Change copyright year from 2008 to 2009.
[dss.git] / exec.c
1 /*
2 * Copyright (C) 2003-2009 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file exec.c Helper functions for spawning new processes. */
8
9 #include <string.h>
10 #include <sys/types.h>
11 #include <sys/stat.h>
12 #include <fcntl.h>
13 #include <unistd.h>
14 #include <assert.h>
15 #include <stdlib.h>
16 #include <signal.h>
17
18
19 #include "gcc-compat.h"
20 #include "log.h"
21 #include "error.h"
22 #include "string.h"
23
24
25 /**
26 * Spawn a new process and redirect fd 0, 1, and 2.
27 *
28 * \param pid Will hold the pid of the created process upon return.
29 * \param file Path of the executable to execute.
30 * \param args The argument array for the command.
31 * \param fds a Pointer to a value-result array.
32 *
33 * \return Standard.
34 *
35 * \sa null(4), pipe(2), dup2(2), fork(2), exec(3).
36 */
37 int dss_exec(pid_t *pid, const char *file, char *const *const args, int *fds)
38 {
39 int ret, in[2] = {-1, -1}, out[2] = {-1, -1}, err[2] = {-1, -1},
40 null = -1; /* ;) */
41
42 ret = -E_DUP_PIPE;
43 if (fds[0] > 0 && pipe(in) < 0)
44 goto err_out;
45 if (fds[1] > 0 && pipe(out) < 0)
46 goto err_out;
47 if (fds[2] > 0 && pipe(err) < 0)
48 goto err_out;
49 if (!fds[0] || !fds[1] || !fds[2]) {
50 ret = -E_NULL_OPEN;
51 null = open("/dev/null", O_RDWR);
52 if (null < 0)
53 goto err_out;
54 }
55 if ((*pid = fork()) < 0)
56 exit(EXIT_FAILURE);
57 if (!(*pid)) { /* child */
58 if (fds[0] >= 0) {
59 if (fds[0]) {
60 close(in[1]);
61 if (in[0] != STDIN_FILENO)
62 dup2(in[0], STDIN_FILENO);
63 } else
64 dup2(null, STDIN_FILENO);
65 }
66 if (fds[1] >= 0) {
67 if (fds[1]) {
68 close(out[0]);
69 if (out[1] != STDOUT_FILENO)
70 dup2(out[1], STDOUT_FILENO);
71 } else
72 dup2(null, STDOUT_FILENO);
73 }
74 if (fds[2] >= 0) {
75 if (fds[2]) {
76 close(err[0]);
77 if (err[1] != STDERR_FILENO)
78 dup2(err[1], STDERR_FILENO);
79 } else
80 dup2(null, STDERR_FILENO);
81 }
82 if (null >= 0)
83 close(null);
84 signal(SIGINT, SIG_DFL);
85 signal(SIGTERM, SIG_DFL);
86 signal(SIGCHLD, SIG_DFL);
87 execvp(file, args);
88 _exit(EXIT_FAILURE);
89 }
90 if (fds[0] > 0) {
91 close(in[0]);
92 *fds = in[1];
93 }
94 if (fds[1] > 0) {
95 close(out[1]);
96 *(fds + 1) = out[0];
97 }
98 if (fds[2] > 0) {
99 close(err[1]);
100 *(fds + 2) = err[0];
101 }
102 if (null >= 0)
103 close(null);
104 return 1;
105 err_out:
106 DSS_ERROR_LOG("failed to exec %s\n", file);
107 if (err[0] >= 0)
108 close(err[0]);
109 if (err[1] >= 0)
110 close(err[1]);
111 if (out[0] >= 0)
112 close(out[0]);
113 if (out[1] >= 0)
114 close(out[1]);
115 if (in[0] >= 0)
116 close(in[0]);
117 if (in[1] >= 0)
118 close(in[1]);
119 if (null >= 0)
120 close(null);
121 return ret;
122 }
123
124
125 /**
126 * Exec the given command.
127 *
128 * \param pid Will hold the pid of the created process upon return.
129 * \param cmdline Holds the command and its arguments, seperated by spaces.
130 * \param fds A pointer to a value-result array.
131 *
132 * This function uses fork/exec to create a new process. \a fds must be a
133 * pointer to three integers, corresponding to stdin, stdout and stderr
134 * respectively. It specifies how to deal with fd 0, 1, 2 in the child. The
135 * contents of \a fds are interpreted as follows:
136 *
137 * - fd[i] < 0: leave fd \a i alone.
138 * - fd[i] = 0: dup fd \a i to \p /dev/null.
139 * - fd[i] > 0: create a pipe and dup i to one end of that pipe.
140 * Upon return, fd[i] contains the file descriptor of the pipe.
141 *
142 * In any case, all unneeded filedescriptors are closed.
143 *
144 * \return Standard.
145 */
146 int dss_exec_cmdline_pid(pid_t *pid, const char *cmdline, int *fds)
147 {
148 int argc, ret;
149 char **argv;
150 char *tmp = dss_strdup(cmdline);
151
152 if (!tmp)
153 exit(EXIT_FAILURE);
154 argc = split_args(tmp, &argv, " \t");
155 ret = dss_exec(pid, argv[0], argv, fds);
156 free(argv);
157 free(tmp);
158 return ret;
159 }
160
161