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 (or log
20 // file). Both have a circular buffer. Log messages are appended to the circular buffer (for a syslog
21 // stream, the messages are prepended with a syslog priority indicator). Both streams start out inactive
22 // (release = true in 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::INFO, loglevel_t::WARN };
32 static bool log_format_syslog[2] = { false, true };
34 static service_set *services = nullptr; // Reference to service set
36 dasynq::time_val release_time; // time the log was released
38 using rearm = dasynq::rearm;
41 class buffered_log_stream : public eventloop_t::fd_watcher_impl<buffered_log_stream>
46 bool partway = false; // if we are partway throught output of a log message
47 bool discarded = false; // if we have discarded a message
48 bool release = true; // if we should inhibit output and release console
50 // A "special message" is not stored in the circular buffer; instead
51 // it is delivered from an external buffer not managed by BufferedLogger.
52 bool special = false; // currently outputting special message?
53 const char *special_buf; // buffer containing special message
54 int msg_index; // index into special message
56 cpbuffer<4096> log_buffer;
61 int current_index = 0; // current/next incoming message index
71 rearm fd_event(eventloop_t &loop, int fd, int flags) noexcept;
73 // Check whether the console can be released.
74 void flush_for_release();
75 bool is_release_set() { return release; }
77 // Commit a log message
80 bool was_first = current_index == 0;
81 current_index = log_buffer.get_length();
82 if (was_first && ! release) {
83 set_enabled(event_loop, true);
89 log_buffer.trim_to(current_index);
94 return log_buffer.get_free();
97 void append(const char *s, size_t len)
99 log_buffer.append(s, len);
102 // Discard buffer; call only when the stream isn't active.
106 log_buffer.trim_to(0);
109 // Mark that a message was discarded due to full buffer
110 void mark_discarded()
116 void release_console();
121 // (One for main log, one for console)
122 static buffered_log_stream log_stream[2];
124 constexpr static int DLOG_MAIN = 0; // main log facility
125 constexpr static int DLOG_CONS = 1; // console
127 void buffered_log_stream::release_console()
130 int flags = fcntl(1, F_GETFL, 0);
131 fcntl(1, F_SETFL, flags & ~O_NONBLOCK);
132 services->pull_console_queue();
134 // release still set, we didn't immediately get the console back; record the
135 // time at which we released:
136 event_loop.get_time(release_time, clock_type::MONOTONIC);
141 void buffered_log_stream::flush_for_release()
145 // Try to flush any messages that are currently buffered. (Console is non-blocking
146 // so it will fail gracefully).
147 if (fd_event(event_loop, fd, dasynq::OUT_EVENTS) == rearm::DISARM) {
148 // Console has already been released at this point.
149 set_enabled(event_loop, false);
151 // fd_event didn't want to disarm, so must be partway through a message; will
152 // release when it's finished.
155 rearm buffered_log_stream::fd_event(eventloop_t &loop, int fd, int flags) noexcept
157 if ((! partway) && (! special) && discarded) {
158 special_buf = "dinit: *** log message discarded due to full buffer ***\n";
164 if ((! partway) && special) {
165 const char * start = special_buf + msg_index;
166 const char * end = std::find(special_buf + msg_index, (const char *)nullptr, '\n');
167 int r = write(fd, start, end - start + 1);
169 if (start + r > end) {
170 // All written: go on to next message in queue
177 return rearm::DISARM;
185 else if (errno != EAGAIN && errno != EINTR && errno != EWOULDBLOCK) {
186 return rearm::REMOVE;
191 // Writing from the regular circular buffer
193 if (current_index == 0) {
195 return rearm::DISARM;
198 // We try to find a complete line (terminated by '\n') in the buffer, and write it
199 // out. Since it may span the circular buffer end, it may consist of two distinct spans,
200 // and so we use writev to write them atomically.
202 struct iovec logiov[2];
204 char *ptr = log_buffer.get_ptr(0);
205 int len = log_buffer.get_contiguous_length(ptr);
206 char *creptr = ptr + len; // contiguous region end
207 char *eptr = std::find(ptr, creptr, '\n');
209 bool will_complete = false; // will complete this message?
210 if (eptr != creptr) {
211 eptr++; // include '\n'
212 will_complete = true;
217 logiov[0].iov_base = ptr;
218 logiov[0].iov_len = len;
219 int iovs_to_write = 1;
221 // Do we need the second span?
