1 files changed, 733 insertions, 72 deletions

diff --git a/run-command.c b/run-command.c
index 7e779d33e..3277cf797 100644
--- a/run-command.c
+++ b/run-command.c
@@ -1,6 +1,73 @@
 #include "cache.h"
 #include "run-command.h"
 #include "exec_cmd.h"
+#include "sigchain.h"
+#include "argv-array.h"
+
+void child_process_init(struct child_process *child)
+{
+	memset(child, 0, sizeof(*child));
+	argv_array_init(&child->args);
+	argv_array_init(&child->env_array);
+}
+
+struct child_to_clean {
+	pid_t pid;
+	struct child_to_clean *next;
+};
+static struct child_to_clean *children_to_clean;
+static int installed_child_cleanup_handler;
+
+static void cleanup_children(int sig)
+{
+	while (children_to_clean) {
+		struct child_to_clean *p = children_to_clean;
+		children_to_clean = p->next;
+		kill(p->pid, sig);
+		free(p);
+	}
+}
+
+static void cleanup_children_on_signal(int sig)
+{
+	cleanup_children(sig);
+	sigchain_pop(sig);
+	raise(sig);
+}
+
+static void cleanup_children_on_exit(void)
+{
+	cleanup_children(SIGTERM);
+}
+
+static void mark_child_for_cleanup(pid_t pid)
+{
+	struct child_to_clean *p = xmalloc(sizeof(*p));
+	p->pid = pid;
+	p->next = children_to_clean;
+	children_to_clean = p;
+
+	if (!installed_child_cleanup_handler) {
+		atexit(cleanup_children_on_exit);
+		sigchain_push_common(cleanup_children_on_signal);
+		installed_child_cleanup_handler = 1;
+	}
+}
+
+static void clear_child_for_cleanup(pid_t pid)
+{
+	struct child_to_clean **pp;
+
+	for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
+		struct child_to_clean *clean_me = *pp;
+
+		if (clean_me->pid == pid) {
+			*pp = clean_me->next;
+			free(clean_me);
+			return;
+		}
+	}
+}
 
 static inline void close_pair(int fd[2])
 {
@@ -8,24 +75,221 @@ static inline void close_pair(int fd[2])
 	close(fd[1]);
 }
 
