6 #include <sys/syslog.h>
12 #include "dinit-log.h"
15 // Dinit logging subsystem.
17 // Note that most actual functions for logging messages are found in the header, dinit-log.h.
19 // We have two separate log "streams": one for the console/stdout, one for the syslog facility. Both have a
20 // circular buffer. Log messages are appended to the circular buffer (for the syslog stream, the messages
21 // are prepended with a syslog priority indicator). Both streams start out inactive (release = true in
22 // buffered_log_stream), which means they will buffer messages but not write them.
24 // The console log stream needs to be able to release the console, if a service is waiting to acquire it.
25 // This is accomplished by calling flush_for_release() which then completes the output of the current
26 // message (if any) and then assigns the console to a waiting service.
28 extern eventloop_t event_loop;
30 static bool log_current_line[2]; // Whether the current line is being logged (for console, main log)
31 loglevel_t log_level[2] = { loglevel_t::WARN, loglevel_t::WARN };
33 static service_set *services = nullptr; // Reference to service set
35 using rearm = dasynq::rearm;
38 class buffered_log_stream : public eventloop_t::fd_watcher_impl<buffered_log_stream>
43 bool partway = false; // if we are partway throught output of a log message
44 bool discarded = false; // if we have discarded a message
45 bool release = true; // if we should inhibit output and release console
47 // A "special message" is not stored in the circular buffer; instead
48 // it is delivered from an external buffer not managed by BufferedLogger.
49 bool special = false; // currently outputting special message?
50 const char *special_buf; // buffer containing special message
51 int msg_index; // index into special message
53 cpbuffer<4096> log_buffer;
58 int current_index = 0; // current/next incoming message index
68 rearm fd_event(eventloop_t &loop, int fd, int flags) noexcept;
70 // Check whether the console can be released.
71 void flush_for_release();
72 void release_console();
73 bool is_release_set() { return release; }
75 // Commit a log message
78 bool was_first = current_index == 0;
79 current_index = log_buffer.get_length();
80 if (was_first && ! release) {
81 set_enabled(event_loop, true);
87 log_buffer.trim_to(current_index);
92 return log_buffer.get_free();
95 void append(const char *s, size_t len)
97 log_buffer.append(s, len);
100 // Discard buffer; call only when the stream isn't active.
104 log_buffer.trim_to(0);
107 // Mark that a message was discarded due to full buffer
108 void mark_discarded()
116 // (One for main log, one for console)
117 static buffered_log_stream log_stream[2];
119 constexpr static int DLOG_MAIN = 0; // main log facility
120 constexpr static int DLOG_CONS = 1; // console
122 void buffered_log_stream::release_console()
125 int flags = fcntl(1, F_GETFL, 0);
126 fcntl(1, F_SETFL, flags & ~O_NONBLOCK);
127 services->pull_console_queue();
131 void buffered_log_stream::flush_for_release()
135 // Try to flush any messages that are currently buffered. (Console is non-blocking
136 // so it will fail gracefully).
137 if (fd_event(event_loop, fd, dasynq::OUT_EVENTS) == rearm::DISARM) {
138 // Console has already been released at this point.
139 set_enabled(event_loop, false);
141 // fd_event didn't want to disarm, so must be partway through a message; will
142 // release when it's finished.
145 rearm buffered_log_stream::fd_event(eventloop_t &loop, int fd, int flags) noexcept
147 if ((! partway) && (! special) && discarded) {
148 special_buf = "dinit: *** log message discarded due to full buffer ***\n";
152 if ((! partway) && special) {
153 const char * start = special_buf + msg_index;
154 const char * end = std::find(special_buf + msg_index, (const char *)nullptr, '\n');
155 int r = write(fd, start, end - start + 1);
157 if (start + r > end) {
158 // All written: go on to next message in queue
165 return rearm::DISARM;
173 else if (errno != EAGAIN && errno != EINTR && errno != EWOULDBLOCK) {
174 return rearm::REMOVE;
179 // Writing from the regular circular buffer
181 if (current_index == 0) {
183 return rearm::DISARM;
186 // We try to find a complete line (terminated by '\n') in the buffer, and write it
187 // out. Since it may span the circular buffer end, it may consist of two distinct spans,
188 // and so we use writev to write them atomically.
