Merge branch 'jc/config-pathname-type'
[git] / run-command.c
1 #include "cache.h"
2 #include "run-command.h"
3 #include "exec_cmd.h"
4 #include "sigchain.h"
5 #include "argv-array.h"
6 #include "thread-utils.h"
7 #include "strbuf.h"
8
9 void child_process_init(struct child_process *child)
10 {
11         memset(child, 0, sizeof(*child));
12         argv_array_init(&child->args);
13         argv_array_init(&child->env_array);
14 }
15
16 void child_process_clear(struct child_process *child)
17 {
18         argv_array_clear(&child->args);
19         argv_array_clear(&child->env_array);
20 }
21
22 struct child_to_clean {
23         pid_t pid;
24         struct child_to_clean *next;
25 };
26 static struct child_to_clean *children_to_clean;
27 static int installed_child_cleanup_handler;
28
29 static void cleanup_children(int sig, int in_signal)
30 {
31         while (children_to_clean) {
32                 struct child_to_clean *p = children_to_clean;
33                 children_to_clean = p->next;
34                 kill(p->pid, sig);
35                 if (!in_signal)
36                         free(p);
37         }
38 }
39
40 static void cleanup_children_on_signal(int sig)
41 {
42         cleanup_children(sig, 1);
43         sigchain_pop(sig);
44         raise(sig);
45 }
46
47 static void cleanup_children_on_exit(void)
48 {
49         cleanup_children(SIGTERM, 0);
50 }
51
52 static void mark_child_for_cleanup(pid_t pid)
53 {
54         struct child_to_clean *p = xmalloc(sizeof(*p));
55         p->pid = pid;
56         p->next = children_to_clean;
57         children_to_clean = p;
58
59         if (!installed_child_cleanup_handler) {
60                 atexit(cleanup_children_on_exit);
61                 sigchain_push_common(cleanup_children_on_signal);
62                 installed_child_cleanup_handler = 1;
63         }
64 }
65
66 static void clear_child_for_cleanup(pid_t pid)
67 {
68         struct child_to_clean **pp;
69
70         for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
71                 struct child_to_clean *clean_me = *pp;
72
73                 if (clean_me->pid == pid) {
74                         *pp = clean_me->next;
75                         free(clean_me);
76                         return;
77                 }
78         }
79 }
80
81 static inline void close_pair(int fd[2])
82 {
83         close(fd[0]);
84         close(fd[1]);
85 }
86
87 #ifndef GIT_WINDOWS_NATIVE
88 static inline void dup_devnull(int to)
89 {
90         int fd = open("/dev/null", O_RDWR);
91         if (fd < 0)
92                 die_errno(_("open /dev/null failed"));
93         if (dup2(fd, to) < 0)
94                 die_errno(_("dup2(%d,%d) failed"), fd, to);
95         close(fd);
96 }
97 #endif
98
99 static char *locate_in_PATH(const char *file)
100 {
101         const char *p = getenv("PATH");
102         struct strbuf buf = STRBUF_INIT;
103
104         if (!p || !*p)
105                 return NULL;
106
107         while (1) {
108                 const char *end = strchrnul(p, ':');
109
110                 strbuf_reset(&buf);
111
112                 /* POSIX specifies an empty entry as the current directory. */
113                 if (end != p) {
114                         strbuf_add(&buf, p, end - p);
115                         strbuf_addch(&buf, '/');
116                 }
117                 strbuf_addstr(&buf, file);
118
119                 if (!access(buf.buf, F_OK))
120                         return strbuf_detach(&buf, NULL);
121
122                 if (!*end)
123                         break;
124                 p = end + 1;
125         }
126
127         strbuf_release(&buf);
128         return NULL;
129 }
130
131 static int exists_in_PATH(const char *file)
132 {
133         char *r = locate_in_PATH(file);
134         free(r);
135         return r != NULL;
136 }
137
138 int sane_execvp(const char *file, char * const argv[])
139 {
140         if (!execvp(file, argv))
141                 return 0; /* cannot happen ;-) */
142
143         /*
144          * When a command can't be found because one of the directories
145          * listed in $PATH is unsearchable, execvp reports EACCES, but
146          * careful usability testing (read: analysis of occasional bug
147          * reports) reveals that "No such file or directory" is more
148          * intuitive.
149          *
150          * We avoid commands with "/", because execvp will not do $PATH
151          * lookups in that case.
