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/*
* Copyright (C) 2011 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 "exec_utils.h"
#include <sys/types.h>
#include <sys/wait.h>
#include <string>
#include <vector>
#include "android-base/stringprintf.h"
#include "android-base/strings.h"
#include "runtime.h"
namespace art {
using android::base::StringPrintf;
namespace {
std::string ToCommandLine(const std::vector<std::string>& args) {
return android::base::Join(args, ' ');
}
// Fork and execute a command specified in a subprocess.
// If there is a runtime (Runtime::Current != nullptr) then the subprocess is created with the
// same environment that existed when the runtime was started.
// Returns the process id of the child process on success, -1 otherwise.
pid_t ExecWithoutWait(std::vector<std::string>& arg_vector) {
// Convert the args to char pointers.
const char* program = arg_vector[0].c_str();
std::vector<char*> args;
for (const auto& arg : arg_vector) {
args.push_back(const_cast<char*>(arg.c_str()));
}
args.push_back(nullptr);
// fork and exec
pid_t pid = fork();
if (pid == 0) {
// no allocation allowed between fork and exec
// change process groups, so we don't get reaped by ProcessManager
setpgid(0, 0);
// (b/30160149): protect subprocesses from modifications to LD_LIBRARY_PATH, etc.
// Use the snapshot of the environment from the time the runtime was created.
char** envp = (Runtime::Current() == nullptr) ? nullptr : Runtime::Current()->GetEnvSnapshot();
if (envp == nullptr) {
execv(program, &args[0]);
} else {
execve(program, &args[0], envp);
}
PLOG(ERROR) << "Failed to execve(" << ToCommandLine(arg_vector) << ")";
// _exit to avoid atexit handlers in child.
_exit(1);
} else {
return pid;
}
}
} // namespace
int ExecAndReturnCode(std::vector<std::string>& arg_vector, std::string* error_msg) {
pid_t pid = ExecWithoutWait(arg_vector);
if (pid == -1) {
*error_msg = StringPrintf("Failed to execv(%s) because fork failed: %s",
ToCommandLine(arg_vector).c_str(), strerror(errno));
return -1;
}
// wait for subprocess to finish
int status = -1;
pid_t got_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
if (got_pid != pid) {
*error_msg = StringPrintf("Failed after fork for execv(%s) because waitpid failed: "
"wanted %d, got %d: %s",
ToCommandLine(arg_vector).c_str(), pid, got_pid, strerror(errno));
return -1;
}
if (WIFEXITED(status)) {
return WEXITSTATUS(status);
}
return -1;
}
int ExecAndReturnCode(std::vector<std::string>& arg_vector,
time_t timeout_secs,
bool* timed_out,
std::string* error_msg) {
*timed_out = false;
// Start subprocess.
pid_t pid = ExecWithoutWait(arg_vector);
if (pid == -1) {
*error_msg = StringPrintf("Failed to execv(%s) because fork failed: %s",
ToCommandLine(arg_vector).c_str(), strerror(errno));
return -1;
}
// Add SIGCHLD to the signal set.
sigset_t child_mask, original_mask;
sigemptyset(&child_mask);
sigaddset(&child_mask, SIGCHLD);
if (sigprocmask(SIG_BLOCK, &child_mask, &original_mask) == -1) {
*error_msg = StringPrintf("Failed to set sigprocmask(): %s", strerror(errno));
return -1;
}
// Wait for a SIGCHLD notification.
errno = 0;
timespec ts = {timeout_secs, 0};
int wait_result = TEMP_FAILURE_RETRY(sigtimedwait(&child_mask, nullptr, &ts));
int wait_errno = errno;
// Restore the original signal set.
if (sigprocmask(SIG_SETMASK, &original_mask, nullptr) == -1) {
*error_msg = StringPrintf("Fail to restore sigprocmask(): %s", strerror(errno));
if (wait_result == 0) {
return -1;
}
}
// Having restored the signal set, see if we need to terminate the subprocess.
if (wait_result == -1) {
if (wait_errno == EAGAIN) {
*error_msg = "Timed out.";
*timed_out = true;
} else {
*error_msg = StringPrintf("Failed to sigtimedwait(): %s", strerror(errno));
}
if (kill(pid, SIGKILL) != 0) {
PLOG(ERROR) << "Failed to kill() subprocess: ";
}
}
// Wait for subprocess to finish.
int status = -1;
pid_t got_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
if (got_pid != pid) {
*error_msg = StringPrintf("Failed after fork for execv(%s) because waitpid failed: "
"wanted %d, got %d: %s",
ToCommandLine(arg_vector).c_str(), pid, got_pid, strerror(errno));
return -1;
}
if (WIFEXITED(status)) {
return WEXITSTATUS(status);
}
return -1;
}
bool Exec(std::vector<std::string>& arg_vector, std::string* error_msg) {
int status = ExecAndReturnCode(arg_vector, error_msg);
if (status != 0) {
*error_msg = StringPrintf("Failed execv(%s) because non-0 exit status",
ToCommandLine(arg_vector).c_str());
return false;
}
return true;
}
} // namespace art
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