222 if (! will_complete && len != log_buffer.get_length()) {
223 ptr = log_buffer.get_buf_base();
224 creptr = ptr + log_buffer.get_length() - len;
225 eptr = std::find(ptr, creptr, '\n');
226 if (eptr != creptr) {
227 eptr++; // include '\n'
228 // It should not ever be the case that we do not now have a complete message
229 will_complete = true;
231 logiov[1].iov_base = ptr;
232 logiov[1].iov_len = eptr - ptr;
233 len += logiov[1].iov_len;
237 ssize_t r = writev(fd, logiov, iovs_to_write);
240 bool complete = (r == len) && will_complete;
241 log_buffer.consume(len);
242 partway = ! complete;
244 current_index -= len;
245 if (current_index == 0 || release) {
246 // No more messages buffered / stop logging to console:
248 return rearm::DISARM;
252 else if (errno != EAGAIN && errno != EINTR && errno != EWOULDBLOCK) {
253 return rearm::REMOVE;
257 // We've written something by the time we get here. We could fall through to below, but
258 // let's give other events a chance to be processed by returning now.
262 // Initialise the logging subsystem
263 // Potentially throws std::bad_alloc or std::system_error
264 void init_log(service_set *sset, bool syslog_format)
267 log_stream[DLOG_CONS].add_watch(event_loop, STDOUT_FILENO, dasynq::OUT_EVENTS, false);
268 enable_console_log(true);
270 // The main (non-console) log won't be active yet, but we set the format here so that we
271 // buffer messages in the correct format:
272 log_format_syslog[DLOG_MAIN] = syslog_format;
275 // Set up the main log to output to the given file descriptor.
276 // Potentially throws std::bad_alloc or std::system_error
277 void setup_main_log(int fd)
279 log_stream[DLOG_MAIN].init(fd);
280 log_stream[DLOG_MAIN].add_watch(event_loop, fd, dasynq::OUT_EVENTS);
283 bool is_log_flushed() noexcept
285 return log_stream[DLOG_CONS].current_index == 0;
288 // Enable or disable console logging. If disabled, console logging will be disabled on the
289 // completion of output of the current message (if any), at which point the first service record
290 // queued in the service set will acquire the console.
291 void enable_console_log(bool enable) noexcept
293 bool log_to_console = ! log_stream[DLOG_CONS].is_release_set();
294 if (enable && ! log_to_console) {
295 // Set non-blocking IO:
296 int flags = fcntl(STDOUT_FILENO, F_GETFL, 0);
297 fcntl(STDOUT_FILENO, F_SETFL, flags | O_NONBLOCK);
299 log_stream[DLOG_CONS].init(STDOUT_FILENO);
300 log_stream[DLOG_CONS].set_enabled(event_loop, true);
302 else if (! enable && log_to_console) {
303 log_stream[DLOG_CONS].flush_for_release();
307 void discard_console_log_buffer() noexcept
309 // Only discard if more than a second has passed since we released the console.
310 dasynq::time_val current_time;
311 event_loop.get_time(current_time, clock_type::MONOTONIC);
312 if (current_time - release_time >= dasynq::time_val(1, 0)) {
313 log_stream[DLOG_CONS].discard();
317 // Variadic method to calculate the sum of string lengths:
318 static int sum_length(const char *arg) noexcept
320 return std::strlen(arg);
323 template <typename ... T> static int sum_length(const char * first, T ... args) noexcept
325 return sum_length(first) + sum_length(args...);
328 // Variadic method to append strings to a buffer:
329 static void append(buffered_log_stream &buf, const char *s)
331 buf.append(s, std::strlen(s));
334 template <typename ... T> static void append(buffered_log_stream &buf, const char *u, T ... t)
340 static int log_level_to_syslog_level(loglevel_t l)
343 case loglevel_t::DEBUG:
345 case loglevel_t::INFO:
347 case loglevel_t::WARN:
349 case loglevel_t::ERROR:
357 // Variadic method to log a sequence of strings as a single message to a particular facility:
358 template <typename ... T> static void push_to_log(int idx, T ... args) noexcept