152          *
153          * The reassignment of EACCES to errno looks like a no-op below,
154          * but we need to protect against exists_in_PATH overwriting errno.
155          */
156         if (errno == EACCES && !strchr(file, '/'))
157                 errno = exists_in_PATH(file) ? EACCES : ENOENT;
158         else if (errno == ENOTDIR && !strchr(file, '/'))
159                 errno = ENOENT;
160         return -1;
161 }
162
163 static const char **prepare_shell_cmd(struct argv_array *out, const char **argv)
164 {
165         if (!argv[0])
166                 die("BUG: shell command is empty");
167
168         if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
169 #ifndef GIT_WINDOWS_NATIVE
170                 argv_array_push(out, SHELL_PATH);
171 #else
172                 argv_array_push(out, "sh");
173 #endif
174                 argv_array_push(out, "-c");
175
176                 /*
177                  * If we have no extra arguments, we do not even need to
178                  * bother with the "$@" magic.
179                  */
180                 if (!argv[1])
181                         argv_array_push(out, argv[0]);
182                 else
183                         argv_array_pushf(out, "%s \"$@\"", argv[0]);
184         }
185
186         argv_array_pushv(out, argv);
187         return out->argv;
188 }
189
190 #ifndef GIT_WINDOWS_NATIVE
191 static int execv_shell_cmd(const char **argv)
192 {
193         struct argv_array nargv = ARGV_ARRAY_INIT;
194         prepare_shell_cmd(&nargv, argv);
195         trace_argv_printf(nargv.argv, "trace: exec:");
196         sane_execvp(nargv.argv[0], (char **)nargv.argv);
197         argv_array_clear(&nargv);
198         return -1;
199 }
200 #endif
201
202 #ifndef GIT_WINDOWS_NATIVE
203 static int child_notifier = -1;
204
205 static void notify_parent(void)
206 {
207         /*
208          * execvp failed.  If possible, we'd like to let start_command
209          * know, so failures like ENOENT can be handled right away; but
210          * otherwise, finish_command will still report the error.
211          */
212         xwrite(child_notifier, "", 1);
213 }
214 #endif
215
216 static inline void set_cloexec(int fd)
217 {
218         int flags = fcntl(fd, F_GETFD);
219         if (flags >= 0)
220                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
221 }
222
223 static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
224 {
225         int status, code = -1;
226         pid_t waiting;
227         int failed_errno = 0;
228
229         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
230                 ;       /* nothing */
231         if (in_signal)
232                 return 0;
233
234         if (waiting < 0) {
235                 failed_errno = errno;
236                 error("waitpid for %s failed: %s", argv0, strerror(errno));
237         } else if (waiting != pid) {
238                 error("waitpid is confused (%s)", argv0);
239         } else if (WIFSIGNALED(status)) {
240                 code = WTERMSIG(status);
241                 if (code != SIGINT && code != SIGQUIT && code != SIGPIPE)
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                 }
258         } else {
259                 error("waitpid is confused (%s)", argv0);
260         }
261
262         clear_child_for_cleanup(pid);
263
264         errno = failed_errno;
265         return code;
266 }
267
268 int start_command(struct child_process *cmd)
269 {
270         int need_in, need_out, need_err;
271         int fdin[2], fdout[2], fderr[2];
272         int failed_errno;
273         char *str;
274
275         if (!cmd->argv)
276                 cmd->argv = cmd->args.argv;
277         if (!cmd->env)
278                 cmd->env = cmd->env_array.argv;
279
280         /*
281          * In case of errors we must keep the promise to close FDs
282          * that have been passed in via ->in and ->out.