190 struct iovec logiov[2];
192 char *ptr = log_buffer.get_ptr(0);
193 int len = log_buffer.get_contiguous_length(ptr);
194 char *creptr = ptr + len; // contiguous region end
195 char *eptr = std::find(ptr, creptr, '\n');
197 bool will_complete = false; // will complete this message?
198 if (eptr != creptr) {
199 eptr++; // include '\n'
200 will_complete = true;
205 logiov[0].iov_base = ptr;
206 logiov[0].iov_len = len;
207 int iovs_to_write = 1;
209 // Do we need the second span?
210 if (! will_complete && len != log_buffer.get_length()) {
211 ptr = log_buffer.get_buf_base();
212 creptr = ptr + log_buffer.get_length() - len;
213 eptr = std::find(ptr, creptr, '\n');
214 if (eptr != creptr) {
215 eptr++; // include '\n'
216 // It should not ever be the case that we do not now have a complete message
217 will_complete = true;
219 logiov[1].iov_base = ptr;
220 logiov[1].iov_len = eptr - ptr;
221 len += logiov[1].iov_len;
225 ssize_t r = writev(fd, logiov, iovs_to_write);
228 bool complete = (r == len) && will_complete;
229 log_buffer.consume(len);
230 partway = ! complete;
232 current_index -= len;
233 if (current_index == 0 || release) {
234 // No more messages buffered / stop logging to console:
236 return rearm::DISARM;
240 else if (errno != EAGAIN && errno != EINTR && errno != EWOULDBLOCK) {
241 return rearm::REMOVE;
245 // We've written something by the time we get here. We could fall through to below, but
246 // let's give other events a chance to be processed by returning now.
250 // Initialise the logging subsystem
251 // Potentially throws std::bad_alloc or std::system_error
252 void init_log(service_set *sset)
255 log_stream[DLOG_CONS].add_watch(event_loop, STDOUT_FILENO, dasynq::OUT_EVENTS, false);
256 enable_console_log(true);
259 // Set up the main log to output to the given file descriptor.
260 // Potentially throws std::bad_alloc or std::system_error
261 void setup_main_log(int fd)
263 log_stream[DLOG_MAIN].init(fd);
264 log_stream[DLOG_MAIN].add_watch(event_loop, fd, dasynq::OUT_EVENTS);
267 bool is_log_flushed() noexcept
269 return log_stream[DLOG_CONS].current_index == 0;
272 // Enable or disable console logging. If disabled, console logging will be disabled on the
273 // completion of output of the current message (if any), at which point the first service record
274 // queued in the service set will acquire the console.
275 void enable_console_log(bool enable) noexcept
277 bool log_to_console = ! log_stream[DLOG_CONS].is_release_set();
278 if (enable && ! log_to_console) {
279 // Console is fd 1 - stdout
280 // Set non-blocking IO:
281 int flags = fcntl(1, F_GETFL, 0);
282 fcntl(1, F_SETFL, flags | O_NONBLOCK);
284 log_stream[DLOG_CONS].init(STDOUT_FILENO);
285 log_stream[DLOG_CONS].set_enabled(event_loop, true);
287 else if (! enable && log_to_console) {
288 log_stream[DLOG_CONS].flush_for_release();
292 void discard_console_log_buffer() noexcept
294 log_stream[DLOG_CONS].discard();
297 // Variadic method to calculate the sum of string lengths:
298 static int sum_length(const char *arg) noexcept
300 return std::strlen(arg);
303 template <typename ... T> static int sum_length(const char * first, T ... args) noexcept
305 return sum_length(first) + sum_length(args...);
308 // Variadic method to append strings to a buffer:
309 static void append(buffered_log_stream &buf, const char *s)
311 buf.append(s, std::strlen(s));
314 template <typename ... T> static void append(buffered_log_stream &buf, const char *u, T ... t)
320 static int log_level_to_syslog_level(loglevel_t l)
323 case loglevel_t::DEBUG:
