merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

1 files changed, 1485 insertions, 0 deletions

diff --git a/third_party/git/daemon.c b/third_party/git/daemon.c
new file mode 100644
index 0000000000..9d2e0d20ef
--- /dev/null
+++ b/third_party/git/daemon.c
@@ -0,0 +1,1485 @@
+#include "cache.h"
+#include "config.h"
+#include "pkt-line.h"
+#include "run-command.h"
+#include "strbuf.h"
+#include "string-list.h"
+
+#ifdef NO_INITGROUPS
+#define initgroups(x, y) (0) /* nothing */
+#endif
+
+static enum log_destination {
+	LOG_DESTINATION_UNSET = -1,
+	LOG_DESTINATION_NONE = 0,
+	LOG_DESTINATION_STDERR = 1,
+	LOG_DESTINATION_SYSLOG = 2,
+} log_destination = LOG_DESTINATION_UNSET;
+static int verbose;
+static int reuseaddr;
+static int informative_errors;
+
+static const char daemon_usage[] =
+"git daemon [--verbose] [--syslog] [--export-all]\n"
+"           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
+"           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
+"           [--user-path | --user-path=<path>]\n"
+"           [--interpolated-path=<path>]\n"
+"           [--reuseaddr] [--pid-file=<file>]\n"
+"           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
+"           [--access-hook=<path>]\n"
+"           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
+"                      [--detach] [--user=<user> [--group=<group>]]\n"
+"           [--log-destination=(stderr|syslog|none)]\n"
+"           [<directory>...]";
+
+/* List of acceptable pathname prefixes */
+static const char **ok_paths;
+static int strict_paths;
+
+/* If this is set, git-daemon-export-ok is not required */
+static int export_all_trees;
+
+/* Take all paths relative to this one if non-NULL */
+static const char *base_path;
+static const char *interpolated_path;
+static int base_path_relaxed;
+
+/* If defined, ~user notation is allowed and the string is inserted
+ * after ~user/.  E.g. a request to git://host/~alice/frotz would
+ * go to /home/alice/pub_git/frotz with --user-path=pub_git.
+ */
+static const char *user_path;
+
+/* Timeout, and initial timeout */
+static unsigned int timeout;
+static unsigned int init_timeout;
+
+struct hostinfo {
+	struct strbuf hostname;
+	struct strbuf canon_hostname;
+	struct strbuf ip_address;
+	struct strbuf tcp_port;
+	unsigned int hostname_lookup_done:1;
+	unsigned int saw_extended_args:1;
+};
+
+static void lookup_hostname(struct hostinfo *hi);
+
+static const char *get_canon_hostname(struct hostinfo *hi)
+{
+	lookup_hostname(hi);
+	return hi->canon_hostname.buf;
+}
+
+static const char *get_ip_address(struct hostinfo *hi)
+{
+	lookup_hostname(hi);
+	return hi->ip_address.buf;
+}
+
+static void logreport(int priority, const char *err, va_list params)
+{
+	switch (log_destination) {
+	case LOG_DESTINATION_SYSLOG: {
+		char buf[1024];
+		vsnprintf(buf, sizeof(buf), err, params);
+		syslog(priority, "%s", buf);
+		break;
+	}
+	case LOG_DESTINATION_STDERR:
+		/*
+		 * Since stderr is set to buffered mode, the
+		 * logging of different processes will not overlap
+		 * unless they overflow the (rather big) buffers.
+		 */
+		fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
+		vfprintf(stderr, err, params);
+		fputc('\n', stderr);
+		fflush(stderr);
+		break;
+	case LOG_DESTINATION_NONE:
+		break;
+	case LOG_DESTINATION_UNSET:
+		BUG("log destination not initialized correctly");
+	}
+}
+
+__attribute__((format (printf, 1, 2)))
+static void logerror(const char *err, ...)
+{
+	va_list params;
+	va_start(params, err);
+	logreport(LOG_ERR, err, params);
+	va_end(params);
+}
+
+__attribute__((format (printf, 1, 2)))
+static void loginfo(const char *err, ...)
+{
+	va_list params;
+	if (!verbose)
+		return;
+	va_start(params, err);
+	logreport(LOG_INFO, err, params);
+	va_end(params);
+}
+
+static void NORETURN daemon_die(const char *err, va_list params)
+{
+	logreport(LOG_ERR, err, params);
+	exit(1);
+}
+
+struct expand_path_context {
+	const char *directory;
+	struct hostinfo *hostinfo;
+};
+
+static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
+{
+	struct expand_path_context *context = ctx;
+	struct hostinfo *hi = context->hostinfo;
+
+	switch (placeholder[0]) {
+	case 'H':
+		strbuf_addbuf(sb, &hi->hostname);
+		return 1;
+	case 'C':
+		if (placeholder[1] == 'H') {
+			strbuf_addstr(sb, get_canon_hostname(hi));
+			return 2;
+		}
+		break;
+	case 'I':
+		if (placeholder[1] == 'P') {
+			strbuf_addstr(sb, get_ip_address(hi));
+			return 2;
+		}
+		break;
+	case 'P':
+		strbuf_addbuf(sb, &hi->tcp_port);
+		return 1;
+	case 'D':
+		strbuf_addstr(sb, context->directory);
+		return 1;
+	}
+	return 0;
+}
+
+static const char *path_ok(const char *directory, struct hostinfo *hi)
+{
+	static char rpath[PATH_MAX];
+	static char interp_path[PATH_MAX];
+	size_t rlen;
+	const char *path;
+	const char *dir;
+
+	dir = directory;
+
+	if (daemon_avoid_alias(dir)) {
+		logerror("'%s': aliased", dir);
+		return NULL;
+	}
+
+	if (*dir == '~') {
+		if (!user_path) {
+			logerror("'%s': User-path not allowed", dir);
+			return NULL;
+		}
+		if (*user_path) {
+			/* Got either "~alice" or "~alice/foo";
+			 * rewrite them to "~alice/%s" or
+			 * "~alice/%s/foo".
