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 static inline void dup_devnull(int to)
  12 {
  13         int fd = open("/dev/null", O_RDWR);
  14         dup2(fd, to);
  15         close(fd);
  16 }
  17
  18 #ifndef WIN32
  19 static int child_err = 2;
  20 static int child_notifier = -1;
  21
  22 static void notify_parent(void)
  23 {
  24         write(child_notifier, "", 1);
  25 }
  26
  27 static NORETURN void die_child(const char *err, va_list params)
  28 {
  29         char msg[4096];
  30         int len = vsnprintf(msg, sizeof(msg), err, params);
  31         if (len > sizeof(msg))
  32                 len = sizeof(msg);
  33
  34         write(child_err, "fatal: ", 7);
  35         write(child_err, msg, len);
  36         write(child_err, "\n", 1);
  37         exit(128);
  38 }
  39
  40 static inline void set_cloexec(int fd)
  41 {
  42         int flags = fcntl(fd, F_GETFD);
  43         if (flags >= 0)
  44                 fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
  45 }
  46 #endif
  47
  48 static int wait_or_whine(pid_t pid, const char *argv0, int silent_exec_failure)
  49 {
  50         int status, code = -1;
  51         pid_t waiting;
  52         int failed_errno = 0;
  53
  54         while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
  55                 ;       /* nothing */
  56
  57         if (waiting < 0) {
  58                 failed_errno = errno;
  59                 error("waitpid for %s failed: %s", argv0, strerror(errno));
  60         } else if (waiting != pid) {
  61                 error("waitpid is confused (%s)", argv0);
  62         } else if (WIFSIGNALED(status)) {
  63                 code = WTERMSIG(status);
  64                 error("%s died of signal %d", argv0, code);
  65                 /*
  66                  * This return value is chosen so that code & 0xff
  67                  * mimics the exit code that a POSIX shell would report for
  68                  * a program that died from this signal.
  69                  */
  70                 code -= 128;
  71         } else if (WIFEXITED(status)) {
  72                 code = WEXITSTATUS(status);
  73                 /*
  74                  * Convert special exit code when execvp failed.
  75                  */
  76                 if (code == 127) {
  77                         code = -1;
  78                         failed_errno = ENOENT;
  79                         if (!silent_exec_failure)
  80                                 error("cannot run %s: %s", argv0,
  81                                         strerror(ENOENT));
  82                 }
  83         } else {
  84                 error("waitpid is confused (%s)", argv0);
  85         }
  86         errno = failed_errno;
  87         return code;
  88 }
  89
  90 int start_command(struct child_process *cmd)
  91 {
  92         int need_in, need_out, need_err;
  93         int fdin[2], fdout[2], fderr[2];
  94         int failed_errno = failed_errno;
  95
  96         /*
  97          * In case of errors we must keep the promise to close FDs
  98          * that have been passed in via ->in and ->out.
  99          */
 100
 101         need_in = !cmd->no_stdin && cmd->in < 0;
 102         if (need_in) {
 103                 if (pipe(fdin) < 0) {
 104                         failed_errno = errno;
 105                         if (cmd->out > 0)
 106                                 close(cmd->out);
 107                         goto fail_pipe;
 108                 }
 109                 cmd->in = fdin[1];
 110         }
 111
 112         need_out = !cmd->no_stdout
 113                 && !cmd->stdout_to_stderr
 114                 && cmd->out < 0;
 115         if (need_out) {
 116                 if (pipe(fdout) < 0) {
 117                         failed_errno = errno;
 118                         if (need_in)
 119                                 close_pair(fdin);
 120                         else if (cmd->in)
 121                                 close(cmd->in);
 122                         goto fail_pipe;
 123                 }
 124                 cmd->out = fdout[0];
 125         }
 126
 127         need_err = !cmd->no_stderr && cmd->err < 0;
 128         if (need_err) {
 129                 if (pipe(fderr) < 0) {
 130                         failed_errno = errno;
 131                         if (need_in)
 132                                 close_pair(fdin);
 133                         else if (cmd->in)
 134                                 close(cmd->in);
 135                         if (need_out)
 136                                 close_pair(fdout);
 137                         else if (cmd->out)
 138                                 close(cmd->out);
 139 fail_pipe:
 140                         error("cannot create pipe for %s: %s",
 141                                 cmd->argv[0], strerror(failed_errno));
 142                         errno = failed_errno;
 143                         return -1;
 144                 }
 145                 cmd->err = fderr[0];
 146         }
 147
 148         trace_argv_printf(cmd->argv, "trace: run_command:");
 149
 150 #ifndef WIN32
 151 {
 152         int notify_pipe[2];
 153         if (pipe(notify_pipe))
 154                 notify_pipe[0] = notify_pipe[1] = -1;
 155
 156         fflush(NULL);
 157         cmd->pid = fork();
 158         if (!cmd->pid) {
 159                 /*
 160                  * Redirect the channel to write syscall error messages to
 161                  * before redirecting the process's stderr so that all die()
 162                  * in subsequent call paths use the parent's stderr.
