text: /* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to
   * deal in the Software without restriction, including without limitation the
   * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
   * sell copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   * IN THE SOFTWARE.
   */
  
  #include "uv.h"
  #include "internal.h"
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <assert.h>
  #include <errno.h>
  
  #include <sys/types.h>
  #include <sys/wait.h>
  #include <unistd.h>
  #include <fcntl.h>
  #include <poll.h>
  
  #if defined(__APPLE__) && !TARGET_OS_IPHONE
  # include <crt_externs.h>
  # define environ (*_NSGetEnviron())
  #else
  extern char **environ;
  #endif
  
  
  static QUEUE* uv__process_queue(uv_loop_t* loop, int pid) {
    assert(pid > 0);
    return loop->process_handles + pid % ARRAY_SIZE(loop->process_handles);
  }
  
  
  static void uv__chld(uv_signal_t* handle, int signum) {
    uv_process_t* process;
    uv_loop_t* loop;
    int exit_status;
    int term_signal;
    unsigned int i;
    int status;
    pid_t pid;
    QUEUE pending;
    QUEUE* h;
    QUEUE* q;
  
    assert(signum == SIGCHLD);
  
    QUEUE_INIT(&pending);
    loop = handle->loop;
  
    for (i = 0; i < ARRAY_SIZE(loop->process_handles); i++) {
      h = loop->process_handles + i;
      q = QUEUE_HEAD(h);
  
      while (q != h) {
        process = QUEUE_DATA(q, uv_process_t, queue);
        q = QUEUE_NEXT(q);
  
        do
          pid = waitpid(process->pid, &status, WNOHANG);
        while (pid == -1 && errno == EINTR);
  
        if (pid == 0)
          continue;
  
        if (pid == -1) {
          if (errno != ECHILD)
            abort();
          continue;
        }
  
        process->status = status;
        QUEUE_REMOVE(&process->queue);
        QUEUE_INSERT_TAIL(&pending, &process->queue);
      }
  
      while (!QUEUE_EMPTY(&pending)) {
        q = QUEUE_HEAD(&pending);
        QUEUE_REMOVE(q);
        QUEUE_INIT(q);
  
        process = QUEUE_DATA(q, uv_process_t, queue);
        uv__handle_stop(process);
  
        if (process->exit_cb == NULL)
          continue;
  
        exit_status = 0;
        if (WIFEXITED(process->status))
          exit_status = WEXITSTATUS(process->status);
  
        term_signal = 0;
        if (WIFSIGNALED(process->status))
          term_signal = WTERMSIG(process->status);
  
        if (process->errorno != 0)
          exit_status = process->errorno;  /* execve() failed */
  
        process->exit_cb(process, exit_status, term_signal);
      }
    }
  }
  
  
  int uv__make_socketpair(int fds[2], int flags) {
  #if defined(__linux__)
    static int no_cloexec;
  
    if (no_cloexec)
      goto skip;
  
    if (socketpair(AF_UNIX, SOCK_STREAM | UV__SOCK_CLOEXEC | flags, 0, fds) == 0)
      return 0;
  
    /* Retry on EINVAL, it means SOCK_CLOEXEC is not supported.
     * Anything else is a genuine error.
     */
    if (errno != EINVAL)
      return -errno;
  
    no_cloexec = 1;
  
  skip:
  #endif
  
    if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds))
      return -errno;
  
    uv__cloexec(fds[0], 1);
    uv__cloexec(fds[1], 1);
  
    if (flags & UV__F_NONBLOCK) {
      uv__nonblock(fds[0], 1);
      uv__nonblock(fds[1], 1);
    }
  
    return 0;
  }
  
  
  int uv__make_pipe(int fds[2], int flags) {
  #if defined(__linux__)
    static int no_pipe2;
  
    if (no_pipe2)
      goto skip;
  
    if (uv__pipe2(fds, flags | UV__O_CLOEXEC) == 0)
      return 0;
  
    if (errno != ENOSYS)
      return -errno;
  
    no_pipe2 = 1;
  
  skip:
  #endif
  
    if (pipe(fds))
      return -errno;
  
    uv__cloexec(fds[0], 1);
    uv__cloexec(fds[1], 1);
  
    if (flags & UV__F_NONBLOCK) {
      uv__nonblock(fds[0], 1);
      uv__nonblock(fds[1], 1);
    }
  