+			 */
+			int namlen, restlen = strlen(dir);
+			const char *slash = strchr(dir, '/');
+			if (!slash)
+				slash = dir + restlen;
+			namlen = slash - dir;
+			restlen -= namlen;
+			loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
+			rlen = snprintf(rpath, sizeof(rpath), "%.*s/%s%.*s",
+					namlen, dir, user_path, restlen, slash);
+			if (rlen >= sizeof(rpath)) {
+				logerror("user-path too large: %s", rpath);
+				return NULL;
+			}
+			dir = rpath;
+		}
+	}
+	else if (interpolated_path && hi->saw_extended_args) {
+		struct strbuf expanded_path = STRBUF_INIT;
+		struct expand_path_context context;
+
+		context.directory = directory;
+		context.hostinfo = hi;
+
+		if (*dir != '/') {
+			/* Allow only absolute */
+			logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
+			return NULL;
+		}
+
+		strbuf_expand(&expanded_path, interpolated_path,
+			      expand_path, &context);
+
+		rlen = strlcpy(interp_path, expanded_path.buf,
+			       sizeof(interp_path));
+		if (rlen >= sizeof(interp_path)) {
+			logerror("interpolated path too large: %s",
+				 interp_path);
+			return NULL;
+		}
+
+		strbuf_release(&expanded_path);
+		loginfo("Interpolated dir '%s'", interp_path);
+
+		dir = interp_path;
+	}
+	else if (base_path) {
+		if (*dir != '/') {
+			/* Allow only absolute */
+			logerror("'%s': Non-absolute path denied (base-path active)", dir);
+			return NULL;
+		}
+		rlen = snprintf(rpath, sizeof(rpath), "%s%s", base_path, dir);
+		if (rlen >= sizeof(rpath)) {
+			logerror("base-path too large: %s", rpath);
+			return NULL;
+		}
+		dir = rpath;
+	}
+
+	path = enter_repo(dir, strict_paths);
+	if (!path && base_path && base_path_relaxed) {
+		/*
+		 * if we fail and base_path_relaxed is enabled, try without
+		 * prefixing the base path
+		 */
+		dir = directory;
+		path = enter_repo(dir, strict_paths);
+	}
+
+	if (!path) {
+		logerror("'%s' does not appear to be a git repository", dir);
+		return NULL;
+	}
+
+	if ( ok_paths && *ok_paths ) {
+		const char **pp;
+		int pathlen = strlen(path);
+
+		/* The validation is done on the paths after enter_repo
+		 * appends optional {.git,.git/.git} and friends, but
+		 * it does not use getcwd().  So if your /pub is
+		 * a symlink to /mnt/pub, you can whitelist /pub and
+		 * do not have to say /mnt/pub.
+		 * Do not say /pub/.
+		 */
+		for ( pp = ok_paths ; *pp ; pp++ ) {
+			int len = strlen(*pp);
+			if (len <= pathlen &&
+			    !memcmp(*pp, path, len) &&
+			    (path[len] == '\0' ||
+			     (!strict_paths && path[len] == '/')))
+				return path;
+		}
+	}
+	else {
+		/* be backwards compatible */
+		if (!strict_paths)
+			return path;
+	}
+
+	logerror("'%s': not in whitelist", path);
+	return NULL;		/* Fallthrough. Deny by default */
+}
+
+typedef int (*daemon_service_fn)(const struct argv_array *env);
+struct daemon_service {
+	const char *name;
+	const char *config_name;
+	daemon_service_fn fn;
+	int enabled;
+	int overridable;
+};
+
+static int daemon_error(const char *dir, const char *msg)
+{
+	if (!informative_errors)
+		msg = "access denied or repository not exported";
+	packet_write_fmt(1, "ERR %s: %s", msg, dir);
+	return -1;
+}
+
+static const char *access_hook;
+
+static int run_access_hook(struct daemon_service *service, const char *dir,
+			   const char *path, struct hostinfo *hi)
+{
+	struct child_process child = CHILD_PROCESS_INIT;
+	struct strbuf buf = STRBUF_INIT;
+	const char *argv[8];
+	const char **arg = argv;
+	char *eol;
+	int seen_errors = 0;
+
+	*arg++ = access_hook;
+	*arg++ = service->name;
+	*arg++ = path;
+	*arg++ = hi->hostname.buf;
+	*arg++ = get_canon_hostname(hi);
+	*arg++ = get_ip_address(hi);
+	*arg++ = hi->tcp_port.buf;
+	*arg = NULL;
+
+	child.use_shell = 1;
+	child.argv = argv;
+	child.no_stdin = 1;
+	child.no_stderr = 1;
+	child.out = -1;
+	if (start_command(&child)) {
+		logerror("daemon access hook '%s' failed to start",
+			 access_hook);
+		goto error_return;
+	}
+	if (strbuf_read(&buf, child.out, 0) < 0) {
+		logerror("failed to read from pipe to daemon access hook '%s'",
+			 access_hook);
+		strbuf_reset(&buf);
+		seen_errors = 1;
+	}
+	if (close(child.out) < 0) {
+		logerror("failed to close pipe to daemon access hook '%s'",
+			 access_hook);
+		seen_errors = 1;
+	}
+	if (finish_command(&child))
+		seen_errors = 1;
+
+	if (!seen_errors) {
+		strbuf_release(&buf);
+		return 0;
+	}
+
+error_return:
+	strbuf_ltrim(&buf);
+	if (!buf.len)
+		strbuf_addstr(&buf, "service rejected");
+	eol = strchr(buf.buf, '\n');
+	if (eol)
+		*eol = '\0';
+	errno = EACCES;
+	daemon_error(dir, buf.buf);
+	strbuf_release(&buf);
+	return -1;
+}
+
+static int run_service(const char *dir, struct daemon_service *service,
