchild
|
//! \param[in] preserve_fd A file descriptor to be inherited by the grandchild
|
||||||
//! process. This file descriptor is inherited in addition to the three file
|
//! process. This file descriptor is inherited in addition to the three file
|
||||||
@ -45,13 +45,16 @@ namespace crashpad {
|
|||||||
//! if no additional file descriptors are to be inherited.
|
//! if no additional file descriptors are to be inherited.
|
||||||
//! \param[in] use_path Whether to consult the `PATH` environment variable when
|
//! \param[in] use_path Whether to consult the `PATH` environment variable when
|
||||||
//! requested to start an executable at a non-absolute path. If `false`,
|
//! requested to start an executable at a non-absolute path. If `false`,
|
||||||
//! `posix_spawn()`, which does not consult `PATH`, will be used. If `true`,
|
//! `execv()`, which does not consult `PATH`, will be used. If `true`,
|
||||||
//! `posix_spawnp()`, which does consult `PATH`, will be used.
|
//! `execvp()`, which does consult `PATH`, will be used.
|
||||||
//! \param[in] child_function If not `nullptr`, this function will be called in
|
//! \param[in] child_function If not `nullptr`, this function will be called in
|
||||||
//! the intermediate child process, prior to the `posix_spawn()`. Take note
|
//! the intermediate child process, prior to the second `fork()`. Take note
|
||||||
//! that this function will run in the context of a forked process, and must
|
//! that this function will run in the context of a forked process, and must
|
||||||
//! be safe for that purpose.
|
//! be safe for that purpose.
|
||||||
//!
|
//!
|
||||||
|
//! Setting both \a envp to a value other than `nullptr` and \a use_path to
|
||||||
|
//! `true` is not currently supported.
|
||||||
|
//!
|
||||||
//! \return `true` on success, and `false` on failure with a message logged.
|
//! \return `true` on success, and `false` on failure with a message logged.
|
||||||
//! Only failures that occur in the parent process that indicate a definite
|
//! Only failures that occur in the parent process that indicate a definite
|
||||||
//! failure to start the the grandchild are reported in the return value.
|
//! failure to start the the grandchild are reported in the return value.
|
||||||
@ -60,12 +63,12 @@ namespace crashpad {
|
|||||||
//! terminating. The caller assumes the responsibility for detecting such
|
//! terminating. The caller assumes the responsibility for detecting such
|
||||||
//! failures, for example, by observing a failure to perform a successful
|
//! failures, for example, by observing a failure to perform a successful
|
||||||
//! handshake with the grandchild process.
|
//! handshake with the grandchild process.
|
||||||
bool ForkAndSpawn(const std::vector<std::string>& argv,
|
bool DoubleForkAndExec(const std::vector<std::string>& argv,
|
||||||
const std::vector<std::string>* envp,
|
const std::vector<std::string>* envp,
|
||||||
int preserve_fd,
|
int preserve_fd,
|
||||||
bool use_path,
|
bool use_path,
|
||||||
void (*child_function)());
|
void (*child_function)());
|
||||||
|
|
||||||
} // namespace crashpad
|
} // namespace crashpad
|
||||||
|
|
||||||
#endif // CRASHPAD_UTIL_POSIX_FORK_AND_SPAWN_H_
|
#endif // CRASHPAD_UTIL_POSIX_DOUBLE_FORK_AND_EXEC_H_
|
@ -1,235 +0,0 @@
|
|||||||
// Copyright 2017 The Crashpad Authors. All rights reserved.
|
|
||||||
//
|
|
||||||
// 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 "util/posix/fork_and_spawn.h"
|
|
||||||
|
|
||||||
#include <errno.h>
|
|
||||||
#include <spawn.h>
|
|
||||||
#include <stdlib.h>
|
|
||||||
#include <string.h>
|
|
||||||
#include <sys/wait.h>
|
|
||||||
#include <unistd.h>
|
|
||||||
|
|
||||||
#include "base/check.h"
|
|
||||||
#include "base/check_op.h"
|
|
||||||
#include "base/logging.h"
|
|
||||||
#include "base/posix/eintr_wrapper.h"
|
|
||||||
#include "base/strings/stringprintf.h"
|
|
||||||
#include "build/build_config.h"
|
|
||||||
#include "util/posix/close_multiple.h"
|
|
||||||
|
|
||||||
extern char** environ;
|
|
||||||
|
|
||||||
namespace crashpad {
|
|
||||||
|
|
||||||
namespace {
|
|
||||||
|
|
||||||
#if BUILDFLAG(IS_APPLE)
|
|
||||||
|
|
||||||
