master-service.c   [plain text]

/* Copyright (c) 2005-2011 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "lib-signals.h"
#include "ioloop.h"
#include "array.h"
#include "env-util.h"
#include "home-expand.h"
#include "process-title.h"
#include "restrict-access.h"
#include "fd-close-on-exec.h"
#include "settings-parser.h"
#include "syslog-util.h"
#include "master-login.h"
#include "master-service-private.h"
#include "master-service-settings.h"

#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <syslog.h>

#define DEFAULT_CONFIG_FILE_PATH SYSCONFDIR"/dovecot.conf"

/* getenv(MASTER_CONFIG_FILE_ENV) provides path to configuration file/socket */
#define MASTER_CONFIG_FILE_ENV "CONFIG_FILE"

/* getenv(MASTER_DOVECOT_VERSION_ENV) provides master's version number */
#define MASTER_DOVECOT_VERSION_ENV "DOVECOT_VERSION"

/* when we're full of connections, how often to check if login state has
   changed. we normally notice it immediately because of a signal, so this is
   just a fallback against race conditions. */
#define MASTER_SERVICE_STATE_CHECK_MSECS 1000

/* If die callback hasn't managed to stop the service for this many seconds,
   force it. */
#define MASTER_SERVICE_DIE_TIMEOUT_MSECS (30*1000)

struct master_service *master_service;

static void master_service_io_listeners_close(struct master_service *service);
static void master_service_refresh_login_state(struct master_service *service);

const char *master_service_getopt_string(void)
{
	return "c:ko:Os:L";
}

static void sig_die(const siginfo_t *si, void *context)
{
	struct master_service *service = context;

	/* SIGINT comes either from master process or from keyboard. we don't
	   want to log it in either case.*/
	if (si->si_signo != SIGINT) {
		i_warning("Killed with signal %d (by pid=%s uid=%s code=%s)",
			  si->si_signo, dec2str(si->si_pid),
			  dec2str(si->si_uid),
			  lib_signal_code_to_str(si->si_signo, si->si_code));
	} else if ((service->flags & MASTER_SERVICE_FLAG_NO_IDLE_DIE) != 0) {
		/* never die when idling */
		return;
	} else if ((service->flags & MASTER_SERVICE_FLAG_STANDALONE) == 0) {
		/* SIGINT came from master. die only if we're not handling
		   any clients currently. */
		if (service->master_status.available_count !=
		    service->total_available_count)
			return;
	}

	service->killed = TRUE;
	io_loop_stop(service->ioloop);
}

static void
sig_state_changed(const siginfo_t *si ATTR_UNUSED, void *context)
{
	struct master_service *service = context;

	master_service_refresh_login_state(service);
}

static void master_service_verify_version_string(struct master_service *service)
{
	if (service->version_string != NULL &&
	    strcmp(service->version_string, PACKAGE_VERSION) != 0) {
		i_fatal("Dovecot version mismatch: "
			"Master is v%s, %s is v"PACKAGE_VERSION" "
			"(if you don't care, set version_ignore=yes)",
			service->version_string, service->name);
	}
}

struct master_service *
master_service_init(const char *name, enum master_service_flags flags,
		    int *argc, char **argv[], const char *getopt_str)
{
	struct master_service *service;
	const char *str;

	i_assert(name != NULL);

#ifdef DEBUG
	if (getenv("GDB") == NULL &&
	    (flags & MASTER_SERVICE_FLAG_STANDALONE) == 0) {
		int count;

		str = getenv("SOCKET_COUNT");
		count = str == NULL ? 0 : atoi(str);
		fd_debug_verify_leaks(MASTER_LISTEN_FD_FIRST + count, 1024);
	}
#endif
	if ((flags & MASTER_SERVICE_FLAG_STANDALONE) == 0) {
		/* make sure we can dump core, at least until
		   privileges are dropped. (i'm not really sure why this
		   is needed, because doing the same just before exec
		   doesn't help, and exec shouldn't affect this with
		   non-setuid/gid binaries..) */
		restrict_access_allow_coredumps(TRUE);
	}

