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 bool is_release_set() { return release; }
74 // Commit a log message
77 bool was_first = current_index == 0;
78 current_index = log_buffer.get_length();
79 if (was_first && ! release) {
80 set_enabled(event_loop, true);
86 log_buffer.trim_to(current_index);
91 return log_buffer.get_free();
94 void append(const char *s, size_t len)
96 log_buffer.append(s, len);
99 // Discard buffer; call only when the stream isn't active.
103 log_buffer.trim_to(0);
106 // Mark that a message was discarded due to full buffer
107 void mark_discarded()
113 void release_console();
118 // (One for main log, one for console)
119 static buffered_log_stream log_stream[2];
121 constexpr static int DLOG_MAIN = 0; // main log facility
122 constexpr static int DLOG_CONS = 1; // console
124 void buffered_log_stream::release_console()
127 int flags = fcntl(1, F_GETFL, 0);
128 fcntl(1, F_SETFL, flags & ~O_NONBLOCK);
129 services->pull_console_queue();
133 void buffered_log_stream::flush_for_release()
137 // Try to flush any messages that are currently buffered. (Console is non-blocking
138 // so it will fail gracefully).
139 if (fd_event(event_loop, fd, dasynq::OUT_EVENTS) == rearm::DISARM) {
140 // Console has already been released at this point.
141 set_enabled(event_loop, false);
143 // fd_event didn't want to disarm, so must be partway through a message; will
144 // release when it's finished.
147 rearm buffered_log_stream::fd_event(eventloop_t &loop, int fd, int flags) noexcept
149 if ((! partway) && (! special) && discarded) {
150 special_buf = "dinit: *** log message discarded due to full buffer ***\n";
154 if ((! partway) && special) {
155 const char * start = special_buf + msg_index;
156 const char * end = std::find(special_buf + msg_index, (const char *)nullptr, '\n');
157 int r = write(fd, start, end - start + 1);
159 if (start + r > end) {
160 // All written: go on to next message in queue
167 return rearm::DISARM;
175 else if (errno != EAGAIN && errno != EINTR && errno != EWOULDBLOCK) {
176 return rearm::REMOVE;
181 // Writing from the regular circular buffer
183 if (current_index == 0) {
185 return rearm::DISARM;
188 // We try to find a complete line (terminated by '\n') in the buffer, and write it
189 // out. Since it may span the circular buffer end, it may consist of two distinct spans,
190 // and so we use writev to write them atomically.
192 struct iovec logiov[2];
194 char *ptr = log_buffer.get_ptr(0);
195 int len = log_buffer.get_contiguous_length(ptr);
196 char *creptr = ptr + len; // contiguous region end
197 char *eptr = std::find(ptr, creptr, '\n');
199 bool will_complete = false; // will complete this message?
200 if (eptr != creptr) {
201 eptr++; // include '\n'
202 will_complete = true;
207 logiov[0].iov_base = ptr;
208 logiov[0].iov_len = len;
209 int iovs_to_write = 1;
211 // Do we need the second span?
212 if (! will_complete && len != log_buffer.get_length()) {
213 ptr = log_buffer.get_buf_base();
214 creptr = ptr + log_buffer.get_length() - len;
215 eptr = std::find(ptr, creptr, '\n');
216 if (eptr != creptr) {
217 eptr++; // include '\n'
218 // It should not ever be the case that we do not now have a complete message
219 will_complete = true;
221 logiov[1].iov_base = ptr;
222 logiov[1].iov_len = eptr - ptr;
223 len += logiov[1].iov_len;
227 ssize_t r = writev(fd, logiov, iovs_to_write);
230 bool complete = (r == len) && will_complete;
231 log_buffer.consume(len);
232 partway = ! complete;
234 current_index -= len;
235 if (current_index == 0 || release) {
236 // No more messages buffered / stop logging to console:
238 return rearm::DISARM;
242 else if (errno != EAGAIN && errno != EINTR && errno != EWOULDBLOCK) {
243 return rearm::REMOVE;
247 // We've written something by the time we get here. We could fall through to below, but
248 // let's give other events a chance to be processed by returning now.
252 // Initialise the logging subsystem
253 // Potentially throws std::bad_alloc or std::system_error
254 void init_log(service_set *sset)
257 log_stream[DLOG_CONS].add_watch(event_loop, STDOUT_FILENO, dasynq::OUT_EVENTS, false);
258 enable_console_log(true);
261 // Set up the main log to output to the given file descriptor.
262 // Potentially throws std::bad_alloc or std::system_error
263 void setup_main_log(int fd)
265 log_stream[DLOG_MAIN].init(fd);
266 log_stream[DLOG_MAIN].add_watch(event_loop, fd, dasynq::OUT_EVENTS);
269 bool is_log_flushed() noexcept
271 return log_stream[DLOG_CONS].current_index == 0;
274 // Enable or disable console logging. If disabled, console logging will be disabled on the
275 // completion of output of the current message (if any), at which point the first service record
276 // queued in the service set will acquire the console.
