1// SPDX-License-Identifier: GPL-2.0
2#include <unistd.h>
3#include <sys/types.h>
4#include <sys/stat.h>
5#include <fcntl.h>
6#include <string.h>
7#include <linux/string.h>
8#include <errno.h>
9#include <sys/wait.h>
10#include "subcmd-util.h"
11#include "run-command.h"
12#include "exec-cmd.h"
13
14#define STRERR_BUFSIZE 128
15
16static inline void close_pair(int fd[2])
17{
18 close(fd[0]);
19 close(fd[1]);
20}
21
22static inline void dup_devnull(int to)
23{
24 int fd = open("/dev/null", O_RDWR);
25 dup2(fd, to);
26 close(fd);
27}
28
29int start_command(struct child_process *cmd)
30{
31 int need_in, need_out, need_err;
32 int fdin[2], fdout[2], fderr[2];
33 char sbuf[STRERR_BUFSIZE];
34
35 /*
36 * In case of errors we must keep the promise to close FDs
37 * that have been passed in via ->in and ->out.
38 */
39
40 need_in = !cmd->no_stdin && cmd->in < 0;
41 if (need_in) {
42 if (pipe(fdin) < 0) {
43 if (cmd->out > 0)
44 close(cmd->out);
45 return -ERR_RUN_COMMAND_PIPE;
46 }
47 cmd->in = fdin[1];
48 }
49
50 need_out = !cmd->no_stdout
51 && !cmd->stdout_to_stderr
52 && cmd->out < 0;
53 if (need_out) {
54 if (pipe(fdout) < 0) {
55 if (need_in)
56 close_pair(fd: fdin);
57 else if (cmd->in)
58 close(cmd->in);
59 return -ERR_RUN_COMMAND_PIPE;
60 }
61 cmd->out = fdout[0];
62 }
63
64 need_err = !cmd->no_stderr && cmd->err < 0;
65 if (need_err) {
66 if (pipe(fderr) < 0) {
67 if (need_in)
68 close_pair(fd: fdin);
69 else if (cmd->in)
70 close(cmd->in);
71 if (need_out)
72 close_pair(fd: fdout);
73 else if (cmd->out)
74 close(cmd->out);
75 return -ERR_RUN_COMMAND_PIPE;
76 }
77 cmd->err = fderr[0];
78 }
79
80 fflush(NULL);
81 cmd->pid = fork();
82 if (!cmd->pid) {
83 if (cmd->no_stdin)
84 dup_devnull(to: 0);
85 else if (need_in) {
86 dup2(fdin[0], 0);
87 close_pair(fd: fdin);
88 } else if (cmd->in) {
89 dup2(cmd->in, 0);
90 close(cmd->in);
91 }
92
93 if (cmd->no_stderr)
94 dup_devnull(to: 2);
95 else if (need_err) {
96 dup2(fderr[1], 2);
97 close_pair(fd: fderr);
98 }
99
100 if (cmd->no_stdout)
101 dup_devnull(to: 1);
102 else if (cmd->stdout_to_stderr)
103 dup2(2, 1);
104 else if (need_out) {
105 dup2(fdout[1], 1);
106 close_pair(fd: fdout);
107 } else if (cmd->out > 1) {
108 dup2(cmd->out, 1);
109 close(cmd->out);
110 }
111
112 if (cmd->dir && chdir(cmd->dir))
113 die(err: "exec %s: cd to %s failed (%s)", cmd->argv[0],
114 cmd->dir, str_error_r(errno, sbuf, sizeof(sbuf)));
115 if (cmd->env) {
116 for (; *cmd->env; cmd->env++) {
117 if (strchr(*cmd->env, '='))
118 putenv((char*)*cmd->env);
119 else
120 unsetenv(*cmd->env);
121 }
122 }
123 if (cmd->preexec_cb)
124 cmd->preexec_cb();
125 if (cmd->no_exec_cmd)
126 exit(cmd->no_exec_cmd(cmd));
127 if (cmd->exec_cmd) {
128 execv_cmd(argv: cmd->argv);
129 } else {
130 execvp(cmd->argv[0], (char *const*) cmd->argv);
131 }
132 exit(127);
133 }
134
135 if (cmd->pid < 0) {
136 int err = errno;
137 if (need_in)
138 close_pair(fd: fdin);
139 else if (cmd->in)
140 close(cmd->in);
141 if (need_out)
142 close_pair(fd: fdout);
143 else if (cmd->out)
144 close(cmd->out);
145 if (need_err)
146 close_pair(fd: fderr);
147 return err == ENOENT ?
148 -ERR_RUN_COMMAND_EXEC :
149 -ERR_RUN_COMMAND_FORK;
150 }
151
152 if (need_in)
153 close(fdin[0]);
154 else if (cmd->in)
155 close(cmd->in);
156
157 if (need_out)
158 close(fdout[1]);
159 else if (cmd->out)
160 close(cmd->out);
161
162 if (need_err)
163 close(fderr[1]);
164
165 return 0;
166}
167
168static int wait_or_whine(pid_t pid)
169{
170 char sbuf[STRERR_BUFSIZE];
171
172 for (;;) {
173 int status, code;
174 pid_t waiting = waitpid(pid, &status, 0);
175
176 if (waiting < 0) {
177 if (errno == EINTR)
178 continue;
179 fprintf(stderr, " Error: waitpid failed (%s)",
180 str_error_r(errno, sbuf, sizeof(sbuf)));
181 return -ERR_RUN_COMMAND_WAITPID;
182 }
183 if (waiting != pid)
184 return -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
185 if (WIFSIGNALED(status))
186 return -ERR_RUN_COMMAND_WAITPID_SIGNAL;
187
188 if (!WIFEXITED(status))
189 return -ERR_RUN_COMMAND_WAITPID_NOEXIT;
190 code = WEXITSTATUS(status);
191 switch (code) {
192 case 127:
193 return -ERR_RUN_COMMAND_EXEC;
194 case 0:
195 return 0;
196 default:
197 return -code;
198 }
199 }
200}
201
202int finish_command(struct child_process *cmd)
203{
204 return wait_or_whine(pid: cmd->pid);
205}
206
207int run_command(struct child_process *cmd)
208{
209 int code = start_command(cmd);
210 if (code)
211 return code;
212 return finish_command(cmd);
213}
214
215static void prepare_run_command_v_opt(struct child_process *cmd,
216 const char **argv,
217 int opt)
218{
219 memset(cmd, 0, sizeof(*cmd));
220 cmd->argv = argv;
221 cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
222 cmd->exec_cmd = opt & RUN_EXEC_CMD ? 1 : 0;
223 cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
224}
225
226int run_command_v_opt(const char **argv, int opt)
227{
228 struct child_process cmd;
229 prepare_run_command_v_opt(cmd: &cmd, argv, opt);
230 return run_command(cmd: &cmd);
231}
232

source code of linux/tools/lib/subcmd/run-command.c