    return 0;
  }
  
  
  /*
   * Used for initializing stdio streams like options->stdin_stream. Returns
   * zero on success.
   */
  static int uv__process_init_stdio(uv_stdio_container_t* container, int fds[2]) {
    int mask;
    int fd;
  
    mask = UV_IGNORE | UV_CREATE_PIPE | UV_INHERIT_FD | UV_INHERIT_STREAM;
  
    switch (container->flags & mask) {
    case UV_IGNORE:
      return 0;
  
    case UV_CREATE_PIPE:
      assert(container->data.stream != NULL);
      if (container->data.stream->type != UV_NAMED_PIPE)
        return -EINVAL;
      else
        return uv__make_socketpair(fds, 0);
  
    case UV_INHERIT_FD:
    case UV_INHERIT_STREAM:
      if (container->flags & UV_INHERIT_FD)
        fd = container->data.fd;
      else
        fd = uv__stream_fd(container->data.stream);
  
      if (fd == -1)
        return -EINVAL;
  
      fds[1] = fd;
      return 0;
  
    default:
      assert(0 && "Unexpected flags");
      return -EINVAL;
    }
  }
  
  
  static int uv__process_open_stream(uv_stdio_container_t* container,
                                     int pipefds[2],
                                     int writable) {
    int flags;
  
    if (!(container->flags & UV_CREATE_PIPE) || pipefds[0] < 0)
      return 0;
  
    if (uv__close(pipefds[1]))
      if (errno != EINTR && errno != EINPROGRESS)
        abort();
  
    pipefds[1] = -1;
    uv__nonblock(pipefds[0], 1);
  
    if (container->data.stream->type == UV_NAMED_PIPE &&
        ((uv_pipe_t*)container->data.stream)->ipc)
      flags = UV_STREAM_READABLE | UV_STREAM_WRITABLE;
    else if (writable)
      flags = UV_STREAM_WRITABLE;
    else
      flags = UV_STREAM_READABLE;
  
    return uv__stream_open(container->data.stream, pipefds[0], flags);
  }
  
  
  static void uv__process_close_stream(uv_stdio_container_t* container) {
    if (!(container->flags & UV_CREATE_PIPE)) return;
    uv__stream_close((uv_stream_t*)container->data.stream);
  }
  
  
  static void uv__write_int(int fd, int val) {
    ssize_t n;
  
    do
      n = write(fd, &val, sizeof(val));
    while (n == -1 && errno == EINTR);
  
    if (n == -1 && errno == EPIPE)
      return; /* parent process has quit */
  
    assert(n == sizeof(val));
  }
  
  
  static void uv__process_child_init(const uv_process_options_t* options,
                                     int stdio_count,
                                     int (*pipes)[2],
                                     int error_fd) {
    int close_fd;
    int use_fd;
    int fd;
  
    if (options->flags & UV_PROCESS_DETACHED)
      setsid();
  
    for (fd = 0; fd < stdio_count; fd++) {
      close_fd = pipes[fd][0];
      use_fd = pipes[fd][1];
  
      if (use_fd >= 0) {
        if (close_fd != -1)
          uv__close(close_fd);
      }
      else if (fd >= 3)
        continue;
      else {
        /* redirect stdin, stdout and stderr to /dev/null even if UV_IGNORE is
         * set
         */
        use_fd = open("/dev/null", fd == 0 ? O_RDONLY : O_RDWR);
  
        if (use_fd == -1) {
          uv__write_int(error_fd, -errno);
          perror("failed to open stdio");
          _exit(127);
        }
      }
  
      if (fd == use_fd)
        uv__cloexec(use_fd, 0);
      else {
        dup2(use_fd, fd);
        uv__close(use_fd);
      }
  
      if (fd <= 2)
        uv__nonblock(fd, 0);
    }
  
    if (options->cwd != NULL && chdir(options->cwd)) {
      uv__write_int(error_fd, -errno);
      perror("chdir()");
      _exit(127);
    }
  
    if ((options->flags & UV_PROCESS_SETGID) && setgid(options->gid)) {
      uv__write_int(error_fd, -errno);
      perror("setgid()");
      _exit(127);
    }
  
    if ((options->flags & UV_PROCESS_SETUID) && setuid(options->uid)) {
      uv__write_int(error_fd, -errno);
      perror("setuid()");
      _exit(127);
    }
  
    if (options->env != NULL) {
      environ = options->env;
    }
  
    execvp(options->file, options->args);
    uv__write_int(error_fd, -errno);
    perror("execvp()");
    _exit(127);
  }
  