+		       struct hostinfo *hi, const struct argv_array *env)
+{
+	const char *path;
+	int enabled = service->enabled;
+	struct strbuf var = STRBUF_INIT;
+
+	loginfo("Request %s for '%s'", service->name, dir);
+
+	if (!enabled && !service->overridable) {
+		logerror("'%s': service not enabled.", service->name);
+		errno = EACCES;
+		return daemon_error(dir, "service not enabled");
+	}
+
+	if (!(path = path_ok(dir, hi)))
+		return daemon_error(dir, "no such repository");
+
+	/*
+	 * Security on the cheap.
+	 *
+	 * We want a readable HEAD, usable "objects" directory, and
+	 * a "git-daemon-export-ok" flag that says that the other side
+	 * is ok with us doing this.
+	 *
+	 * path_ok() uses enter_repo() and does whitelist checking.
+	 * We only need to make sure the repository is exported.
+	 */
+
+	if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
+		logerror("'%s': repository not exported.", path);
+		errno = EACCES;
+		return daemon_error(dir, "repository not exported");
+	}
+
+	if (service->overridable) {
+		strbuf_addf(&var, "daemon.%s", service->config_name);
+		git_config_get_bool(var.buf, &enabled);
+		strbuf_release(&var);
+	}
+	if (!enabled) {
+		logerror("'%s': service not enabled for '%s'",
+			 service->name, path);
+		errno = EACCES;
+		return daemon_error(dir, "service not enabled");
+	}
+
+	/*
+	 * Optionally, a hook can choose to deny access to the
+	 * repository depending on the phase of the moon.
+	 */
+	if (access_hook && run_access_hook(service, dir, path, hi))
+		return -1;
+
+	/*
+	 * We'll ignore SIGTERM from now on, we have a
+	 * good client.
+	 */
+	signal(SIGTERM, SIG_IGN);
+
+	return service->fn(env);
+}
+
+static void copy_to_log(int fd)
+{
+	struct strbuf line = STRBUF_INIT;
+	FILE *fp;
+
+	fp = fdopen(fd, "r");
+	if (fp == NULL) {
+		logerror("fdopen of error channel failed");
+		close(fd);
+		return;
+	}
+
+	while (strbuf_getline_lf(&line, fp) != EOF) {
+		logerror("%s", line.buf);
+		strbuf_setlen(&line, 0);
+	}
+
+	strbuf_release(&line);
+	fclose(fp);
+}
+
+static int run_service_command(struct child_process *cld)
+{
+	argv_array_push(&cld->args, ".");
+	cld->git_cmd = 1;
+	cld->err = -1;
+	if (start_command(cld))
+		return -1;
+
+	close(0);
+	close(1);
+
+	copy_to_log(cld->err);
+
+	return finish_command(cld);
+}
+
+static int upload_pack(const struct argv_array *env)
+{
+	struct child_process cld = CHILD_PROCESS_INIT;
+	argv_array_pushl(&cld.args, "upload-pack", "--strict", NULL);
+	argv_array_pushf(&cld.args, "--timeout=%u", timeout);
+
+	argv_array_pushv(&cld.env_array, env->argv);
+
+	return run_service_command(&cld);
+}
+
+static int upload_archive(const struct argv_array *env)
+{
+	struct child_process cld = CHILD_PROCESS_INIT;
+	argv_array_push(&cld.args, "upload-archive");
+
+	argv_array_pushv(&cld.env_array, env->argv);
+
+	return run_service_command(&cld);
+}
+
+static int receive_pack(const struct argv_array *env)
+{
+	struct child_process cld = CHILD_PROCESS_INIT;
+	argv_array_push(&cld.args, "receive-pack");
+
+	argv_array_pushv(&cld.env_array, env->argv);
+
+	return run_service_command(&cld);
+}
+
+static struct daemon_service daemon_service[] = {
+	{ "upload-archive", "uploadarch", upload_archive, 0, 1 },
+	{ "upload-pack", "uploadpack", upload_pack, 1, 1 },
+	{ "receive-pack", "receivepack", receive_pack, 0, 1 },
+};
+
+static void enable_service(const char *name, int ena)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
+		if (!strcmp(daemon_service[i].name, name)) {
+			daemon_service[i].enabled = ena;
+			return;
+		}
+	}
+	die("No such service %s", name);
+}
+
+static void make_service_overridable(const char *name, int ena)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
+		if (!strcmp(daemon_service[i].name, name)) {
+			daemon_service[i].overridable = ena;
+			return;
+		}
+	}
+	die("No such service %s", name);
+}
+
+static void parse_host_and_port(char *hostport, char **host,
+	char **port)
+{
+	if (*hostport == '[') {
+		char *end;
+
+		end = strchr(hostport, ']');
+		if (!end)
+			die("Invalid request ('[' without ']')");
+		*end = '\0';
+		*host = hostport + 1;
+		if (!end[1])
+			*port = NULL;
+		else if (end[1] == ':')
+			*port = end + 2;
+		else
+			die("Garbage after end of host part");
+	} else {
+		*host = hostport;
+		*port = strrchr(hostport, ':');
+		if (*port) {
+			**port = '\0';
+			++*port;
+		}
+	}
+}
+
+/*
+ * Sanitize a string from the client so that it's OK to be inserted into a
+ * filesystem path. Specifically, we disallow slashes, runs of "..", and
+ * trailing and leading dots, which means that the client cannot escape
+ * our base path via ".." traversal.
