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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/process/launch.h"
#include <crt_externs.h>
#include <mach/mach.h>
#include <spawn.h>
#include <string.h>
#include <sys/wait.h>
#include "base/logging.h"
#include "base/posix/eintr_wrapper.h"
#include "base/threading/thread_restrictions.h"
namespace base {
namespace {
// DPSXCHECK is a Debug Posix Spawn Check macro. The posix_spawn* family of
// functions return an errno value, as opposed to setting errno directly. This
// macro emulates a DPCHECK().
#define DPSXCHECK(expr) \
do { \
int rv = (expr); \
DCHECK_EQ(rv, 0) << #expr << ": -" << rv << " " << strerror(rv); \
} while (0)
class PosixSpawnAttr {
public:
PosixSpawnAttr() { DPSXCHECK(posix_spawnattr_init(&attr_)); }
~PosixSpawnAttr() { DPSXCHECK(posix_spawnattr_destroy(&attr_)); }
posix_spawnattr_t* get() { return &attr_; }
private:
posix_spawnattr_t attr_;
};
class PosixSpawnFileActions {
public:
PosixSpawnFileActions() {
DPSXCHECK(posix_spawn_file_actions_init(&file_actions_));
}
~PosixSpawnFileActions() {
DPSXCHECK(posix_spawn_file_actions_destroy(&file_actions_));
}
void Open(int filedes, const char* path, int mode) {
DPSXCHECK(posix_spawn_file_actions_addopen(&file_actions_, filedes, path,
mode, 0));
}
void Dup2(int filedes, int newfiledes) {
DPSXCHECK(
posix_spawn_file_actions_adddup2(&file_actions_, filedes, newfiledes));
}
void Inherit(int filedes) {
DPSXCHECK(posix_spawn_file_actions_addinherit_np(&file_actions_, filedes));
}
const posix_spawn_file_actions_t* get() const { return &file_actions_; }
private:
posix_spawn_file_actions_t file_actions_;
DISALLOW_COPY_AND_ASSIGN(PosixSpawnFileActions);
};
} // namespace
void RestoreDefaultExceptionHandler() {
// This function is tailored to remove the Breakpad exception handler.
// exception_mask matches s_exception_mask in
// breakpad/src/client/mac/handler/exception_handler.cc
const exception_mask_t exception_mask = EXC_MASK_BAD_ACCESS |
EXC_MASK_BAD_INSTRUCTION |
EXC_MASK_ARITHMETIC |
EXC_MASK_BREAKPOINT;
// Setting the exception port to MACH_PORT_NULL may not be entirely
// kosher to restore the default exception handler, but in practice,
// it results in the exception port being set to Apple Crash Reporter,
// the desired behavior.
task_set_exception_ports(mach_task_self(), exception_mask, MACH_PORT_NULL,
EXCEPTION_DEFAULT, THREAD_STATE_NONE);
}
Process LaunchProcessPosixSpawn(const std::vector<std::string>& argv,
const LaunchOptions& options) {
DCHECK(!options.pre_exec_delegate)
<< "LaunchProcessPosixSpawn does not support PreExecDelegate";
DCHECK(options.current_directory.empty())
<< "LaunchProcessPosixSpawn does not support current_directory";
PosixSpawnAttr attr;
short flags = POSIX_SPAWN_CLOEXEC_DEFAULT;
if (options.new_process_group) {
flags |= POSIX_SPAWN_SETPGROUP;
DPSXCHECK(posix_spawnattr_setpgroup(attr.get(), 0));
}
DPSXCHECK(posix_spawnattr_setflags(attr.get(), flags));
PosixSpawnFileActions file_actions;
// Process file descriptors for the child. By default, LaunchProcess will
// open stdin to /dev/null and inherit stdout and stderr.
bool inherit_stdout = true, inherit_stderr = true;
bool null_stdin = true;
if (options.fds_to_remap) {
for (const auto& dup2_pair : *options.fds_to_remap) {
if (dup2_pair.second == STDIN_FILENO) {
null_stdin = false;
} else if (dup2_pair.second == STDOUT_FILENO) {
inherit_stdout = false;
} else if (dup2_pair.second == STDERR_FILENO) {
inherit_stderr = false;
}
if (dup2_pair.first == dup2_pair.second) {
file_actions.Inherit(dup2_pair.second);
} else {
file_actions.Dup2(dup2_pair.first, dup2_pair.second);
}
}
}
if (null_stdin) {
file_actions.Open(STDIN_FILENO, "/dev/null", O_RDONLY);
}
if (inherit_stdout) {
file_actions.Inherit(STDOUT_FILENO);
}
if (inherit_stderr) {
file_actions.Inherit(STDERR_FILENO);
}
std::unique_ptr<char* []> argv_cstr(new char*[argv.size() + 1]);
for (size_t i = 0; i < argv.size(); i++) {
argv_cstr[i] = const_cast<char*>(argv[i].c_str());
}
argv_cstr[argv.size()] = nullptr;
std::unique_ptr<char* []> owned_environ;
char** new_environ = options.clear_environ ? nullptr : *_NSGetEnviron();
if (!options.environ.empty()) {
owned_environ = AlterEnvironment(new_environ, options.environ);
new_environ = owned_environ.get();
}
const char* executable_path = !options.real_path.empty()
? options.real_path.value().c_str()
: argv_cstr[0];
// Use posix_spawnp as some callers expect to have PATH consulted.
pid_t pid;
int rv = posix_spawnp(&pid, executable_path, file_actions.get(), attr.get(),
&argv_cstr[0], new_environ);
if (rv != 0) {
DLOG(ERROR) << "posix_spawnp(" << executable_path << "): -" << rv << " "
<< strerror(rv);
return Process();
}
if (options.wait) {
// While this isn't strictly disk IO, waiting for another process to
// finish is the sort of thing ThreadRestrictions is trying to prevent.
base::ThreadRestrictions::AssertIOAllowed();
pid_t ret = HANDLE_EINTR(waitpid(pid, nullptr, 0));
DPCHECK(ret > 0);
}
return Process(pid);
}
} // namespace base
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