1/*	$NetBSD: log.c,v 1.1 2024/02/18 20:57:49 christos Exp $	*/
2
3/*
4 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
5 *
6 * SPDX-License-Identifier: MPL-2.0
7 *
8 * This Source Code Form is subject to the terms of the Mozilla Public
9 * License, v. 2.0. If a copy of the MPL was not distributed with this
10 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
11 *
12 * See the COPYRIGHT file distributed with this work for additional
13 * information regarding copyright ownership.
14 */
15
16/*! \file */
17
18#include <errno.h>
19#include <inttypes.h>
20#include <limits.h>
21#include <stdbool.h>
22#include <stdlib.h>
23#include <sys/types.h> /* dev_t FreeBSD 2.1 */
24#include <time.h>
25
26#include <isc/atomic.h>
27#include <isc/dir.h>
28#include <isc/file.h>
29#include <isc/log.h>
30#include <isc/magic.h>
31#include <isc/mem.h>
32#include <isc/platform.h>
33#include <isc/print.h>
34#include <isc/rwlock.h>
35#include <isc/stat.h>
36#include <isc/stdio.h>
37#include <isc/string.h>
38#include <isc/time.h>
39#include <isc/util.h>
40
41#define LCTX_MAGIC	    ISC_MAGIC('L', 'c', 't', 'x')
42#define VALID_CONTEXT(lctx) ISC_MAGIC_VALID(lctx, LCTX_MAGIC)
43
44#define LCFG_MAGIC	   ISC_MAGIC('L', 'c', 'f', 'g')
45#define VALID_CONFIG(lcfg) ISC_MAGIC_VALID(lcfg, LCFG_MAGIC)
46
47#define RDLOCK(lp)   RWLOCK(lp, isc_rwlocktype_read);
48#define WRLOCK(lp)   RWLOCK(lp, isc_rwlocktype_write);
49#define RDUNLOCK(lp) RWUNLOCK(lp, isc_rwlocktype_read);
50#define WRUNLOCK(lp) RWUNLOCK(lp, isc_rwlocktype_write);
51
52/*
53 * XXXDCL make dynamic?
54 */
55#define LOG_BUFFER_SIZE (8 * 1024)
56
57/*!
58 * This is the structure that holds each named channel.  A simple linked
59 * list chains all of the channels together, so an individual channel is
60 * found by doing strcmp()s with the names down the list.  Their should
61 * be no performance penalty from this as it is expected that the number
62 * of named channels will be no more than a dozen or so, and name lookups
63 * from the head of the list are only done when isc_log_usechannel() is
64 * called, which should also be very infrequent.
65 */
66typedef struct isc_logchannel isc_logchannel_t;
67
68struct isc_logchannel {
69	char *name;
70	unsigned int type;
71	int level;
72	unsigned int flags;
73	isc_logdestination_t destination;
74	ISC_LINK(isc_logchannel_t) link;
75};
76
77/*!
78 * The logchannellist structure associates categories and modules with
79 * channels.  First the appropriate channellist is found based on the
80 * category, and then each structure in the linked list is checked for
81 * a matching module.  It is expected that the number of channels
82 * associated with any given category will be very short, no more than
83 * three or four in the more unusual cases.
84 */
85typedef struct isc_logchannellist isc_logchannellist_t;
86
87struct isc_logchannellist {
88	const isc_logmodule_t *module;
89	isc_logchannel_t *channel;
90	ISC_LINK(isc_logchannellist_t) link;
91};
92
93/*!
94 * This structure is used to remember messages for pruning via
95 * isc_log_[v]write1().
96 */
97typedef struct isc_logmessage isc_logmessage_t;
98
99struct isc_logmessage {
100	char *text;
101	isc_time_t time;
102	ISC_LINK(isc_logmessage_t) link;
103};
104
105/*!
106 * The isc_logconfig structure is used to store the configurable information
107 * about where messages are actually supposed to be sent -- the information
108 * that could changed based on some configuration file, as opposed to the
109 * the category/module specification of isc_log_[v]write[1] that is compiled
110 * into a program, or the debug_level which is dynamic state information.
111 */
112struct isc_logconfig {
113	unsigned int magic;
114	isc_log_t *lctx;
115	ISC_LIST(isc_logchannel_t) channels;
116	ISC_LIST(isc_logchannellist_t) * channellists;
117	unsigned int channellist_count;
118	unsigned int duplicate_interval;
119	int_fast32_t highest_level;
120	char *tag;
121	bool dynamic;
122};
123
124/*!
125 * This isc_log structure provides the context for the isc_log functions.
126 * The log context locks itself in isc_log_doit, the internal backend to
127 * isc_log_write.  The locking is necessary both to provide exclusive access
128 * to the buffer into which the message is formatted and to guard against
129 * competing threads trying to write to the same syslog resource.  (On
130 * some systems, such as BSD/OS, stdio is thread safe but syslog is not.)
131 * Unfortunately, the lock cannot guard against a _different_ logging
132 * context in the same program competing for syslog's attention.  Thus
133 * There Can Be Only One, but this is not enforced.
134 * XXXDCL enforce it?
135 *
136 * Note that the category and module information is not locked.
137 * This is because in the usual case, only one isc_log_t is ever created
138 * in a program, and the category/module registration happens only once.
139 * XXXDCL it might be wise to add more locking overall.
140 */
141struct isc_log {
142	/* Not locked. */
143	unsigned int magic;
144	isc_mem_t *mctx;
145	isc_logcategory_t *categories;
146	unsigned int category_count;
147	isc_logmodule_t *modules;
148	unsigned int module_count;
149	atomic_int_fast32_t debug_level;
150	isc_rwlock_t lcfg_rwl;
151	/* Locked by isc_log lcfg_rwl */
152	isc_logconfig_t *logconfig;
153	isc_mutex_t lock;
154	/* Locked by isc_log lock. */
155	char buffer[LOG_BUFFER_SIZE];
156	ISC_LIST(isc_logmessage_t) messages;
157	atomic_bool dynamic;
158	atomic_int_fast32_t highest_level;
159};
160
161/*!
162 * Used when ISC_LOG_PRINTLEVEL is enabled for a channel.
163 */
164static const char *log_level_strings[] = { "debug",   "info",  "notice",
165					   "warning", "error", "critical" };
166
167/*!
168 * Used to convert ISC_LOG_* priorities into syslog priorities.
169 * XXXDCL This will need modification for NT.
170 */
171static const int syslog_map[] = { LOG_DEBUG,   LOG_INFO, LOG_NOTICE,
172				  LOG_WARNING, LOG_ERR,	 LOG_CRIT };
173
174/*!
175 * When adding new categories, a corresponding ISC_LOGCATEGORY_foo
176 * definition needs to be added to <isc/log.h>.
177 *
178 * The default category is provided so that the internal default can
179 * be overridden.  Since the default is always looked up as the first
180 * channellist in the log context, it must come first in isc_categories[].
181 */
182LIBISC_EXTERNAL_DATA isc_logcategory_t isc_categories[] = { { "default",
183							      0 }, /* "default
184								      must come
185								      first. */
186							    { "general", 0 },
187							    { NULL, 0 } };
188
189/*!
190 * See above comment for categories on LIBISC_EXTERNAL_DATA, and apply it to
191 * modules.