283          */
284
285         need_in = !cmd->no_stdin && cmd->in < 0;
286         if (need_in) {
287                 if (pipe(fdin) < 0) {
288                         failed_errno = errno;
289                         if (cmd->out > 0)
290                                 close(cmd->out);
291                         str = "standard input";
292                         goto fail_pipe;
293                 }
294                 cmd->in = fdin[1];
295         }
296
297         need_out = !cmd->no_stdout
298                 && !cmd->stdout_to_stderr
299                 && cmd->out < 0;
300         if (need_out) {
301                 if (pipe(fdout) < 0) {
302                         failed_errno = errno;
303                         if (need_in)
304                                 close_pair(fdin);
305                         else if (cmd->in)
306                                 close(cmd->in);
307                         str = "standard output";
308                         goto fail_pipe;
309                 }
310                 cmd->out = fdout[0];
311         }
312
313         need_err = !cmd->no_stderr && cmd->err < 0;
314         if (need_err) {
315                 if (pipe(fderr) < 0) {
316                         failed_errno = errno;
317                         if (need_in)
318                                 close_pair(fdin);
319                         else if (cmd->in)
320                                 close(cmd->in);
321                         if (need_out)
322                                 close_pair(fdout);
323                         else if (cmd->out)
324                                 close(cmd->out);
325                         str = "standard error";
326 fail_pipe:
327                         error("cannot create %s pipe for %s: %s",
328                                 str, cmd->argv[0], strerror(failed_errno));
329                         child_process_clear(cmd);
330                         errno = failed_errno;
331                         return -1;
332                 }
333                 cmd->err = fderr[0];
334         }
335
336         trace_argv_printf(cmd->argv, "trace: run_command:");
337         fflush(NULL);
338
339 #ifndef GIT_WINDOWS_NATIVE
340 {
341         int notify_pipe[2];
342         if (pipe(notify_pipe))
343                 notify_pipe[0] = notify_pipe[1] = -1;
344
345         cmd->pid = fork();
346         failed_errno = errno;
347         if (!cmd->pid) {
348                 /*
349                  * Redirect the channel to write syscall error messages to
350                  * before redirecting the process's stderr so that all die()
351                  * in subsequent call paths use the parent's stderr.
352                  */
353                 if (cmd->no_stderr || need_err) {
354                         int child_err = dup(2);
355                         set_cloexec(child_err);
356                         set_error_handle(fdopen(child_err, "w"));
357                 }
358
359                 close(notify_pipe[0]);
360                 set_cloexec(notify_pipe[1]);
361                 child_notifier = notify_pipe[1];
362                 atexit(notify_parent);
363
364                 if (cmd->no_stdin)
365                         dup_devnull(0);
366                 else if (need_in) {
367                         dup2(fdin[0], 0);
368                         close_pair(fdin);
369                 } else if (cmd->in) {
370                         dup2(cmd->in, 0);
371                         close(cmd->in);
372                 }
373
374                 if (cmd->no_stderr)
375                         dup_devnull(2);
376                 else if (need_err) {
377                         dup2(fderr[1], 2);
378                         close_pair(fderr);
379                 } else if (cmd->err > 1) {
380                         dup2(cmd->err, 2);
381                         close(cmd->err);
382                 }
383
384                 if (cmd->no_stdout)
385                         dup_devnull(1);
386                 else if (cmd->stdout_to_stderr)
387                         dup2(2, 1);
388                 else if (need_out) {
389                         dup2(fdout[1], 1);
390                         close_pair(fdout);
391                 } else if (cmd->out > 1) {
392                         dup2(cmd->out, 1);
393                         close(cmd->out);
394                 }
395
396                 if (cmd->dir && chdir(cmd->dir))
397                         die_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
398                             cmd->dir);
399                 if (cmd->env) {
400                         for (; *cmd->env; cmd->env++) {
401                                 if (strchr(*cmd->env, '='))
402                                         putenv((char *)*cmd->env);
403                                 else
404                                         unsetenv(*cmd->env);
405                         }
406                 }
407                 if (cmd->git_cmd)
408                         execv_git_cmd(cmd->argv);
409                 else if (cmd->use_shell)
410                         execv_shell_cmd(cmd->argv);
411                 else
412                         sane_execvp(cmd->argv[0], (char *const*) cmd->argv);
413                 if (errno == ENOENT) {
414                         if (!cmd->silent_exec_failure)
415                                 error("cannot run %s: %s", cmd->argv[0],
416                                         strerror(ENOENT));
417                         exit(127);
418                 } else {
419                         die_errno("cannot exec '%s'", cmd->argv[0]);
420                 }
421         }
422         if (cmd->pid < 0)
423                 error("cannot fork() for %s: %s", cmd->argv[0],
424                         strerror(errno));
425         else if (cmd->clean_on_exit)
426                 mark_child_for_cleanup(cmd->pid);
427
428         /*
429          * Wait for child's execvp. If the execvp succeeds (or if fork()
430          * failed), EOF is seen immediately by the parent. Otherwise, the
431          * child process sends a single byte.
432          * Note that use of this infrastructure is completely advisory,
433          * therefore, we keep error checks minimal.
434          */
435         close(notify_pipe[1]);
436         if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
437                 /*
438                  * At this point we know that fork() succeeded, but execvp()
439                  * failed. Errors have been reported to our stderr.
