// 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.
|
|
#ifndef CRASHPAD_UTIL_POSIX_DOUBLE_FORK_AND_EXEC_H_
|
#define CRASHPAD_UTIL_POSIX_DOUBLE_FORK_AND_EXEC_H_
|
|
#include <string>
|
#include <vector>
|
|
namespace crashpad {
|
|
//! \brief Executes a (grand-)child process.
|
//!
|
//! The grandchild process will be started through the
|
//! double-`fork()`-and-`execv()` pattern. This allows the grandchild to fully
|
//! 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,
|
//! providing isolation from signals not intended for it. The grandchild’s
|
//! parent process, in terms of the process tree hierarchy, will be the process
|
//! with process ID 1, relieving any other process of the responsibility to reap
|
//! it via `waitpid()`. Aside from the three file descriptors associated with
|
//! the standard input/output streams and any file descriptor passed in \a
|
//! preserve_fd, the grandchild will not inherit any file descriptors from the
|
//! parent process.
|
//!
|
//! \param[in] argv The argument vector to start the grandchild process with.
|
//! `argv[0]` is used as the path to the executable.
|
//! \param[in] envp A vector of environment variables of the form `var=value` to
|
//! be passed to `execve()`. If this value is `nullptr`, the current
|
//! environment is used.
|
//! \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
|
//! descriptors associated with the standard input/output streams. Use `-1`
|
//! if no additional file descriptors are to be inherited.
|
//! \param[in] use_path Whether to consult the `PATH` environment variable when
|
//! requested to start an executable at a non-absolute path. If `false`,
|
//! `execv()`, which does not consult `PATH`, will be used. If `true`,
|
//! `execvp()`, which does consult `PATH`, will be used.
|
//! \param[in] child_function If not `nullptr`, this function will be called in
|
//! 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
|
//! 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.
|
//! Only failures that occur in the parent process that indicate a definite
|
//! failure to start the the grandchild are reported in the return value.
|
//! Failures in the intermediate child or grandchild processes cannot be
|
//! reported in the return value, and are addressed by logging a message and
|
//! terminating. The caller assumes the responsibility for detecting such
|
//! failures, for example, by observing a failure to perform a successful
|
//! handshake with the grandchild process.
|
bool DoubleForkAndExec(const std::vector<std::string>& argv,
|
const std::vector<std::string>* envp,
|
int preserve_fd,
|
bool use_path,
|
void (*child_function)());
|
|
} // namespace crashpad
|
|
#endif // CRASHPAD_UTIL_POSIX_DOUBLE_FORK_AND_EXEC_H_
|