192 */
193LIBISC_EXTERNAL_DATA isc_logmodule_t isc_modules[] = {
194	{ "socket", 0 }, { "time", 0 },	  { "interface", 0 }, { "timer", 0 },
195	{ "file", 0 },	 { "netmgr", 0 }, { "other", 0 },     { NULL, 0 }
196};
197
198/*!
199 * This essentially constant structure must be filled in at run time,
200 * because its channel member is pointed to a channel that is created
201 * dynamically with isc_log_createchannel.
202 */
203static isc_logchannellist_t default_channel;
204
205/*!
206 * libisc logs to this context.
207 */
208LIBISC_EXTERNAL_DATA isc_log_t *isc_lctx = NULL;
209
210/*!
211 * Forward declarations.
212 */
213static void
214assignchannel(isc_logconfig_t *lcfg, unsigned int category_id,
215	      const isc_logmodule_t *module, isc_logchannel_t *channel);
216
217static void
218sync_channellist(isc_logconfig_t *lcfg);
219
220static void
221sync_highest_level(isc_log_t *lctx, isc_logconfig_t *lcfg);
222
223static isc_result_t
224greatest_version(isc_logfile_t *file, int versions, int *greatest);
225
226static void
227isc_log_doit(isc_log_t *lctx, isc_logcategory_t *category,
228	     isc_logmodule_t *module, int level, bool write_once,
229	     const char *format, va_list args) ISC_FORMAT_PRINTF(6, 0);
230
231/*@{*/
232/*!
233 * Convenience macros.
234 */
235
236#define FACILITY(channel)	 (channel->destination.facility)
237#define FILE_NAME(channel)	 (channel->destination.file.name)
238#define FILE_STREAM(channel)	 (channel->destination.file.stream)
239#define FILE_VERSIONS(channel)	 (channel->destination.file.versions)
240#define FILE_SUFFIX(channel)	 (channel->destination.file.suffix)
241#define FILE_MAXSIZE(channel)	 (channel->destination.file.maximum_size)
242#define FILE_MAXREACHED(channel) (channel->destination.file.maximum_reached)
243
244/*@}*/
245/****
246**** Public interfaces.
247****/
248
249/*
250 * Establish a new logging context, with default channels.
251 */
252void
253isc_log_create(isc_mem_t *mctx, isc_log_t **lctxp, isc_logconfig_t **lcfgp) {
254	isc_log_t *lctx;
255	isc_logconfig_t *lcfg = NULL;
256
257	REQUIRE(mctx != NULL);
258	REQUIRE(lctxp != NULL && *lctxp == NULL);
259	REQUIRE(lcfgp == NULL || *lcfgp == NULL);
260
261	lctx = isc_mem_get(mctx, sizeof(*lctx));
262	lctx->mctx = NULL;
263	isc_mem_attach(mctx, &lctx->mctx);
264	lctx->categories = NULL;
265	lctx->category_count = 0;
266	lctx->modules = NULL;
267	lctx->module_count = 0;
268	atomic_init(&lctx->debug_level, 0);
269
270	ISC_LIST_INIT(lctx->messages);
271
272	isc_mutex_init(&lctx->lock);
273	isc_rwlock_init(&lctx->lcfg_rwl, 0, 0);
274
275	/*
276	 * Normally setting the magic number is the last step done
277	 * in a creation function, but a valid log context is needed
278	 * by isc_log_registercategories and isc_logconfig_create.
279	 * If either fails, the lctx is destroyed and not returned
280	 * to the caller.
281	 */
282	lctx->magic = LCTX_MAGIC;
283
284	isc_log_registercategories(lctx, isc_categories);
285	isc_log_registermodules(lctx, isc_modules);
286	isc_logconfig_create(lctx, &lcfg);
287
288	sync_channellist(lcfg);
289
290	lctx->logconfig = lcfg;
291
292	atomic_init(&lctx->highest_level, lcfg->highest_level);
293	atomic_init(&lctx->dynamic, lcfg->dynamic);
294
295	*lctxp = lctx;
296	if (lcfgp != NULL) {
297		*lcfgp = lcfg;
298	}
299}
300
301void
302isc_logconfig_create(isc_log_t *lctx, isc_logconfig_t **lcfgp) {
303	isc_logconfig_t *lcfg;
304	isc_logdestination_t destination;
305	int level = ISC_LOG_INFO;
306
307	REQUIRE(lcfgp != NULL && *lcfgp == NULL);
308	REQUIRE(VALID_CONTEXT(lctx));
309
310	lcfg = isc_mem_get(lctx->mctx, sizeof(*lcfg));
311
312	lcfg->lctx = lctx;
313	lcfg->channellists = NULL;
314	lcfg->channellist_count = 0;
315	lcfg->duplicate_interval = 0;
316	lcfg->highest_level = level;
317	lcfg->tag = NULL;
318	lcfg->dynamic = false;
319	ISC_LIST_INIT(lcfg->channels);
320	lcfg->magic = LCFG_MAGIC;
321
322	/*
323	 * Create the default channels:
324	 *      default_syslog, default_stderr, default_debug and null.
325	 */
326	destination.facility = LOG_DAEMON;
327	isc_log_createchannel(lcfg, "default_syslog", ISC_LOG_TOSYSLOG, level,
328			      &destination, 0);
329
330	destination.file.stream = stderr;
331	destination.file.name = NULL;
332	destination.file.versions = ISC_LOG_ROLLNEVER;
333	destination.file.suffix = isc_log_rollsuffix_increment;
334	destination.file.maximum_size = 0;
335	isc_log_createchannel(lcfg, "default_stderr", ISC_LOG_TOFILEDESC, level,
336			      &destination, ISC_LOG_PRINTTIME);
337
338	/*
339	 * Set the default category's channel to default_stderr,
340	 * which is at the head of the channels list because it was
341	 * just created.
342	 */
343	default_channel.channel = ISC_LIST_HEAD(lcfg->channels);
344
345	destination.file.stream = stderr;
346	destination.file.name = NULL;
347	destination.file.versions = ISC_LOG_ROLLNEVER;
348	destination.file.suffix = isc_log_rollsuffix_increment;
349	destination.file.maximum_size = 0;
350	isc_log_createchannel(lcfg, "default_debug", ISC_LOG_TOFILEDESC,
351			      ISC_LOG_DYNAMIC, &destination, ISC_LOG_PRINTTIME);
352
353	isc_log_createchannel(lcfg, "null", ISC_LOG_TONULL, ISC_LOG_DYNAMIC,
354			      NULL, 0);
355
356	*lcfgp = lcfg;
357}
358
359void
360isc_logconfig_use(isc_log_t *lctx, isc_logconfig_t *lcfg) {
361	isc_logconfig_t *old_cfg;
362
363	REQUIRE(VALID_CONTEXT(lctx));
364	REQUIRE(VALID_CONFIG(lcfg));
365	REQUIRE(lcfg->lctx == lctx);
366
367	/*
368	 * Ensure that lcfg->channellist_count == lctx->category_count.
369	 * They won't be equal if isc_log_usechannel has not been called
370	 * since any call to isc_log_registercategories.