360 if (! log_current_line[idx]) return;
361 int amount = sum_length(args...);
362 if (log_stream[idx].get_free() >= amount) {
363 append(log_stream[idx], args...);
364 log_stream[idx].commit_msg();
367 log_stream[idx].mark_discarded();
371 // Variadic method to potentially log a sequence of strings as a single message with the given log level:
372 template <typename ... T> static void do_log(loglevel_t lvl, bool to_cons, T ... args) noexcept
374 log_current_line[DLOG_CONS] = (lvl >= log_level[DLOG_CONS]) && to_cons;
375 log_current_line[DLOG_MAIN] = (lvl >= log_level[DLOG_MAIN]);
376 push_to_log(DLOG_CONS, args...);
378 if (log_current_line[DLOG_MAIN]) {
379 if (log_format_syslog[DLOG_MAIN]) {
381 snprintf(svcbuf, 10, "<%d>", LOG_DAEMON | log_level_to_syslog_level(lvl));
382 push_to_log(DLOG_MAIN, svcbuf, args...);
385 push_to_log(DLOG_MAIN, args...);
390 template <typename ... T> static void do_log_cons(T ... args) noexcept
392 log_current_line[DLOG_CONS] = true;
393 log_current_line[DLOG_MAIN] = false;
394 push_to_log(DLOG_CONS, args...);
397 // Log to the main facility at NOTICE level
398 template <typename ... T> static void do_log_main(T ... args) noexcept
400 log_current_line[DLOG_CONS] = false;
401 log_current_line[DLOG_MAIN] = true;
403 if (log_format_syslog[DLOG_MAIN]) {
405 snprintf(svcbuf, 10, "<%d>", LOG_DAEMON | LOG_NOTICE);
406 push_to_log(DLOG_MAIN, svcbuf, args...);
409 push_to_log(DLOG_MAIN, args...);
413 // Log a message. A newline will be appended.
414 void log(loglevel_t lvl, const char *msg) noexcept
416 do_log(lvl, true, "dinit: ", msg, "\n");
419 void log(loglevel_t lvl, bool to_cons, const char *msg) noexcept
421 do_log(lvl, to_cons, "dinit: ", msg, "\n");
424 // Log part of a message. A series of calls to do_log_part must be followed by a call to do_log_commit.
425 template <typename T> static void do_log_part(int idx, T arg) noexcept
427 if (log_current_line[idx]) {
428 int amount = sum_length(arg);
429 if (log_stream[idx].get_free() >= amount) {
430 append(log_stream[idx], arg);
433 log_stream[idx].rollback_msg();
434 log_current_line[idx] = false;
435 log_stream[idx].mark_discarded();
440 // Commit a message that was issued as a series of parts (via do_log_part).
441 static void do_log_commit(int idx) noexcept
443 if (log_current_line[idx]) {
444 log_stream[idx].commit_msg();
448 // Log a multi-part message beginning
449 void log_msg_begin(loglevel_t lvl, const char *msg) noexcept
451 log_current_line[DLOG_CONS] = lvl >= log_level[DLOG_CONS];
452 log_current_line[DLOG_MAIN] = lvl >= log_level[DLOG_MAIN];
454 // Prepend the syslog priority level string ("<N>") for the main log:
455 if (log_current_line[DLOG_MAIN]) {
456 if (log_format_syslog[DLOG_MAIN]) {
458 snprintf(svcbuf, 10, "<%d>", LOG_DAEMON | log_level_to_syslog_level(lvl));
459 do_log_part(DLOG_MAIN, svcbuf);
463 for (int i = 0; i < 2; i++) {
464 do_log_part(i, "dinit: ");
469 // Continue a multi-part log message
470 void log_msg_part(const char *msg) noexcept
472 do_log_part(DLOG_CONS, msg);
473 do_log_part(DLOG_MAIN, msg);
476 // Complete a multi-part log message
477 void log_msg_end(const char *msg) noexcept
479 for (int i = 0; i < 2; i++) {
481 do_log_part(i, "\n");
486 void log_service_started(const char *service_name) noexcept
488 do_log_cons("[ OK ] ", service_name, "\n");
489 do_log_main("dinit: service ", service_name, " started.\n");
492 void log_service_failed(const char *service_name) noexcept
494 do_log_cons("[FAILED] ", service_name, "\n");
495 do_log_main("dinit: service ", service_name, " failed to start.\n");
498 void log_service_stopped(const char *service_name) noexcept
500 do_log_cons("[STOPPD] ", service_name, "\n");
501 do_log_main("dinit: service ", service_name, " stopped.\n");