Get rid of make_err_msg() and log_err_msg().
[dss.git] / exec.c
1 /** \file exec.c Helper functions for spawning new processes. */
2
3 #include <string.h>
4 #include <sys/types.h>
5 #include <sys/stat.h>
6 #include <fcntl.h>
7 #include <unistd.h>
8 #include <assert.h>
9 #include <stdlib.h>
10 #include <signal.h>
11
12
13 #include "gcc-compat.h"
14 #include "log.h"
15 #include "error.h"
16 #include "string.h"
17
18
19 /**
20 * Spawn a new process and redirect fd 0, 1, and 2.
21 *
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.
26 *
27 * \return Standard.
28 *
29 * \sa null(4), pipe(2), dup2(2), fork(2), exec(3).
30 */
31 int dss_exec(pid_t *pid, const char *file, char *const *const args, int *fds)
32 {
33 int ret, in[2] = {-1, -1}, out[2] = {-1, -1}, err[2] = {-1, -1},
34 null = -1; /* ;) */
35
36 ret = -E_DUP_PIPE;
37 if (fds[0] > 0 && pipe(in) < 0)
38 goto err_out;
39 if (fds[1] > 0 && pipe(out) < 0)
40 goto err_out;
41 if (fds[2] > 0 && pipe(err) < 0)
42 goto err_out;
43 if (!fds[0] || !fds[1] || !fds[2]) {
44 ret = -E_NULL_OPEN;
45 null = open("/dev/null", O_RDONLY);
46 if (null < 0)
47 goto err_out;
48 }
49 if ((*pid = fork()) < 0)
50 exit(EXIT_FAILURE);
51 if (!(*pid)) { /* child */
52 if (fds[0] >= 0) {
53 if (fds[0]) {
54 close(in[1]);
55 if (in[0] != STDIN_FILENO)
56 dup2(in[0], STDIN_FILENO);
57 } else
58 dup2(null, STDIN_FILENO);
59 }
60 if (fds[1] >= 0) {
61 if (fds[1]) {
62 close(out[0]);
63 if (out[1] != STDOUT_FILENO)
64 dup2(out[1], STDOUT_FILENO);
65 } else
66 dup2(null, STDOUT_FILENO);
67 }
68 if (fds[2] >= 0) {
69 if (fds[2]) {
70 close(err[0]);
71 if (err[1] != STDERR_FILENO)
72 dup2(err[1], STDERR_FILENO);
73 } else
74 dup2(null, STDERR_FILENO);
75 }
76 if (null >= 0)
77 close(null);
78 signal(SIGINT, SIG_DFL);
79 signal(SIGTERM, SIG_DFL);
80 signal(SIGCHLD, SIG_DFL);
81 execvp(file, args);
82 _exit(EXIT_FAILURE);
83 }
84 if (fds[0] > 0) {
85 close(in[0]);
86 *fds = in[1];
87 }
88 if (fds[1] > 0) {
89 close(out[1]);
90 *(fds + 1) = out[0];
91 }
92 if (fds[2] > 0) {
93 close(err[1]);
94 *(fds + 2) = err[0];
95 }
96 if (null >= 0)
97 close(null);
98 return 1;
99 err_out:
100 DSS_ERROR_LOG("failed to exec %s\n", file);
101 if (err[0] >= 0)
102 close(err[0]);
103 if (err[1] >= 0)
104 close(err[1]);
105 if (out[0] >= 0)
106 close(out[0]);
107 if (out[1] >= 0)
108 close(out[1]);
109 if (in[0] >= 0)
110 close(in[0]);
111 if (in[1] >= 0)
112 close(in[1]);
113 if (null >= 0)
114 close(null);
115 return ret;
116 }
117
118
119 /**
120 * Exec the given command.
121 *
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.
125 *
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:
130 *
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.
135 *
136 * In any case, all unneeded filedescriptors are closed.
137 *
138 * \return Standard.
139 */
140 int dss_exec_cmdline_pid(pid_t *pid, const char *cmdline, int *fds)
141 {
142 int argc, ret;
143 char **argv;
144 char *tmp = dss_strdup(cmdline);
145
146 if (!tmp)
147 exit(EXIT_FAILURE);
148 argc = split_args(tmp, &argv, " \t");
149 ret = dss_exec(pid, argv[0], argv, fds);
150 free(argv);
151 free(tmp);
152 return ret;
153 }
154
155