440                  */
441                 wait_or_whine(cmd->pid, cmd->argv[0], 0);
442                 failed_errno = errno;
443                 cmd->pid = -1;
444         }
445         close(notify_pipe[0]);
446 }
447 #else
448 {
449         int fhin = 0, fhout = 1, fherr = 2;
450         const char **sargv = cmd->argv;
451         struct argv_array nargv = ARGV_ARRAY_INIT;
452
453         if (cmd->no_stdin)
454                 fhin = open("/dev/null", O_RDWR);
455         else if (need_in)
456                 fhin = dup(fdin[0]);
457         else if (cmd->in)
458                 fhin = dup(cmd->in);
459
460         if (cmd->no_stderr)
461                 fherr = open("/dev/null", O_RDWR);
462         else if (need_err)
463                 fherr = dup(fderr[1]);
464         else if (cmd->err > 2)
465                 fherr = dup(cmd->err);
466
467         if (cmd->no_stdout)
468                 fhout = open("/dev/null", O_RDWR);
469         else if (cmd->stdout_to_stderr)
470                 fhout = dup(fherr);
471         else if (need_out)
472                 fhout = dup(fdout[1]);
473         else if (cmd->out > 1)
474                 fhout = dup(cmd->out);
475
476         if (cmd->git_cmd)
477                 cmd->argv = prepare_git_cmd(&nargv, cmd->argv);
478         else if (cmd->use_shell)
479                 cmd->argv = prepare_shell_cmd(&nargv, cmd->argv);
480
481         cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
482                         cmd->dir, fhin, fhout, fherr);
483         failed_errno = errno;
484         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
485                 error("cannot spawn %s: %s", cmd->argv[0], strerror(errno));
486         if (cmd->clean_on_exit && cmd->pid >= 0)
487                 mark_child_for_cleanup(cmd->pid);
488
489         argv_array_clear(&nargv);
490         cmd->argv = sargv;
491         if (fhin != 0)
492                 close(fhin);
493         if (fhout != 1)
494                 close(fhout);
495         if (fherr != 2)
496                 close(fherr);
497 }
498 #endif
499
500         if (cmd->pid < 0) {
501                 if (need_in)
502                         close_pair(fdin);
503                 else if (cmd->in)
504                         close(cmd->in);
505                 if (need_out)
506                         close_pair(fdout);
507                 else if (cmd->out)
508                         close(cmd->out);
509                 if (need_err)
510                         close_pair(fderr);
511                 else if (cmd->err)
512                         close(cmd->err);
513                 child_process_clear(cmd);
514                 errno = failed_errno;
515                 return -1;
516         }
517
518         if (need_in)
519                 close(fdin[0]);
520         else if (cmd->in)
521                 close(cmd->in);
522
523         if (need_out)
524                 close(fdout[1]);
525         else if (cmd->out)
526                 close(cmd->out);
527
528         if (need_err)
529                 close(fderr[1]);
530         else if (cmd->err)
531                 close(cmd->err);
532
533         return 0;
534 }
535
536 int finish_command(struct child_process *cmd)
537 {
538         int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
539         child_process_clear(cmd);
540         return ret;
541 }
542
543 int finish_command_in_signal(struct child_process *cmd)
544 {
545         return wait_or_whine(cmd->pid, cmd->argv[0], 1);
546 }
547
548
549 int run_command(struct child_process *cmd)
550 {
551         int code;
552
553         if (cmd->out < 0 || cmd->err < 0)
554                 die("BUG: run_command with a pipe can cause deadlock");
555
556         code = start_command(cmd);
557         if (code)
558                 return code;
559         return finish_command(cmd);
560 }
561
562 int run_command_v_opt(const char **argv, int opt)
563 {
564         return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
565 }
566
567 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
568 {
569         struct child_process cmd = CHILD_PROCESS_INIT;
570         cmd.argv = argv;
571         cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
572         cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
573         cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
574         cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
575         cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
576         cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
577         cmd.dir = dir;
578         cmd.env = env;
579         return run_command(&cmd);
580 }
581
582 #ifndef NO_PTHREADS
583 static pthread_t main_thread;
584 static int main_thread_set;
585 static pthread_key_t async_key;
586 static pthread_key_t async_die_counter;
587
588 static void *run_thread(void *data)
589 {
590         struct async *async = data;
591         intptr_t ret;
592
593         if (async->isolate_sigpipe) {
594                 sigset_t mask;
595                 sigemptyset(&mask);
596                 sigaddset(&mask, SIGPIPE);
597                 if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
