NetworkManager/src/nm-logging.c

// SPDX-License-Identifier: GPL-2.0+
/* NetworkManager -- Network link manager
 *
 * Copyright (C) 2006 - 2012 Red Hat, Inc.
 * Copyright (C) 2006 - 2008 Novell, Inc.
 */

#include "nm-default.h"

#include "nm-logging.h"

#include <dlfcn.h>
#include <syslog.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <strings.h>

#if SYSTEMD_JOURNAL
#define SD_JOURNAL_SUPPRESS_LOCATION
#include <systemd/sd-journal.h>
#endif

#include "nm-glib-aux/nm-time-utils.h"
#include "nm-errors.h"

/*****************************************************************************/

/* Notes about thread-safety:
 *
 * NetworkManager generally is single-threaded and uses a (GLib) mainloop.
 * However, nm-logging is in parts thread-safe. That means:
 *
 * - functions that configure logging (nm_logging_init(), nm_logging_setup()) and
 *   most other functions MUST be called only from the main-thread. These functions
 *   are expected to be called infrequently, so they may or may not use a mutex
 *   (but the overhead is negligible here).
 *
 * - functions that do the actual logging logging (nm_log(), nm_logging_enabled()) are
 *   thread-safe and may be used from multiple threads.
 *    - When called from the not-main-thread, @mt_require_locking must be set to %TRUE.
 *      In this case, a Mutex will be used for accessing the global state.
 *    - When called from the main-thread, they may optionally pass @mt_require_locking %FALSE.
 *      This avoids extra locking and is in particular interesting for nm_logging_enabled(),
 *      which is expected to be called frequently and from the main-thread.
 *
 * Note that the logging macros honor %NM_THREAD_SAFE_ON_MAIN_THREAD define, to automatically
 * set @mt_require_locking. That means, by default %NM_THREAD_SAFE_ON_MAIN_THREAD is "1",
 * and code that only runs on the main-thread (which is the majority), can get away
 * without locking.
 */

/*****************************************************************************/

G_STATIC_ASSERT (LOG_EMERG   == 0);
G_STATIC_ASSERT (LOG_ALERT   == 1);
G_STATIC_ASSERT (LOG_CRIT    == 2);
G_STATIC_ASSERT (LOG_ERR     == 3);
G_STATIC_ASSERT (LOG_WARNING == 4);
G_STATIC_ASSERT (LOG_NOTICE  == 5);
G_STATIC_ASSERT (LOG_INFO    == 6);
G_STATIC_ASSERT (LOG_DEBUG   == 7);

/* We have more then 32 logging domains. Assert that it compiles to a 64 bit sized enum */
G_STATIC_ASSERT (sizeof (NMLogDomain) >= sizeof (guint64));

/* Combined domains */
#define LOGD_ALL_STRING     "ALL"
#define LOGD_DEFAULT_STRING "DEFAULT"
#define LOGD_DHCP_STRING    "DHCP"
#define LOGD_IP_STRING      "IP"

/*****************************************************************************/

typedef enum {
	LOG_BACKEND_GLIB,
	LOG_BACKEND_SYSLOG,
	LOG_BACKEND_JOURNAL,
} LogBackend;

typedef struct {
	NMLogDomain num;
	const char *name;
} LogDesc;

typedef struct {
	const char *name;
	const char *level_str;

	/* nm-logging uses syslog internally. Note that the three most-verbose syslog levels
	 * are LOG_DEBUG, LOG_INFO and LOG_NOTICE. Journal already highlights LOG_NOTICE
	 * as special.
	 *
	 * On the other hand, we have three levels LOGL_TRACE, LOGL_DEBUG and LOGL_INFO,
	 * which are regular messages not to be highlighted. For that reason, we must map
	 * LOGL_TRACE and LOGL_DEBUG both to syslog level LOG_DEBUG. */
	int syslog_level;

	GLogLevelFlags g_log_level;
} LogLevelDesc;

typedef struct {
	char *logging_domains_to_string;
} GlobalMain;

typedef struct {
	NMLogLevel log_level;
	bool uses_syslog:1;
	bool init_pre_done:1;
	bool init_done:1;
	bool debug_stderr:1;
	const char *prefix;
	const char *syslog_identifier;

	/* before we setup syslog (during start), the backend defaults to GLIB, meaning:
	 * we use g_log() for all logging. At that point, the application is not yet supposed
	 * to do any logging and doing so indicates a bug.
	 *
	 * Afterwards, the backend is either SYSLOG or JOURNAL. From that point, also
	 * g_log() is redirected to this backend via a logging handler. */
	LogBackend log_backend;
} Global;

/*****************************************************************************/

G_LOCK_DEFINE_STATIC (log);