+ */
+static void sanitize_client(struct strbuf *out, const char *in)
+{
+	for (; *in; in++) {
+		if (*in == '/')
+			continue;
+		if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
+			continue;
+		strbuf_addch(out, *in);
+	}
+
+	while (out->len && out->buf[out->len - 1] == '.')
+		strbuf_setlen(out, out->len - 1);
+}
+
+/*
+ * Like sanitize_client, but we also perform any canonicalization
+ * to make life easier on the admin.
+ */
+static void canonicalize_client(struct strbuf *out, const char *in)
+{
+	sanitize_client(out, in);
+	strbuf_tolower(out);
+}
+
+/*
+ * Read the host as supplied by the client connection.
+ *
+ * Returns a pointer to the character after the NUL byte terminating the host
+ * arguemnt, or 'extra_args' if there is no host arguemnt.
+ */
+static char *parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
+{
+	char *val;
+	int vallen;
+	char *end = extra_args + buflen;
+
+	if (extra_args < end && *extra_args) {
+		hi->saw_extended_args = 1;
+		if (strncasecmp("host=", extra_args, 5) == 0) {
+			val = extra_args + 5;
+			vallen = strlen(val) + 1;
+			loginfo("Extended attribute \"host\": %s", val);
+			if (*val) {
+				/* Split <host>:<port> at colon. */
+				char *host;
+				char *port;
+				parse_host_and_port(val, &host, &port);
+				if (port)
+					sanitize_client(&hi->tcp_port, port);
+				canonicalize_client(&hi->hostname, host);
+				hi->hostname_lookup_done = 0;
+			}
+
+			/* On to the next one */
+			extra_args = val + vallen;
+		}
+		if (extra_args < end && *extra_args)
+			die("Invalid request");
+	}
+
+	return extra_args;
+}
+
+static void parse_extra_args(struct hostinfo *hi, struct argv_array *env,
+			     char *extra_args, int buflen)
+{
+	const char *end = extra_args + buflen;
+	struct strbuf git_protocol = STRBUF_INIT;
+
+	/* First look for the host argument */
+	extra_args = parse_host_arg(hi, extra_args, buflen);
+
+	/* Look for additional arguments places after a second NUL byte */
+	for (; extra_args < end; extra_args += strlen(extra_args) + 1) {
+		const char *arg = extra_args;
+
+		/*
+		 * Parse the extra arguments, adding most to 'git_protocol'
+		 * which will be used to set the 'GIT_PROTOCOL' envvar in the
+		 * service that will be run.
+		 *
+		 * If there ends up being a particular arg in the future that
+		 * git-daemon needs to parse specificly (like the 'host' arg)
+		 * then it can be parsed here and not added to 'git_protocol'.
+		 */
+		if (*arg) {
+			if (git_protocol.len > 0)
+				strbuf_addch(&git_protocol, ':');
+			strbuf_addstr(&git_protocol, arg);
+		}
+	}
+
+	if (git_protocol.len > 0) {
+		loginfo("Extended attribute \"protocol\": %s", git_protocol.buf);
+		argv_array_pushf(env, GIT_PROTOCOL_ENVIRONMENT "=%s",
+				 git_protocol.buf);
+	}
+	strbuf_release(&git_protocol);
+}
+
+/*
+ * Locate canonical hostname and its IP address.