598                         ret = error("unable to block SIGPIPE in async thread");
599                         return (void *)ret;
600                 }
601         }
602
603         pthread_setspecific(async_key, async);
604         ret = async->proc(async->proc_in, async->proc_out, async->data);
605         return (void *)ret;
606 }
607
608 static NORETURN void die_async(const char *err, va_list params)
609 {
610         vreportf("fatal: ", err, params);
611
612         if (in_async()) {
613                 struct async *async = pthread_getspecific(async_key);
614                 if (async->proc_in >= 0)
615                         close(async->proc_in);
616                 if (async->proc_out >= 0)
617                         close(async->proc_out);
618                 pthread_exit((void *)128);
619         }
620
621         exit(128);
622 }
623
624 static int async_die_is_recursing(void)
625 {
626         void *ret = pthread_getspecific(async_die_counter);
627         pthread_setspecific(async_die_counter, (void *)1);
628         return ret != NULL;
629 }
630
631 int in_async(void)
632 {
633         if (!main_thread_set)
634                 return 0; /* no asyncs started yet */
635         return !pthread_equal(main_thread, pthread_self());
636 }
637
638 void NORETURN async_exit(int code)
639 {
640         pthread_exit((void *)(intptr_t)code);
641 }
642
643 #else
644
645 static struct {
646         void (**handlers)(void);
647         size_t nr;
648         size_t alloc;
649 } git_atexit_hdlrs;
650
651 static int git_atexit_installed;
652
653 static void git_atexit_dispatch(void)
654 {
655         size_t i;
656
657         for (i=git_atexit_hdlrs.nr ; i ; i--)
658                 git_atexit_hdlrs.handlers[i-1]();
659 }
660
661 static void git_atexit_clear(void)
662 {
663         free(git_atexit_hdlrs.handlers);
664         memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
665         git_atexit_installed = 0;
666 }
667
668 #undef atexit
669 int git_atexit(void (*handler)(void))
670 {
671         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
672         git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
673         if (!git_atexit_installed) {
674                 if (atexit(&git_atexit_dispatch))
675                         return -1;
676                 git_atexit_installed = 1;
677         }
678         return 0;
679 }
680 #define atexit git_atexit
681
682 static int process_is_async;
683 int in_async(void)
684 {
685         return process_is_async;
686 }
687
688 void NORETURN async_exit(int code)
689 {
690         exit(code);
691 }
692
693 #endif
694
695 int start_async(struct async *async)
696 {
697         int need_in, need_out;
698         int fdin[2], fdout[2];
699         int proc_in, proc_out;
700
701         need_in = async->in < 0;
702         if (need_in) {
703                 if (pipe(fdin) < 0) {
704                         if (async->out > 0)
705                                 close(async->out);
706                         return error("cannot create pipe: %s", strerror(errno));
707                 }
708                 async->in = fdin[1];
709         }
710
711         need_out = async->out < 0;
712         if (need_out) {
713                 if (pipe(fdout) < 0) {
714                         if (need_in)
715                                 close_pair(fdin);
716                         else if (async->in)
717                                 close(async->in);
718                         return error("cannot create pipe: %s", strerror(errno));
719                 }
720                 async->out = fdout[0];
721         }
722
723         if (need_in)
724                 proc_in = fdin[0];
725         else if (async->in)
726                 proc_in = async->in;
727         else
728                 proc_in = -1;
729
730         if (need_out)
731                 proc_out = fdout[1];
732         else if (async->out)
733                 proc_out = async->out;
734         else
735                 proc_out = -1;
736
737 #ifdef NO_PTHREADS
738         /* Flush stdio before fork() to avoid cloning buffers */
739         fflush(NULL);
740
741         async->pid = fork();
742         if (async->pid < 0) {
743                 error("fork (async) failed: %s", strerror(errno));
744                 goto error;
745         }
746         if (!async->pid) {
747                 if (need_in)
748                         close(fdin[1]);
749                 if (need_out)
750                         close(fdout[0]);
751                 git_atexit_clear();
752                 process_is_async = 1;
753                 exit(!!async->proc(proc_in, proc_out, async->data));
754         }
755
756         mark_child_for_cleanup(async->pid);
757
758         if (need_in)
759                 close(fdin[0]);
760         else if (async->in)
761                 close(async->in);
762
763         if (need_out)
764                 close(fdout[1]);
765         else if (async->out)
766                 close(async->out);
767 #else
768         if (!main_thread_set) {
769                 /*
770                  * We assume that the first time that start_async is called
771                  * it is from the main thread.