/* This data must only be accessed from the main-thread (and as
 * such does not need any lock). */
static GlobalMain gl_main = { };

static union {
	/* a union with an immutable and a mutable alias for the Global.
	 * Since nm-logging must be thread-safe, we must take care at which
	 * places we only read value ("imm") and where we modify them ("mut"). */
	Global       mut;
	const Global imm;
} gl = {
	.imm = {
		/* nm_logging_setup ("INFO", LOGD_DEFAULT_STRING, NULL, NULL); */
		.log_level = LOGL_INFO,
		.log_backend = LOG_BACKEND_GLIB,
		.syslog_identifier = "SYSLOG_IDENTIFIER="G_LOG_DOMAIN,
		.prefix = "",
	},
};

NMLogDomain _nm_logging_enabled_state[_LOGL_N_REAL] = {
	/* nm_logging_setup ("INFO", LOGD_DEFAULT_STRING, NULL, NULL);
	 *
	 * Note: LOGD_VPN_PLUGIN is special and must be disabled for
	 * DEBUG and TRACE levels. */
	[LOGL_INFO] = LOGD_DEFAULT,
	[LOGL_WARN] = LOGD_DEFAULT,
	[LOGL_ERR]  = LOGD_DEFAULT,
};

/*****************************************************************************/

static const LogLevelDesc level_desc[_LOGL_N] = {
	[LOGL_TRACE] = { "TRACE", "<trace>", LOG_DEBUG,   G_LOG_LEVEL_DEBUG,   },
	[LOGL_DEBUG] = { "DEBUG", "<debug>", LOG_DEBUG,   G_LOG_LEVEL_DEBUG,   },
	[LOGL_INFO]  = { "INFO",  "<info>",  LOG_INFO,    G_LOG_LEVEL_INFO,    },
	[LOGL_WARN]  = { "WARN",  "<warn>",  LOG_WARNING, G_LOG_LEVEL_MESSAGE, },
	[LOGL_ERR]   = { "ERR",   "<error>", LOG_ERR,     G_LOG_LEVEL_MESSAGE, },
	[_LOGL_OFF]  = { "OFF",   NULL,      0,           0,                   },
	[_LOGL_KEEP] = { "KEEP",  NULL,      0,           0,                   },
};

static const LogDesc domain_desc[] = {
	{ LOGD_PLATFORM,  "PLATFORM" },
	{ LOGD_RFKILL,    "RFKILL" },
	{ LOGD_ETHER,     "ETHER" },
	{ LOGD_WIFI,      "WIFI" },
	{ LOGD_BT,        "BT" },
	{ LOGD_MB,        "MB" },
	{ LOGD_DHCP4,     "DHCP4" },
	{ LOGD_DHCP6,     "DHCP6" },
	{ LOGD_PPP,       "PPP" },
	{ LOGD_WIFI_SCAN, "WIFI_SCAN" },
	{ LOGD_IP4,       "IP4" },
	{ LOGD_IP6,       "IP6" },
	{ LOGD_AUTOIP4,   "AUTOIP4" },
	{ LOGD_DNS,       "DNS" },
	{ LOGD_VPN,       "VPN" },
	{ LOGD_SHARING,   "SHARING" },
	{ LOGD_SUPPLICANT,"SUPPLICANT" },
	{ LOGD_AGENTS,    "AGENTS" },
	{ LOGD_SETTINGS,  "SETTINGS" },
	{ LOGD_SUSPEND,   "SUSPEND" },
	{ LOGD_CORE,      "CORE" },
	{ LOGD_DEVICE,    "DEVICE" },
	{ LOGD_OLPC,      "OLPC" },
	{ LOGD_INFINIBAND,"INFINIBAND" },
	{ LOGD_FIREWALL,  "FIREWALL" },
	{ LOGD_ADSL,      "ADSL" },
	{ LOGD_BOND,      "BOND" },
	{ LOGD_VLAN,      "VLAN" },
	{ LOGD_BRIDGE,    "BRIDGE" },
	{ LOGD_DBUS_PROPS,"DBUS_PROPS" },
	{ LOGD_TEAM,      "TEAM" },
	{ LOGD_CONCHECK,  "CONCHECK" },
	{ LOGD_DCB,       "DCB" },
	{ LOGD_DISPATCH,  "DISPATCH" },
	{ LOGD_AUDIT,     "AUDIT" },
	{ LOGD_SYSTEMD,   "SYSTEMD" },
	{ LOGD_VPN_PLUGIN,"VPN_PLUGIN" },
	{ LOGD_PROXY,     "PROXY" },
	{ 0 },
};

/*****************************************************************************/

static char *_domains_to_string (gboolean include_level_override,
                                 NMLogLevel log_level,
                                 const NMLogDomain log_state[static _LOGL_N_REAL]);

/*****************************************************************************/

static gboolean
_syslog_identifier_valid_domain (const char *domain)
{
	char c;

	if (!domain || !domain[0])
		return FALSE;