	/* NOTE: we start rooted, so keep the code minimal until
	   restrict_access_by_env() is called */
	lib_init();
	/* Set a logging prefix temporarily. This will be ignored once the log
	   is properly initialized */
	i_set_failure_prefix(t_strdup_printf("%s(init): ", name));

	/* ignore these signals as early as possible */
        lib_signals_ignore(SIGPIPE, TRUE);
        lib_signals_ignore(SIGALRM, FALSE);

	if (getenv(MASTER_UID_ENV) == NULL)
		flags |= MASTER_SERVICE_FLAG_STANDALONE;

	process_title_init(argv);

	service = i_new(struct master_service, 1);
	service->argc = *argc;
	service->argv = *argv;
	service->name = i_strdup(name);
	/* keep getopt_str first in case it contains "+" */
	service->getopt_str = getopt_str == NULL ?
		i_strdup(master_service_getopt_string()) :
		i_strconcat(getopt_str, master_service_getopt_string(), NULL);
	service->flags = flags;
	service->ioloop = io_loop_create();
	service->service_count_left = (unsigned int)-1;
	service->config_fd = -1;

	service->config_path = getenv(MASTER_CONFIG_FILE_ENV);
	if (service->config_path == NULL) {
		service->config_path = DEFAULT_CONFIG_FILE_PATH;
		service->config_path_is_default = TRUE;
	}

	if ((flags & MASTER_SERVICE_FLAG_STANDALONE) == 0) {
		service->version_string = getenv(MASTER_DOVECOT_VERSION_ENV);
		service->socket_count = 1;
	} else {
		service->version_string = PACKAGE_VERSION;
	}
	str = getenv("SOCKET_COUNT");
	if (str != NULL)
		service->socket_count = atoi(str);
	str = getenv("SSL_SOCKET_COUNT");
	if (str != NULL)
		service->ssl_socket_count = atoi(str);

	/* set up some kind of logging until we know exactly how and where
	   we want to log */
	if (getenv("LOG_SERVICE") != NULL)
		i_set_failure_internal();
	if (getenv("USER") != NULL) {
		i_set_failure_prefix(t_strdup_printf("%s(%s): ",
						     name, getenv("USER")));
	} else {
		i_set_failure_prefix(t_strdup_printf("%s: ", name));
	}

	master_service_verify_version_string(service);
	return service;
}

int master_getopt(struct master_service *service)
{
	int c;

	while ((c = getopt(service->argc, service->argv,
			   service->getopt_str)) > 0) {
		if (!master_service_parse_option(service, c, optarg))
			break;
	}
	return c;
}

void master_service_init_log(struct master_service *service,
			     const char *prefix)
{
	const char *path;

	if ((service->flags & MASTER_SERVICE_FLAG_STANDALONE) != 0 &&
	    (service->flags & MASTER_SERVICE_FLAG_DONT_LOG_TO_STDERR) == 0) {
		i_set_failure_file("/dev/stderr", "");
		return;
	}

	if (getenv("LOG_SERVICE") != NULL && !service->log_directly) {
		/* logging via log service */
		i_set_failure_internal();
		i_set_failure_prefix(prefix);
		return;
	}

	if (service->set == NULL) {
		i_set_failure_file("/dev/stderr", prefix);
		return;
	}

	if (strcmp(service->set->log_path, "syslog") != 0) {
		/* error logging goes to file or stderr */
		path = home_expand(service->set->log_path);
		i_set_failure_file(path, prefix);
	}

	if (strcmp(service->set->log_path, "syslog") == 0 ||
	    strcmp(service->set->info_log_path, "syslog") == 0 ||
	    strcmp(service->set->debug_log_path, "syslog") == 0) {
		/* something gets logged to syslog */
		int facility;

