2 * Copyright (C) 2003-2008 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file exec.c Helper functions for spawning new processes. */
9 #include "close_on_fork.h"
14 * Spawn a new process and redirect fd 0, 1, and 2.
16 * \param pid Will hold the pid of the created process upon return.
17 * \param file Path of the executable to execute.
18 * \param args The argument array for the command.
19 * \param fds a Pointer to a value-result array.
23 * \sa null(4), pipe(2), dup2(2), fork(2), exec(3).
25 static int para_exec(pid_t *pid, const char *file, char *const *const args, int *fds)
27 int ret, in[2] = {-1, -1}, out[2] = {-1, -1}, err[2] = {-1, -1},
31 if (fds[0] > 0 && pipe(in) < 0)
33 if (fds[1] > 0 && pipe(out) < 0)
35 if (fds[2] > 0 && pipe(err) < 0)
37 if (!fds[0] || !fds[1] || !fds[2]) {
39 null = open("/dev/null", O_RDONLY);
43 if ((*pid = fork()) < 0)
45 if (!(*pid)) { /* child */
46 close_listed_fds(); /* close unneeded fds */
50 if (in[0] != STDIN_FILENO)
51 dup2(in[0], STDIN_FILENO);
53 dup2(null, STDIN_FILENO);
58 if (out[1] != STDOUT_FILENO)
59 dup2(out[1], STDOUT_FILENO);
61 dup2(null, STDOUT_FILENO);
66 if (err[1] != STDERR_FILENO)
67 dup2(err[1], STDERR_FILENO);
69 dup2(null, STDERR_FILENO);
110 * Exec the given command.
112 * \param pid Will hold the pid of the created process upon return.
113 * \param cmdline Holds the command and its arguments, seperated by spaces.
114 * \param fds A pointer to a value-result array.
116 * This function uses fork/exec to create a new process. \a fds must be a
117 * pointer to three integers, corresponding to stdin, stdout and stderr
118 * respectively. It specifies how to deal with fd 0, 1, 2 in the child. The
119 * contents of \a fds are interpreted as follows:
121 * - fd[i] < 0: leave fd \a i alone.
122 * - fd[i] = 0: dup fd \a i to \p /dev/null.
123 * - fd[i] > 0: create a pipe and dup i to one end of that pipe.
124 * Upon return, fd[i] contains the file descriptor of the pipe.
126 * In any case, all unneeded filedescriptors are closed.
130 int para_exec_cmdline_pid(pid_t *pid, const char *cmdline, int *fds)
134 char *tmp = para_strdup(cmdline);
138 argc = split_args(tmp, &argv, " \t");
139 ret = para_exec(pid, argv[0], argv, fds);