325 case loglevel_t::INFO:
327 case loglevel_t::WARN:
329 case loglevel_t::ERROR:
337 // Variadic method to log a sequence of strings as a single message to a particular facility:
338 template <typename ... T> static void push_to_log(int idx, T ... args) noexcept
340 if (! log_current_line[idx]) return;
341 int amount = sum_length(args...);
342 if (log_stream[idx].get_free() >= amount) {
343 append(log_stream[idx], args...);
344 log_stream[idx].commit_msg();
347 log_stream[idx].mark_discarded();
351 // Variadic method to potentially log a sequence of strings as a single message with the given log level:
352 template <typename ... T> static void do_log(loglevel_t lvl, T ... args) noexcept
354 log_current_line[DLOG_CONS] = lvl >= log_level[DLOG_CONS];
355 log_current_line[DLOG_MAIN] = lvl >= log_level[DLOG_MAIN];
356 push_to_log(DLOG_CONS, args...);
358 if (log_current_line[DLOG_MAIN]) {
360 snprintf(svcbuf, 10, "<%d>", LOG_DAEMON | log_level_to_syslog_level(lvl));
362 push_to_log(DLOG_MAIN, svcbuf, args...);
366 template <typename ... T> static void do_log_cons(T ... args) noexcept
368 log_current_line[DLOG_CONS] = true;
369 log_current_line[DLOG_MAIN] = false;
370 push_to_log(DLOG_CONS, args...);
373 // Log to the main facility at NOTICE level
374 template <typename ... T> static void do_log_main(T ... args) noexcept
376 log_current_line[DLOG_CONS] = false;
377 log_current_line[DLOG_MAIN] = true;
380 snprintf(svcbuf, 10, "<%d>", LOG_DAEMON | LOG_NOTICE);
382 push_to_log(DLOG_MAIN, svcbuf, args...);
385 // Log a message. A newline will be appended.
386 void log(loglevel_t lvl, const char *msg) noexcept
388 do_log(lvl, "dinit: ", msg, "\n");
391 // Log part of a message. A series of calls to do_log_part must be followed by a call to do_log_commit.
392 template <typename T> static void do_log_part(int idx, T arg) noexcept
394 if (log_current_line[idx]) {
395 int amount = sum_length(arg);
396 if (log_stream[idx].get_free() >= amount) {
397 append(log_stream[idx], arg);
400 log_stream[idx].rollback_msg();
401 log_current_line[idx] = false;
402 log_stream[idx].mark_discarded();
407 // Commit a message that was issued as a series of parts (via do_log_part).
408 static void do_log_commit(int idx) noexcept
410 if (log_current_line[idx]) {
411 log_stream[idx].commit_msg();
415 // Log a multi-part message beginning
416 void log_msg_begin(loglevel_t lvl, const char *msg) noexcept
418 log_current_line[DLOG_CONS] = lvl >= log_level[DLOG_CONS];
419 log_current_line[DLOG_MAIN] = lvl >= log_level[DLOG_MAIN];
421 if (log_current_line[DLOG_MAIN]) {
423 snprintf(svcbuf, 10, "<%d>", LOG_DAEMON | log_level_to_syslog_level(lvl));
424 do_log_part(DLOG_MAIN, svcbuf);
427 for (int i = 0; i < 2; i++) {
428 do_log_part(i, "dinit: ");
433 // Continue a multi-part log message
434 void log_msg_part(const char *msg) noexcept
436 do_log_part(DLOG_CONS, msg);
437 do_log_part(DLOG_MAIN, msg);
440 // Complete a multi-part log message
441 void log_msg_end(const char *msg) noexcept
443 for (int i = 0; i < 2; i++) {
445 do_log_part(i, "\n");
450 void log_service_started(const char *service_name) noexcept
452 do_log_cons("[ OK ] ", service_name, "\n");
453 do_log_main("dinit: service ", service_name, " started.\n");
456 void log_service_failed(const char *service_name) noexcept
458 do_log_cons("[FAILED] ", service_name, "\n");
459 do_log_main("dinit: service ", service_name, " failed to start.\n");
462 void log_service_stopped(const char *service_name) noexcept
464 do_log_cons("[STOPPD] ", service_name, "\n");
465 do_log_main("dinit: service ", service_name, " stopped.\n");