		if (!syslog_facility_find(service->set->syslog_facility,
					  &facility))
			facility = LOG_MAIL;
		i_set_failure_syslog("dovecot", LOG_NDELAY, facility);
		i_set_failure_prefix(prefix);

		if (strcmp(service->set->log_path, "syslog") != 0) {
			/* set error handlers back to file */
			i_set_fatal_handler(NULL);
			i_set_error_handler(NULL);
		}
	}

	if (*service->set->info_log_path != '\0' &&
	    strcmp(service->set->info_log_path, "syslog") != 0) {
		path = home_expand(service->set->info_log_path);
		if (*path != '\0')
			i_set_info_file(path);
	}

	if (*service->set->debug_log_path != '\0' &&
	    strcmp(service->set->debug_log_path, "syslog") != 0) {
		path = home_expand(service->set->debug_log_path);
		if (*path != '\0')
			i_set_debug_file(path);
	}
	i_set_failure_timestamp_format(service->set->log_timestamp);
}

void master_service_set_die_with_master(struct master_service *service,
					bool set)
{
	service->die_with_master = set;
}

void master_service_set_die_callback(struct master_service *service,
				     void (*callback)(void))
{
	service->die_callback = callback;
}

bool master_service_parse_option(struct master_service *service,
				 int opt, const char *arg)
{
	switch (opt) {
	case 'c':
		service->config_path = arg;
		service->config_path_is_default = FALSE;
		break;
	case 'k':
		service->keep_environment = TRUE;
		break;
	case 'o':
		if (!array_is_created(&service->config_overrides))
			i_array_init(&service->config_overrides, 16);
		array_append(&service->config_overrides, &arg, 1);
		break;
	case 'O':
		service->flags |= MASTER_SERVICE_FLAG_NO_CONFIG_SETTINGS;
		break;
	case 'L':
		service->log_directly = TRUE;
		break;
	default:
		return FALSE;
	}
	return TRUE;
}

static void master_service_error(struct master_service *service)
{
	master_service_stop_new_connections(service);
	if (service->master_status.available_count ==
	    service->total_available_count || service->die_with_master) {
		if (service->die_callback == NULL)
			master_service_stop(service);
		else {
			service->to_die =
				timeout_add(MASTER_SERVICE_DIE_TIMEOUT_MSECS,
					    master_service_stop,
					    service);
			service->die_callback();
		}
	}
}

static void master_status_error(void *context)
{
	struct master_service *service = context;

	/* status fd is a write-only pipe, so if we're here it means the
	   master wants us to die (or died itself). don't die until all
	   service connections are finished. */
	io_remove(&service->io_status_error);

	/* the log fd may also be closed already, don't die when trying to
	   log later */
	i_set_failure_ignore_errors(TRUE);

	master_service_error(service);
}

void master_service_init_finish(struct master_service *service)
{
	enum libsig_flags sigint_flags = LIBSIG_FLAG_DELAYED;
	struct stat st;
	const char *value;
	unsigned int count;

	i_assert(service->total_available_count == 0);
	i_assert(service->service_count_left == (unsigned int)-1);

	/* set default signal handlers */
	lib_signals_init();
	if ((service->flags & MASTER_SERVICE_FLAG_STANDALONE) == 0)
		sigint_flags |= LIBSIG_FLAG_RESTART;
        lib_signals_set_handler(SIGINT, sigint_flags, sig_die, service);
	lib_signals_set_handler(SIGTERM, LIBSIG_FLAG_DELAYED, sig_die, service);
	if ((service->flags & MASTER_SERVICE_FLAG_TRACK_LOGIN_STATE) != 0) {
		lib_signals_set_handler(SIGUSR1, LIBSIG_FLAGS_SAFE,
					sig_state_changed, service);
	}

	if ((service->flags & MASTER_SERVICE_FLAG_STANDALONE) == 0) {
		if (fstat(MASTER_STATUS_FD, &st) < 0 || !S_ISFIFO(st.st_mode))
			i_fatal("Must be started by dovecot master process");