277 void enable_console_log(bool enable) noexcept
279 bool log_to_console = ! log_stream[DLOG_CONS].is_release_set();
280 if (enable && ! log_to_console) {
281 // Set non-blocking IO:
282 int flags = fcntl(STDOUT_FILENO, F_GETFL, 0);
283 fcntl(STDOUT_FILENO, F_SETFL, flags | O_NONBLOCK);
285 log_stream[DLOG_CONS].init(STDOUT_FILENO);
286 log_stream[DLOG_CONS].set_enabled(event_loop, true);
288 else if (! enable && log_to_console) {
289 log_stream[DLOG_CONS].flush_for_release();
293 void discard_console_log_buffer() noexcept
295 log_stream[DLOG_CONS].discard();
298 // Variadic method to calculate the sum of string lengths:
299 static int sum_length(const char *arg) noexcept
301 return std::strlen(arg);
304 template <typename ... T> static int sum_length(const char * first, T ... args) noexcept
306 return sum_length(first) + sum_length(args...);
309 // Variadic method to append strings to a buffer:
310 static void append(buffered_log_stream &buf, const char *s)
312 buf.append(s, std::strlen(s));
315 template <typename ... T> static void append(buffered_log_stream &buf, const char *u, T ... t)
321 static int log_level_to_syslog_level(loglevel_t l)
324 case loglevel_t::DEBUG:
326 case loglevel_t::INFO:
328 case loglevel_t::WARN:
330 case loglevel_t::ERROR:
338 // Variadic method to log a sequence of strings as a single message to a particular facility:
339 template <typename ... T> static void push_to_log(int idx, T ... args) noexcept
341 if (! log_current_line[idx]) return;
342 int amount = sum_length(args...);
343 if (log_stream[idx].get_free() >= amount) {
344 append(log_stream[idx], args...);
345 log_stream[idx].commit_msg();
348 log_stream[idx].mark_discarded();
352 // Variadic method to potentially log a sequence of strings as a single message with the given log level:
353 template <typename ... T> static void do_log(loglevel_t lvl, bool to_cons, T ... args) noexcept
355 log_current_line[DLOG_CONS] = (lvl >= log_level[DLOG_CONS]) && to_cons;
356 log_current_line[DLOG_MAIN] = (lvl >= log_level[DLOG_MAIN]);
357 push_to_log(DLOG_CONS, args...);
359 if (log_current_line[DLOG_MAIN]) {
361 snprintf(svcbuf, 10, "<%d>", LOG_DAEMON | log_level_to_syslog_level(lvl));
363 push_to_log(DLOG_MAIN, svcbuf, args...);
367 template <typename ... T> static void do_log_cons(T ... args) noexcept
369 log_current_line[DLOG_CONS] = true;
370 log_current_line[DLOG_MAIN] = false;
371 push_to_log(DLOG_CONS, args...);
374 // Log to the main facility at NOTICE level
375 template <typename ... T> static void do_log_main(T ... args) noexcept
377 log_current_line[DLOG_CONS] = false;
378 log_current_line[DLOG_MAIN] = true;
381 snprintf(svcbuf, 10, "<%d>", LOG_DAEMON | LOG_NOTICE);
383 push_to_log(DLOG_MAIN, svcbuf, args...);
386 // Log a message. A newline will be appended.
387 void log(loglevel_t lvl, const char *msg) noexcept
389 do_log(lvl, true, "dinit: ", msg, "\n");
392 void log(loglevel_t lvl, bool to_cons, const char *msg) noexcept
394 do_log(lvl, to_cons, "dinit: ", msg, "\n");
397 // Log part of a message. A series of calls to do_log_part must be followed by a call to do_log_commit.
398 template <typename T> static void do_log_part(int idx, T arg) noexcept
400 if (log_current_line[idx]) {
401 int amount = sum_length(arg);
402 if (log_stream[idx].get_free() >= amount) {
403 append(log_stream[idx], arg);
406 log_stream[idx].rollback_msg();
407 log_current_line[idx] = false;
408 log_stream[idx].mark_discarded();
413 // Commit a message that was issued as a series of parts (via do_log_part).
414 static void do_log_commit(int idx) noexcept
416 if (log_current_line[idx]) {
417 log_stream[idx].commit_msg();
421 // Log a multi-part message beginning
422 void log_msg_begin(loglevel_t lvl, const char *msg) noexcept
424 log_current_line[DLOG_CONS] = lvl >= log_level[DLOG_CONS];
425 log_current_line[DLOG_MAIN] = lvl >= log_level[DLOG_MAIN];
427 // Prepend the syslog priority level string ("<N>") for the main log:
428 if (log_current_line[DLOG_MAIN]) {
430 snprintf(svcbuf, 10, "<%d>", LOG_DAEMON | log_level_to_syslog_level(lvl));
431 do_log_part(DLOG_MAIN, svcbuf);
434 for (int i = 0; i < 2; i++) {
435 do_log_part(i, "dinit: ");
440 // Continue a multi-part log message
441 void log_msg_part(const char *msg) noexcept
443 do_log_part(DLOG_CONS, msg);
444 do_log_part(DLOG_MAIN, msg);
447 // Complete a multi-part log message
448 void log_msg_end(const char *msg) noexcept
450 for (int i = 0; i < 2; i++) {
452 do_log_part(i, "\n");
457 void log_service_started(const char *service_name) noexcept
459 do_log_cons("[ OK ] ", service_name, "\n");
460 do_log_main("dinit: service ", service_name, " started.\n");
463 void log_service_failed(const char *service_name) noexcept
465 do_log_cons("[FAILED] ", service_name, "\n");
466 do_log_main("dinit: service ", service_name, " failed to start.\n");
469 void log_service_stopped(const char *service_name) noexcept
471 do_log_cons("[STOPPD] ", service_name, "\n");
472 do_log_main("dinit: service ", service_name, " stopped.\n");