	/* we pass the syslog identifier as format string. No funny stuff. */

	for (; (c = domain[0]); domain++) {
		if (   (c >= 'a' && c <= 'z')
		    || (c >= 'A' && c <= 'Z')
		    || (c >= '0' && c <= '9')
		    || NM_IN_SET (c, '-', '_'))
			continue;
		return FALSE;
	}
	return TRUE;
}

static gboolean
_syslog_identifier_assert (const char *syslog_identifier)
{
	g_assert (syslog_identifier);
	g_assert (g_str_has_prefix (syslog_identifier, "SYSLOG_IDENTIFIER="));
	g_assert (_syslog_identifier_valid_domain (&syslog_identifier[NM_STRLEN ("SYSLOG_IDENTIFIER=")]));
	return TRUE;
}

static const char *
syslog_identifier_domain (const char *syslog_identifier)
{
	nm_assert (_syslog_identifier_assert (syslog_identifier));
	return &syslog_identifier[NM_STRLEN ("SYSLOG_IDENTIFIER=")];
}

#if SYSTEMD_JOURNAL
static const char *
syslog_identifier_full (const char *syslog_identifier)
{
	nm_assert (_syslog_identifier_assert (syslog_identifier));
	return &syslog_identifier[0];
}
#endif

/*****************************************************************************/

static gboolean
match_log_level (const char  *level,
                 NMLogLevel  *out_level,
                 GError     **error)
{
	int i;

	for (i = 0; i < G_N_ELEMENTS (level_desc); i++) {
		if (!g_ascii_strcasecmp (level_desc[i].name, level)) {
			*out_level = i;
			return TRUE;
		}
	}

	g_set_error (error, NM_MANAGER_ERROR, NM_MANAGER_ERROR_UNKNOWN_LOG_LEVEL,
	             _("Unknown log level '%s'"), level);
	return FALSE;
}

gboolean
nm_logging_setup (const char  *level,
                  const char  *domains,
                  char       **bad_domains,
                  GError     **error)
{
	GString *unrecognized = NULL;
	NMLogDomain cur_log_state[_LOGL_N_REAL];
	NMLogDomain new_log_state[_LOGL_N_REAL];
	NMLogLevel cur_log_level;
	NMLogLevel new_log_level;
	gs_free const char **domains_v = NULL;
	gsize i_d;
	int i;
	gboolean had_platform_debug;
	gs_free char *domains_free = NULL;

	NM_ASSERT_ON_MAIN_THREAD ();

	g_return_val_if_fail (!bad_domains || !*bad_domains, FALSE);
	g_return_val_if_fail (!error || !*error, FALSE);

	cur_log_level = gl.imm.log_level;
	memcpy (cur_log_state, _nm_logging_enabled_state, sizeof (cur_log_state));

	new_log_level = cur_log_level;

	if (!domains || !*domains) {
		domains_free = _domains_to_string (FALSE,
		                                   cur_log_level,
		                                   cur_log_state);
		domains = domains_free;
	}

	for (i = 0; i < G_N_ELEMENTS (new_log_state); i++)
		new_log_state[i] = 0;

	if (level && *level) {
		if (!match_log_level (level, &new_log_level, error))
			return FALSE;
		if (new_log_level == _LOGL_KEEP) {
			new_log_level = cur_log_level;
			for (i = 0; i < G_N_ELEMENTS (new_log_state); i++)
				new_log_state[i] = cur_log_state[i];
		}
	}

	domains_v = nm_utils_strsplit_set (domains, ", ");
	for (i_d = 0; domains_v && domains_v[i_d]; i_d++) {
		const char *s = domains_v[i_d];
		const char *p;
		const LogDesc *diter;
		NMLogLevel domain_log_level;
		NMLogDomain bits;

		/* LOGD_VPN_PLUGIN is protected, that is, when setting ALL or DEFAULT,
		 * it does not enable the verbose levels DEBUG and TRACE, because that
		 * may expose sensitive data. */
		NMLogDomain protect = LOGD_NONE;

		p = strchr (s, ':');
		if (p) {
			*((char *) p) = '\0';
			if (!match_log_level (p + 1, &domain_log_level, error))
				return FALSE;
		} else
			domain_log_level = new_log_level;

		bits = 0;

		if (domains_free) {
			/* The caller didn't provide any domains to set (`nmcli general logging level DEBUG`).
			 * We reset all domains that were previously set, but we still want to protect
			 * VPN_PLUGIN domain. */
			protect = LOGD_VPN_PLUGIN;
		}

		/* Check for combined domains */
		if (!g_ascii_strcasecmp (s, LOGD_ALL_STRING)) {
			bits = LOGD_ALL;
			protect = LOGD_VPN_PLUGIN;
		} else if (!g_ascii_strcasecmp (s, LOGD_DEFAULT_STRING)) {
			bits = LOGD_DEFAULT;
			protect = LOGD_VPN_PLUGIN;
		} else if (!g_ascii_strcasecmp (s, LOGD_DHCP_STRING))
			bits = LOGD_DHCP;
		else if (!g_ascii_strcasecmp (s, LOGD_IP_STRING))
			bits = LOGD_IP;

