Windows: avoid the "dup dance" when spawning a child process
[git/git.git] / run-command.c
1 #include "cache.h"
2 #include "run-command.h"
3 #include "exec_cmd.h"
4
5 static inline void close_pair(int fd[2])
6 {
7 close(fd[0]);
8 close(fd[1]);
9 }
10
11 #ifndef WIN32
12 static inline void dup_devnull(int to)
13 {
14 int fd = open("/dev/null", O_RDWR);
15 dup2(fd, to);
16 close(fd);
17 }
18 #endif
19
20 int start_command(struct child_process *cmd)
21 {
22 int need_in, need_out, need_err;
23 int fdin[2], fdout[2], fderr[2];
24 int failed_errno = failed_errno;
25
26 /*
27 * In case of errors we must keep the promise to close FDs
28 * that have been passed in via ->in and ->out.
29 */
30
31 need_in = !cmd->no_stdin && cmd->in < 0;
32 if (need_in) {
33 if (pipe(fdin) < 0) {
34 failed_errno = errno;
35 if (cmd->out > 0)
36 close(cmd->out);
37 goto fail_pipe;
38 }
39 cmd->in = fdin[1];
40 }
41
42 need_out = !cmd->no_stdout
43 && !cmd->stdout_to_stderr
44 && cmd->out < 0;
45 if (need_out) {
46 if (pipe(fdout) < 0) {
47 failed_errno = errno;
48 if (need_in)
49 close_pair(fdin);
50 else if (cmd->in)
51 close(cmd->in);
52 goto fail_pipe;
53 }
54 cmd->out = fdout[0];
55 }
56
57 need_err = !cmd->no_stderr && cmd->err < 0;
58 if (need_err) {
59 if (pipe(fderr) < 0) {
60 failed_errno = errno;
61 if (need_in)
62 close_pair(fdin);
63 else if (cmd->in)
64 close(cmd->in);
65 if (need_out)
66 close_pair(fdout);
67 else if (cmd->out)
68 close(cmd->out);
69 fail_pipe:
70 error("cannot create pipe for %s: %s",
71 cmd->argv[0], strerror(failed_errno));
72 errno = failed_errno;
73 return -1;
74 }
75 cmd->err = fderr[0];
76 }
77
78 trace_argv_printf(cmd->argv, "trace: run_command:");
79
80 #ifndef WIN32
81 fflush(NULL);
82 cmd->pid = fork();
83 if (!cmd->pid) {
84 if (cmd->no_stdin)
85 dup_devnull(0);
86 else if (need_in) {
87 dup2(fdin[0], 0);
88 close_pair(fdin);
89 } else if (cmd->in) {
90 dup2(cmd->in, 0);
91 close(cmd->in);
92 }
93
94 if (cmd->no_stderr)
95 dup_devnull(2);
96 else if (need_err) {
97 dup2(fderr[1], 2);
98 close_pair(fderr);
99 }
100
101 if (cmd->no_stdout)
102 dup_devnull(1);
103 else if (cmd->stdout_to_stderr)
104 dup2(2, 1);
105 else if (need_out) {
106 dup2(fdout[1], 1);
107 close_pair(fdout);
108 } else if (cmd->out > 1) {
109 dup2(cmd->out, 1);
110 close(cmd->out);
111 }
112
113 if (cmd->dir && chdir(cmd->dir))
114 die_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
115 cmd->dir);
116 if (cmd->env) {
117 for (; *cmd->env; cmd->env++) {
118 if (strchr(*cmd->env, '='))
119 putenv((char *)*cmd->env);
120 else
121 unsetenv(*cmd->env);
122 }
123 }
124 if (cmd->preexec_cb)
125 cmd->preexec_cb();
126 if (cmd->git_cmd) {
127 execv_git_cmd(cmd->argv);
128 } else {
129 execvp(cmd->argv[0], (char *const*) cmd->argv);
130 }
131 trace_printf("trace: exec '%s' failed: %s\n", cmd->argv[0],
132 strerror(errno));