371	 */
372	sync_channellist(lcfg);
373
374	WRLOCK(&lctx->lcfg_rwl);
375	old_cfg = lctx->logconfig;
376	lctx->logconfig = lcfg;
377	sync_highest_level(lctx, lcfg);
378	WRUNLOCK(&lctx->lcfg_rwl);
379
380	isc_logconfig_destroy(&old_cfg);
381}
382
383void
384isc_log_destroy(isc_log_t **lctxp) {
385	isc_log_t *lctx;
386	isc_logconfig_t *lcfg;
387	isc_mem_t *mctx;
388	isc_logmessage_t *message;
389
390	REQUIRE(lctxp != NULL && VALID_CONTEXT(*lctxp));
391
392	lctx = *lctxp;
393	*lctxp = NULL;
394	mctx = lctx->mctx;
395
396	/* Stop the logging as a first thing */
397	atomic_store_release(&lctx->debug_level, 0);
398	atomic_store_release(&lctx->highest_level, 0);
399	atomic_store_release(&lctx->dynamic, false);
400
401	WRLOCK(&lctx->lcfg_rwl);
402	lcfg = lctx->logconfig;
403	lctx->logconfig = NULL;
404	WRUNLOCK(&lctx->lcfg_rwl);
405
406	if (lcfg != NULL) {
407		isc_logconfig_destroy(&lcfg);
408	}
409
410	isc_rwlock_destroy(&lctx->lcfg_rwl);
411	isc_mutex_destroy(&lctx->lock);
412
413	while ((message = ISC_LIST_HEAD(lctx->messages)) != NULL) {
414		ISC_LIST_UNLINK(lctx->messages, message, link);
415
416		isc_mem_put(mctx, message,
417			    sizeof(*message) + strlen(message->text) + 1);
418	}
419
420	lctx->buffer[0] = '\0';
421	lctx->categories = NULL;
422	lctx->category_count = 0;
423	lctx->modules = NULL;
424	lctx->module_count = 0;
425	lctx->mctx = NULL;
426	lctx->magic = 0;
427
428	isc_mem_putanddetach(&mctx, lctx, sizeof(*lctx));
429}
430
431void
432isc_logconfig_destroy(isc_logconfig_t **lcfgp) {
433	isc_logconfig_t *lcfg;
434	isc_mem_t *mctx;
435	isc_logchannel_t *channel;
436	char *filename;
437	unsigned int i;
438
439	REQUIRE(lcfgp != NULL && VALID_CONFIG(*lcfgp));
440
441	lcfg = *lcfgp;
442	*lcfgp = NULL;
443
444	/*
445	 * This function cannot be called with a logconfig that is in
446	 * use by a log context.
447	 */
448	REQUIRE(lcfg->lctx != NULL);
449
450	RDLOCK(&lcfg->lctx->lcfg_rwl);
451	REQUIRE(lcfg->lctx->logconfig != lcfg);
452	RDUNLOCK(&lcfg->lctx->lcfg_rwl);
453
454	mctx = lcfg->lctx->mctx;
455
456	while ((channel = ISC_LIST_HEAD(lcfg->channels)) != NULL) {
457		ISC_LIST_UNLINK(lcfg->channels, channel, link);
458
459		if (channel->type == ISC_LOG_TOFILE) {
460			/*
461			 * The filename for the channel may have ultimately
462			 * started its life in user-land as a const string,
463			 * but in isc_log_createchannel it gets copied
464			 * into writable memory and is not longer truly const.
465			 */
466			DE_CONST(FILE_NAME(channel), filename);
467			isc_mem_free(mctx, filename);
468
469			if (FILE_STREAM(channel) != NULL) {
470				(void)fclose(FILE_STREAM(channel));
471			}
472		}
473
474		isc_mem_free(mctx, channel->name);
475		isc_mem_put(mctx, channel, sizeof(*channel));
476	}
477
478	for (i = 0; i < lcfg->channellist_count; i++) {
479		isc_logchannellist_t *item;
480		while ((item = ISC_LIST_HEAD(lcfg->channellists[i])) != NULL) {
481			ISC_LIST_UNLINK(lcfg->channellists[i], item, link);
482			isc_mem_put(mctx, item, sizeof(*item));
483		}
484	}
485
486	if (lcfg->channellist_count > 0) {
487		isc_mem_put(mctx, lcfg->channellists,
488			    lcfg->channellist_count *
489				    sizeof(ISC_LIST(isc_logchannellist_t)));
490	}
491
492	lcfg->dynamic = false;
493	if (lcfg->tag != NULL) {
494		isc_mem_free(lcfg->lctx->mctx, lcfg->tag);
495	}
496	lcfg->tag = NULL;
497	lcfg->highest_level = 0;
498	lcfg->duplicate_interval = 0;
499	lcfg->magic = 0;
500
501	isc_mem_put(mctx, lcfg, sizeof(*lcfg));
502}
503
504void
505isc_log_registercategories(isc_log_t *lctx, isc_logcategory_t categories[]) {
506	isc_logcategory_t *catp;
507
508	REQUIRE(VALID_CONTEXT(lctx));
509	REQUIRE(categories != NULL && categories[0].name != NULL);
510
511	/*
512	 * XXXDCL This somewhat sleazy situation of using the last pointer
513	 * in one category array to point to the next array exists because
514	 * this registration function returns void and I didn't want to have
515	 * change everything that used it by making it return an isc_result_t.
516	 * It would need to do that if it had to allocate memory to store
517	 * pointers to each array passed in.
518	 */
519	if (lctx->categories == NULL) {
520		lctx->categories = categories;
521	} else {
522		/*
523		 * Adjust the last (NULL) pointer of the already registered
524		 * categories to point to the incoming array.
525		 */
526		for (catp = lctx->categories; catp->name != NULL;) {
527			if (catp->id == UINT_MAX) {
528				/*
529				 * The name pointer points to the next array.
530				 * Ick.
531				 */
532				DE_CONST(catp->name, catp);
533			} else {
534				catp++;
535			}
536		}
537
538		catp->name = (void *)categories;
539		catp->id = UINT_MAX;
540	}
541
542	/*
543	 * Update the id number of the category with its new global id.
544	 */
545	for (catp = categories; catp->name != NULL; catp++) {
546		catp->id = lctx->category_count++;
547	}
548}
549
550isc_logcategory_t *
551isc_log_categorybyname(isc_log_t *lctx, const char *name) {
552	isc_logcategory_t *catp;
553
554	REQUIRE(VALID_CONTEXT(lctx));
555	REQUIRE(name != NULL);
556
557	for (catp = lctx->categories; catp->name != NULL;) {
558		if (catp->id == UINT_MAX) {
559			/*
560			 * catp is neither modified nor returned to the
561			 * caller, so removing its const qualifier is ok.
562			 */
563			DE_CONST(catp->name, catp);
564		} else {
565			if (strcmp(catp->name, name) == 0) {
566				return (catp);
567			}
568			catp++;
569		}
570	}
571
572	return (NULL);
573}
574
575void
576isc_log_registermodules(isc_log_t *lctx, isc_logmodule_t modules[]) {
577	isc_logmodule_t *modp;
578
579	REQUIRE(VALID_CONTEXT(lctx));
580	REQUIRE(modules != NULL && modules[0].name != NULL);
581
582	/*
583	 * XXXDCL This somewhat sleazy situation of using the last pointer
584	 * in one category array to point to the next array exists because
585	 * this registration function returns void and I didn't want to have
586	 * change everything that used it by making it return an isc_result_t.