+ */
+static void lookup_hostname(struct hostinfo *hi)
+{
+	if (!hi->hostname_lookup_done && hi->hostname.len) {
+#ifndef NO_IPV6
+		struct addrinfo hints;
+		struct addrinfo *ai;
+		int gai;
+		static char addrbuf[HOST_NAME_MAX + 1];
+
+		memset(&hints, 0, sizeof(hints));
+		hints.ai_flags = AI_CANONNAME;
+
+		gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
+		if (!gai) {
+			struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
+
+			inet_ntop(AF_INET, &sin_addr->sin_addr,
+				  addrbuf, sizeof(addrbuf));
+			strbuf_addstr(&hi->ip_address, addrbuf);
+
+			if (ai->ai_canonname)
+				sanitize_client(&hi->canon_hostname,
+						ai->ai_canonname);
+			else
+				strbuf_addbuf(&hi->canon_hostname,
+					      &hi->ip_address);
+
+			freeaddrinfo(ai);
+		}
+#else
+		struct hostent *hent;
+		struct sockaddr_in sa;
+		char **ap;
+		static char addrbuf[HOST_NAME_MAX + 1];
+
+		hent = gethostbyname(hi->hostname.buf);
+		if (hent) {
+			ap = hent->h_addr_list;
+			memset(&sa, 0, sizeof sa);
+			sa.sin_family = hent->h_addrtype;
+			sa.sin_port = htons(0);
+			memcpy(&sa.sin_addr, *ap, hent->h_length);
+
+			inet_ntop(hent->h_addrtype, &sa.sin_addr,
+				  addrbuf, sizeof(addrbuf));
+
+			sanitize_client(&hi->canon_hostname, hent->h_name);
+			strbuf_addstr(&hi->ip_address, addrbuf);
+		}
+#endif
+		hi->hostname_lookup_done = 1;
+	}
+}
+
+static void hostinfo_init(struct hostinfo *hi)
+{
+	memset(hi, 0, sizeof(*hi));
+	strbuf_init(&hi->hostname, 0);
+	strbuf_init(&hi->canon_hostname, 0);
+	strbuf_init(&hi->ip_address, 0);
+	strbuf_init(&hi->tcp_port, 0);
+}
+
+static void hostinfo_clear(struct hostinfo *hi)
+{
+	strbuf_release(&hi->hostname);
+	strbuf_release(&hi->canon_hostname);
+	strbuf_release(&hi->ip_address);
+	strbuf_release(&hi->tcp_port);
+}
+
+static void set_keep_alive(int sockfd)
+{
+	int ka = 1;
+
+	if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
+		if (errno != ENOTSOCK)
+			logerror("unable to set SO_KEEPALIVE on socket: %s",
+				strerror(errno));
+	}
+}
+
+static int execute(void)
+{
+	char *line = packet_buffer;
+	int pktlen, len, i;
+	char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
+	struct hostinfo hi;
+	struct argv_array env = ARGV_ARRAY_INIT;
+
+	hostinfo_init(&hi);
+
+	if (addr)
+		loginfo("Connection from %s:%s", addr, port);
+
+	set_keep_alive(0);
+	alarm(init_timeout ? init_timeout : timeout);
+	pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
+	alarm(0);
+
+	len = strlen(line);
+	if (len && line[len-1] == '\n')
+		line[len-1] = 0;
+
+	/* parse additional args hidden behind a NUL byte */
+	if (len != pktlen)
+		parse_extra_args(&hi, &env, line + len + 1, pktlen - len - 1);
+
+	for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
+		struct daemon_service *s = &(daemon_service[i]);
+		const char *arg;
+
+		if (skip_prefix(line, "git-", &arg) &&
+		    skip_prefix(arg, s->name, &arg) &&
+		    *arg++ == ' ') {
+			/*
+			 * Note: The directory here is probably context sensitive,
+			 * and might depend on the actual service being performed.
+			 */
+			int rc = run_service(arg, s, &hi, &env);
+			hostinfo_clear(&hi);
+			argv_array_clear(&env);
+			return rc;
+		}
+	}
+
+	hostinfo_clear(&hi);
+	argv_array_clear(&env);
+	logerror("Protocol error: '%s'", line);
+	return -1;
+}
+
+static int addrcmp(const struct sockaddr_storage *s1,
+    const struct sockaddr_storage *s2)
+{
+	const struct sockaddr *sa1 = (const struct sockaddr*) s1;
+	const struct sockaddr *sa2 = (const struct sockaddr*) s2;
+
+	if (sa1->sa_family != sa2->sa_family)
+		return sa1->sa_family - sa2->sa_family;
+	if (sa1->sa_family == AF_INET)
+		return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
+		    &((struct sockaddr_in *)s2)->sin_addr,
+		    sizeof(struct in_addr));
+#ifndef NO_IPV6
+	if (sa1->sa_family == AF_INET6)
+		return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
+		    &((struct sockaddr_in6 *)s2)->sin6_addr,
+		    sizeof(struct in6_addr));
+#endif
+	return 0;
+}
+
+static int max_connections = 32;
+
+static unsigned int live_children;
+
+static struct child {
+	struct child *next;
+	struct child_process cld;
+	struct sockaddr_storage address;
+} *firstborn;
+
+static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
+{
+	struct child *newborn, **cradle;
+
+	newborn = xcalloc(1, sizeof(*newborn));
+	live_children++;
+	memcpy(&newborn->cld, cld, sizeof(*cld));
+	memcpy(&newborn->address, addr, addrlen);
+	for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
+		if (!addrcmp(&(*cradle)->address, &newborn->address))
+			break;
+	newborn->next = *cradle;
+	*cradle = newborn;
+}
+
+/*
+ * This gets called if the number of connections grows
+ * past "max_connections".
+ *
+ * We kill the newest connection from a duplicate IP.