+#ifndef GIT_WINDOWS_NATIVE
 static inline void dup_devnull(int to)
 {
 	int fd = open("/dev/null", O_RDWR);
-	dup2(fd, to);
+	if (fd < 0)
+		die_errno(_("open /dev/null failed"));
+	if (dup2(fd, to) < 0)
+		die_errno(_("dup2(%d,%d) failed"), fd, to);
 	close(fd);
 }
+#endif
+
+static char *locate_in_PATH(const char *file)
+{
+	const char *p = getenv("PATH");
+	struct strbuf buf = STRBUF_INIT;
+
+	if (!p || !*p)
+		return NULL;
+
+	while (1) {
+		const char *end = strchrnul(p, ':');
+
+		strbuf_reset(&buf);
+
+		/* POSIX specifies an empty entry as the current directory. */
+		if (end != p) {
+			strbuf_add(&buf, p, end - p);
+			strbuf_addch(&buf, '/');
+		}
+		strbuf_addstr(&buf, file);
+
+		if (!access(buf.buf, F_OK))
+			return strbuf_detach(&buf, NULL);
+
+		if (!*end)
+			break;
+		p = end + 1;
+	}
+
+	strbuf_release(&buf);
+	return NULL;
+}
+
+static int exists_in_PATH(const char *file)
+{
+	char *r = locate_in_PATH(file);
+	free(r);
+	return r != NULL;
+}
+
+int sane_execvp(const char *file, char * const argv[])
+{
+	if (!execvp(file, argv))
+		return 0; /* cannot happen ;-) */
+
+	/*
+	 * When a command can't be found because one of the directories
+	 * listed in $PATH is unsearchable, execvp reports EACCES, but
+	 * careful usability testing (read: analysis of occasional bug
+	 * reports) reveals that "No such file or directory" is more
+	 * intuitive.
+	 *
+	 * We avoid commands with "/", because execvp will not do $PATH
+	 * lookups in that case.
+	 *
+	 * The reassignment of EACCES to errno looks like a no-op below,
+	 * but we need to protect against exists_in_PATH overwriting errno.
+	 */
+	if (errno == EACCES && !strchr(file, '/'))
+		errno = exists_in_PATH(file) ? EACCES : ENOENT;
+	else if (errno == ENOTDIR && !strchr(file, '/'))
+		errno = ENOENT;
+	return -1;
+}
+
+static const char **prepare_shell_cmd(const char **argv)
+{
+	int argc, nargc = 0;
+	const char **nargv;
+
+	for (argc = 0; argv[argc]; argc++)
+		; /* just counting */
+	/* +1 for NULL, +3 for "sh -c" plus extra $0 */
+	nargv = xmalloc(sizeof(*nargv) * (argc + 1 + 3));
+
+	if (argc < 1)
+		die("BUG: shell command is empty");
+
+	if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
+#ifndef GIT_WINDOWS_NATIVE
+		nargv[nargc++] = SHELL_PATH;
+#else
+		nargv[nargc++] = "sh";
+#endif
+		nargv[nargc++] = "-c";
+
+		if (argc < 2)
+			nargv[nargc++] = argv[0];
+		else {
+			struct strbuf arg0 = STRBUF_INIT;
+			strbuf_addf(&arg0, "%s \"$@\"", argv[0]);
+			nargv[nargc++] = strbuf_detach(&arg0, NULL);
+		}
+	}
+
+	for (argc = 0; argv[argc]; argc++)
+		nargv[nargc++] = argv[argc];
+	nargv[nargc] = NULL;
+
+	return nargv;
+}
+
+#ifndef GIT_WINDOWS_NATIVE
+static int execv_shell_cmd(const char **argv)
+{
+	const char **nargv = prepare_shell_cmd(argv);
+	trace_argv_printf(nargv, "trace: exec:");
+	sane_execvp(nargv[0], (char **)nargv);
+	free(nargv);
+	return -1;
+}
+#endif
+
+#ifndef GIT_WINDOWS_NATIVE
+static int child_notifier = -1;
+
+static void notify_parent(void)
+{
+	/*
+	 * execvp failed.  If possible, we'd like to let start_command
+	 * know, so failures like ENOENT can be handled right away; but
+	 * otherwise, finish_command will still report the error.
+	 */
+	xwrite(child_notifier, "", 1);
+}
+#endif
+
+static inline void set_cloexec(int fd)
+{
+	int flags = fcntl(fd, F_GETFD);
+	if (flags >= 0)
+		fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
+}
+
+static int wait_or_whine(pid_t pid, const char *argv0)
+{
+	int status, code = -1;
+	pid_t waiting;
+	int failed_errno = 0;
+
+	while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
+		;	/* nothing */
+
+	if (waiting < 0) {
+		failed_errno = errno;
+		error("waitpid for %s failed: %s", argv0, strerror(errno));
+	} else if (waiting != pid) {
+		error("waitpid is confused (%s)", argv0);
+	} else if (WIFSIGNALED(status)) {
+		code = WTERMSIG(status);
+		if (code != SIGINT && code != SIGQUIT)
+			error("%s died of signal %d", argv0, code);
+		/*
+		 * This return value is chosen so that code & 0xff
+		 * mimics the exit code that a POSIX shell would report for
+		 * a program that died from this signal.
+		 */
+		code += 128;
+	} else if (WIFEXITED(status)) {
+		code = WEXITSTATUS(status);
+		/*
+		 * Convert special exit code when execvp failed.
+		 */
+		if (code == 127) {
+			code = -1;
+			failed_errno = ENOENT;
+		}
+	} else {
+		error("waitpid is confused (%s)", argv0);
+	}
+
+	clear_child_for_cleanup(pid);
+
+	errno = failed_errno;
+	return code;
+}
 
 int start_command(struct child_process *cmd)
 {
-	int need_in, need_out;
-	int fdin[2], fdout[2];
+	int need_in, need_out, need_err;
+	int fdin[2], fdout[2], fderr[2];
+	int failed_errno;
+	char *str;
+
+	if (!cmd->argv)
+		cmd->argv = cmd->args.argv;
+	if (!cmd->env)
+		cmd->env = cmd->env_array.argv;
+
+	/*
+	 * In case of errors we must keep the promise to close FDs
+	 * that have been passed in via ->in and ->out.
+	 */
 
 	need_in = !cmd->no_stdin && cmd->in < 0;
 	if (need_in) {
-		if (pipe(fdin) < 0)
-			return -ERR_RUN_COMMAND_PIPE;
+		if (pipe(fdin) < 0) {
+			failed_errno = errno;
+			if (cmd->out > 0)
+				close(cmd->out);
+			str = "standard input";
+			goto fail_pipe;
+		}
 		cmd->in = fdin[1];
-		cmd->close_in = 1;
 	}
 