587	 * It would need to do that if it had to allocate memory to store
588	 * pointers to each array passed in.
589	 */
590	if (lctx->modules == NULL) {
591		lctx->modules = modules;
592	} else {
593		/*
594		 * Adjust the last (NULL) pointer of the already registered
595		 * modules to point to the incoming array.
596		 */
597		for (modp = lctx->modules; modp->name != NULL;) {
598			if (modp->id == UINT_MAX) {
599				/*
600				 * The name pointer points to the next array.
601				 * Ick.
602				 */
603				DE_CONST(modp->name, modp);
604			} else {
605				modp++;
606			}
607		}
608
609		modp->name = (void *)modules;
610		modp->id = UINT_MAX;
611	}
612
613	/*
614	 * Update the id number of the module with its new global id.
615	 */
616	for (modp = modules; modp->name != NULL; modp++) {
617		modp->id = lctx->module_count++;
618	}
619}
620
621isc_logmodule_t *
622isc_log_modulebyname(isc_log_t *lctx, const char *name) {
623	isc_logmodule_t *modp;
624
625	REQUIRE(VALID_CONTEXT(lctx));
626	REQUIRE(name != NULL);
627
628	for (modp = lctx->modules; modp->name != NULL;) {
629		if (modp->id == UINT_MAX) {
630			/*
631			 * modp is neither modified nor returned to the
632			 * caller, so removing its const qualifier is ok.
633			 */
634			DE_CONST(modp->name, modp);
635		} else {
636			if (strcmp(modp->name, name) == 0) {
637				return (modp);
638			}
639			modp++;
640		}
641	}
642
643	return (NULL);
644}
645
646void
647isc_log_createchannel(isc_logconfig_t *lcfg, const char *name,
648		      unsigned int type, int level,
649		      const isc_logdestination_t *destination,
650		      unsigned int flags) {
651	isc_logchannel_t *channel;
652	isc_mem_t *mctx;
653	unsigned int permitted = ISC_LOG_PRINTALL | ISC_LOG_DEBUGONLY |
654				 ISC_LOG_BUFFERED | ISC_LOG_ISO8601 |
655				 ISC_LOG_UTC;
656
657	REQUIRE(VALID_CONFIG(lcfg));
658	REQUIRE(name != NULL);
659	REQUIRE(type == ISC_LOG_TOSYSLOG || type == ISC_LOG_TOFILE ||
660		type == ISC_LOG_TOFILEDESC || type == ISC_LOG_TONULL);
661	REQUIRE(destination != NULL || type == ISC_LOG_TONULL);
662	REQUIRE(level >= ISC_LOG_CRITICAL);
663	REQUIRE((flags & ~permitted) == 0);
664
665	/* XXXDCL find duplicate names? */
666
667	mctx = lcfg->lctx->mctx;
668
669	channel = isc_mem_get(mctx, sizeof(*channel));
670
671	channel->name = isc_mem_strdup(mctx, name);
672
673	channel->type = type;
674	channel->level = level;
675	channel->flags = flags;
676	ISC_LINK_INIT(channel, link);
677
678	switch (type) {
679	case ISC_LOG_TOSYSLOG:
680		FACILITY(channel) = destination->facility;
681		break;
682
683	case ISC_LOG_TOFILE:
684		/*
685		 * The file name is copied because greatest_version wants
686		 * to scribble on it, so it needs to be definitely in
687		 * writable memory.
688		 */
689		FILE_NAME(channel) = isc_mem_strdup(mctx,
690						    destination->file.name);
691		FILE_STREAM(channel) = NULL;
692		FILE_VERSIONS(channel) = destination->file.versions;
693		FILE_SUFFIX(channel) = destination->file.suffix;
694		FILE_MAXSIZE(channel) = destination->file.maximum_size;
695		FILE_MAXREACHED(channel) = false;
696		break;
697
698	case ISC_LOG_TOFILEDESC:
699		FILE_NAME(channel) = NULL;
700		FILE_STREAM(channel) = destination->file.stream;
701		FILE_MAXSIZE(channel) = 0;
702		FILE_VERSIONS(channel) = ISC_LOG_ROLLNEVER;
703		FILE_SUFFIX(channel) = isc_log_rollsuffix_increment;
704		break;
705
706	case ISC_LOG_TONULL:
707		/* Nothing. */
708		break;
709
710	default:
711		UNREACHABLE();
712	}
713
714	ISC_LIST_PREPEND(lcfg->channels, channel, link);
715
716	/*
717	 * If default_stderr was redefined, make the default category
718	 * point to the new default_stderr.
719	 */
720	if (strcmp(name, "default_stderr") == 0) {
721		default_channel.channel = channel;
722	}
723}
724
725isc_result_t
726isc_log_usechannel(isc_logconfig_t *lcfg, const char *name,
727		   const isc_logcategory_t *category,
728		   const isc_logmodule_t *module) {
729	isc_log_t *lctx;
730	isc_logchannel_t *channel;
731
732	REQUIRE(VALID_CONFIG(lcfg));
733	REQUIRE(name != NULL);
734
735	lctx = lcfg->lctx;
736
737	REQUIRE(category == NULL || category->id < lctx->category_count);
738	REQUIRE(module == NULL || module->id < lctx->module_count);
739
740	for (channel = ISC_LIST_HEAD(lcfg->channels); channel != NULL;
741	     channel = ISC_LIST_NEXT(channel, link))
742	{
743		if (strcmp(name, channel->name) == 0) {
744			break;
745		}
746	}
747
748	if (channel == NULL) {
749		return (ISC_R_NOTFOUND);
750	}
751
752	if (category != NULL) {
753		assignchannel(lcfg, category->id, module, channel);
754	} else {
755		/*
756		 * Assign to all categories.  Note that this includes
757		 * the default channel.
758		 */
759		for (size_t i = 0; i < lctx->category_count; i++) {
760			assignchannel(lcfg, i, module, channel);
761		}
762	}
763
764	/*
765	 * Update the highest logging level, if the current lcfg is in use.
766	 */
767	if (lcfg->lctx->logconfig == lcfg) {
768		sync_highest_level(lctx, lcfg);
769	}
770
771	return (ISC_R_SUCCESS);
772}
773
774void
775isc_log_write(isc_log_t *lctx, isc_logcategory_t *category,
776	      isc_logmodule_t *module, int level, const char *format, ...) {
777	va_list args;
778
779	/*
780	 * Contract checking is done in isc_log_doit().
781	 */
782
783	va_start(args, format);
784	isc_log_doit(lctx, category, module, level, false, format, args);
785	va_end(args);
786}
787
788void
789isc_log_vwrite(isc_log_t *lctx, isc_logcategory_t *category,
790	       isc_logmodule_t *module, int level, const char *format,
791	       va_list args) {
792	/*
793	 * Contract checking is done in isc_log_doit().
794	 */
795	isc_log_doit(lctx, category, module, level, false, format, args);
796}
797
798void
799isc_log_write1(isc_log_t *lctx, isc_logcategory_t *category,
800	       isc_logmodule_t *module, int level, const char *format, ...) {
801	va_list args;
802
803	/*
804	 * Contract checking is done in isc_log_doit().
