process.c 12.8 KB
Newer Older
1 2 3 4 5 6 7 8 9
/*
 * Copyright (C) the libgit2 contributors. All rights reserved.
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */

#include <stdio.h>
#include <sys/wait.h>
10
#include <signal.h>
11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148
#include <git2.h>

#include "git2_util.h"
#include "vector.h"
#include "process.h"
#include "strlist.h"

extern char **environ;

struct git_process {
	char **args;
	char **env;

	char *cwd;

	unsigned int capture_in  : 1,
	             capture_out : 1,
	             capture_err : 1;

	pid_t pid;

	int child_in;
	int child_out;
	int child_err;
	git_process_result_status status;
};

GIT_INLINE(bool) is_delete_env(const char *env)
{
	char *c = index(env, '=');

	if (c == NULL)
		return false;

	return *(c+1) == '\0';
}

static int merge_env(
	char ***out,
	const char **env,
	size_t env_len,
	bool exclude_env)
{
	git_vector merged = GIT_VECTOR_INIT;
	char **kv, *dup;
	size_t max, cnt;
	int error = 0;

	for (max = env_len, kv = environ; !exclude_env && *kv; kv++)
		max++;

	if ((error = git_vector_init(&merged, max, NULL)) < 0)
		goto on_error;

	for (cnt = 0; env && cnt < env_len; cnt++) {
		if (is_delete_env(env[cnt]))
			continue;

		dup = git__strdup(env[cnt]);
		GIT_ERROR_CHECK_ALLOC(dup);

		if ((error = git_vector_insert(&merged, dup)) < 0)
			goto on_error;
	}

	if (!exclude_env) {
		for (kv = environ; *kv; kv++) {
			if (env && git_strlist_contains_key(env, env_len, *kv, '='))
				continue;

			dup = git__strdup(*kv);
			GIT_ERROR_CHECK_ALLOC(dup);

			if ((error = git_vector_insert(&merged, dup)) < 0)
				goto on_error;
		}
	}

	if (merged.length == 0) {
		*out = NULL;
		error = 0;
		goto on_error;
	}

	git_vector_insert(&merged, NULL);

	*out = (char **)merged.contents;

	return 0;

on_error:
	git_vector_free_deep(&merged);
	return error;
}

int git_process_new(
	git_process **out,
	const char **args,
	size_t args_len,
	const char **env,
	size_t env_len,
	git_process_options *opts)
{
	git_process *process;

	GIT_ASSERT_ARG(out && args && args_len > 0);

	*out = NULL;

	process = git__calloc(sizeof(git_process), 1);
	GIT_ERROR_CHECK_ALLOC(process);

	if (git_strlist_copy_with_null(&process->args, args, args_len) < 0 ||
	    merge_env(&process->env, env, env_len, opts->exclude_env) < 0) {
		git_process_free(process);
		return -1;
	}

	if (opts) {
		process->capture_in = opts->capture_in;
		process->capture_out = opts->capture_out;
		process->capture_err = opts->capture_err;

		if (opts->cwd) {
			process->cwd = git__strdup(opts->cwd);
			GIT_ERROR_CHECK_ALLOC(process->cwd);
		}
	}

	process->child_in  = -1;
	process->child_out = -1;
	process->child_err = -1;
	process->status    = -1;

	*out = process;
	return 0;
}

149 150 151 152 153 154 155 156 157 158 159 160 161
extern int git_process_new_from_cmdline(
	git_process **out,
	const char *cmdline,
	const char **env,
	size_t env_len,
	git_process_options *opts)
{
	const char *args[] = { "/bin/sh", "-c", cmdline };

	return git_process_new(out,
		args, ARRAY_SIZE(args), env, env_len, opts);
}

162 163 164 165 166 167
#define CLOSE_FD(fd) \
	if (fd >= 0) {     \
		close(fd); \
		fd = -1;   \
	}