 	need_out = !cmd->no_stdout
@@ -33,24 +297,69 @@ int start_command(struct child_process *cmd)
 		&& cmd->out < 0;
 	if (need_out) {
 		if (pipe(fdout) < 0) {
+			failed_errno = errno;
 			if (need_in)
 				close_pair(fdin);
-			return -ERR_RUN_COMMAND_PIPE;
+			else if (cmd->in)
+				close(cmd->in);
+			str = "standard output";
+			goto fail_pipe;
 		}
 		cmd->out = fdout[0];
-		cmd->close_out = 1;
 	}
 
-	cmd->pid = fork();
-	if (cmd->pid < 0) {
-		if (need_in)
-			close_pair(fdin);
-		if (need_out)
-			close_pair(fdout);
-		return -ERR_RUN_COMMAND_FORK;
+	need_err = !cmd->no_stderr && cmd->err < 0;
+	if (need_err) {
+		if (pipe(fderr) < 0) {
+			failed_errno = errno;
+			if (need_in)
+				close_pair(fdin);
+			else if (cmd->in)
+				close(cmd->in);
+			if (need_out)
+				close_pair(fdout);
+			else if (cmd->out)
+				close(cmd->out);
+			str = "standard error";
+fail_pipe:
+			error("cannot create %s pipe for %s: %s",
+				str, cmd->argv[0], strerror(failed_errno));
+			argv_array_clear(&cmd->args);
+			argv_array_clear(&cmd->env_array);
+			errno = failed_errno;
+			return -1;
+		}
+		cmd->err = fderr[0];
 	}
 
+	trace_argv_printf(cmd->argv, "trace: run_command:");
+	fflush(NULL);
+
+#ifndef GIT_WINDOWS_NATIVE
+{
+	int notify_pipe[2];
+	if (pipe(notify_pipe))
+		notify_pipe[0] = notify_pipe[1] = -1;
+
+	cmd->pid = fork();
+	failed_errno = errno;
 	if (!cmd->pid) {
+		/*
+		 * Redirect the channel to write syscall error messages to
+		 * before redirecting the process's stderr so that all die()
+		 * in subsequent call paths use the parent's stderr.
+		 */
+		if (cmd->no_stderr || need_err) {
+			int child_err = dup(2);
+			set_cloexec(child_err);
+			set_error_handle(fdopen(child_err, "w"));
+		}
+
+		close(notify_pipe[0]);
+		set_cloexec(notify_pipe[1]);
+		child_notifier = notify_pipe[1];
+		atexit(notify_parent);
+
 		if (cmd->no_stdin)
 			dup_devnull(0);
 		else if (need_in) {
@@ -61,6 +370,16 @@ int start_command(struct child_process *cmd)
 			close(cmd->in);
 		}
 
+		if (cmd->no_stderr)
+			dup_devnull(2);
+		else if (need_err) {
+			dup2(fderr[1], 2);
+			close_pair(fderr);
+		} else if (cmd->err > 1) {
+			dup2(cmd->err, 2);
+			close(cmd->err);
+		}
+
 		if (cmd->no_stdout)
 			dup_devnull(1);
 		else if (cmd->stdout_to_stderr)
@@ -74,22 +393,127 @@ int start_command(struct child_process *cmd)
 		}
 