805	 */
806
807	va_start(args, format);
808	isc_log_doit(lctx, category, module, level, true, format, args);
809	va_end(args);
810}
811
812void
813isc_log_vwrite1(isc_log_t *lctx, isc_logcategory_t *category,
814		isc_logmodule_t *module, int level, const char *format,
815		va_list args) {
816	/*
817	 * Contract checking is done in isc_log_doit().
818	 */
819	isc_log_doit(lctx, category, module, level, true, format, args);
820}
821
822void
823isc_log_setcontext(isc_log_t *lctx) {
824	isc_lctx = lctx;
825}
826
827void
828isc_log_setdebuglevel(isc_log_t *lctx, unsigned int level) {
829	REQUIRE(VALID_CONTEXT(lctx));
830
831	atomic_store_release(&lctx->debug_level, level);
832	/*
833	 * Close ISC_LOG_DEBUGONLY channels if level is zero.
834	 */
835	if (level == 0) {
836		RDLOCK(&lctx->lcfg_rwl);
837		isc_logconfig_t *lcfg = lctx->logconfig;
838		if (lcfg != NULL) {
839			LOCK(&lctx->lock);
840			for (isc_logchannel_t *channel =
841				     ISC_LIST_HEAD(lcfg->channels);
842			     channel != NULL;
843			     channel = ISC_LIST_NEXT(channel, link))
844			{
845				if (channel->type == ISC_LOG_TOFILE &&
846				    (channel->flags & ISC_LOG_DEBUGONLY) != 0 &&
847				    FILE_STREAM(channel) != NULL)
848				{
849					(void)fclose(FILE_STREAM(channel));
850					FILE_STREAM(channel) = NULL;
851				}
852			}
853			UNLOCK(&lctx->lock);
854		}
855		RDUNLOCK(&lctx->lcfg_rwl);
856	}
857}
858
859unsigned int
860isc_log_getdebuglevel(isc_log_t *lctx) {
861	REQUIRE(VALID_CONTEXT(lctx));
862
863	return (atomic_load_acquire(&lctx->debug_level));
864}
865
866void
867isc_log_setduplicateinterval(isc_logconfig_t *lcfg, unsigned int interval) {
868	REQUIRE(VALID_CONFIG(lcfg));
869
870	lcfg->duplicate_interval = interval;
871}
872
873unsigned int
874isc_log_getduplicateinterval(isc_logconfig_t *lcfg) {
875	REQUIRE(VALID_CONTEXT(lcfg));
876
877	return (lcfg->duplicate_interval);
878}
879
880void
881isc_log_settag(isc_logconfig_t *lcfg, const char *tag) {
882	REQUIRE(VALID_CONFIG(lcfg));
883
884	if (tag != NULL && *tag != '\0') {
885		if (lcfg->tag != NULL) {
886			isc_mem_free(lcfg->lctx->mctx, lcfg->tag);
887		}
888		lcfg->tag = isc_mem_strdup(lcfg->lctx->mctx, tag);
889	} else {
890		if (lcfg->tag != NULL) {
891			isc_mem_free(lcfg->lctx->mctx, lcfg->tag);
892		}
893		lcfg->tag = NULL;
894	}
895}
896
897char *
898isc_log_gettag(isc_logconfig_t *lcfg) {
899	REQUIRE(VALID_CONFIG(lcfg));
900
901	return (lcfg->tag);
902}
903
904/* XXXDCL NT  -- This interface will assuredly be changing. */
905void
906isc_log_opensyslog(const char *tag, int options, int facility) {
907	(void)openlog(tag, options, facility);
908}
909
910void
911isc_log_closefilelogs(isc_log_t *lctx) {
912	REQUIRE(VALID_CONTEXT(lctx));
913
914	RDLOCK(&lctx->lcfg_rwl);
915	isc_logconfig_t *lcfg = lctx->logconfig;
916	if (lcfg != NULL) {
917		LOCK(&lctx->lock);
918		for (isc_logchannel_t *channel = ISC_LIST_HEAD(lcfg->channels);
919		     channel != NULL; channel = ISC_LIST_NEXT(channel, link))
920		{
921			if (channel->type == ISC_LOG_TOFILE &&
922			    FILE_STREAM(channel) != NULL)
923			{
924				(void)fclose(FILE_STREAM(channel));
925				FILE_STREAM(channel) = NULL;
926			}
927		}
928		UNLOCK(&lctx->lock);
929	}
930	RDUNLOCK(&lctx->lcfg_rwl);
931}
932
933/****
934**** Internal functions
935****/
936
937static void
938assignchannel(isc_logconfig_t *lcfg, unsigned int category_id,
939	      const isc_logmodule_t *module, isc_logchannel_t *channel) {
940	isc_logchannellist_t *new_item;
941	isc_log_t *lctx;
942
943	REQUIRE(VALID_CONFIG(lcfg));
944
945	lctx = lcfg->lctx;
946
947	REQUIRE(category_id < lctx->category_count);
948	REQUIRE(module == NULL || module->id < lctx->module_count);
949	REQUIRE(channel != NULL);
950
951	/*
952	 * Ensure lcfg->channellist_count == lctx->category_count.
953	 */
954	sync_channellist(lcfg);
955
956	new_item = isc_mem_get(lctx->mctx, sizeof(*new_item));
957
958	new_item->channel = channel;
959	new_item->module = module;
960	ISC_LIST_INITANDPREPEND(lcfg->channellists[category_id], new_item,
961				link);
962
963	/*
964	 * Remember the highest logging level set by any channel in the
965	 * logging config, so isc_log_doit() can quickly return if the
966	 * message is too high to be logged by any channel.
967	 */
968	if (channel->type != ISC_LOG_TONULL) {
969		if (lcfg->highest_level < channel->level) {
970			lcfg->highest_level = channel->level;
971		}
972		if (channel->level == ISC_LOG_DYNAMIC) {
973			lcfg->dynamic = true;
974		}
975	}
976}
977
978/*
979 * This would ideally be part of isc_log_registercategories(), except then
980 * that function would have to return isc_result_t instead of void.
981 */
982static void
983sync_channellist(isc_logconfig_t *lcfg) {
984	unsigned int bytes;
985	isc_log_t *lctx;
986	void *lists;
987
988	REQUIRE(VALID_CONFIG(lcfg));
989
990	lctx = lcfg->lctx;
991
992	REQUIRE(lctx->category_count != 0);
993
994	if (lctx->category_count == lcfg->channellist_count) {
995		return;
996	}
997
998	bytes = lctx->category_count * sizeof(ISC_LIST(isc_logchannellist_t));
999
1000	lists = isc_mem_get(lctx->mctx, bytes);
1001
1002	memset(lists, 0, bytes);
1003
1004	if (lcfg->channellist_count != 0) {
1005		bytes = lcfg->channellist_count *
1006			sizeof(ISC_LIST(isc_logchannellist_t));
1007		memmove(lists, lcfg->channellists, bytes);
1008		isc_mem_put(lctx->mctx, lcfg->channellists, bytes);
1009	}
1010
1011	lcfg->channellists = lists;
1012	lcfg->channellist_count = lctx->category_count;
1013}
1014
1015static void
1016sync_highest_level(isc_log_t *lctx, isc_logconfig_t *lcfg) {
1017	atomic_store(&lctx->highest_level, lcfg->highest_level);
1018	atomic_store(&lctx->dynamic, lcfg->dynamic);
1019}
1020
1021static isc_result_t
1022greatest_version(isc_logfile_t *file, int versions, int *greatestp) {
1023	char *bname, *digit_end;
1024	const char *dirname;
1025	int version, greatest = -1;
1026	size_t bnamelen;
1027	isc_dir_t dir;
1028	isc_result_t result;
1029	char sep = '/';
1030#ifdef _WIN32
1031	char *bname2;
1032#endif /* ifdef _WIN32 */
1033
1034	/*
1035	 * It is safe to DE_CONST the file.name because it was copied
1036	 * with isc_mem_strdup().