+ */
+static void kill_some_child(void)
+{
+	const struct child *blanket, *next;
+
+	if (!(blanket = firstborn))
+		return;
+
+	for (; (next = blanket->next); blanket = next)
+		if (!addrcmp(&blanket->address, &next->address)) {
+			kill(blanket->cld.pid, SIGTERM);
+			break;
+		}
+}
+
+static void check_dead_children(void)
+{
+	int status;
+	pid_t pid;
+
+	struct child **cradle, *blanket;
+	for (cradle = &firstborn; (blanket = *cradle);)
+		if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
+			const char *dead = "";
+			if (status)
+				dead = " (with error)";
+			loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
+
+			/* remove the child */
+			*cradle = blanket->next;
+			live_children--;
+			child_process_clear(&blanket->cld);
+			free(blanket);
+		} else
+			cradle = &blanket->next;
+}
+
+static struct argv_array cld_argv = ARGV_ARRAY_INIT;
+static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
+{
+	struct child_process cld = CHILD_PROCESS_INIT;
+
+	if (max_connections && live_children >= max_connections) {
+		kill_some_child();
+		sleep(1);  /* give it some time to die */
+		check_dead_children();
+		if (live_children >= max_connections) {
+			close(incoming);
+			logerror("Too many children, dropping connection");
+			return;
+		}
+	}
+
+	if (addr->sa_family == AF_INET) {
+		char buf[128] = "";
+		struct sockaddr_in *sin_addr = (void *) addr;
+		inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
+		argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
+		argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
+				 ntohs(sin_addr->sin_port));
+#ifndef NO_IPV6
+	} else if (addr->sa_family == AF_INET6) {
+		char buf[128] = "";
+		struct sockaddr_in6 *sin6_addr = (void *) addr;
+		inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
+		argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
+		argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
+				 ntohs(sin6_addr->sin6_port));
+#endif
+	}
+
+	cld.argv = cld_argv.argv;
+	cld.in = incoming;
+	cld.out = dup(incoming);
+
+	if (start_command(&cld))
+		logerror("unable to fork");
+	else
+		add_child(&cld, addr, addrlen);
+}
+
+static void child_handler(int signo)
+{
+	/*
+	 * Otherwise empty handler because systemcalls will get interrupted
+	 * upon signal receipt
+	 * SysV needs the handler to be rearmed
+	 */
+	signal(SIGCHLD, child_handler);
+}
+
+static int set_reuse_addr(int sockfd)
+{
+	int on = 1;
+
+	if (!reuseaddr)
+		return 0;
+	return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
+			  &on, sizeof(on));
+}
+
+struct socketlist {
+	int *list;
+	size_t nr;
+	size_t alloc;
+};
+
+static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
+{
+#ifdef NO_IPV6
+	static char ip[INET_ADDRSTRLEN];
+#else
+	static char ip[INET6_ADDRSTRLEN];
+#endif
+
+	switch (family) {
+#ifndef NO_IPV6
+	case AF_INET6:
+		inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
+		break;
+#endif
+	case AF_INET:
+		inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
+		break;
+	default:
+		xsnprintf(ip, sizeof(ip), "<unknown>");
+	}
+	return ip;
+}
+
+#ifndef NO_IPV6
+
+static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
+{
+	int socknum = 0;
+	char pbuf[NI_MAXSERV];
+	struct addrinfo hints, *ai0, *ai;
+	int gai;
+	long flags;
+
+	xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = AF_UNSPEC;
+	hints.ai_socktype = SOCK_STREAM;
+	hints.ai_protocol = IPPROTO_TCP;
+	hints.ai_flags = AI_PASSIVE;
+
+	gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
+	if (gai) {
+		logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
+		return 0;
+	}
+
+	for (ai = ai0; ai; ai = ai->ai_next) {
+		int sockfd;
+
+		sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
+		if (sockfd < 0)
+			continue;
+		if (sockfd >= FD_SETSIZE) {
+			logerror("Socket descriptor too large");
+			close(sockfd);
+			continue;
+		}
+
+#ifdef IPV6_V6ONLY
+		if (ai->ai_family == AF_INET6) {
+			int on = 1;
+			setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
+				   &on, sizeof(on));
+			/* Note: error is not fatal */
+		}
+#endif
+
+		if (set_reuse_addr(sockfd)) {
+			logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
+			close(sockfd);
+			continue;
+		}
+
+		set_keep_alive(sockfd);
+
+		if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
+			logerror("Could not bind to %s: %s",
+				 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
+				 strerror(errno));
+			close(sockfd);
+			continue;	/* not fatal */
+		}
+		if (listen(sockfd, 5) < 0) {
+			logerror("Could not listen to %s: %s",
+				 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
+				 strerror(errno));
+			close(sockfd);
+			continue;	/* not fatal */
+		}
+
+		flags = fcntl(sockfd, F_GETFD, 0);
+		if (flags >= 0)
+			fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
+
+		ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
+		socklist->list[socklist->nr++] = sockfd;