 		if (cmd->dir && chdir(cmd->dir))
-			die("exec %s: cd to %s failed (%s)", cmd->argv[0],
-			    cmd->dir, strerror(errno));
+			die_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
+			    cmd->dir);
 		if (cmd->env) {
 			for (; *cmd->env; cmd->env++) {
 				if (strchr(*cmd->env, '='))
-					putenv((char*)*cmd->env);
+					putenv((char *)*cmd->env);
 				else
 					unsetenv(*cmd->env);
 			}
 		}
-		if (cmd->git_cmd) {
+		if (cmd->git_cmd)
 			execv_git_cmd(cmd->argv);
+		else if (cmd->use_shell)
+			execv_shell_cmd(cmd->argv);
+		else
+			sane_execvp(cmd->argv[0], (char *const*) cmd->argv);
+		if (errno == ENOENT) {
+			if (!cmd->silent_exec_failure)
+				error("cannot run %s: %s", cmd->argv[0],
+					strerror(ENOENT));
+			exit(127);
 		} else {
-			execvp(cmd->argv[0], (char *const*) cmd->argv);
+			die_errno("cannot exec '%s'", cmd->argv[0]);
 		}
-		die("exec %s failed.", cmd->argv[0]);
+	}
+	if (cmd->pid < 0)
+		error("cannot fork() for %s: %s", cmd->argv[0],
+			strerror(errno));
+	else if (cmd->clean_on_exit)
+		mark_child_for_cleanup(cmd->pid);
+
+	/*
+	 * Wait for child's execvp. If the execvp succeeds (or if fork()
+	 * failed), EOF is seen immediately by the parent. Otherwise, the
+	 * child process sends a single byte.
+	 * Note that use of this infrastructure is completely advisory,
+	 * therefore, we keep error checks minimal.
+	 */
+	close(notify_pipe[1]);
+	if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
+		/*
+		 * At this point we know that fork() succeeded, but execvp()
+		 * failed. Errors have been reported to our stderr.
+		 */
+		wait_or_whine(cmd->pid, cmd->argv[0]);
+		failed_errno = errno;
+		cmd->pid = -1;
+	}
+	close(notify_pipe[0]);
+}
+#else
+{
+	int fhin = 0, fhout = 1, fherr = 2;
+	const char **sargv = cmd->argv;
+
+	if (cmd->no_stdin)
+		fhin = open("/dev/null", O_RDWR);
+	else if (need_in)
+		fhin = dup(fdin[0]);
+	else if (cmd->in)
+		fhin = dup(cmd->in);
+
+	if (cmd->no_stderr)
+		fherr = open("/dev/null", O_RDWR);
+	else if (need_err)
+		fherr = dup(fderr[1]);
+	else if (cmd->err > 2)
+		fherr = dup(cmd->err);
+
+	if (cmd->no_stdout)
+		fhout = open("/dev/null", O_RDWR);
+	else if (cmd->stdout_to_stderr)
+		fhout = dup(fherr);
+	else if (need_out)
+		fhout = dup(fdout[1]);
+	else if (cmd->out > 1)
+		fhout = dup(cmd->out);
+
+	if (cmd->git_cmd)
+		cmd->argv = prepare_git_cmd(cmd->argv);
+	else if (cmd->use_shell)
+		cmd->argv = prepare_shell_cmd(cmd->argv);
+
+	cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
+			cmd->dir, fhin, fhout, fherr);
+	failed_errno = errno;
+	if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
+		error("cannot spawn %s: %s", cmd->argv[0], strerror(errno));
+	if (cmd->clean_on_exit && cmd->pid >= 0)
+		mark_child_for_cleanup(cmd->pid);
+
+	if (cmd->git_cmd)
+		free(cmd->argv);
+
+	cmd->argv = sargv;
+	if (fhin != 0)
+		close(fhin);
+	if (fhout != 1)
+		close(fhout);
+	if (fherr != 2)
+		close(fherr);
+}
+#endif
+
+	if (cmd->pid < 0) {
+		if (need_in)
+			close_pair(fdin);
+		else if (cmd->in)
+			close(cmd->in);
+		if (need_out)
+			close_pair(fdout);
+		else if (cmd->out)
+			close(cmd->out);
+		if (need_err)
+			close_pair(fderr);
+		else if (cmd->err)
+			close(cmd->err);
+		argv_array_clear(&cmd->args);
+		argv_array_clear(&cmd->env_array);
+		errno = failed_errno;
+		return -1;
 	}
 
 	if (need_in)
@@ -99,82 +523,319 @@ int start_command(struct child_process *cmd)
 
 	if (need_out)
 		close(fdout[1]);
-	else if (cmd->out > 1)
+	else if (cmd->out)
 		close(cmd->out);
 
+	if (need_err)
+		close(fderr[1]);
+	else if (cmd->err)
+		close(cmd->err);
+
 	return 0;
 }
 
 int finish_command(struct child_process *cmd)
 {
-	if (cmd->close_in)
-		close(cmd->in);
-	if (cmd->close_out)
-		close(cmd->out);
-
-	for (;;) {
-		int status, code;
-		pid_t waiting = waitpid(cmd->pid, &status, 0);
-
-		if (waiting < 0) {
-			if (errno == EINTR)
-				continue;
-			error("waitpid failed (%s)", strerror(errno));
-			return -ERR_RUN_COMMAND_WAITPID;
-		}
-		if (waiting != cmd->pid)
-			return -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
-		if (WIFSIGNALED(status))
-			return -ERR_RUN_COMMAND_WAITPID_SIGNAL;
-
-		if (!WIFEXITED(status))
-			return -ERR_RUN_COMMAND_WAITPID_NOEXIT;
-		code = WEXITSTATUS(status);
-		if (code)
-			return -code;
-		return 0;
-	}
+	int ret = wait_or_whine(cmd->pid, cmd->argv[0]);
+	argv_array_clear(&cmd->args);
+	argv_array_clear(&cmd->env_array);
+	return ret;
 }
 