1037	 */
1038	bname = strrchr(file->name, sep);
1039#ifdef _WIN32
1040	bname2 = strrchr(file->name, '\\');
1041	if ((bname != NULL && bname2 != NULL && bname2 > bname) ||
1042	    (bname == NULL && bname2 != NULL))
1043	{
1044		bname = bname2;
1045		sep = '\\';
1046	}
1047#endif /* ifdef _WIN32 */
1048	if (bname != NULL) {
1049		*bname++ = '\0';
1050		dirname = file->name;
1051	} else {
1052		DE_CONST(file->name, bname);
1053		dirname = ".";
1054	}
1055	bnamelen = strlen(bname);
1056
1057	isc_dir_init(&dir);
1058	result = isc_dir_open(&dir, dirname);
1059
1060	/*
1061	 * Replace the file separator if it was taken out.
1062	 */
1063	if (bname != file->name) {
1064		*(bname - 1) = sep;
1065	}
1066
1067	/*
1068	 * Return if the directory open failed.
1069	 */
1070	if (result != ISC_R_SUCCESS) {
1071		return (result);
1072	}
1073
1074	while (isc_dir_read(&dir) == ISC_R_SUCCESS) {
1075		if (dir.entry.length > bnamelen &&
1076		    strncmp(dir.entry.name, bname, bnamelen) == 0 &&
1077		    dir.entry.name[bnamelen] == '.')
1078		{
1079			version = strtol(&dir.entry.name[bnamelen + 1],
1080					 &digit_end, 10);
1081			/*
1082			 * Remove any backup files that exceed versions.
1083			 */
1084			if (*digit_end == '\0' && version >= versions) {
1085				result = isc_file_remove(dir.entry.name);
1086				if (result != ISC_R_SUCCESS &&
1087				    result != ISC_R_FILENOTFOUND)
1088				{
1089					syslog(LOG_ERR,
1090					       "unable to remove "
1091					       "log file '%s': %s",
1092					       dir.entry.name,
1093					       isc_result_totext(result));
1094				}
1095			} else if (*digit_end == '\0' && version > greatest) {
1096				greatest = version;
1097			}
1098		}
1099	}
1100	isc_dir_close(&dir);
1101
1102	*greatestp = greatest;
1103
1104	return (ISC_R_SUCCESS);
1105}
1106
1107static void
1108insert_sort(int64_t to_keep[], int64_t versions, int64_t version) {
1109	int i = 0;
1110	while (i < versions && version < to_keep[i]) {
1111		i++;
1112	}
1113	if (i == versions) {
1114		return;
1115	}
1116	if (i < versions - 1) {
1117		memmove(&to_keep[i + 1], &to_keep[i],
1118			sizeof(to_keep[0]) * (versions - i - 1));
1119	}
1120	to_keep[i] = version;
1121}
1122
1123static int64_t
1124last_to_keep(int64_t versions, isc_dir_t *dirp, char *bname, size_t bnamelen) {
1125	int64_t to_keep[ISC_LOG_MAX_VERSIONS] = { 0 };
1126	int64_t version = 0;
1127
1128	if (versions <= 0) {
1129		return (INT64_MAX);
1130	}
1131
1132	if (versions > ISC_LOG_MAX_VERSIONS) {
1133		versions = ISC_LOG_MAX_VERSIONS;
1134	}
1135	/*
1136	 * First we fill 'to_keep' structure using insertion sort
1137	 */
1138	memset(to_keep, 0, sizeof(to_keep));
1139	while (isc_dir_read(dirp) == ISC_R_SUCCESS) {
1140		char *digit_end = NULL;
1141		char *ename = NULL;
1142
1143		if (dirp->entry.length <= bnamelen ||
1144		    strncmp(dirp->entry.name, bname, bnamelen) != 0 ||
1145		    dirp->entry.name[bnamelen] != '.')
1146		{
1147			continue;
1148		}
1149
1150		ename = &dirp->entry.name[bnamelen + 1];
1151		version = strtoull(ename, &digit_end, 10);
1152		if (*digit_end == '\0') {
1153			insert_sort(to_keep, versions, version);
1154		}
1155	}
1156
1157	isc_dir_reset(dirp);
1158
1159	/*
1160	 * to_keep[versions - 1] is the last one we want to keep
1161	 */
1162	return (to_keep[versions - 1]);
1163}
1164
1165static isc_result_t
1166remove_old_tsversions(isc_logfile_t *file, int versions) {
1167	isc_result_t result;
1168	char *bname = NULL, *digit_end = NULL;
1169	const char *dirname = NULL;
1170	int64_t version, last = INT64_MAX;
1171	size_t bnamelen;
1172	isc_dir_t dir;
1173	char sep = '/';
1174#ifdef _WIN32
1175	char *bname2;
1176#endif /* ifdef _WIN32 */
1177	/*
1178	 * It is safe to DE_CONST the file.name because it was copied
1179	 * with isc_mem_strdup().
1180	 */
1181	bname = strrchr(file->name, sep);
1182#ifdef _WIN32
1183	bname2 = strrchr(file->name, '\\');
1184	if ((bname != NULL && bname2 != NULL && bname2 > bname) ||
1185	    (bname == NULL && bname2 != NULL))
1186	{
1187		bname = bname2;
1188		sep = '\\';
1189	}
1190#endif /* ifdef _WIN32 */
1191	if (bname != NULL) {
1192		*bname++ = '\0';
1193		dirname = file->name;
1194	} else {
1195		DE_CONST(file->name, bname);
1196		dirname = ".";
1197	}
1198	bnamelen = strlen(bname);
1199
1200	isc_dir_init(&dir);
1201	result = isc_dir_open(&dir, dirname);
1202
1203	/*
1204	 * Replace the file separator if it was taken out.
1205	 */
1206	if (bname != file->name) {
1207		*(bname - 1) = sep;
1208	}
1209
1210	/*
1211	 * Return if the directory open failed.
1212	 */
1213	if (result != ISC_R_SUCCESS) {
1214		return (result);
1215	}
1216
1217	last = last_to_keep(versions, &dir, bname, bnamelen);
1218
1219	/*
1220	 * Then we remove all files that we don't want to_keep
1221	 */
1222	while (isc_dir_read(&dir) == ISC_R_SUCCESS) {
1223		if (dir.entry.length > bnamelen &&
1224		    strncmp(dir.entry.name, bname, bnamelen) == 0 &&
1225		    dir.entry.name[bnamelen] == '.')