 163                  */
 164                 if (cmd->no_stderr || need_err) {
 165                         child_err = dup(2);
 166                         set_cloexec(child_err);
 167                 }
 168                 set_die_routine(die_child);
 169
 170                 close(notify_pipe[0]);
 171                 set_cloexec(notify_pipe[1]);
 172                 child_notifier = notify_pipe[1];
 173                 atexit(notify_parent);
 174
 175                 if (cmd->no_stdin)
 176                         dup_devnull(0);
 177                 else if (need_in) {
 178                         dup2(fdin[0], 0);
 179                         close_pair(fdin);
 180                 } else if (cmd->in) {
 181                         dup2(cmd->in, 0);
 182                         close(cmd->in);
 183                 }
 184
 185                 if (cmd->no_stderr)
 186                         dup_devnull(2);
 187                 else if (need_err) {
 188                         dup2(fderr[1], 2);
 189                         close_pair(fderr);
 190                 }
 191
 192                 if (cmd->no_stdout)
 193                         dup_devnull(1);
 194                 else if (cmd->stdout_to_stderr)
 195                         dup2(2, 1);
 196                 else if (need_out) {
 197                         dup2(fdout[1], 1);
 198                         close_pair(fdout);
 199                 } else if (cmd->out > 1) {
 200                         dup2(cmd->out, 1);
 201                         close(cmd->out);
 202                 }
 203
 204                 if (cmd->dir && chdir(cmd->dir))
 205                         die_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
 206                             cmd->dir);
 207                 if (cmd->env) {
 208                         for (; *cmd->env; cmd->env++) {
 209                                 if (strchr(*cmd->env, '='))
 210                                         putenv((char *)*cmd->env);
 211                                 else
 212                                         unsetenv(*cmd->env);
 213                         }
 214                 }
 215                 if (cmd->preexec_cb) {
 216                         /*
 217                          * We cannot predict what the pre-exec callback does.
 218                          * Forgo parent notification.
 219                          */
 220                         close(child_notifier);
 221                         child_notifier = -1;
 222
 223                         cmd->preexec_cb();
 224                 }
 225                 if (cmd->git_cmd) {
 226                         execv_git_cmd(cmd->argv);
 227                 } else {
 228                         execvp(cmd->argv[0], (char *const*) cmd->argv);
 229                 }
 230                 /*
 231                  * Do not check for cmd->silent_exec_failure; the parent
 232                  * process will check it when it sees this exit code.
 233                  */
 234                 if (errno == ENOENT)
 235                         exit(127);
 236                 else
 237                         die_errno("cannot exec '%s'", cmd->argv[0]);
 238         }
 239         if (cmd->pid < 0)
 240                 error("cannot fork() for %s: %s", cmd->argv[0],
 241                         strerror(failed_errno = errno));
 242
 243         /*
 244          * Wait for child's execvp. If the execvp succeeds (or if fork()
 245          * failed), EOF is seen immediately by the parent. Otherwise, the
 246          * child process sends a single byte.