		/* Check for compatibility domains */
		else if (!g_ascii_strcasecmp (s, "HW"))
			bits = LOGD_PLATFORM;
		else if (!g_ascii_strcasecmp (s, "WIMAX"))
			continue;

		else {
			for (diter = &domain_desc[0]; diter->name; diter++) {
				if (!g_ascii_strcasecmp (diter->name, s)) {
					bits = diter->num;
					break;
				}
			}

			if (!bits) {
				if (!bad_domains) {
					g_set_error (error, NM_MANAGER_ERROR, NM_MANAGER_ERROR_UNKNOWN_LOG_DOMAIN,
					             _("Unknown log domain '%s'"), s);
					return FALSE;
				}

				if (unrecognized)
					g_string_append (unrecognized, ", ");
				else
					unrecognized = g_string_new (NULL);
				g_string_append (unrecognized, s);
				continue;
			}
		}

		if (domain_log_level == _LOGL_KEEP) {
			for (i = 0; i < G_N_ELEMENTS (new_log_state); i++)
				new_log_state[i] = (new_log_state[i] & ~bits) | (cur_log_state[i] & bits);
		} else {
			for (i = 0; i < G_N_ELEMENTS (new_log_state); i++) {
				if (i < domain_log_level)
					new_log_state[i] &= ~bits;
				else {
					new_log_state[i] |= bits;
					if (   (protect & bits)
					    && i < LOGL_INFO)
						new_log_state[i] &= ~protect;
				}
			}
		}
	}

	g_clear_pointer (&gl_main.logging_domains_to_string, g_free);

	had_platform_debug = _nm_logging_enabled_lockfree (LOGL_DEBUG, LOGD_PLATFORM);

	G_LOCK (log);

	gl.mut.log_level = new_log_level;
	for (i = 0; i < G_N_ELEMENTS (new_log_state); i++)
		_nm_logging_enabled_state[i] = new_log_state[i];

	G_UNLOCK (log);

	if (   had_platform_debug
	    && !_nm_logging_enabled_lockfree (LOGL_DEBUG, LOGD_PLATFORM)) {
		/* when debug logging is enabled, platform will cache all access to
		 * sysctl. When the user disables debug-logging, we want to clear that
		 * cache right away. */
		_nm_logging_clear_platform_logging_cache ();
	}

	if (unrecognized)
		*bad_domains = g_string_free (unrecognized, FALSE);

	return TRUE;
}

const char *
nm_logging_level_to_string (void)
{
	NM_ASSERT_ON_MAIN_THREAD ();

	return level_desc[gl.imm.log_level].name;
}

const char *
nm_logging_all_levels_to_string (void)
{
	static GString *str;

	if (G_UNLIKELY (!str)) {
		int i;

		str = g_string_new (NULL);
		for (i = 0; i < G_N_ELEMENTS (level_desc); i++) {
			if (str->len)
				g_string_append_c (str, ',');
			g_string_append (str, level_desc[i].name);
		}
	}

	return str->str;
}

const char *
nm_logging_domains_to_string (void)
{
	NM_ASSERT_ON_MAIN_THREAD ();

	if (G_UNLIKELY (!gl_main.logging_domains_to_string)) {
		gl_main.logging_domains_to_string = _domains_to_string (TRUE,
		                                                        gl.imm.log_level,
		                                                        _nm_logging_enabled_state);
	}

	return gl_main.logging_domains_to_string;
}

static char *
_domains_to_string (gboolean include_level_override,
                    NMLogLevel log_level,
                    const NMLogDomain log_state[static _LOGL_N_REAL])
{
	const LogDesc *diter;
	GString *str;
	int i;

	/* We don't just return g_strdup() the logging domains that were set during
	 * nm_logging_setup(), because we want to expand "DEFAULT" and "ALL".
	 */

	str = g_string_sized_new (75);
	for (diter = &domain_desc[0]; diter->name; diter++) {
		/* If it's set for any lower level, it will also be set for LOGL_ERR */
		if (!(diter->num & log_state[LOGL_ERR]))
			continue;

		if (str->len)
			g_string_append_c (str, ',');
		g_string_append (str, diter->name);

		if (!include_level_override)
			continue;