+		socknum++;
+	}
+
+	freeaddrinfo(ai0);
+
+	return socknum;
+}
+
+#else /* NO_IPV6 */
+
+static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
+{
+	struct sockaddr_in sin;
+	int sockfd;
+	long flags;
+
+	memset(&sin, 0, sizeof sin);
+	sin.sin_family = AF_INET;
+	sin.sin_port = htons(listen_port);
+
+	if (listen_addr) {
+		/* Well, host better be an IP address here. */
+		if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
+			return 0;
+	} else {
+		sin.sin_addr.s_addr = htonl(INADDR_ANY);
+	}
+
+	sockfd = socket(AF_INET, SOCK_STREAM, 0);
+	if (sockfd < 0)
+		return 0;
+
+	if (set_reuse_addr(sockfd)) {
+		logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
+		close(sockfd);
+		return 0;
+	}
+
+	set_keep_alive(sockfd);
+
+	if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
+		logerror("Could not bind to %s: %s",
+			 ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
+			 strerror(errno));
+		close(sockfd);
+		return 0;
+	}
+
+	if (listen(sockfd, 5) < 0) {
+		logerror("Could not listen to %s: %s",
+			 ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
+			 strerror(errno));
+		close(sockfd);
+		return 0;
+	}
+
+	flags = fcntl(sockfd, F_GETFD, 0);
+	if (flags >= 0)
+		fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
+
+	ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
+	socklist->list[socklist->nr++] = sockfd;
+	return 1;
+}
+
+#endif
+
+static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
+{
+	if (!listen_addr->nr)
+		setup_named_sock(NULL, listen_port, socklist);
+	else {
+		int i, socknum;
+		for (i = 0; i < listen_addr->nr; i++) {
+			socknum = setup_named_sock(listen_addr->items[i].string,
+						   listen_port, socklist);
+
+			if (socknum == 0)
+				logerror("unable to allocate any listen sockets for host %s on port %u",
+					 listen_addr->items[i].string, listen_port);
+		}
+	}
+}
+
+static int service_loop(struct socketlist *socklist)
+{
+	struct pollfd *pfd;
+	int i;
+
+	pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
+
+	for (i = 0; i < socklist->nr; i++) {
+		pfd[i].fd = socklist->list[i];
+		pfd[i].events = POLLIN;
+	}
+
+	signal(SIGCHLD, child_handler);
+
+	for (;;) {
+		int i;
+
+		check_dead_children();
+
+		if (poll(pfd, socklist->nr, -1) < 0) {
+			if (errno != EINTR) {
+				logerror("Poll failed, resuming: %s",
+				      strerror(errno));
+				sleep(1);
+			}
+			continue;
+		}
+
+		for (i = 0; i < socklist->nr; i++) {
+			if (pfd[i].revents & POLLIN) {
+				union {
+					struct sockaddr sa;
+					struct sockaddr_in sai;
+#ifndef NO_IPV6
+					struct sockaddr_in6 sai6;
+#endif
+				} ss;
+				socklen_t sslen = sizeof(ss);
+				int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
+				if (incoming < 0) {
+					switch (errno) {
+					case EAGAIN:
+					case EINTR:
+					case ECONNABORTED:
+						continue;
+					default:
+						die_errno("accept returned");
+					}
+				}
+				handle(incoming, &ss.sa, sslen);
+			}
+		}
+	}
+}
+
+#ifdef NO_POSIX_GOODIES
+
+struct credentials;
+
+static void drop_privileges(struct credentials *cred)
+{
+	/* nothing */
+}
+
+static struct credentials *prepare_credentials(const char *user_name,
+    const char *group_name)
+{
+	die("--user not supported on this platform");
+}
+
+#else
+
+struct credentials {
+	struct passwd *pass;
+	gid_t gid;
+};
+
+static void drop_privileges(struct credentials *cred)
+{
+	if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
+	    setgid (cred->gid) || setuid(cred->pass->pw_uid)))
+		die("cannot drop privileges");
+}
+
+static struct credentials *prepare_credentials(const char *user_name,
+    const char *group_name)
+{
+	static struct credentials c;
+
+	c.pass = getpwnam(user_name);
+	if (!c.pass)
+		die("user not found - %s", user_name);
+
+	if (!group_name)
+		c.gid = c.pass->pw_gid;
+	else {
+		struct group *group = getgrnam(group_name);
+		if (!group)
+			die("group not found - %s", group_name);
+
+		c.gid = group->gr_gid;
+	}
+
+	return &c;
+}
+#endif
+
+static int serve(struct string_list *listen_addr, int listen_port,
+    struct credentials *cred)
+{
+	struct socketlist socklist = { NULL, 0, 0 };
+
+	socksetup(listen_addr, listen_port, &socklist);
+	if (socklist.nr == 0)
+		die("unable to allocate any listen sockets on port %u",
+		    listen_port);
+
+	drop_privileges(cred);
+
+	loginfo("Ready to rumble");
+
+	return service_loop(&socklist);
+}
+
+int cmd_main(int argc, const char **argv)
+{
+	int listen_port = 0;
+	struct string_list listen_addr = STRING_LIST_INIT_NODUP;
+	int serve_mode = 0, inetd_mode = 0;
+	const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
+	int detach = 0;
+	struct credentials *cred = NULL;
+	int i;
+
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+		const char *v;
+
+		if (skip_prefix(arg, "--listen=", &v)) {
+			string_list_append(&listen_addr, xstrdup_tolower(v));
+			continue;
+		}
+		if (skip_prefix(arg, "--port=", &v)) {