 247          * Note that use of this infrastructure is completely advisory,
 248          * therefore, we keep error checks minimal.
 249          */
 250         close(notify_pipe[1]);
 251         if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
 252                 /*
 253                  * At this point we know that fork() succeeded, but execvp()
 254                  * failed. Errors have been reported to our stderr.
 255                  */
 256                 wait_or_whine(cmd->pid, cmd->argv[0],
 257                               cmd->silent_exec_failure);
 258                 failed_errno = errno;
 259                 cmd->pid = -1;
 260         }
 261         close(notify_pipe[0]);
 262 }
 263 #else
 264 {
 265         int s0 = -1, s1 = -1, s2 = -1;  /* backups of stdin, stdout, stderr */
 266         const char **sargv = cmd->argv;
 267         char **env = environ;
 268
 269         if (cmd->no_stdin) {
 270                 s0 = dup(0);
 271                 dup_devnull(0);
 272         } else if (need_in) {
 273                 s0 = dup(0);
 274                 dup2(fdin[0], 0);
 275         } else if (cmd->in) {
 276                 s0 = dup(0);
 277                 dup2(cmd->in, 0);
 278         }
 279
 280         if (cmd->no_stderr) {
 281                 s2 = dup(2);
 282                 dup_devnull(2);
 283         } else if (need_err) {
 284                 s2 = dup(2);
 285                 dup2(fderr[1], 2);
 286         }
 287
 288         if (cmd->no_stdout) {
 289                 s1 = dup(1);
 290                 dup_devnull(1);
 291         } else if (cmd->stdout_to_stderr) {
 292                 s1 = dup(1);
 293                 dup2(2, 1);
 294         } else if (need_out) {
 295                 s1 = dup(1);
 296                 dup2(fdout[1], 1);
 297         } else if (cmd->out > 1) {
 298                 s1 = dup(1);
 299                 dup2(cmd->out, 1);
 300         }
 301
 302         if (cmd->dir)
 303                 die("chdir in start_command() not implemented");
 304         if (cmd->env)
 305                 env = make_augmented_environ(cmd->env);
 306
 307         if (cmd->git_cmd) {
 308                 cmd->argv = prepare_git_cmd(cmd->argv);
 309         }
 310
 311         cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, env);
 312         failed_errno = errno;
 313         if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 314                 error("cannot spawn %s: %s", cmd->argv[0], strerror(errno));
 315
 316         if (cmd->env)
 317                 free_environ(env);
 318         if (cmd->git_cmd)
 319                 free(cmd->argv);
 320
 321         cmd->argv = sargv;
 322         if (s0 >= 0)
 323                 dup2(s0, 0), close(s0);
 324         if (s1 >= 0)
 325                 dup2(s1, 1), close(s1);
 326         if (s2 >= 0)
 327                 dup2(s2, 2), close(s2);
 328 }
 329 #endif
 330
 331         if (cmd->pid < 0) {
 332                 if (need_in)
 333                         close_pair(fdin);
 334                 else if (cmd->in)
 335                         close(cmd->in);
 336                 if (need_out)
 337                         close_pair(fdout);
 338                 else if (cmd->out)
 339                         close(cmd->out);
 340                 if (need_err)
 341                         close_pair(fderr);
 342                 errno = failed_errno;
 343                 return -1;
 344         }
 345
 346         if (need_in)
 347                 close(fdin[0]);
 348         else if (cmd->in)
 349                 close(cmd->in);
 350
 351         if (need_out)
 352                 close(fdout[1]);
 353         else if (cmd->out)
 354                 close(cmd->out);
 355
 356         if (need_err)
 357                 close(fderr[1]);
 358
 359         return 0;
 360 }
 361
 362 int finish_command(struct child_process *cmd)
 363 {
 364         return wait_or_whine(cmd->pid, cmd->argv[0], cmd->silent_exec_failure);
 365 }
 366
 367 int run_command(struct child_process *cmd)
 368 {
 369         int code = start_command(cmd);
 370         if (code)
 371                 return code;
 372         return finish_command(cmd);