168
static int try_read_status(size_t *out, int fd, void *buf, size_t len)
169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194
{
	size_t read_len = 0;
	int ret = -1;

	while (ret && read_len < len) {
		ret = read(fd, buf + read_len, len - read_len);

		if (ret < 0 && errno != EAGAIN && errno != EINTR) {
			git_error_set(GIT_ERROR_OS, "could not read child status");
			return -1;
		}

		read_len += ret;
	}

	*out = read_len;
	return 0;
}


static int read_status(int fd)
{
	size_t status_len = sizeof(int) * 3, read_len = 0;
	char buffer[status_len], fn[128];
	int error, fn_error, os_error, fn_len = 0;

195
	if ((error = try_read_status(&read_len, fd, buffer, status_len)) < 0)
196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213
		return error;

	/* Immediate EOF indicates the exec succeeded. */
	if (read_len == 0)
		return 0;

	if (read_len < status_len) {
		git_error_set(GIT_ERROR_INVALID, "child status truncated");
		return -1;
	}

	memcpy(&fn_error, &buffer[0], sizeof(int));
	memcpy(&os_error, &buffer[sizeof(int)], sizeof(int));
	memcpy(&fn_len, &buffer[sizeof(int) * 2], sizeof(int));

	if (fn_len > 0) {
		fn_len = min(fn_len, (int)(ARRAY_SIZE(fn) - 1));

214
		if ((error = try_read_status(&read_len, fd, fn, fn_len)) < 0)
215 216 217 218 219 220 221 222 223 224 225 226 227 228 229
			return error;

		fn[fn_len] = '\0';
	} else {
		fn[0] = '\0';
	}

	if (fn_error) {
		errno = os_error;
		git_error_set(GIT_ERROR_OS, "could not %s", fn[0] ? fn : "(unknown)");
	}

	return fn_error;
}

230
static bool try_write_status(int fd, const void *buf, size_t len)
231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261
{
	size_t write_len;
	int ret;

	for (write_len = 0; write_len < len; ) {
		ret = write(fd, buf + write_len, len - write_len);

		if (ret <= 0)
			break;

		write_len += ret;
	}

	return (len == write_len);
}

static void write_status(int fd, const char *fn, int error, int os_error)
{
	size_t status_len = sizeof(int) * 3, fn_len;
	char buffer[status_len];

	fn_len = strlen(fn);

	if (fn_len > INT_MAX)
		fn_len = INT_MAX;

	memcpy(&buffer[0], &error, sizeof(int));
	memcpy(&buffer[sizeof(int)], &os_error, sizeof(int));
	memcpy(&buffer[sizeof(int) * 2], &fn_len, sizeof(int));

	/* Do our best effort to write all the status. */
262
	if (!try_write_status(fd, buffer, status_len))
263 264 265
		return;

	if (fn_len)
266
		try_write_status(fd, fn, fn_len);
267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372
}

int git_process_start(git_process *process)
{
	int in[2] = { -1, -1 }, out[2] = { -1, -1 },
	    err[2] = { -1, -1 }, status[2] = { -1, -1 };
	int fdflags, state, error;
	pid_t pid;

	/* Set up the pipes to read from/write to the process */
	if ((process->capture_in && pipe(in) < 0) ||
	    (process->capture_out && pipe(out) < 0) ||
	    (process->capture_err && pipe(err) < 0)) {
		git_error_set(GIT_ERROR_OS, "could not create pipe");
		goto on_error;
	}

	/* Set up a self-pipe for status from the forked process. */
	if (pipe(status) < 0 ||
	    (fdflags = fcntl(status[1], F_GETFD)) < 0 ||
	    fcntl(status[1], F_SETFD, fdflags | FD_CLOEXEC) < 0) {
		git_error_set(GIT_ERROR_OS, "could not create pipe");
		goto on_error;
	}

	switch (pid = fork()) {
	case -1:
		git_error_set(GIT_ERROR_OS, "could not fork");
		goto on_error;

	/* Child: start the process. */
	case 0:
		/* Close the opposing side of the pipes */
		CLOSE_FD(status[0]);

		if (process->capture_in) {
			CLOSE_FD(in[1]);
			dup2(in[0],  STDIN_FILENO);
		}

		if (process->capture_out) {
			CLOSE_FD(out[0]);
			dup2(out[1], STDOUT_FILENO);
		}

		if (process->capture_err) {
			CLOSE_FD(err[0]);
			dup2(err[1], STDERR_FILENO);
		}

		if (process->cwd && (error = chdir(process->cwd)) < 0) {
			write_status(status[1], "chdir", error, errno);
			exit(0);
		}