 int run_command(struct child_process *cmd)
 {
-	int code = start_command(cmd);
+	int code;
+
+	if (cmd->out < 0 || cmd->err < 0)
+		die("BUG: run_command with a pipe can cause deadlock");
+
+	code = start_command(cmd);
 	if (code)
 		return code;
 	return finish_command(cmd);
 }
 
-static void prepare_run_command_v_opt(struct child_process *cmd,
-				      const char **argv,
-				      int opt)
+int run_command_v_opt(const char **argv, int opt)
 {
-	memset(cmd, 0, sizeof(*cmd));
-	cmd->argv = argv;
-	cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
-	cmd->git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
-	cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
+	return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 }
 
-int run_command_v_opt(const char **argv, int opt)
+int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
 {
-	struct child_process cmd;
-	prepare_run_command_v_opt(&cmd, argv, opt);
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	cmd.argv = argv;
+	cmd.no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
+	cmd.git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
+	cmd.stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
+	cmd.silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
+	cmd.use_shell = opt & RUN_USING_SHELL ? 1 : 0;
+	cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
+	cmd.dir = dir;
+	cmd.env = env;
 	return run_command(&cmd);
 }
 
-int run_command_v_opt_cd(const char **argv, int opt, const char *dir)
+#ifndef NO_PTHREADS
+static pthread_t main_thread;
+static int main_thread_set;
+static pthread_key_t async_key;
+static pthread_key_t async_die_counter;
+
+static void *run_thread(void *data)
 {
-	struct child_process cmd;
-	prepare_run_command_v_opt(&cmd, argv, opt);
-	cmd.dir = dir;
-	return run_command(&cmd);
+	struct async *async = data;
+	intptr_t ret;
+
+	pthread_setspecific(async_key, async);
+	ret = async->proc(async->proc_in, async->proc_out, async->data);
+	return (void *)ret;
 }
 