1226		{
1227			char *ename = &dir.entry.name[bnamelen + 1];
1228			version = strtoull(ename, &digit_end, 10);
1229			/*
1230			 * Remove any backup files that exceed versions.
1231			 */
1232			if (*digit_end == '\0' && version < last) {
1233				result = isc_file_remove(dir.entry.name);
1234				if (result != ISC_R_SUCCESS &&
1235				    result != ISC_R_FILENOTFOUND)
1236				{
1237					syslog(LOG_ERR,
1238					       "unable to remove "
1239					       "log file '%s': %s",
1240					       dir.entry.name,
1241					       isc_result_totext(result));
1242				}
1243			}
1244		}
1245	}
1246
1247	isc_dir_close(&dir);
1248
1249	return (ISC_R_SUCCESS);
1250}
1251
1252static isc_result_t
1253roll_increment(isc_logfile_t *file) {
1254	int i, n, greatest;
1255	char current[PATH_MAX + 1];
1256	char newpath[PATH_MAX + 1];
1257	const char *path;
1258	isc_result_t result = ISC_R_SUCCESS;
1259
1260	REQUIRE(file != NULL);
1261	REQUIRE(file->versions != 0);
1262
1263	path = file->name;
1264
1265	if (file->versions == ISC_LOG_ROLLINFINITE) {
1266		/*
1267		 * Find the first missing entry in the log file sequence.
1268		 */
1269		for (greatest = 0; greatest < INT_MAX; greatest++) {
1270			n = snprintf(current, sizeof(current), "%s.%u", path,
1271				     (unsigned)greatest);
1272			if (n >= (int)sizeof(current) || n < 0 ||
1273			    !isc_file_exists(current))
1274			{
1275				break;
1276			}
1277		}
1278	} else {
1279		/*
1280		 * Get the largest existing version and remove any
1281		 * version greater than the permitted version.
1282		 */
1283		result = greatest_version(file, file->versions, &greatest);
1284		if (result != ISC_R_SUCCESS) {
1285			return (result);
1286		}
1287
1288		/*
1289		 * Increment if greatest is not the actual maximum value.
1290		 */
1291		if (greatest < file->versions - 1) {
1292			greatest++;
1293		}
1294	}
1295
1296	for (i = greatest; i > 0; i--) {
1297		result = ISC_R_SUCCESS;
1298		n = snprintf(current, sizeof(current), "%s.%u", path,
1299			     (unsigned)(i - 1));
1300		if (n >= (int)sizeof(current) || n < 0) {
1301			result = ISC_R_NOSPACE;
1302		}
1303		if (result == ISC_R_SUCCESS) {
1304			n = snprintf(newpath, sizeof(newpath), "%s.%u", path,
1305				     (unsigned)i);
1306			if (n >= (int)sizeof(newpath) || n < 0) {
1307				result = ISC_R_NOSPACE;
1308			}
1309		}
1310		if (result == ISC_R_SUCCESS) {
1311			result = isc_file_rename(current, newpath);
1312		}
1313		if (result != ISC_R_SUCCESS && result != ISC_R_FILENOTFOUND) {
1314			syslog(LOG_ERR,
1315			       "unable to rename log file '%s.%u' to "
1316			       "'%s.%u': %s",
1317			       path, i - 1, path, i, isc_result_totext(result));
1318		}
1319	}
1320
1321	n = snprintf(newpath, sizeof(newpath), "%s.0", path);
1322	if (n >= (int)sizeof(newpath) || n < 0) {
1323		result = ISC_R_NOSPACE;
1324	} else {
1325		result = isc_file_rename(path, newpath);
1326	}
1327	if (result != ISC_R_SUCCESS && result != ISC_R_FILENOTFOUND) {
1328		syslog(LOG_ERR, "unable to rename log file '%s' to '%s.0': %s",
1329		       path, path, isc_result_totext(result));
1330	}
1331
1332	return (ISC_R_SUCCESS);
1333}
1334
1335static isc_result_t
1336roll_timestamp(isc_logfile_t *file) {
1337	int n;
1338	char newts[PATH_MAX + 1];
1339	char newpath[PATH_MAX + 1];
1340	const char *path;
1341	isc_time_t now;
1342	isc_result_t result = ISC_R_SUCCESS;
1343
1344	REQUIRE(file != NULL);
1345	REQUIRE(file->versions != 0);
1346
1347	path = file->name;
1348
1349	/*
1350	 * First find all the logfiles and remove the oldest ones
1351	 * Save one fewer than file->versions because we'll be renaming
1352	 * the existing file to a timestamped version after this.
1353	 */
1354	if (file->versions != ISC_LOG_ROLLINFINITE) {
1355		remove_old_tsversions(file, file->versions - 1);
1356	}
1357
1358	/* Then just rename the current logfile */
1359	isc_time_now(&now);
1360	isc_time_formatshorttimestamp(&now, newts, PATH_MAX + 1);
1361	n = snprintf(newpath, sizeof(newpath), "%s.%s", path, newts);
1362	if (n >= (int)sizeof(newpath) || n < 0) {
1363		result = ISC_R_NOSPACE;
1364	} else {
1365		result = isc_file_rename(path, newpath);
1366	}
1367	if (result != ISC_R_SUCCESS && result != ISC_R_FILENOTFOUND) {
1368		syslog(LOG_ERR, "unable to rename log file '%s' to '%s.0': %s",
1369		       path, path, isc_result_totext(result));
1370	}
1371
1372	return (ISC_R_SUCCESS);
1373}
1374
1375isc_result_t
1376isc_logfile_roll(isc_logfile_t *file) {
1377	isc_result_t result;
1378
1379	REQUIRE(file != NULL);
1380
1381	/*
1382	 * Do nothing (not even excess version trimming) if ISC_LOG_ROLLNEVER
1383	 * is specified.  Apparently complete external control over the log
1384	 * files is desired.
1385	 */
1386	if (file->versions == ISC_LOG_ROLLNEVER) {
1387		return (ISC_R_SUCCESS);
1388	} else if (file->versions == 0) {
1389		result = isc_file_remove(file->name);
1390		if (result != ISC_R_SUCCESS && result != ISC_R_FILENOTFOUND) {
1391			syslog(LOG_ERR, "unable to remove log file '%s': %s",
1392			       file->name, isc_result_totext(result));
1393		}
1394		return (ISC_R_SUCCESS);
1395	}
1396
1397	switch (file->suffix) {
1398	case isc_log_rollsuffix_increment:
1399		return (roll_increment(file));
1400	case isc_log_rollsuffix_timestamp:
1401		return (roll_timestamp(file));
1402	default:
1403		return (ISC_R_UNEXPECTED);
1404	}
1405}
1406
1407static isc_result_t
1408isc_log_open(isc_logchannel_t *channel) {
1409	struct stat statbuf;
1410	bool regular_file;
1411	bool roll = false;
1412	isc_result_t result = ISC_R_SUCCESS;
1413	const char *path;
1414
1415	REQUIRE(channel->type == ISC_LOG_TOFILE);
1416	REQUIRE(FILE_STREAM(channel) == NULL);
1417
1418	path = FILE_NAME(channel);
1419
1420	REQUIRE(path != NULL && *path != '\0');
1421
1422	/*
1423	 * Determine type of file; only regular files will be
1424	 * version renamed, and only if the base file exists
1425	 * and either has no size limit or has reached its size limit.