772                  */
773                 main_thread_set = 1;
774                 main_thread = pthread_self();
775                 pthread_key_create(&async_key, NULL);
776                 pthread_key_create(&async_die_counter, NULL);
777                 set_die_routine(die_async);
778                 set_die_is_recursing_routine(async_die_is_recursing);
779         }
780
781         if (proc_in >= 0)
782                 set_cloexec(proc_in);
783         if (proc_out >= 0)
784                 set_cloexec(proc_out);
785         async->proc_in = proc_in;
786         async->proc_out = proc_out;
787         {
788                 int err = pthread_create(&async->tid, NULL, run_thread, async);
789                 if (err) {
790                         error("cannot create thread: %s", strerror(err));
791                         goto error;
792                 }
793         }
794 #endif
795         return 0;
796
797 error:
798         if (need_in)
799                 close_pair(fdin);
800         else if (async->in)
801                 close(async->in);
802
803         if (need_out)
804                 close_pair(fdout);
805         else if (async->out)
806                 close(async->out);
807         return -1;
808 }
809
810 int finish_async(struct async *async)
811 {
812 #ifdef NO_PTHREADS
813         return wait_or_whine(async->pid, "child process", 0);
814 #else
815         void *ret = (void *)(intptr_t)(-1);
816
817         if (pthread_join(async->tid, &ret))
818                 error("pthread_join failed");
819         return (int)(intptr_t)ret;
820 #endif
821 }
822
823 const char *find_hook(const char *name)
824 {
825         static struct strbuf path = STRBUF_INIT;
826
827         strbuf_reset(&path);
828         if (git_hooks_path)
829                 strbuf_addf(&path, "%s/%s", git_hooks_path, name);
830         else
831                 strbuf_git_path(&path, "hooks/%s", name);
832         if (access(path.buf, X_OK) < 0)
833                 return NULL;
834         return path.buf;
835 }
836
837 int run_hook_ve(const char *const *env, const char *name, va_list args)
838 {
839         struct child_process hook = CHILD_PROCESS_INIT;
840         const char *p;
841
842         p = find_hook(name);
843         if (!p)
844                 return 0;
845
846         argv_array_push(&hook.args, p);
847         while ((p = va_arg(args, const char *)))
848                 argv_array_push(&hook.args, p);
849         hook.env = env;
850         hook.no_stdin = 1;
851         hook.stdout_to_stderr = 1;
852
853         return run_command(&hook);
854 }
855
856 int run_hook_le(const char *const *env, const char *name, ...)
857 {
858         va_list args;
859         int ret;
860
861         va_start(args, name);
862         ret = run_hook_ve(env, name, args);
863         va_end(args);
864
865         return ret;
866 }
867
868 int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint)
869 {
870         cmd->out = -1;
871         if (start_command(cmd) < 0)
872                 return -1;
873
874         if (strbuf_read(buf, cmd->out, hint) < 0) {
875                 close(cmd->out);
876                 finish_command(cmd); /* throw away exit code */
877                 return -1;
878         }
879
880         close(cmd->out);
881         return finish_command(cmd);
882 }
883
884 enum child_state {
885         GIT_CP_FREE,
886         GIT_CP_WORKING,
887         GIT_CP_WAIT_CLEANUP,
888 };
889
890 struct parallel_processes {
891         void *data;
892
893         int max_processes;
894         int nr_processes;
895
896         get_next_task_fn get_next_task;
897         start_failure_fn start_failure;
898         task_finished_fn task_finished;
899
900         struct {
901                 enum child_state state;
902                 struct child_process process;
903                 struct strbuf err;
904                 void *data;
905         } *children;
906         /*
907          * The struct pollfd is logically part of *children,
908          * but the system call expects it as its own array.