		/* Check if it's logging at a lower level than the default. */
		for (i = 0; i < log_level; i++) {
			if (diter->num & log_state[i]) {
				g_string_append_printf (str, ":%s", level_desc[i].name);
				break;
			}
		}
		/* Check if it's logging at a higher level than the default. */
		if (!(diter->num & log_state[log_level])) {
			for (i = log_level + 1; i < _LOGL_N_REAL; i++) {
				if (diter->num & log_state[i]) {
					g_string_append_printf (str, ":%s", level_desc[i].name);
					break;
				}
			}
		}
	}
	return g_string_free (str, FALSE);
}

static char _all_logging_domains_to_str[273];

const char *
nm_logging_all_domains_to_string (void)
{
	static const char *volatile str = NULL;
	const char *s;

again:
	s = g_atomic_pointer_get (&str);
	if (G_UNLIKELY (!s)) {
		static gsize once = 0;
		const LogDesc *diter;
		gsize buf_l;
		char *buf_p;

		if (!g_once_init_enter (&once))
			goto again;

		buf_p = _all_logging_domains_to_str;
		buf_l = sizeof (_all_logging_domains_to_str);

		nm_utils_strbuf_append_str (&buf_p, &buf_l, LOGD_DEFAULT_STRING);
		for (diter = &domain_desc[0]; diter->name; diter++) {
			nm_utils_strbuf_append_c (&buf_p, &buf_l, ',');
			nm_utils_strbuf_append_str (&buf_p, &buf_l, diter->name);
			if (diter->num == LOGD_DHCP6)
				nm_utils_strbuf_append_str (&buf_p, &buf_l, ","LOGD_DHCP_STRING);
			else if (diter->num == LOGD_IP6)
				nm_utils_strbuf_append_str (&buf_p, &buf_l, ","LOGD_IP_STRING);
		}
		nm_utils_strbuf_append_str (&buf_p, &buf_l, LOGD_ALL_STRING);

		/* Did you modify the logging domains (or their names)? Adjust the size of
		 * _all_logging_domains_to_str buffer above to have the exact size. */
		nm_assert (strlen (_all_logging_domains_to_str) == sizeof (_all_logging_domains_to_str) - 1);
		nm_assert (buf_l == 1);

		s = _all_logging_domains_to_str;
		g_atomic_pointer_set (&str, s);
		g_once_init_leave (&once, 1);
	}

	return s;
}

/**
 * nm_logging_get_level:
 * @domain: find the lowest enabled logging level for the
 *   given domain. If this is a set of multiple
 *   domains, the most verbose level will be returned.
 *
 * Returns: the lowest (most verbose) logging level for the
 *   give @domain, or %_LOGL_OFF if it is disabled.
 **/
NMLogLevel
nm_logging_get_level (NMLogDomain domain)
{
	NMLogLevel sl = _LOGL_OFF;

	G_STATIC_ASSERT (LOGL_TRACE == 0);
	while (   sl > LOGL_TRACE
	       && _nm_logging_enabled_lockfree (sl - 1, domain))
		sl--;
	return sl;
}

gboolean
_nm_logging_enabled_locking (NMLogLevel level,
                             NMLogDomain domain)
{
	gboolean v;

	G_LOCK (log);
	v = _nm_logging_enabled_lockfree (level, domain);
	G_UNLOCK (log);
	return v;
}

gboolean
_nm_log_enabled_impl (gboolean mt_require_locking,
                      NMLogLevel level,
                      NMLogDomain domain)
{
	return nm_logging_enabled_mt (mt_require_locking, level, domain);
}

#if SYSTEMD_JOURNAL
static void
_iovec_set (struct iovec *iov, const void *str, gsize len)
{
	iov->iov_base = (void *) str;
	iov->iov_len = len;
}

static void
_iovec_set_string (struct iovec *iov, const char *str)
{
	_iovec_set (iov, str, strlen (str));
}

#define _iovec_set_string_literal(iov, str) _iovec_set ((iov), ""str"", NM_STRLEN (str))

_nm_printf (3, 4)
static void
_iovec_set_format (struct iovec *iov, char **iov_free, const char *format, ...)
{
	va_list ap;
	char *str;

	va_start (ap, format);
	str = g_strdup_vprintf (format, ap);
	va_end (ap);

	_iovec_set_string (iov, str);
	*iov_free = str;
}

#define _iovec_set_format_a(iov, reserve_extra, format, ...) \
	G_STMT_START { \
		const gsize _size = (reserve_extra) + (NM_STRLEN (format) + 3); \
		char *const _buf = g_alloca (_size); \
		int _len; \
		\
		G_STATIC_ASSERT_EXPR ((reserve_extra) + (NM_STRLEN (format) + 3) <= 96); \
		\
		_len = g_snprintf (_buf, _size, ""format"", ##__VA_ARGS__);\
		\
		nm_assert (_len >= 0); \
		nm_assert (_len < _size); \
		nm_assert (_len == strlen (_buf)); \
		\
		_iovec_set ((iov), _buf, _len); \
	} G_STMT_END

#define _iovec_set_format_str_a(iov, max_str_len, format, str_arg) \
	G_STMT_START { \
		const char *_str_arg = (str_arg); \
		\
		nm_assert (_str_arg && strlen (_str_arg) < (max_str_len)); \
		_iovec_set_format_a ((iov), (max_str_len), format, str_arg); \
	} G_STMT_END