		/* initialize master_status structure */
		value = getenv(MASTER_UID_ENV);
		if (value == NULL ||
		    str_to_uint(value, &service->master_status.uid) < 0)
			i_fatal(MASTER_UID_ENV" missing");
		service->master_status.pid = getpid();

		/* set the default limit */
		value = getenv(MASTER_CLIENT_LIMIT_ENV);
		if (value == NULL || str_to_uint(value, &count) < 0 ||
		    count == 0)
			i_fatal(MASTER_CLIENT_LIMIT_ENV" missing");
		master_service_set_client_limit(service, count);

		/* set the default service count */
		value = getenv(MASTER_SERVICE_COUNT_ENV);
		if (value != NULL && str_to_uint(value, &count) == 0 &&
		    count > 0)
			master_service_set_service_count(service, count);

		/* start listening errors for status fd, it means master died */
		service->io_status_error = io_add(MASTER_DEAD_FD, IO_ERROR,
						  master_status_error, service);
	} else {
		master_service_set_client_limit(service, 1);
		master_service_set_service_count(service, 1);
	}

	master_service_io_listeners_add(service);

	if ((service->flags & MASTER_SERVICE_FLAG_STD_CLIENT) != 0) {
		/* we already have a connection to be served */
		service->master_status.available_count--;
	}
	master_status_update(service);
}

void master_service_env_clean(void)
{
	const char *value = getenv(DOVECOT_PRESERVE_ENVS_ENV);

	if (value == NULL || *value == '\0')
		env_clean();
	else T_BEGIN {
		value = t_strconcat(value, " "DOVECOT_PRESERVE_ENVS_ENV, NULL);
		env_clean_except(t_strsplit_spaces(value, " "));
	} T_END;
}

void master_service_set_client_limit(struct master_service *service,
				     unsigned int client_limit)
{
	unsigned int used;

	i_assert(service->master_status.available_count ==
		 service->total_available_count);

	used = service->total_available_count -
		service->master_status.available_count;
	i_assert(client_limit >= used);

	service->total_available_count = client_limit;
	service->master_status.available_count = client_limit - used;
}

unsigned int master_service_get_client_limit(struct master_service *service)
{
	return service->total_available_count;
}

void master_service_set_service_count(struct master_service *service,
				      unsigned int count)
{
	unsigned int used;

	used = service->total_available_count -
		service->master_status.available_count;
	i_assert(count >= used);

	if (service->total_available_count > count) {
		service->total_available_count = count;
		service->master_status.available_count = count - used;
	}
	service->service_count_left = count;
}

unsigned int master_service_get_service_count(struct master_service *service)
{
	return service->service_count_left;
}

unsigned int master_service_get_socket_count(struct master_service *service)
{
	return service->socket_count;
}

void master_service_set_avail_overflow_callback(struct master_service *service,
						void (*callback)(void))
{
	service->avail_overflow_callback = callback;
}

const char *master_service_get_config_path(struct master_service *service)
{
	return service->config_path;
}

const char *master_service_get_version_string(struct master_service *service)
{
	return service->version_string;
}

const char *master_service_get_name(struct master_service *service)
{
	return service->name;
}

void master_service_run(struct master_service *service,
			master_service_connection_callback_t *callback)
{
	service->callback = callback;
	io_loop_run(service->ioloop);
	service->callback = NULL;
}

void master_service_stop(struct master_service *service)
{
        io_loop_stop(service->ioloop);
}

void master_service_stop_new_connections(struct master_service *service)
{
	unsigned int current_count;

	if (service->stopping)
		return;

	service->stopping = TRUE;
	master_service_io_listeners_remove(service);
	master_service_io_listeners_close(service);

