2 * Copyright (C) 2003-2009 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. */
10 #include "close_on_fork.h"
16 * Spawn a new process and redirect fd 0, 1, and 2.
18 * \param pid Will hold the pid of the created process upon return.
19 * \param file Path of the executable to execute.
20 * \param args The argument array for the command.
21 * \param fds a Pointer to a value-result array.
25 * \sa null(4), pipe(2), dup2(2), fork(2), exec(3).
27 static int para_exec(pid_t *pid, const char *file, char *const *const args, int *fds)
29 int ret, in[2] = {-1, -1}, out[2] = {-1, -1}, err[2] = {-1, -1},
33 if (fds[0] > 0 && pipe(in) < 0)
35 if (fds[1] > 0 && pipe(out) < 0)
37 if (fds[2] > 0 && pipe(err) < 0)
39 if (!fds[0] || !fds[1] || !fds[2]) {
40 ret = para_open("/dev/null", O_RDWR, 42);
47 ret = -ERRNO_TO_PARA_ERROR(errno);
51 if (!(*pid)) { /* child */
55 if (in[0] != STDIN_FILENO)
56 dup2(in[0], STDIN_FILENO);
58 dup2(null, STDIN_FILENO);
63 if (out[1] != STDOUT_FILENO)
64 dup2(out[1], STDOUT_FILENO);
66 dup2(null, STDOUT_FILENO);
71 if (err[1] != STDERR_FILENO)
72 dup2(err[1], STDERR_FILENO);
74 dup2(null, STDERR_FILENO);
111 PARA_ERROR_LOG("%s\n", para_strerror(-ret));
116 * Exec the given command.
118 * \param pid Will hold the pid of the created process upon return.
119 * \param cmdline Holds the command and its arguments, seperated by spaces.
120 * \param fds A pointer to a value-result array.
122 * This function uses fork/exec to create a new process. \a fds must be a
123 * pointer to three integers, corresponding to stdin, stdout and stderr
124 * respectively. It specifies how to deal with fd 0, 1, 2 in the child. The
125 * contents of \a fds are interpreted as follows:
127 * - fd[i] < 0: leave fd \a i alone.
128 * - fd[i] = 0: dup fd \a i to \p /dev/null.
129 * - fd[i] > 0: create a pipe and dup i to one end of that pipe.
130 * Upon return, fd[i] contains the file descriptor of the pipe.
132 * In any case, all unneeded filedescriptors are closed.
136 int para_exec_cmdline_pid(pid_t *pid, const char *cmdline, int *fds)
140 char *tmp = para_strdup(cmdline);
142 argc = split_args(tmp, &argv, " \t");
143 ret = para_exec(pid, argv[0], argv, fds);