#endif

void
_nm_log_impl (const char *file,
              guint line,
              const char *func,
              gboolean mt_require_locking,
              NMLogLevel level,
              NMLogDomain domain,
              int error,
              const char *ifname,
              const char *conn_uuid,
              const char *fmt,
              ...)
{
	va_list args;
	char *msg;
	GTimeVal tv;
	int errsv;
	const NMLogDomain *cur_log_state;
	NMLogDomain cur_log_state_copy[_LOGL_N_REAL];
	Global g_copy;
	const Global *g;

	if (G_UNLIKELY (mt_require_locking)) {
		G_LOCK (log);
		/* we evaluate logging-enabled under lock. There is still a race that
		 * we might log the message below *after* logging was disabled. That means,
		 * when disabling logging, we might still log messages. */
		if (!_nm_logging_enabled_lockfree (level, domain)) {
			G_UNLOCK (log);
			return;
		}
		g_copy = gl.imm;
		memcpy (cur_log_state_copy, _nm_logging_enabled_state, sizeof (cur_log_state_copy));
		G_UNLOCK (log);
		g = &g_copy;
		cur_log_state = cur_log_state_copy;
	} else {
		NM_ASSERT_ON_MAIN_THREAD ();
		if (!_nm_logging_enabled_lockfree (level, domain))
			return;
		g = &gl.imm;
		cur_log_state = _nm_logging_enabled_state;
	}

	(void) cur_log_state;

	errsv = errno;

	/* Make sure that %m maps to the specified error */
	if (error != 0) {
		if (error < 0)
			error = -error;
		errno = error;
	}

	va_start (args, fmt);
	msg = g_strdup_vprintf (fmt, args);
	va_end (args);

#define MESSAGE_FMT "%s%-7s [%ld.%04ld] %s"
#define MESSAGE_ARG(prefix, tv, msg) \
    prefix, \
    level_desc[level].level_str, \
    (tv).tv_sec, \
    ((tv).tv_usec / 100), \
    (msg)

	g_get_current_time (&tv);

	if (g->debug_stderr)
		g_printerr (MESSAGE_FMT"\n", MESSAGE_ARG (g->prefix, tv, msg));

	switch (g->log_backend) {
#if SYSTEMD_JOURNAL
	case LOG_BACKEND_JOURNAL:
		{
			gint64 now, boottime;
			struct iovec iov_data[15];
			struct iovec *iov = iov_data;
			char *iov_free_data[5];
			char **iov_free = iov_free_data;

			now = nm_utils_get_monotonic_timestamp_ns ();
			boottime = nm_utils_monotonic_timestamp_as_boottime (now, 1);

			_iovec_set_format_a (iov++, 30, "PRIORITY=%d", level_desc[level].syslog_level);
			_iovec_set_format (iov++, iov_free++, "MESSAGE="MESSAGE_FMT, MESSAGE_ARG (g->prefix, tv, msg));
			_iovec_set_string (iov++, syslog_identifier_full (g->syslog_identifier));
			_iovec_set_format_a (iov++, 30, "SYSLOG_PID=%ld", (long) getpid ());
			{
				const LogDesc *diter;
				NMLogDomain dom_all = domain;
				char s_log_domains_buf[NM_STRLEN ("NM_LOG_DOMAINS=") + sizeof (_all_logging_domains_to_str)];
				char *s_log_domains = s_log_domains_buf;
				gsize l_log_domains = sizeof (s_log_domains_buf);

				nm_utils_strbuf_append_str (&s_log_domains, &l_log_domains, "NM_LOG_DOMAINS=");
				for (diter = &domain_desc[0]; dom_all != 0 && diter->name; diter++) {
					if (!NM_FLAGS_ANY (dom_all, diter->num))
						continue;
					if (dom_all != domain)
						nm_utils_strbuf_append_c (&s_log_domains, &l_log_domains, ',');
					nm_utils_strbuf_append_str (&s_log_domains, &l_log_domains, diter->name);
					dom_all &= ~diter->num;
				}
				nm_assert (l_log_domains > 0);
				_iovec_set (iov++, s_log_domains_buf, s_log_domains - s_log_domains_buf);
			}
			G_STATIC_ASSERT_EXPR (LOG_FAC (LOG_DAEMON) == 3);
			_iovec_set_string_literal (iov++, "SYSLOG_FACILITY=3");
			_iovec_set_format_str_a (iov++, 15, "NM_LOG_LEVEL=%s", level_desc[level].name);
			if (func)
				_iovec_set_format (iov++, iov_free++, "CODE_FUNC=%s", func);
			_iovec_set_format (iov++, iov_free++, "CODE_FILE=%s", file ?: "");
			_iovec_set_format_a (iov++, 20, "CODE_LINE=%u", line);
			_iovec_set_format_a (iov++, 60, "TIMESTAMP_MONOTONIC=%lld.%06lld", (long long) (now / NM_UTILS_NS_PER_SECOND), (long long) ((now % NM_UTILS_NS_PER_SECOND) / 1000));
			_iovec_set_format_a (iov++, 60, "TIMESTAMP_BOOTTIME=%lld.%06lld", (long long) (boottime / NM_UTILS_NS_PER_SECOND), (long long) ((boottime % NM_UTILS_NS_PER_SECOND) / 1000));
			if (error != 0)
				_iovec_set_format_a (iov++, 30, "ERRNO=%d", error);
			if (ifname)
				_iovec_set_format (iov++, iov_free++, "NM_DEVICE=%s", ifname);
			if (conn_uuid)
				_iovec_set_format (iov++, iov_free++, "NM_CONNECTION=%s", conn_uuid);