	/* make sure we stop after servicing current connections */
	current_count = service->total_available_count -
		service->master_status.available_count;
	service->service_count_left = current_count;
	service->total_available_count = current_count;

	if (current_count == 0)
		master_service_stop(service);
	else {
		/* notify master that we're not accepting any more
		   connections */
		service->master_status.available_count = 0;
		master_status_update(service);
	}
	if (service->login != NULL)
		master_login_stop(service->login);
}

bool master_service_is_killed(struct master_service *service)
{
	return service->killed;
}

void master_service_anvil_send(struct master_service *service, const char *cmd)
{
	ssize_t ret;

	if ((service->flags & MASTER_SERVICE_FLAG_STANDALONE) != 0)
		return;

	ret = write(MASTER_ANVIL_FD, cmd, strlen(cmd));
	if (ret < 0) {
		if (errno == EPIPE) {
			/* anvil process was probably recreated, don't bother
			   logging an error about losing connection to it */
			return;
		}
		i_error("write(anvil) failed: %m");
	} else if (ret == 0)
		i_error("write(anvil) failed: EOF");
	else {
		i_assert((size_t)ret == strlen(cmd));
	}
}

void master_service_client_connection_accept(struct master_service_connection *conn)
{
	conn->accepted = TRUE;
}

void master_service_client_connection_destroyed(struct master_service *service)
{
	/* we can listen again */
	master_service_io_listeners_add(service);

	i_assert(service->total_available_count > 0);
	i_assert(service->service_count_left > 0);

	if (service->service_count_left == service->total_available_count) {
		service->total_available_count--;
                service->service_count_left--;
	} else {
		if (service->service_count_left != (unsigned int)-1)
			service->service_count_left--;

		i_assert(service->master_status.available_count <
			 service->total_available_count);
		service->master_status.available_count++;
	}

	if (service->service_count_left == 0) {
		i_assert(service->master_status.available_count ==
			 service->total_available_count);
		master_service_stop(service);
	} else if ((service->io_status_error == NULL ||
		    service->listeners == NULL) &&
		   service->master_status.available_count ==
		   service->total_available_count) {
		/* we've finished handling all clients, and
		   a) master has closed the connection
		   b) there are no listeners (std-client?) */
		master_service_stop(service);
	} else {
		master_status_update(service);
	}
}

static void master_service_set_login_state(struct master_service *service,
					   enum master_login_state state)
{
	if (service->to_overflow_state != NULL)
		timeout_remove(&service->to_overflow_state);

	switch (state) {
	case MASTER_LOGIN_STATE_NONFULL:
		service->call_avail_overflow = FALSE;
		if (service->master_status.available_count > 0)
			return;

		/* some processes should now be able to handle new connections,
		   although we can't. but there may be race conditions, so
		   make sure that we'll check again soon if the state has
		   changed to "full" without our knowledge. */
		service->to_overflow_state =
			timeout_add(MASTER_SERVICE_STATE_CHECK_MSECS,
				    master_service_refresh_login_state,
				    service);
		return;
	case MASTER_LOGIN_STATE_FULL:
		/* make sure we're listening for more connections */
		service->call_avail_overflow = TRUE;
		master_service_io_listeners_add(service);
		return;
	}
	i_error("Invalid master login state: %d", state);
}

static void master_service_refresh_login_state(struct master_service *service)
{
	int ret;

	ret = lseek(MASTER_LOGIN_NOTIFY_FD, 0, SEEK_CUR);
	if (ret < 0)
		i_error("lseek(login notify fd) failed: %m");
	else
		master_service_set_login_state(service, ret);
}

void master_service_close_config_fd(struct master_service *service)
{
	if (service->config_fd != -1) {
		if (close(service->config_fd) < 0)
			i_error("close(master config fd) failed: %m");
		service->config_fd = -1;
	}
}

void master_service_deinit(struct master_service **_service)
{
	struct master_service *service = *_service;

