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// Copyright 2018 The gVisor Authors.
//
// 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 "test/util/multiprocess_util.h"
#include <asm/unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/prctl.h>
#include <unistd.h>
#include "absl/strings/str_cat.h"
#include "test/util/cleanup.h"
#include "test/util/file_descriptor.h"
#include "test/util/posix_error.h"
#include "test/util/save_util.h"
#include "test/util/test_util.h"
namespace gvisor {
namespace testing {
namespace {
// exec_fn wraps a variant of the exec family, e.g. execve or execveat.
PosixErrorOr<Cleanup> ForkAndExecHelper(const std::function<void()>& exec_fn,
const std::function<void()>& fn,
pid_t* child, int* execve_errno) {
int pfds[2];
int ret = pipe2(pfds, O_CLOEXEC);
if (ret < 0) {
return PosixError(errno, "pipe failed");
}
FileDescriptor rfd(pfds[0]);
FileDescriptor wfd(pfds[1]);
int parent_stdout = dup(STDOUT_FILENO);
if (parent_stdout < 0) {
return PosixError(errno, "dup stdout");
}
int parent_stderr = dup(STDERR_FILENO);
if (parent_stdout < 0) {
return PosixError(errno, "dup stderr");
}
pid_t pid = fork();
if (pid < 0) {
return PosixError(errno, "fork failed");
} else if (pid == 0) {
// Child.
rfd.reset();
if (dup2(parent_stdout, STDOUT_FILENO) < 0) {
_exit(3);
}
if (dup2(parent_stderr, STDERR_FILENO) < 0) {
_exit(4);
}
close(parent_stdout);
close(parent_stderr);
// Clean ourself up in case the parent doesn't.
if (prctl(PR_SET_PDEATHSIG, SIGKILL)) {
_exit(3);
}
if (fn) {
fn();
}
// Call variant of exec function.
exec_fn();
int error = errno;
if (WriteFd(pfds[1], &error, sizeof(error)) != sizeof(error)) {
// We can't do much if the write fails, but we can at least exit with a
// different code.
_exit(2);
}
_exit(1);
}
// Parent.
if (child) {
*child = pid;
}
auto cleanup = Cleanup([pid] {
kill(pid, SIGKILL);
RetryEINTR(waitpid)(pid, nullptr, 0);
});
wfd.reset();
int read_errno;
ret = ReadFd(rfd.get(), &read_errno, sizeof(read_errno));
if (ret == 0) {
// Other end of the pipe closed, execve must have succeeded.
read_errno = 0;
} else if (ret < 0) {
return PosixError(errno, "read pipe failed");
} else if (ret != sizeof(read_errno)) {
return PosixError(EPIPE, absl::StrCat("pipe read wrong size ", ret));
}
if (execve_errno) {
*execve_errno = read_errno;
}
return std::move(cleanup);
}
} // namespace
PosixErrorOr<Cleanup> ForkAndExec(const std::string& filename,
const ExecveArray& argv,
const ExecveArray& envv,
const std::function<void()>& fn, pid_t* child,
int* execve_errno) {
char* const* argv_data = argv.get();
char* const* envv_data = envv.get();
const std::function<void()> exec_fn = [=] {
execve(filename.c_str(), argv_data, envv_data);
};
return ForkAndExecHelper(exec_fn, fn, child, execve_errno);
}
PosixErrorOr<Cleanup> ForkAndExecveat(const int32_t dirfd,
const std::string& pathname,
const ExecveArray& argv,
const ExecveArray& envv, const int flags,
const std::function<void()>& fn,
pid_t* child, int* execve_errno) {
char* const* argv_data = argv.get();
char* const* envv_data = envv.get();
const std::function<void()> exec_fn = [=] {
syscall(__NR_execveat, dirfd, pathname.c_str(), argv_data, envv_data,
flags);
};
return ForkAndExecHelper(exec_fn, fn, child, execve_errno);
}
PosixErrorOr<int> InForkedProcess(const std::function<void()>& fn) {
pid_t pid = fork();
if (pid == 0) {
fn();
_exit(0);
}
MaybeSave();
if (pid < 0) {
return PosixError(errno, "fork failed");
}
int status;
if (waitpid(pid, &status, 0) < 0) {
return PosixError(errno, "waitpid failed");
}
return status;
}
} // namespace testing
} // namespace gvisor
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