			nm_assert (iov <= &iov_data[G_N_ELEMENTS (iov_data)]);
			nm_assert (iov_free <= &iov_free_data[G_N_ELEMENTS (iov_free_data)]);

			sd_journal_sendv (iov_data, iov - iov_data);

			for (; --iov_free >= iov_free_data; )
				g_free (*iov_free);
		}
		break;
#endif
	case LOG_BACKEND_SYSLOG:
		syslog (level_desc[level].syslog_level,
		        MESSAGE_FMT, MESSAGE_ARG (g->prefix, tv, msg));
		break;
	default:
		g_log (syslog_identifier_domain (g->syslog_identifier), level_desc[level].g_log_level,
		       MESSAGE_FMT, MESSAGE_ARG (g->prefix, tv, msg));
		break;
	}

	g_free (msg);

	errno = errsv;
}

/*****************************************************************************/

void
_nm_utils_monotonic_timestamp_initialized (const struct timespec *tp,
                                           gint64 offset_sec,
                                           gboolean is_boottime)
{
	NM_ASSERT_ON_MAIN_THREAD ();

	if (_nm_logging_enabled_lockfree (LOGL_DEBUG, LOGD_CORE)) {
		time_t now = time (NULL);
		struct tm tm;
		char s[255];

		strftime (s, sizeof (s), "%Y-%m-%d %H:%M:%S", localtime_r (&now, &tm));
		nm_log_dbg (LOGD_CORE, "monotonic timestamp started counting 1.%09ld seconds ago with "
		                       "an offset of %lld.0 seconds to %s (local time is %s)",
		                       tp->tv_nsec,
		                       (long long) -offset_sec,
		                       is_boottime ? "CLOCK_BOOTTIME" : "CLOCK_MONOTONIC", s);
	}
}

/*****************************************************************************/

static void
nm_log_handler (const char *log_domain,
                GLogLevelFlags level,
                const char *message,
                gpointer ignored)
{
	int syslog_priority;

	switch (level & G_LOG_LEVEL_MASK) {
	case G_LOG_LEVEL_ERROR:
		syslog_priority = LOG_CRIT;
		break;
	case G_LOG_LEVEL_CRITICAL:
		syslog_priority = LOG_ERR;
		break;
	case G_LOG_LEVEL_WARNING:
		syslog_priority = LOG_WARNING;
		break;
	case G_LOG_LEVEL_MESSAGE:
		syslog_priority = LOG_NOTICE;
		break;
	case G_LOG_LEVEL_DEBUG:
		syslog_priority = LOG_DEBUG;
		break;
	case G_LOG_LEVEL_INFO:
	default:
		syslog_priority = LOG_INFO;
		break;
	}

	/* we don't need any locking here. The glib log handler gets only registered
	 * once during nm_logging_init() and the global data is not modified afterwards. */
	nm_assert (gl.imm.init_done);

	if (gl.imm.debug_stderr)
		g_printerr ("%s%s\n", gl.imm.prefix, message ?: "");

	switch (gl.imm.log_backend) {
#if SYSTEMD_JOURNAL
	case LOG_BACKEND_JOURNAL:
		{
			gint64 now, boottime;

			now = nm_utils_get_monotonic_timestamp_ns ();
			boottime = nm_utils_monotonic_timestamp_as_boottime (now, 1);

			sd_journal_send ("PRIORITY=%d", syslog_priority,
			                 "MESSAGE=%s%s", gl.imm.prefix, message ?: "",
			                 syslog_identifier_full (gl.imm.syslog_identifier),
			                 "SYSLOG_PID=%ld", (long) getpid (),
			                 "SYSLOG_FACILITY=3",
			                 "GLIB_DOMAIN=%s", log_domain ?: "",
			                 "GLIB_LEVEL=%d", (int) (level & G_LOG_LEVEL_MASK),
			                 "TIMESTAMP_MONOTONIC=%lld.%06lld", (long long) (now / NM_UTILS_NS_PER_SECOND), (long long) ((now % NM_UTILS_NS_PER_SECOND) / 1000),
			                 "TIMESTAMP_BOOTTIME=%lld.%06lld", (long long) (boottime / NM_UTILS_NS_PER_SECOND), (long long) ((boottime % NM_UTILS_NS_PER_SECOND) / 1000),
			                 NULL);
		}
		break;
#endif
	default:
		syslog (syslog_priority, "%s%s", gl.imm.prefix, message ?: "");
		break;
	}
}

gboolean
nm_logging_syslog_enabled (void)
{
	NM_ASSERT_ON_MAIN_THREAD ();

	return gl.imm.uses_syslog;
}

void
nm_logging_init_pre (const char *syslog_identifier,
                     char *prefix_take)
{
	/* this function may be called zero or one times, and only
	 * - on the main thread
	 * - not after nm_logging_init(). */