909          */
910         struct pollfd *pfd;
911
912         unsigned shutdown : 1;
913
914         int output_owner;
915         struct strbuf buffered_output; /* of finished children */
916 };
917
918 static int default_start_failure(struct strbuf *out,
919                                  void *pp_cb,
920                                  void *pp_task_cb)
921 {
922         return 0;
923 }
924
925 static int default_task_finished(int result,
926                                  struct strbuf *out,
927                                  void *pp_cb,
928                                  void *pp_task_cb)
929 {
930         return 0;
931 }
932
933 static void kill_children(struct parallel_processes *pp, int signo)
934 {
935         int i, n = pp->max_processes;
936
937         for (i = 0; i < n; i++)
938                 if (pp->children[i].state == GIT_CP_WORKING)
939                         kill(pp->children[i].process.pid, signo);
940 }
941
942 static struct parallel_processes *pp_for_signal;
943
944 static void handle_children_on_signal(int signo)
945 {
946         kill_children(pp_for_signal, signo);
947         sigchain_pop(signo);
948         raise(signo);
949 }
950
951 static void pp_init(struct parallel_processes *pp,
952                     int n,
953                     get_next_task_fn get_next_task,
954                     start_failure_fn start_failure,
955                     task_finished_fn task_finished,
956                     void *data)
957 {
958         int i;
959
960         if (n < 1)
961                 n = online_cpus();
962
963         pp->max_processes = n;
964
965         trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
966
967         pp->data = data;
968         if (!get_next_task)
969                 die("BUG: you need to specify a get_next_task function");
970         pp->get_next_task = get_next_task;
971
972         pp->start_failure = start_failure ? start_failure : default_start_failure;
973         pp->task_finished = task_finished ? task_finished : default_task_finished;
974
975         pp->nr_processes = 0;
976         pp->output_owner = 0;
977         pp->shutdown = 0;
978         pp->children = xcalloc(n, sizeof(*pp->children));
979         pp->pfd = xcalloc(n, sizeof(*pp->pfd));
980         strbuf_init(&pp->buffered_output, 0);
981
982         for (i = 0; i < n; i++) {
983                 strbuf_init(&pp->children[i].err, 0);
984                 child_process_init(&pp->children[i].process);
985                 pp->pfd[i].events = POLLIN | POLLHUP;
986                 pp->pfd[i].fd = -1;
987         }
988
989         pp_for_signal = pp;
990         sigchain_push_common(handle_children_on_signal);
991 }
992
993 static void pp_cleanup(struct parallel_processes *pp)
994 {
995         int i;
996
997         trace_printf("run_processes_parallel: done");
998         for (i = 0; i < pp->max_processes; i++) {
999                 strbuf_release(&pp->children[i].err);
1000                 child_process_clear(&pp->children[i].process);
1001         }
1002
1003         free(pp->children);
1004         free(pp->pfd);
1005
1006         /*
1007          * When get_next_task added messages to the buffer in its last
1008          * iteration, the buffered output is non empty.
1009          */
1010         strbuf_write(&pp->buffered_output, stderr);
1011         strbuf_release(&pp->buffered_output);
1012
1013         sigchain_pop_common();
1014 }
1015
1016 /* returns
1017  *  0 if a new task was started.
1018  *  1 if no new jobs was started (get_next_task ran out of work, non critical
1019  *    problem with starting a new command)
1020  * <0 no new job was started, user wishes to shutdown early. Use negative code
1021  *    to signal the children.
1022  */
1023 static int pp_start_one(struct parallel_processes *pp)
1024 {
1025         int i, code;
1026
1027         for (i = 0; i < pp->max_processes; i++)
1028                 if (pp->children[i].state == GIT_CP_FREE)
1029                         break;
1030         if (i == pp->max_processes)
1031                 die("BUG: bookkeeping is hard");
1032
1033         code = pp->get_next_task(&pp->children[i].process,
1034                                  &pp->children[i].err,
1035                                  pp->data,
1036                                  &pp->children[i].data);
1037         if (!code) {
1038                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1039                 strbuf_reset(&pp->children[i].err);
1040                 return 1;
1041         }
1042         pp->children[i].process.err = -1;
1043         pp->children[i].process.stdout_to_stderr = 1;
1044         pp->children[i].process.no_stdin = 1;
1045
1046         if (start_command(&pp->children[i].process)) {
1047                 code = pp->start_failure(&pp->children[i].err,
1048                                          pp->data,
1049                                          &pp->children[i].data);
1050                 strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1051                 strbuf_reset(&pp->children[i].err);
1052                 if (code)
1053                         pp->shutdown = 1;
1054                 return code;
1055         }
1056
1057         pp->nr_processes++;
1058         pp->children[i].state = GIT_CP_WORKING;
1059         pp->pfd[i].fd = pp->children[i].process.err;
1060         return 0;
1061 }
1062
1063 static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
1064 {
1065         int i;
1066
1067         while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