class PosixSpawnAttr {
|
|
||||||
public:
|
|
||||||
PosixSpawnAttr() {
|
|
||||||
PCHECK((errno = posix_spawnattr_init(&attr_)) == 0)
|
|
||||||
<< "posix_spawnattr_init";
|
|
||||||
}
|
|
||||||
|
|
||||||
PosixSpawnAttr(const PosixSpawnAttr&) = delete;
|
|
||||||
PosixSpawnAttr& operator=(const PosixSpawnAttr&) = delete;
|
|
||||||
|
|
||||||
~PosixSpawnAttr() {
|
|
||||||
PCHECK((errno = posix_spawnattr_destroy(&attr_)) == 0)
|
|
||||||
<< "posix_spawnattr_destroy";
|
|
||||||
}
|
|
||||||
|
|
||||||
void SetFlags(short flags) {
|
|
||||||
PCHECK((errno = posix_spawnattr_setflags(&attr_, flags)) == 0)
|
|
||||||
<< "posix_spawnattr_setflags";
|
|
||||||
}
|
|
||||||
|
|
||||||
const posix_spawnattr_t* Get() const { return &attr_; }
|
|
||||||
|
|
||||||
private:
|
|
||||||
posix_spawnattr_t attr_;
|
|
||||||
};
|
|
||||||
|
|
||||||
class PosixSpawnFileActions {
|
|
||||||
public:
|
|
||||||
PosixSpawnFileActions() {
|
|
||||||
PCHECK((errno = posix_spawn_file_actions_init(&file_actions_)) == 0)
|
|
||||||
<< "posix_spawn_file_actions_init";
|
|
||||||
}
|
|
||||||
|
|
||||||
PosixSpawnFileActions(const PosixSpawnFileActions&) = delete;
|
|
||||||
PosixSpawnFileActions& operator=(const PosixSpawnFileActions&) = delete;
|
|
||||||
|
|
||||||
~PosixSpawnFileActions() {
|
|
||||||
PCHECK((errno = posix_spawn_file_actions_destroy(&file_actions_)) == 0)
|
|
||||||
<< "posix_spawn_file_actions_destroy";
|
|
||||||
}
|
|
||||||
|
|
||||||
void AddInheritedFileDescriptor(int fd) {
|
|
||||||
PCHECK((errno = posix_spawn_file_actions_addinherit_np(&file_actions_,
|
|
||||||
fd)) == 0)
|
|
||||||
<< "posix_spawn_file_actions_addinherit_np";
|
|
||||||
}
|
|
||||||
|
|
||||||
const posix_spawn_file_actions_t* Get() const { return &file_actions_; }
|
|
||||||
|
|
||||||
private:
|
|
||||||
posix_spawn_file_actions_t file_actions_;
|
|
||||||
};
|
|
||||||
|
|
||||||
#endif
|
|
||||||
|
|
||||||
} // namespace
|
|
||||||
|
|
||||||
bool ForkAndSpawn(const std::vector<std::string>& argv,
|
|
||||||
const std::vector<std::string>* envp,
|
|
||||||
int preserve_fd,
|
|
||||||
bool use_path,
|
|
||||||
void (*child_function)()) {
|
|
||||||
// argv_c contains const char* pointers and is terminated by nullptr. This is
|
|
||||||
// suitable for passing to posix_spawn() or posix_spawnp(). Although argv_c is
|
|
||||||
// not used in the parent process, it must be built in the parent process
|
|
||||||
// because it’s unsafe to do so in the child.
|
|
||||||
std::vector<const char*> argv_c;
|
|
||||||
argv_c.reserve(argv.size() + 1);
|
|
||||||
for (const std::string& argument : argv) {
|
|
||||||
argv_c.push_back(argument.c_str());
|
|
||||||
}
|
|
||||||
argv_c.push_back(nullptr);
|
|
||||||
|
|
||||||
std::vector<const char*> envp_c;
|
|
||||||
if (envp) {
|
|
||||||
envp_c.reserve(envp->size() + 1);
|
|
||||||
for (const std::string& variable : *envp) {
|
|
||||||
envp_c.push_back(variable.c_str());
|
|
||||||
}
|
|
||||||
envp_c.push_back(nullptr);
|
|
||||||
}
|
|
||||||
|
|
||||||
// The three processes involved are parent, child, and grandchild. The child
|
|
||||||
// exits immediately after spawning the grandchild, so the grandchild becomes
|
|
||||||
// an orphan and its parent process ID becomes 1. This relieves the parent and
|
|
||||||
// child of the responsibility to reap the grandchild with waitpid() or
|
|
||||||
// similar. The grandchild is expected to outlive the parent process, so the
|
|
||||||
// parent shouldn’t be concerned with reaping it. This approach means that
|
|
||||||
// accidental early termination of the handler process will not result in a
|
|
||||||
// zombie process.
|
|
||||||
pid_t pid = fork();
|
|
||||||
if (pid < 0) {
|
|
||||||
PLOG(ERROR) << "fork";
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
|
|
||||||
if (pid == 0) {
|
|
||||||
// Child process.
|
|
||||||
|
|
||||||
if (child_function) {
|
|
||||||
child_function();
|
|
||||||
}
|
|
||||||
|
|
||||||
// Call setsid(), creating a new process group and a new session, both led
|
|
||||||
// by this process. The new process group has no controlling terminal. This
|
|
||||||
// disconnects it from signals generated by the parent process’ terminal.