	*_service = NULL;

	master_service_io_listeners_remove(service);

	master_service_close_config_fd(service);
	if (service->to_die != NULL)
		timeout_remove(&service->to_die);
	if (service->to_overflow_state != NULL)
		timeout_remove(&service->to_overflow_state);
	if (service->to_status != NULL)
		timeout_remove(&service->to_status);
	if (service->io_status_error != NULL)
		io_remove(&service->io_status_error);
	if (service->io_status_write != NULL)
		io_remove(&service->io_status_write);
	if (array_is_created(&service->config_overrides))
		array_free(&service->config_overrides);

	if (service->set_parser != NULL) {
		settings_parser_deinit(&service->set_parser);
		pool_unref(&service->set_pool);
	}
	lib_signals_deinit();
	io_loop_destroy(&service->ioloop);

	i_free(service->listeners);
	i_free(service->getopt_str);
	i_free(service->name);
	i_free(service);

	lib_deinit();
}

static void master_service_listen(struct master_service_listener *l)
{
	struct master_service *service = l->service;
	struct master_service_connection conn;

	if (service->master_status.available_count == 0) {
		/* we are full. stop listening for now, unless overflow
		   callback destroys one of the existing connections */
		if (service->call_avail_overflow &&
		    service->avail_overflow_callback != NULL)
			service->avail_overflow_callback();

		if (service->master_status.available_count == 0) {
			master_service_io_listeners_remove(service);
			return;
		}
	}

	memset(&conn, 0, sizeof(conn));
	conn.listen_fd = l->fd;
	conn.fd = net_accept(l->fd, &conn.remote_ip, &conn.remote_port);
	if (conn.fd < 0) {
		struct stat st;
		int orig_errno = errno;

		if (conn.fd == -1)
			return;

		if (errno == ENOTSOCK) {
			/* it's not a socket. should be a fifo. */
		} else if (errno == EINVAL &&
			   (fstat(l->fd, &st) == 0 && S_ISFIFO(st.st_mode))) {
			/* BSDI fails accept(fifo) with EINVAL. */
		} else {
			errno = orig_errno;
			i_error("net_accept() failed: %m");
			master_service_error(service);
			return;
		}
		/* use the "listener" as the connection fd and stop the
		   listener. */
		conn.fd = l->fd;
		conn.listen_fd = l->fd;
		conn.fifo = TRUE;

		io_remove(&l->io);
		l->fd = -1;
	}
	conn.ssl = l->ssl;
	net_set_nonblock(conn.fd, TRUE);

	i_assert(service->master_status.available_count > 0);
	service->master_status.available_count--;
	master_status_update(service);

	service->callback(&conn);

	if (!conn.accepted) {
		if (close(conn.fd) < 0)
			i_error("close(service connection) failed: %m");
		master_service_client_connection_destroyed(service);
	}
}

static void io_listeners_init(struct master_service *service)
{
	unsigned int i;

	if (service->socket_count == 0)
		return;

	service->listeners =
		i_new(struct master_service_listener, service->socket_count);

	for (i = 0; i < service->socket_count; i++) {
		struct master_service_listener *l = &service->listeners[i];

		l->service = service;
		l->fd = MASTER_LISTEN_FD_FIRST + i;

		if (i >= service->socket_count - service->ssl_socket_count)
			l->ssl = TRUE;
	}
}

void master_service_io_listeners_add(struct master_service *service)
{
	unsigned int i;

	if (service->stopping)
		return;

	if (service->listeners == NULL)
		io_listeners_init(service);

	for (i = 0; i < service->socket_count; i++) {
		struct master_service_listener *l = &service->listeners[i];

		if (l->io == NULL && l->fd != -1) {
			l->io = io_add(MASTER_LISTEN_FD_FIRST + i, IO_READ,
				       master_service_listen, l);
		}
	}
}

void master_service_io_listeners_remove(struct master_service *service)
{
	unsigned int i;

	if (service->listeners != NULL) {
		for (i = 0; i < service->socket_count; i++) {
			if (service->listeners[i].io != NULL)
				io_remove(&service->listeners[i].io);
		}
	}
}