133 exit(127);
134 }
135 if (cmd->pid < 0)
136 error("cannot fork() for %s: %s", cmd->argv[0],
137 strerror(failed_errno = errno));
138 #else
139 {
140 int fhin = 0, fhout = 1, fherr = 2;
141 const char **sargv = cmd->argv;
142 char **env = environ;
143
144 if (cmd->no_stdin)
145 fhin = open("/dev/null", O_RDWR);
146 else if (need_in)
147 fhin = dup(fdin[0]);
148 else if (cmd->in)
149 fhin = dup(cmd->in);
150
151 if (cmd->no_stderr)
152 fherr = open("/dev/null", O_RDWR);
153 else if (need_err)
154 fherr = dup(fderr[1]);
155
156 if (cmd->no_stdout)
157 fhout = open("/dev/null", O_RDWR);
158 else if (cmd->stdout_to_stderr)
159 fhout = dup(fherr);
160 else if (need_out)
161 fhout = dup(fdout[1]);
162 else if (cmd->out > 1)
163 fhout = dup(cmd->out);
164
165 if (cmd->dir)
166 die("chdir in start_command() not implemented");
167 if (cmd->env)
168 env = make_augmented_environ(cmd->env);
169
170 if (cmd->git_cmd) {
171 cmd->argv = prepare_git_cmd(cmd->argv);
172 }
173
174 cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, env,
175 fhin, fhout, fherr);
176 failed_errno = errno;
177 if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
178 error("cannot spawn %s: %s", cmd->argv[0], strerror(errno));
179
180 if (cmd->env)
181 free_environ(env);
182 if (cmd->git_cmd)
183 free(cmd->argv);
184
185 cmd->argv = sargv;
186 if (fhin != 0)
187 close(fhin);
188 if (fhout != 1)
189 close(fhout);
190 if (fherr != 2)
191 close(fherr);
192 }
193 #endif
194
195 if (cmd->pid < 0) {
196 if (need_in)
197 close_pair(fdin);
198 else if (cmd->in)
199 close(cmd->in);
200 if (need_out)
201 close_pair(fdout);
202 else if (cmd->out)
203 close(cmd->out);
204 if (need_err)
205 close_pair(fderr);
206 errno = failed_errno;
207 return -1;
208 }
209
210 if (need_in)
211 close(fdin[0]);
212 else if (cmd->in)
213 close(cmd->in);
214
215 if (need_out)
216 close(fdout[1]);
217 else if (cmd->out)
218 close(cmd->out);
219
220 if (need_err)
221 close(fderr[1]);
222
223 return 0;
224 }
225
226 static int wait_or_whine(pid_t pid, const char *argv0, int silent_exec_failure)
227 {
228 int status, code = -1;
229 pid_t waiting;
230 int failed_errno = 0;
231
232 while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
233 ; /* nothing */
234
235 if (waiting < 0) {
236 failed_errno = errno;
237 error("waitpid for %s failed: %s", argv0, strerror(errno));
238 } else if (waiting != pid) {
239 error("waitpid is confused (%s)", argv0);
240 } else if (WIFSIGNALED(status)) {
241 code = WTERMSIG(status);
242 error("%s died of signal %d", argv0, code);
243 /*
244 * This return value is chosen so that code & 0xff
245 * mimics the exit code that a POSIX shell would report for
246 * a program that died from this signal.
247 */
248 code -= 128;
249 } else if (WIFEXITED(status)) {
250 code = WEXITSTATUS(status);
251 /*
252 * Convert special exit code when execvp failed.