  
  int uv_spawn(uv_loop_t* loop,
               uv_process_t* process,
               const uv_process_options_t* options) {
    int signal_pipe[2] = { -1, -1 };
    int (*pipes)[2];
    int stdio_count;
    QUEUE* q;
    ssize_t r;
    pid_t pid;
    int err;
    int i;
  
    assert(options->file != NULL);
    assert(!(options->flags & ~(UV_PROCESS_DETACHED |
                                UV_PROCESS_SETGID |
                                UV_PROCESS_SETUID |
                                UV_PROCESS_WINDOWS_HIDE |
                                UV_PROCESS_WINDOWS_VERBATIM_ARGUMENTS)));
  
    uv__handle_init(loop, (uv_handle_t*)process, UV_PROCESS);
    QUEUE_INIT(&process->queue);
  
    stdio_count = options->stdio_count;
    if (stdio_count < 3)
      stdio_count = 3;
  
    err = -ENOMEM;
    pipes = malloc(stdio_count * sizeof(*pipes));
    if (pipes == NULL)
      goto error;
  
    for (i = 0; i < stdio_count; i++) {
      pipes[i][0] = -1;
      pipes[i][1] = -1;
    }
  
    for (i = 0; i < options->stdio_count; i++) {
      err = uv__process_init_stdio(options->stdio + i, pipes[i]);
      if (err)
        goto error;
    }
  
    /* This pipe is used by the parent to wait until
     * the child has called `execve()`. We need this
     * to avoid the following race condition:
     *
     *    if ((pid = fork()) > 0) {
     *      kill(pid, SIGTERM);
     *    }
     *    else if (pid == 0) {
     *      execve("/bin/cat", argp, envp);
     *    }
     *
     * The parent sends a signal immediately after forking.
     * Since the child may not have called `execve()` yet,
     * there is no telling what process receives the signal,
     * our fork or /bin/cat.
     *
     * To avoid ambiguity, we create a pipe with both ends
     * marked close-on-exec. Then, after the call to `fork()`,
     * the parent polls the read end until it EOFs or errors with EPIPE.
     */
    err = uv__make_pipe(signal_pipe, 0);
    if (err)
      goto error;
  
    uv_signal_start(&loop->child_watcher, uv__chld, SIGCHLD);
  
    pid = fork();
  
    if (pid == -1) {
      err = -errno;
      uv__close(signal_pipe[0]);
      uv__close(signal_pipe[1]);
      goto error;
    }
  
    if (pid == 0) {
      uv__process_child_init(options, stdio_count, pipes, signal_pipe[1]);
      abort();
    }
  
    uv__close(signal_pipe[1]);
  
    process->status = 0;
    process->errorno = 0;
    do
      r = read(signal_pipe[0], &process->errorno, sizeof(process->errorno));
    while (r == -1 && errno == EINTR);
  
    if (r == 0)
      ; /* okay, EOF */
    else if (r == sizeof(process->errorno))
      ; /* okay, read errorno */
    else if (r == -1 && errno == EPIPE)
      ; /* okay, got EPIPE */
    else
      abort();
  
    uv__close(signal_pipe[0]);
  
    for (i = 0; i < options->stdio_count; i++) {
      err = uv__process_open_stream(options->stdio + i, pipes[i], i == 0);
      if (err == 0)
        continue;
  
      while (i--)
        uv__process_close_stream(options->stdio + i);
  
      goto error;
    }
  
    q = uv__process_queue(loop, pid);
    QUEUE_INSERT_TAIL(q, &process->queue);
  
    process->pid = pid;
    process->exit_cb = options->exit_cb;
    uv__handle_start(process);
  
    free(pipes);
    return 0;
  
  error:
    for (i = 0; i < stdio_count; i++) {
      uv__close(pipes[i][0]);
      uv__close(pipes[i][1]);
    }
    free(pipes);
  
    return err;
  }
  
  
  int uv_process_kill(uv_process_t* process, int signum) {
    return uv_kill(process->pid, signum);
  }
  
  
  int uv_kill(int pid, int signum) {
    if (kill(pid, signum))
      return -errno;
    else
      return 0;
  }
  
  
  void uv__process_close(uv_process_t* handle) {
    /* TODO stop signal watcher when this is the last handle */
    QUEUE_REMOVE(&handle->queue);
    uv__handle_stop(handle);
  }
  