-int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
+static NORETURN void die_async(const char *err, va_list params)
 {
-	struct child_process cmd;
-	prepare_run_command_v_opt(&cmd, argv, opt);
-	cmd.dir = dir;
-	cmd.env = env;
-	return run_command(&cmd);
+	vreportf("fatal: ", err, params);
+
+	if (!pthread_equal(main_thread, pthread_self())) {
+		struct async *async = pthread_getspecific(async_key);
+		if (async->proc_in >= 0)
+			close(async->proc_in);
+		if (async->proc_out >= 0)
+			close(async->proc_out);
+		pthread_exit((void *)128);
+	}
+
+	exit(128);
+}
+
+static int async_die_is_recursing(void)
+{
+	void *ret = pthread_getspecific(async_die_counter);
+	pthread_setspecific(async_die_counter, (void *)1);
+	return ret != NULL;
+}
+
+#else
+
+static struct {
+	void (**handlers)(void);
+	size_t nr;
+	size_t alloc;
+} git_atexit_hdlrs;
+
+static int git_atexit_installed;
+
+static void git_atexit_dispatch(void)
+{
+	size_t i;
+
+	for (i=git_atexit_hdlrs.nr ; i ; i--)
+		git_atexit_hdlrs.handlers[i-1]();
+}
+
+static void git_atexit_clear(void)
+{
+	free(git_atexit_hdlrs.handlers);
+	memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
+	git_atexit_installed = 0;
+}
+
+#undef atexit
+int git_atexit(void (*handler)(void))
+{
+	ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
+	git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
+	if (!git_atexit_installed) {
+		if (atexit(&git_atexit_dispatch))
+			return -1;
+		git_atexit_installed = 1;
+	}
+	return 0;
+}
+#define atexit git_atexit
+
+#endif
+
+int start_async(struct async *async)
+{
+	int need_in, need_out;
+	int fdin[2], fdout[2];
+	int proc_in, proc_out;
+
+	need_in = async->in < 0;
+	if (need_in) {
+		if (pipe(fdin) < 0) {
+			if (async->out > 0)
+				close(async->out);
+			return error("cannot create pipe: %s", strerror(errno));
+		}
+		async->in = fdin[1];
+	}
+
+	need_out = async->out < 0;
+	if (need_out) {
+		if (pipe(fdout) < 0) {
+			if (need_in)
+				close_pair(fdin);
+			else if (async->in)
+				close(async->in);
+			return error("cannot create pipe: %s", strerror(errno));
+		}
+		async->out = fdout[0];
+	}
+
+	if (need_in)
+		proc_in = fdin[0];
+	else if (async->in)
+		proc_in = async->in;
+	else
+		proc_in = -1;
+
+	if (need_out)
+		proc_out = fdout[1];
+	else if (async->out)
+		proc_out = async->out;
+	else
+		proc_out = -1;
+
+#ifdef NO_PTHREADS
+	/* Flush stdio before fork() to avoid cloning buffers */
+	fflush(NULL);
+
+	async->pid = fork();
+	if (async->pid < 0) {
+		error("fork (async) failed: %s", strerror(errno));
+		goto error;
+	}
+	if (!async->pid) {
+		if (need_in)
+			close(fdin[1]);
+		if (need_out)
+			close(fdout[0]);
+		git_atexit_clear();
+		exit(!!async->proc(proc_in, proc_out, async->data));
+	}
+
+	mark_child_for_cleanup(async->pid);
+
+	if (need_in)
+		close(fdin[0]);
+	else if (async->in)
+		close(async->in);
+
+	if (need_out)
+		close(fdout[1]);
+	else if (async->out)
+		close(async->out);
+#else
+	if (!main_thread_set) {
+		/*
+		 * We assume that the first time that start_async is called
+		 * it is from the main thread.
+		 */
+		main_thread_set = 1;
+		main_thread = pthread_self();
+		pthread_key_create(&async_key, NULL);
+		pthread_key_create(&async_die_counter, NULL);
+		set_die_routine(die_async);
+		set_die_is_recursing_routine(async_die_is_recursing);
+	}
+
+	if (proc_in >= 0)
+		set_cloexec(proc_in);
+	if (proc_out >= 0)
+		set_cloexec(proc_out);
+	async->proc_in = proc_in;
+	async->proc_out = proc_out;
+	{
+		int err = pthread_create(&async->tid, NULL, run_thread, async);
+		if (err) {
+			error("cannot create thread: %s", strerror(err));
+			goto error;
+		}
+	}
+#endif
+	return 0;
+
+error:
+	if (need_in)
+		close_pair(fdin);
+	else if (async->in)
+		close(async->in);
+
+	if (need_out)
+		close_pair(fdout);
+	else if (async->out)
+		close(async->out);
+	return -1;
+}
+
+int finish_async(struct async *async)
+{
+#ifdef NO_PTHREADS
+	return wait_or_whine(async->pid, "child process");
+#else
+	void *ret = (void *)(intptr_t)(-1);
+
+	if (pthread_join(async->tid, &ret))
+		error("pthread_join failed");
+	return (int)(intptr_t)ret;
+#endif
+}
+
+const char *find_hook(const char *name)
+{
+	static struct strbuf path = STRBUF_INIT;
+
+	strbuf_reset(&path);
+	strbuf_git_path(&path, "hooks/%s", name);
+	if (access(path.buf, X_OK) < 0)
+		return NULL;
+	return path.buf;
+}
+
+int run_hook_ve(const char *const *env, const char *name, va_list args)
+{
+	struct child_process hook = CHILD_PROCESS_INIT;
+	const char *p;
+
+	p = find_hook(name);
+	if (!p)
+		return 0;
+
+	argv_array_push(&hook.args, p);
+	while ((p = va_arg(args, const char *)))
+		argv_array_push(&hook.args, p);
+	hook.env = env;
+	hook.no_stdin = 1;
+	hook.stdout_to_stderr = 1;
+
+	return run_command(&hook);
+}
+
+int run_hook_le(const char *const *env, const char *name, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, name);
+	ret = run_hook_ve(env, name, args);
+	va_end(args);
+
+	return ret;
+}
+
+int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint)
+{
+	cmd->out = -1;
+	if (start_command(cmd) < 0)
+		return -1;
+
+	if (strbuf_read(buf, cmd->out, hint) < 0) {
+		close(cmd->out);
+		finish_command(cmd); /* throw away exit code */
+		return -1;
+	}
+
+	close(cmd->out);
+	return finish_command(cmd);
 }