		/*
		 * Exec the process and write the results back if the
		 * call fails.  If it succeeds, we'll close the status
		 * pipe (via CLOEXEC) and the parent will know.
		 */
		error = execve(process->args[0],
		               process->args,
			       process->env);

		write_status(status[1], "execve", error, errno);
		exit(0);

	/* Parent: make sure the child process exec'd correctly. */
	default:
		/* Close the opposing side of the pipes */
		CLOSE_FD(status[1]);

		if (process->capture_in) {
			CLOSE_FD(in[0]);
			process->child_in  = in[1];
		}

		if (process->capture_out) {
			CLOSE_FD(out[1]);
			process->child_out = out[0];
		}

		if (process->capture_err) {
			CLOSE_FD(err[1]);
			process->child_err = err[0];
		}

		/* Try to read the status */
		process->status = status[0];
		if ((error = read_status(status[0])) < 0) {
			waitpid(process->pid, &state, 0);
			goto on_error;
		}

		process->pid = pid;
		return 0;
	}

on_error:
	CLOSE_FD(in[0]);     CLOSE_FD(in[1]);
	CLOSE_FD(out[0]);    CLOSE_FD(out[1]);
	CLOSE_FD(err[0]);    CLOSE_FD(err[1]);
	CLOSE_FD(status[0]); CLOSE_FD(status[1]);
	return -1;
}

373 374 375 376 377 378 379 380 381 382 383 384 385
int git_process_id(p_pid_t *out, git_process *process)
{
	GIT_ASSERT(out && process);

	if (!process->pid) {
		git_error_set(GIT_ERROR_INVALID, "process not running");
		return -1;
	}

	*out = process->pid;
	return 0;
}

386
static ssize_t process_read(int fd, void *buf, size_t count)
387 388 389 390 391 392
{
	ssize_t ret;

	if (count > SSIZE_MAX)
		count = SSIZE_MAX;

393
	if ((ret = read(fd, buf, count)) < 0) {
394 395 396 397 398 399 400
		git_error_set(GIT_ERROR_OS, "could not read from child process");
		return -1;
	}

	return ret;
}

401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416
ssize_t git_process_read(git_process *process, void *buf, size_t count)
{
	GIT_ASSERT_ARG(process);
	GIT_ASSERT(process->capture_out);

	return process_read(process->child_out, buf, count);
}

ssize_t git_process_read_err(git_process *process, void *buf, size_t count)
{
	GIT_ASSERT_ARG(process);
	GIT_ASSERT(process->capture_err);

	return process_read(process->child_err, buf, count);
}

417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497
#ifdef GIT_THREADS

# define signal_state sigset_t

/*
 * Since signal-handling is process-wide, we cannot simply use
 * SIG_IGN to avoid SIGPIPE. Instead: http://www.microhowto.info:80/howto/ignore_sigpipe_without_affecting_other_threads_in_a_process.html
 */

GIT_INLINE(int) disable_signals(sigset_t *saved_mask)
{
	sigset_t sigpipe_mask;

	sigemptyset(&sigpipe_mask);
	sigaddset(&sigpipe_mask, SIGPIPE);

	if (pthread_sigmask(SIG_BLOCK, &sigpipe_mask, saved_mask) < 0) {
		git_error_set(GIT_ERROR_OS, "could not configure signal mask");
		return -1;
	}

	return 0;
}

GIT_INLINE(int) restore_signals(sigset_t *saved_mask)
{
	sigset_t sigpipe_mask, pending;
	int signal;

	sigemptyset(&sigpipe_mask);
	sigaddset(&sigpipe_mask, SIGPIPE);

	if (sigpending(&pending) < 0) {
		git_error_set(GIT_ERROR_OS, "could not examine pending signals");
		return -1;
	}

	if (sigismember(&pending, SIGPIPE) == 1 &&
	    sigwait(&sigpipe_mask, &signal) < 0) {
		git_error_set(GIT_ERROR_OS, "could not wait for (blocking) signal delivery");
		return -1;
	}