1068                 if (errno == EINTR)
1069                         continue;
1070                 pp_cleanup(pp);
1071                 die_errno("poll");
1072         }
1073
1074         /* Buffer output from all pipes. */
1075         for (i = 0; i < pp->max_processes; i++) {
1076                 if (pp->children[i].state == GIT_CP_WORKING &&
1077                     pp->pfd[i].revents & (POLLIN | POLLHUP)) {
1078                         int n = strbuf_read_once(&pp->children[i].err,
1079                                                  pp->children[i].process.err, 0);
1080                         if (n == 0) {
1081                                 close(pp->children[i].process.err);
1082                                 pp->children[i].state = GIT_CP_WAIT_CLEANUP;
1083                         } else if (n < 0)
1084                                 if (errno != EAGAIN)
1085                                         die_errno("read");
1086                 }
1087         }
1088 }
1089
1090 static void pp_output(struct parallel_processes *pp)
1091 {
1092         int i = pp->output_owner;
1093         if (pp->children[i].state == GIT_CP_WORKING &&
1094             pp->children[i].err.len) {
1095                 strbuf_write(&pp->children[i].err, stderr);
1096                 strbuf_reset(&pp->children[i].err);
1097         }
1098 }
1099
1100 static int pp_collect_finished(struct parallel_processes *pp)
1101 {
1102         int i, code;
1103         int n = pp->max_processes;
1104         int result = 0;
1105
1106         while (pp->nr_processes > 0) {
1107                 for (i = 0; i < pp->max_processes; i++)
1108                         if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
1109                                 break;
1110                 if (i == pp->max_processes)
1111                         break;
1112
1113                 code = finish_command(&pp->children[i].process);
1114
1115                 code = pp->task_finished(code,
1116                                          &pp->children[i].err, pp->data,
1117                                          &pp->children[i].data);
1118
1119                 if (code)
1120                         result = code;
1121                 if (code < 0)
1122                         break;
1123
1124                 pp->nr_processes--;
1125                 pp->children[i].state = GIT_CP_FREE;
1126                 pp->pfd[i].fd = -1;
1127                 child_process_init(&pp->children[i].process);
1128
1129                 if (i != pp->output_owner) {
1130                         strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
1131                         strbuf_reset(&pp->children[i].err);
1132                 } else {
1133                         strbuf_write(&pp->children[i].err, stderr);
1134                         strbuf_reset(&pp->children[i].err);
1135
1136                         /* Output all other finished child processes */
1137                         strbuf_write(&pp->buffered_output, stderr);
1138                         strbuf_reset(&pp->buffered_output);
1139
1140                         /*
1141                          * Pick next process to output live.
1142                          * NEEDSWORK:
1143                          * For now we pick it randomly by doing a round
1144                          * robin. Later we may want to pick the one with
1145                          * the most output or the longest or shortest
1146                          * running process time.
1147                          */
1148                         for (i = 0; i < n; i++)
1149                                 if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
1150                                         break;
1151                         pp->output_owner = (pp->output_owner + i) % n;
1152                 }
1153         }
1154         return result;
1155 }
1156
1157 int run_processes_parallel(int n,
1158                            get_next_task_fn get_next_task,
1159                            start_failure_fn start_failure,
1160                            task_finished_fn task_finished,
1161                            void *pp_cb)
1162 {
1163         int i, code;
1164         int output_timeout = 100;
1165         int spawn_cap = 4;
1166         struct parallel_processes pp;
1167
1168         pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
1169         while (1) {
1170                 for (i = 0;
1171                     i < spawn_cap && !pp.shutdown &&
1172                     pp.nr_processes < pp.max_processes;
1173                     i++) {
1174                         code = pp_start_one(&pp);
1175                         if (!code)
1176                                 continue;
1177                         if (code < 0) {
1178                                 pp.shutdown = 1;
1179                                 kill_children(&pp, -code);
1180                         }
1181                         break;
1182                 }
1183                 if (!pp.nr_processes)
1184                         break;
1185                 pp_buffer_stderr(&pp, output_timeout);
1186                 pp_output(&pp);
1187                 code = pp_collect_finished(&pp);
1188                 if (code) {
1189                         pp.shutdown = 1;
1190                         if (code < 0)
1191                                 kill_children(&pp, -code);
1192                 }
1193         }
1194
1195         pp_cleanup(&pp);
1196         return 0;
1197 }