+			char *end;
+			unsigned long n;
+			n = strtoul(v, &end, 0);
+			if (*v && !*end) {
+				listen_port = n;
+				continue;
+			}
+		}
+		if (!strcmp(arg, "--serve")) {
+			serve_mode = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--inetd")) {
+			inetd_mode = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--verbose")) {
+			verbose = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--syslog")) {
+			log_destination = LOG_DESTINATION_SYSLOG;
+			continue;
+		}
+		if (skip_prefix(arg, "--log-destination=", &v)) {
+			if (!strcmp(v, "syslog")) {
+				log_destination = LOG_DESTINATION_SYSLOG;
+				continue;
+			} else if (!strcmp(v, "stderr")) {
+				log_destination = LOG_DESTINATION_STDERR;
+				continue;
+			} else if (!strcmp(v, "none")) {
+				log_destination = LOG_DESTINATION_NONE;
+				continue;
+			} else
+				die("unknown log destination '%s'", v);
+		}
+		if (!strcmp(arg, "--export-all")) {
+			export_all_trees = 1;
+			continue;
+		}
+		if (skip_prefix(arg, "--access-hook=", &v)) {
+			access_hook = v;
+			continue;
+		}
+		if (skip_prefix(arg, "--timeout=", &v)) {
+			timeout = atoi(v);
+			continue;
+		}
+		if (skip_prefix(arg, "--init-timeout=", &v)) {
+			init_timeout = atoi(v);
+			continue;
+		}
+		if (skip_prefix(arg, "--max-connections=", &v)) {
+			max_connections = atoi(v);
+			if (max_connections < 0)
+				max_connections = 0;	        /* unlimited */
+			continue;
+		}
+		if (!strcmp(arg, "--strict-paths")) {
+			strict_paths = 1;
+			continue;
+		}
+		if (skip_prefix(arg, "--base-path=", &v)) {
+			base_path = v;
+			continue;
+		}
+		if (!strcmp(arg, "--base-path-relaxed")) {
+			base_path_relaxed = 1;
+			continue;
+		}
+		if (skip_prefix(arg, "--interpolated-path=", &v)) {
+			interpolated_path = v;
+			continue;
+		}
+		if (!strcmp(arg, "--reuseaddr")) {
+			reuseaddr = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--user-path")) {
+			user_path = "";
+			continue;
+		}
+		if (skip_prefix(arg, "--user-path=", &v)) {
+			user_path = v;
+			continue;
+		}
+		if (skip_prefix(arg, "--pid-file=", &v)) {
+			pid_file = v;
+			continue;
+		}
+		if (!strcmp(arg, "--detach")) {
+			detach = 1;
+			continue;
+		}
+		if (skip_prefix(arg, "--user=", &v)) {
+			user_name = v;
+			continue;
+		}
+		if (skip_prefix(arg, "--group=", &v)) {
+			group_name = v;
+			continue;
+		}
+		if (skip_prefix(arg, "--enable=", &v)) {
+			enable_service(v, 1);
+			continue;
+		}
+		if (skip_prefix(arg, "--disable=", &v)) {
+			enable_service(v, 0);
+			continue;
+		}
+		if (skip_prefix(arg, "--allow-override=", &v)) {
+			make_service_overridable(v, 1);
+			continue;
+		}
+		if (skip_prefix(arg, "--forbid-override=", &v)) {
+			make_service_overridable(v, 0);
+			continue;
+		}
+		if (!strcmp(arg, "--informative-errors")) {
+			informative_errors = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--no-informative-errors")) {
+			informative_errors = 0;
+			continue;
+		}
+		if (!strcmp(arg, "--")) {
+			ok_paths = &argv[i+1];
+			break;
+		} else if (arg[0] != '-') {
+			ok_paths = &argv[i];
+			break;
+		}
+
+		usage(daemon_usage);
+	}
+
+	if (log_destination == LOG_DESTINATION_UNSET) {
+		if (inetd_mode || detach)
+			log_destination = LOG_DESTINATION_SYSLOG;
+		else
+			log_destination = LOG_DESTINATION_STDERR;
+	}
+
+	if (log_destination == LOG_DESTINATION_SYSLOG) {
+		openlog("git-daemon", LOG_PID, LOG_DAEMON);
+		set_die_routine(daemon_die);
+	} else
+		/* avoid splitting a message in the middle */
+		setvbuf(stderr, NULL, _IOFBF, 4096);
+
+	if (inetd_mode && (detach || group_name || user_name))
+		die("--detach, --user and --group are incompatible with --inetd");
+
+	if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
+		die("--listen= and --port= are incompatible with --inetd");
+	else if (listen_port == 0)
+		listen_port = DEFAULT_GIT_PORT;
+
+	if (group_name && !user_name)
+		die("--group supplied without --user");
+
+	if (user_name)
+		cred = prepare_credentials(user_name, group_name);
+
+	if (strict_paths && (!ok_paths || !*ok_paths))
+		die("option --strict-paths requires a whitelist");
+
+	if (base_path && !is_directory(base_path))
+		die("base-path '%s' does not exist or is not a directory",
+		    base_path);
+
+	if (log_destination != LOG_DESTINATION_STDERR) {
+		if (!freopen("/dev/null", "w", stderr))
+			die_errno("failed to redirect stderr to /dev/null");
+	}
+
+	if (inetd_mode || serve_mode)
+		return execute();
+
+	if (detach) {
+		if (daemonize())
+			die("--detach not supported on this platform");
+	}
+
+	if (pid_file)
+		write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
+
+	/* prepare argv for serving-processes */
+	argv_array_push(&cld_argv, argv[0]); /* git-daemon */
+	argv_array_push(&cld_argv, "--serve");
+	for (i = 1; i < argc; ++i)
+		argv_array_push(&cld_argv, argv[i]);
+
+	return serve(&listen_addr, listen_port, cred);
+}