Initial git checkin.
[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
11
12 #include "gcc-compat.h"
13 #include "error.h"
14 #include "string.h"
15
16
17 /**
18 * Spawn a new process and redirect fd 0, 1, and 2.
19 *
20 * \param pid Will hold the pid of the created process upon return.
21 * \param file Path of the executable to execute.
22 * \param args The argument array for the command.
23 * \param fds a Pointer to a value-result array.
24 *
25 * \return Standard.
26 *
27 * \sa null(4), pipe(2), dup2(2), fork(2), exec(3).
28 */
29 int dss_exec(pid_t *pid, const char *file, char *const *const args, int *fds)
30 {
31 int ret, in[2] = {-1, -1}, out[2] = {-1, -1}, err[2] = {-1, -1},
32 null = -1; /* ;) */
33
34 ret = -E_DUP_PIPE;
35 if (fds[0] > 0 && pipe(in) < 0)
36 goto err_out;
37 if (fds[1] > 0 && pipe(out) < 0)
38 goto err_out;
39 if (fds[2] > 0 && pipe(err) < 0)
40 goto err_out;
41 if (!fds[0] || !fds[1] || !fds[2]) {
42 ret = -E_NULL_OPEN;
43 null = open("/dev/null", O_RDONLY);
44 if (null < 0)
45 goto err_out;
46 }
47 if ((*pid = fork()) < 0)
48 exit(EXIT_FAILURE);
49 if (!(*pid)) { /* child */
50 if (fds[0] >= 0) {
51 if (fds[0]) {
52 close(in[1]);
53 if (in[0] != STDIN_FILENO)
54 dup2(in[0], STDIN_FILENO);
55 } else
56 dup2(null, STDIN_FILENO);
57 }
58 if (fds[1] >= 0) {
59 if (fds[1]) {
60 close(out[0]);
61 if (out[1] != STDOUT_FILENO)
62 dup2(out[1], STDOUT_FILENO);
63 } else
64 dup2(null, STDOUT_FILENO);
65 }
66 if (fds[2] >= 0) {
67 if (fds[2]) {
68 close(err[0]);
69 if (err[1] != STDERR_FILENO)
70 dup2(err[1], STDERR_FILENO);
71 } else
72 dup2(null, STDERR_FILENO);
73 }
74 if (null >= 0)
75 close(null);
76 execvp(file, args);
77 _exit(EXIT_FAILURE);
78 }
79 if (fds[0] > 0) {
80 close(in[0]);
81 *fds = in[1];
82 }
83 if (fds[1] > 0) {
84 close(out[1]);
85 *(fds + 1) = out[0];
86 }
87 if (fds[2] > 0) {
88 close(err[1]);
89 *(fds + 2) = err[0];
90 }
91 if (null >= 0)
92 close(null);
93 return 1;
94 err_out:
95 make_err_msg("failed to exec %s", file);
96 if (err[0] >= 0)
97 close(err[0]);
98 if (err[1] >= 0)
99 close(err[1]);
100 if (out[0] >= 0)
101 close(out[0]);
102 if (out[1] >= 0)
103 close(out[1]);
104 if (in[0] >= 0)
105 close(in[0]);
106 if (in[1] >= 0)
107 close(in[1]);
108 if (null >= 0)
109 close(null);
110 return ret;
111 }