1 /** \file exec.c Helper functions for spawning new processes. */
13 #include "gcc-compat.h"
20 * Spawn a new process and redirect fd 0, 1, and 2.
22 * \param pid Will hold the pid of the created process upon return.
23 * \param file Path of the executable to execute.
24 * \param args The argument array for the command.
25 * \param fds a Pointer to a value-result array.
29 * \sa null(4), pipe(2), dup2(2), fork(2), exec(3).
31 int dss_exec(pid_t *pid, const char *file, char *const *const args, int *fds)
33 int ret, in[2] = {-1, -1}, out[2] = {-1, -1}, err[2] = {-1, -1},
37 if (fds[0] > 0 && pipe(in) < 0)
39 if (fds[1] > 0 && pipe(out) < 0)
41 if (fds[2] > 0 && pipe(err) < 0)
43 if (!fds[0] || !fds[1] || !fds[2]) {
45 null = open("/dev/null", O_RDONLY);
49 if ((*pid = fork()) < 0)
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);
78 signal(SIGINT, SIG_DFL);
79 signal(SIGTERM, SIG_DFL);
80 signal(SIGCHLD, SIG_DFL);
100 DSS_ERROR_LOG("failed to exec %s\n", file);
120 * Exec the given command.
122 * \param pid Will hold the pid of the created process upon return.
123 * \param cmdline Holds the command and its arguments, seperated by spaces.
124 * \param fds A pointer to a value-result array.
126 * This function uses fork/exec to create a new process. \a fds must be a
127 * pointer to three integers, corresponding to stdin, stdout and stderr
128 * respectively. It specifies how to deal with fd 0, 1, 2 in the child. The
129 * contents of \a fds are interpreted as follows:
131 * - fd[i] < 0: leave fd \a i alone.
132 * - fd[i] = 0: dup fd \a i to \p /dev/null.
133 * - fd[i] > 0: create a pipe and dup i to one end of that pipe.
134 * Upon return, fd[i] contains the file descriptor of the pipe.
136 * In any case, all unneeded filedescriptors are closed.
140 int dss_exec_cmdline_pid(pid_t *pid, const char *cmdline, int *fds)
144 char *tmp = dss_strdup(cmdline);
148 argc = split_args(tmp, &argv, " \t");
149 ret = dss_exec(pid, argv[0], argv, fds);