253 */
254 if (code == 127) {
255 code = -1;
256 failed_errno = ENOENT;
257 if (!silent_exec_failure)
258 error("cannot run %s: %s", argv0,
259 strerror(ENOENT));
260 }
261 } else {
262 error("waitpid is confused (%s)", argv0);
263 }
264 errno = failed_errno;
265 return code;
266 }
267
268 int finish_command(struct child_process *cmd)
269 {
270 return wait_or_whine(cmd->pid, cmd->argv[0], cmd->silent_exec_failure);
271 }
272
273 int run_command(struct child_process *cmd)
274 {
275 int code = start_command(cmd);
276 if (code)
277 return code;
278 return finish_command(cmd);
279 }
280
281 static void prepare_run_command_v_opt(struct child_process *cmd,
282 const char **argv,
283 int opt)
284 {
285 memset(cmd, 0, sizeof(*cmd));
286 cmd->argv = argv;
287 cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
288 cmd->git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
289 cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
290 cmd->silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
291 }
292
293 int run_command_v_opt(const char **argv, int opt)
294 {
295 struct child_process cmd;
296 prepare_run_command_v_opt(&cmd, argv, opt);
297 return run_command(&cmd);
298 }
299
300 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
301 {
302 struct child_process cmd;
303 prepare_run_command_v_opt(&cmd, argv, opt);
304 cmd.dir = dir;
305 cmd.env = env;
306 return run_command(&cmd);
307 }
308
309 #ifdef WIN32
310 static unsigned __stdcall run_thread(void *data)
311 {
312 struct async *async = data;
313 return async->proc(async->fd_for_proc, async->data);
314 }
315 #endif
316
317 int start_async(struct async *async)
318 {
319 int pipe_out[2];
320
321 if (pipe(pipe_out) < 0)
322 return error("cannot create pipe: %s", strerror(errno));
323 async->out = pipe_out[0];
324
325 #ifndef WIN32
326 /* Flush stdio before fork() to avoid cloning buffers */
327 fflush(NULL);
328
329 async->pid = fork();
330 if (async->pid < 0) {
331 error("fork (async) failed: %s", strerror(errno));
332 close_pair(pipe_out);
333 return -1;
334 }
335 if (!async->pid) {
336 close(pipe_out[0]);
337 exit(!!async->proc(pipe_out[1], async->data));
338 }
339 close(pipe_out[1]);
340 #else
341 async->fd_for_proc = pipe_out[1];
342 async->tid = (HANDLE) _beginthreadex(NULL, 0, run_thread, async, 0, NULL);
343 if (!async->tid) {
344 error("cannot create thread: %s", strerror(errno));
345 close_pair(pipe_out);
346 return -1;
347 }
348 #endif
349 return 0;
350 }
351
352 int finish_async(struct async *async)
353 {
354 #ifndef WIN32
355 int ret = wait_or_whine(async->pid, "child process", 0);
356 #else
357 DWORD ret = 0;
358 if (WaitForSingleObject(async->tid, INFINITE) != WAIT_OBJECT_0)
359 ret = error("waiting for thread failed: %lu", GetLastError());
360 else if (!GetExitCodeThread(async->tid, &ret))
361 ret = error("cannot get thread exit code: %lu", GetLastError());
362 CloseHandle(async->tid);
363 #endif
364 return ret;
365 }
366
367 int run_hook(const char *index_file, const char *name, ...)
368 {
369 struct child_process hook;
370 const char **argv = NULL, *env[2];
371 char index[PATH_MAX];
372 va_list args;
373 int ret;
374 size_t i = 0, alloc = 0;
375
376 if (access(git_path("hooks/%s", name), X_OK) < 0)
377 return 0;
378
379 va_start(args, name);
380 ALLOC_GROW(argv, i + 1, alloc);
381 argv[i++] = git_path("hooks/%s", name);
382 while (argv[i-1]) {
383 ALLOC_GROW(argv, i + 1, alloc);
384 argv[i++] = va_arg(args, const char *);
385 }
386 va_end(args);
387
388 memset(&hook, 0, sizeof(hook));
389 hook.argv = argv;
390 hook.no_stdin = 1;
391 hook.stdout_to_stderr = 1;
392 if (index_file) {
393 snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
394 env[0] = index;
395 env[1] = NULL;
396 hook.env = env;
397 }
398
399 ret = run_command(&hook);
400 free(argv);
401 return ret;
402 }