static void master_service_io_listeners_close(struct master_service *service)
{
	unsigned int i;

	if (service->listeners != NULL) {
		/* close via listeners. some fds might be pipes that are
		   currently handled as clients. we don't want to close them. */
		for (i = 0; i < service->socket_count; i++) {
			if (service->listeners[i].fd != -1) {
				if (close(service->listeners[i].fd) < 0) {
					i_error("close(listener %d) failed: %m",
						service->listeners[i].fd);
				}
			}
		}
	} else {
		for (i = 0; i < service->socket_count; i++) {
			int fd = MASTER_LISTEN_FD_FIRST + i;

			if (close(fd) < 0)
				i_error("close(listener %d) failed: %m", fd);
		}
	}
}

static bool master_status_update_is_important(struct master_service *service)
{
	if (service->master_status.available_count == 0)
		return TRUE;
	if (!service->initial_status_sent)
		return TRUE;
	return FALSE;
}

void master_status_update(struct master_service *service)
{
	ssize_t ret;
	bool important_update;

	if ((service->flags & MASTER_SERVICE_FLAG_UPDATE_PROCTITLE) != 0 &&
	    service->set != NULL && service->set->verbose_proctitle) T_BEGIN {
		unsigned int used_count = service->total_available_count -
			service->master_status.available_count;

		process_title_set(t_strdup_printf("[%u connections]",
						  used_count));
	} T_END;

	important_update = master_status_update_is_important(service);
	if (service->master_status.pid == 0 ||
	    service->master_status.available_count ==
	    service->last_sent_status_avail_count) {
		/* a) closed, b) updating to same state */
		if (service->to_status != NULL)
			timeout_remove(&service->to_status);
		if (service->io_status_write != NULL)
			io_remove(&service->io_status_write);
		return;
	}
	if (ioloop_time == service->last_sent_status_time &&
	    !important_update) {
		/* don't spam master */
		if (service->to_status != NULL)
			timeout_reset(service->to_status);
		else {
			service->to_status =
				timeout_add(1000, master_status_update,
					    service);
		}
		if (service->io_status_write != NULL)
			io_remove(&service->io_status_write);
		return;
	}

	if (service->to_status != NULL)
		timeout_remove(&service->to_status);

	ret = write(MASTER_STATUS_FD, &service->master_status,
		    sizeof(service->master_status));
	if (ret == sizeof(service->master_status)) {
		/* success */
		if (service->io_status_write != NULL) {
			/* delayed important update sent successfully */
			io_remove(&service->io_status_write);
		}
		service->last_sent_status_time = ioloop_time;
		service->last_sent_status_avail_count =
			service->master_status.available_count;
		service->initial_status_sent = TRUE;
	} else if (ret >= 0) {
		/* shouldn't happen? */
		i_error("write(master_status_fd) returned %d", (int)ret);
		service->master_status.pid = 0;
	} else if (errno != EAGAIN) {
		/* failure */
		if (errno != EPIPE)
			i_error("write(master_status_fd) failed: %m");
		service->master_status.pid = 0;
	} else if (important_update) {
		/* reader is busy, but it's important to get this notification
		   through. send it when possible. */
		if (service->io_status_write == NULL) {
			service->io_status_write =
				io_add(MASTER_STATUS_FD, IO_WRITE,
				       master_status_update, service);
		}
	}
}

bool version_string_verify(const char *line, const char *service_name,
			   unsigned major_version)
{
	unsigned int service_name_len = strlen(service_name);
	bool ret;

	if (strncmp(line, "VERSION\t", 8) != 0)
		return FALSE;
	line += 8;

	if (strncmp(line, service_name, service_name_len) != 0 ||
	    line[service_name_len] != '\t')
		return FALSE;
	line += service_name_len + 1;

	T_BEGIN {
		ret = str_uint_equals(t_strcut(line, '\t'), major_version);
	} T_END;
	return ret;
}