|
|
||||||
//
|
|
||||||
// setsid() is done in the child instead of the grandchild so that the
|
|
||||||
// grandchild will not be a session leader. If it were a session leader, an
|
|
||||||
// accidental open() of a terminal device without O_NOCTTY would make that
|
|
||||||
// terminal the controlling terminal.
|
|
||||||
//
|
|
||||||
// It’s not desirable for the grandchild to have a controlling terminal. The
|
|
||||||
// grandchild manages its own lifetime, such as by monitoring clients on its
|
|
||||||
// own and exiting when it loses all clients and when it deems it
|
|
||||||
// appropraite to do so. It may serve clients in different process groups or
|
|
||||||
// sessions than its original client, and receiving signals intended for its
|
|
||||||
// original client’s process group could be harmful in that case.
|
|
||||||
PCHECK(setsid() != -1) << "setsid";
|
|
||||||
|
|
||||||
// &argv_c[0] is a pointer to a pointer to const char data, but because of
|
|
||||||
// how C (not C++) works, posix_spawn() and posix_spawnp() want a pointer to
|
|
||||||
// a const pointer to char data. They modifies neither the data nor the
|
|
||||||
// pointers, so the const_cast is safe.
|
|
||||||
char* const* argv_for_spawn = const_cast<char* const*>(argv_c.data());
|
|
||||||
|
|
||||||
// This cast is safe for the same reason that the argv_for_spawn cast is.
|
|
||||||
char* const* envp_for_spawn =
|
|
||||||
envp ? const_cast<char* const*>(envp_c.data()) : environ;
|
|
||||||
|
|
||||||
#if BUILDFLAG(IS_APPLE)
|
|
||||||
PosixSpawnAttr attr;
|
|
||||||
attr.SetFlags(POSIX_SPAWN_CLOEXEC_DEFAULT);
|
|
||||||
|
|
||||||
PosixSpawnFileActions file_actions;
|
|
||||||
for (int fd = 0; fd <= STDERR_FILENO; ++fd) {
|
|
||||||
file_actions.AddInheritedFileDescriptor(fd);
|
|
||||||
}
|
|
||||||
file_actions.AddInheritedFileDescriptor(preserve_fd);
|
|
||||||
|
|
||||||
const posix_spawnattr_t* attr_p = attr.Get();
|
|
||||||
const posix_spawn_file_actions_t* file_actions_p = file_actions.Get();
|
|
||||||
#else
|
|
||||||
CloseMultipleNowOrOnExec(STDERR_FILENO + 1, preserve_fd);
|
|
||||||
|
|
||||||
const posix_spawnattr_t* attr_p = nullptr;
|
|
||||||
const posix_spawn_file_actions_t* file_actions_p = nullptr;
|
|
||||||
#endif
|
|
||||||
|
|
||||||
auto posix_spawn_fp = use_path ? posix_spawnp : posix_spawn;
|
|
||||||
if ((errno = posix_spawn_fp(&pid,
|
|
||||||
argv_for_spawn[0],
|
|
||||||
file_actions_p,
|
|
||||||
attr_p,
|
|
||||||
argv_for_spawn,
|
|
||||||
envp_for_spawn)) != 0) {
|
|
||||||
PLOG(FATAL) << (use_path ? "posix_spawnp" : "posix_spawn");
|
|
||||||
}
|
|
||||||
|
|
||||||
// _exit() instead of exit(), because fork() was called.
|
|
||||||
_exit(EXIT_SUCCESS);
|
|
||||||
}
|
|
||||||
|
|
||||||
// waitpid() for the child, so that it does not become a zombie process. The
|
|
||||||
// child normally exits quickly.
|
|
||||||
//
|
|
||||||
// Failures from this point on may result in the accumulation of a zombie, but
|
|
||||||
// should not be considered fatal. Log only warnings, but don’t treat these
|
|
||||||
// failures as a failure of the function overall.
|
|
||||||
int status;
|
|
||||||
pid_t wait_pid = HANDLE_EINTR(waitpid(pid, &status, 0));
|
|
||||||
if (wait_pid == -1) {
|
|
||||||
PLOG(WARNING) << "waitpid";
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
DCHECK_EQ(wait_pid, pid);
|
|
||||||
|
|
||||||
if (WIFSIGNALED(status)) {
|
|
||||||
int sig = WTERMSIG(status);
|
|
||||||
LOG(WARNING) << base::StringPrintf(
|
|
||||||
"intermediate process terminated by signal %d (%s)%s",
|
|
||||||
sig,
|
|
||||||
strsignal(sig),
|
|
||||||
WCOREDUMP(status) ? " (core dumped)" : "");
|
|
||||||
} else if (!WIFEXITED(status)) {
|
|
||||||
LOG(WARNING) << base::StringPrintf(
|
|
||||||
"intermediate process: unknown termination 0x%x", status);
|
|
||||||
} else if (WEXITSTATUS(status) != EXIT_SUCCESS) {
|
|
||||||
LOG(WARNING) << "intermediate process exited with code "
|
|
||||||
<< WEXITSTATUS(status);
|
|
||||||
}
|
|
||||||
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
|
|
||||||
} // namespace crashpad
|
|
Loading…
x
Reference in New Issue
Block a user