	if (pthread_sigmask(SIG_SETMASK, saved_mask, 0) < 0) {
		git_error_set(GIT_ERROR_OS, "could not configure signal mask");
		return -1;
	}

	return 0;
}

#else

# define signal_state struct sigaction

GIT_INLINE(int) disable_signals(struct sigaction *saved_handler)
{
	struct sigaction ign_handler = { 0 };

	ign_handler.sa_handler = SIG_IGN;

	if (sigaction(SIGPIPE, &ign_handler, saved_handler) < 0) {
		git_error_set(GIT_ERROR_OS, "could not configure signal handler");
		return -1;
	}

	return 0;
}

GIT_INLINE(int) restore_signals(struct sigaction *saved_handler)
{
	if (sigaction(SIGPIPE, saved_handler, NULL) < 0) {
		git_error_set(GIT_ERROR_OS, "could not configure signal handler");
		return -1;
	}

	return 0;
}

#endif

498 499
ssize_t git_process_write(git_process *process, const void *buf, size_t count)
{
500
	signal_state saved_signal;
501 502 503 504 505 506 507 508
	ssize_t ret;

	GIT_ASSERT_ARG(process);
	GIT_ASSERT(process->capture_in);

	if (count > SSIZE_MAX)
		count = SSIZE_MAX;

509 510 511 512
	if (disable_signals(&saved_signal) < 0)
		return -1;

	if ((ret = write(process->child_in, buf, count)) < 0)
513
		git_error_set(GIT_ERROR_OS, "could not write to child process");
514 515

	if (restore_signals(&saved_signal) < 0)
516 517
		return -1;

518
	return (ret < 0) ? -1 : ret;
519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625
}

int git_process_close_in(git_process *process)
{
	if (!process->capture_in) {
		git_error_set(GIT_ERROR_INVALID, "input is not open");
		return -1;
	}

	CLOSE_FD(process->child_in);
	return 0;
}

int git_process_close_out(git_process *process)
{
	if (!process->capture_out) {
		git_error_set(GIT_ERROR_INVALID, "output is not open");
		return -1;
	}

	CLOSE_FD(process->child_out);
	return 0;
}

int git_process_close_err(git_process *process)
{
	if (!process->capture_err) {
		git_error_set(GIT_ERROR_INVALID, "error is not open");
		return -1;
	}

	CLOSE_FD(process->child_err);
	return 0;
}

int git_process_close(git_process *process)
{
	CLOSE_FD(process->child_in);
	CLOSE_FD(process->child_out);
	CLOSE_FD(process->child_err);
	CLOSE_FD(process->status);

	return 0;
}

int git_process_wait(git_process_result *result, git_process *process)
{
	int state;

	if (result)
		memset(result, 0, sizeof(git_process_result));

	if (!process->pid) {
		git_error_set(GIT_ERROR_INVALID, "process is stopped");
		return -1;
	}

	if (waitpid(process->pid, &state, 0) < 0) {
		git_error_set(GIT_ERROR_OS, "could not wait for child");
		return -1;
	}

	process->pid = 0;

	if (result) {
		if (WIFEXITED(state)) {
			result->status = GIT_PROCESS_STATUS_NORMAL;
			result->exitcode = WEXITSTATUS(state);
		} else if (WIFSIGNALED(state)) {
			result->status = GIT_PROCESS_STATUS_ERROR;
			result->signal = WTERMSIG(state);
		} else {
			result->status = GIT_PROCESS_STATUS_ERROR;
		}
	}

	return 0;
}

int git_process_result_msg(git_str *out, git_process_result *result)
{
	if (result->status == GIT_PROCESS_STATUS_NONE) {
		return git_str_puts(out, "process not started");
	} else if (result->status == GIT_PROCESS_STATUS_NORMAL) {
		return git_str_printf(out, "process exited with code %d",
		                      result->exitcode);
	} else if (result->signal) {
		return git_str_printf(out, "process exited on signal %d",
		                      result->signal);
	}

	return git_str_puts(out, "unknown error");
}

void git_process_free(git_process *process)
{
	if (!process)
		return;

	if (process->pid)
		git_process_close(process);

	git__free(process->cwd);
	git_strlist_free_with_null(process->args);
	git_strlist_free_with_null(process->env);
	git__free(process);
}