	NM_ASSERT_ON_MAIN_THREAD ();

	if (gl.imm.init_pre_done)
		g_return_if_reached ();

	if (gl.imm.init_done)
		g_return_if_reached ();

	if (!_syslog_identifier_valid_domain (syslog_identifier))
		g_return_if_reached ();

	if (!prefix_take || !prefix_take[0])
		g_return_if_reached ();

	G_LOCK (log);

	gl.mut.init_pre_done = TRUE;

	gl.mut.syslog_identifier = g_strdup_printf ("SYSLOG_IDENTIFIER=%s", syslog_identifier);
	nm_assert (_syslog_identifier_assert (gl.imm.syslog_identifier));

	/* we pass the allocated string on and never free it. */
	gl.mut.prefix = prefix_take;

	G_UNLOCK (log);
}

void
nm_logging_init (const char *logging_backend, gboolean debug)
{
	gboolean fetch_monotonic_timestamp = FALSE;
	gboolean obsolete_debug_backend = FALSE;
	LogBackend x_log_backend;

	/* this function may be called zero or one times, and only on the
	 * main thread. */

	NM_ASSERT_ON_MAIN_THREAD ();

	nm_assert (NM_IN_STRSET (""NM_CONFIG_DEFAULT_LOGGING_BACKEND,
	                         NM_LOG_CONFIG_BACKEND_JOURNAL,
	                         NM_LOG_CONFIG_BACKEND_SYSLOG));

	if (gl.imm.init_done)
		g_return_if_reached ();

	if (!logging_backend)
		logging_backend = ""NM_CONFIG_DEFAULT_LOGGING_BACKEND;

	if (nm_streq (logging_backend, NM_LOG_CONFIG_BACKEND_DEBUG)) {
		/* "debug" was wrongly documented as a valid logging backend. It makes no sense however,
		 * because printing to stderr only makes sense when not demonizing. Whether to daemonize
		 * is only controlled via command line arguments (--no-daemon, --debug) and not via the
		 * logging backend from configuration.
		 *
		 * Fall back to the default. */
		logging_backend = ""NM_CONFIG_DEFAULT_LOGGING_BACKEND;
		obsolete_debug_backend = TRUE;
	}


	G_LOCK (log);

#if SYSTEMD_JOURNAL
	if (!nm_streq (logging_backend, NM_LOG_CONFIG_BACKEND_SYSLOG)) {
		x_log_backend = LOG_BACKEND_JOURNAL;

		/* We only log the monotonic-timestamp with structured logging (journal).
		 * Only in this case, fetch the timestamp. */
		fetch_monotonic_timestamp = TRUE;
	} else
#endif
	{
		x_log_backend = LOG_BACKEND_SYSLOG;
		openlog (syslog_identifier_domain (gl.imm.syslog_identifier), LOG_PID, LOG_DAEMON);
	}

	gl.mut.init_done = TRUE;
	gl.mut.log_backend = x_log_backend;
	gl.mut.uses_syslog = TRUE;
	gl.mut.debug_stderr = debug;

	g_log_set_handler (syslog_identifier_domain (gl.imm.syslog_identifier),
	                   G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL | G_LOG_FLAG_RECURSION,
	                   nm_log_handler,
	                   NULL);

	G_UNLOCK (log);


	if (fetch_monotonic_timestamp) {
		/* ensure we read a monotonic timestamp. Reading the timestamp the first
		 * time causes a logging message. We don't want to do that during _nm_log_impl. */
		nm_utils_get_monotonic_timestamp_ns ();
	}

	if (obsolete_debug_backend)
		nm_log_dbg (LOGD_CORE, "config: ignore deprecated logging backend 'debug', fallback to '%s'", logging_backend);

	if (nm_streq (logging_backend, NM_LOG_CONFIG_BACKEND_SYSLOG)) {
		/* good */
	} else if (nm_streq (logging_backend, NM_LOG_CONFIG_BACKEND_JOURNAL)) {
#if !SYSTEMD_JOURNAL
		nm_log_warn (LOGD_CORE, "config: logging backend 'journal' is not available, fallback to 'syslog'");
#endif
	} else {
		nm_log_warn (LOGD_CORE, "config: invalid logging backend '%s', fallback to '%s'",
		             logging_backend,
#if SYSTEMD_JOURNAL
		             NM_LOG_CONFIG_BACKEND_JOURNAL
#else
		             NM_LOG_CONFIG_BACKEND_SYSLOG
#endif
		             );
	}
}