 373 }
 374
 375 static void prepare_run_command_v_opt(struct child_process *cmd,
 376                                       const char **argv,
 377                                       int opt)
 378 {
 379         memset(cmd, 0, sizeof(*cmd));
 380         cmd->argv = argv;
 381         cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 382         cmd->git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
 383         cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 384         cmd->silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
 385 }
 386
 387 int run_command_v_opt(const char **argv, int opt)
 388 {
 389         struct child_process cmd;
 390         prepare_run_command_v_opt(&cmd, argv, opt);
 391         return run_command(&cmd);
 392 }
 393
 394 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
 395 {
 396         struct child_process cmd;
 397         prepare_run_command_v_opt(&cmd, argv, opt);
 398         cmd.dir = dir;
 399         cmd.env = env;
 400         return run_command(&cmd);
 401 }
 402
 403 #ifdef WIN32
 404 static unsigned __stdcall run_thread(void *data)
 405 {
 406         struct async *async = data;
 407         return async->proc(async->fd_for_proc, async->data);
 408 }
 409 #endif
 410
 411 int start_async(struct async *async)
 412 {
 413         int pipe_out[2];
 414
 415         if (pipe(pipe_out) < 0)
 416                 return error("cannot create pipe: %s", strerror(errno));
 417         async->out = pipe_out[0];
 418
 419 #ifndef WIN32
 420         /* Flush stdio before fork() to avoid cloning buffers */
 421         fflush(NULL);
 422
 423         async->pid = fork();
 424         if (async->pid < 0) {
 425                 error("fork (async) failed: %s", strerror(errno));
 426                 close_pair(pipe_out);
 427                 return -1;
 428         }
 429         if (!async->pid) {
 430                 close(pipe_out[0]);
 431                 exit(!!async->proc(pipe_out[1], async->data));
 432         }
 433         close(pipe_out[1]);
 434 #else
 435         async->fd_for_proc = pipe_out[1];
 436         async->tid = (HANDLE) _beginthreadex(NULL, 0, run_thread, async, 0, NULL);
 437         if (!async->tid) {
 438                 error("cannot create thread: %s", strerror(errno));
 439                 close_pair(pipe_out);
 440                 return -1;
 441         }
 442 #endif
 443         return 0;
 444 }
 445
 446 int finish_async(struct async *async)
 447 {
 448 #ifndef WIN32
 449         int ret = wait_or_whine(async->pid, "child process", 0);
 450 #else
 451         DWORD ret = 0;
 452         if (WaitForSingleObject(async->tid, INFINITE) != WAIT_OBJECT_0)
 453                 ret = error("waiting for thread failed: %lu", GetLastError());
 454         else if (!GetExitCodeThread(async->tid, &ret))
 455                 ret = error("cannot get thread exit code: %lu", GetLastError());
 456         CloseHandle(async->tid);
 457 #endif
 458         return ret;
 459 }
 460
 461 int run_hook(const char *index_file, const char *name, ...)
 462 {
 463         struct child_process hook;
 464         const char **argv = NULL, *env[2];
 465         char index[PATH_MAX];
 466         va_list args;
 467         int ret;
 468         size_t i = 0, alloc = 0;
 469
 470         if (access(git_path("hooks/%s", name), X_OK) < 0)
 471                 return 0;
 472
 473         va_start(args, name);
 474         ALLOC_GROW(argv, i + 1, alloc);
 475         argv[i++] = git_path("hooks/%s", name);
 476         while (argv[i-1]) {
 477                 ALLOC_GROW(argv, i + 1, alloc);
 478                 argv[i++] = va_arg(args, const char *);
 479         }
 480         va_end(args);
 481
 482         memset(&hook, 0, sizeof(hook));
 483         hook.argv = argv;
 484         hook.no_stdin = 1;
 485         hook.stdout_to_stderr = 1;
 486         if (index_file) {
 487                 snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
 488                 env[0] = index;
 489                 env[1] = NULL;
 490                 hook.env = env;
 491         }
 492
 493         ret = run_command(&hook);
 494         free(argv);
 495         return ret;
 496 }