| // 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_ |