1426	 */
1427	if (stat(path, &statbuf) == 0) {
1428		regular_file = S_ISREG(statbuf.st_mode) ? true : false;
1429		/* XXXDCL if not regular_file complain? */
1430		if ((FILE_MAXSIZE(channel) == 0 &&
1431		     FILE_VERSIONS(channel) != ISC_LOG_ROLLNEVER) ||
1432		    (FILE_MAXSIZE(channel) > 0 &&
1433		     statbuf.st_size >= FILE_MAXSIZE(channel)))
1434		{
1435			roll = regular_file;
1436		}
1437	} else if (errno == ENOENT) {
1438		regular_file = true;
1439		POST(regular_file);
1440	} else {
1441		result = ISC_R_INVALIDFILE;
1442	}
1443
1444	/*
1445	 * Version control.
1446	 */
1447	if (result == ISC_R_SUCCESS && roll) {
1448		if (FILE_VERSIONS(channel) == ISC_LOG_ROLLNEVER) {
1449			return (ISC_R_MAXSIZE);
1450		}
1451		result = isc_logfile_roll(&channel->destination.file);
1452		if (result != ISC_R_SUCCESS) {
1453			if ((channel->flags & ISC_LOG_OPENERR) == 0) {
1454				syslog(LOG_ERR,
1455				       "isc_log_open: isc_logfile_roll '%s' "
1456				       "failed: %s",
1457				       FILE_NAME(channel),
1458				       isc_result_totext(result));
1459				channel->flags |= ISC_LOG_OPENERR;
1460			}
1461			return (result);
1462		}
1463	}
1464
1465	result = isc_stdio_open(path, "a", &FILE_STREAM(channel));
1466
1467	return (result);
1468}
1469
1470ISC_NO_SANITIZE_THREAD bool
1471isc_log_wouldlog(isc_log_t *lctx, int level) {
1472	/*
1473	 * Try to avoid locking the mutex for messages which can't
1474	 * possibly be logged to any channels -- primarily debugging
1475	 * messages that the debug level is not high enough to print.
1476	 *
1477	 * If the level is (mathematically) less than or equal to the
1478	 * highest_level, or if there is a dynamic channel and the level is
1479	 * less than or equal to the debug level, the main loop must be
1480	 * entered to see if the message should really be output.
1481	 */
1482	if (lctx == NULL) {
1483		return (false);
1484	}
1485
1486	int highest_level = atomic_load_acquire(&lctx->highest_level);
1487	if (level <= highest_level) {
1488		return (true);
1489	}
1490	if (atomic_load_acquire(&lctx->dynamic)) {
1491		int debug_level = atomic_load_acquire(&lctx->debug_level);
1492		if (level <= debug_level) {
1493			return (true);
1494		}
1495	}
1496
1497	return (false);
1498}
1499
1500static void
1501isc_log_doit(isc_log_t *lctx, isc_logcategory_t *category,
1502	     isc_logmodule_t *module, int level, bool write_once,
1503	     const char *format, va_list args) {
1504	int syslog_level;
1505	const char *time_string;
1506	char local_time[64];
1507	char iso8601z_string[64];
1508	char iso8601l_string[64];
1509	char level_string[24] = { 0 };
1510	struct stat statbuf;
1511	bool matched = false;
1512	bool printtime, iso8601, utc, printtag, printcolon;
1513	bool printcategory, printmodule, printlevel, buffered;
1514	isc_logchannel_t *channel;
1515	isc_logchannellist_t *category_channels;
1516	isc_result_t result;
1517
1518	REQUIRE(lctx == NULL || VALID_CONTEXT(lctx));
1519	REQUIRE(category != NULL);
1520	REQUIRE(module != NULL);
1521	REQUIRE(level != ISC_LOG_DYNAMIC);
1522	REQUIRE(format != NULL);
1523
1524	/*
1525	 * Programs can use libraries that use this logging code without
1526	 * wanting to do any logging, thus the log context is allowed to
1527	 * be non-existent.
1528	 */
1529	if (lctx == NULL) {
1530		return;
1531	}
1532
1533	REQUIRE(category->id < lctx->category_count);
1534	REQUIRE(module->id < lctx->module_count);
1535
1536	if (!isc_log_wouldlog(lctx, level)) {
1537		return;
1538	}
1539
1540	local_time[0] = '\0';
1541	iso8601l_string[0] = '\0';
1542	iso8601z_string[0] = '\0';
1543
1544	RDLOCK(&lctx->lcfg_rwl);
1545	LOCK(&lctx->lock);
1546
1547	lctx->buffer[0] = '\0';
1548
1549	isc_logconfig_t *lcfg = lctx->logconfig;
1550
1551	category_channels = ISC_LIST_HEAD(lcfg->channellists[category->id]);
1552
1553	/*
1554	 * XXXDCL add duplicate filtering? (To not write multiple times
1555	 * to the same source via various channels).
1556	 */
1557	do {
1558		/*
1559		 * If the channel list end was reached and a match was
1560		 * made, everything is finished.
1561		 */
1562		if (category_channels == NULL && matched) {
1563			break;
1564		}
1565
1566		if (category_channels == NULL && !matched &&
1567		    category_channels != ISC_LIST_HEAD(lcfg->channellists[0]))
1568		{
1569			/*
1570			 * No category/module pair was explicitly
1571			 * configured. Try the category named "default".
1572			 */
1573			category_channels =
1574				ISC_LIST_HEAD(lcfg->channellists[0]);
1575		}
1576
1577		if (category_channels == NULL && !matched) {
1578			/*
1579			 * No matching module was explicitly configured
1580			 * for the category named "default".  Use the
1581			 * internal default channel.
1582			 */
1583			category_channels = &default_channel;
1584		}
1585
1586		if (category_channels->module != NULL &&
1587		    category_channels->module != module)
1588		{
1589			category_channels = ISC_LIST_NEXT(category_channels,
1590							  link);
1591			continue;
1592		}
1593
1594		matched = true;
1595
1596		channel = category_channels->channel;
1597		category_channels = ISC_LIST_NEXT(category_channels, link);
1598
1599		int_fast32_t dlevel = atomic_load_acquire(&lctx->debug_level);
1600		if (((channel->flags & ISC_LOG_DEBUGONLY) != 0) && dlevel == 0)
1601		{
1602			continue;
1603		}
1604
1605		if (channel->level == ISC_LOG_DYNAMIC) {
1606			if (dlevel < level) {
1607				continue;
1608			}
1609		} else if (channel->level < level) {
1610			continue;
1611		}
1612
1613		if ((channel->flags & ISC_LOG_PRINTTIME) != 0 &&
1614		    local_time[0] == '\0')
1615		{
1616			isc_time_t isctime;
1617
1618			TIME_NOW(&isctime);
1619
1620			isc_time_formattimestamp(&isctime, local_time,
1621						 sizeof(local_time));
1622			isc_time_formatISO8601ms(&isctime, iso8601z_string,
1623						 sizeof(iso8601z_string));
1624			isc_time_formatISO8601Lms(&isctime, iso8601l_string,
1625						  sizeof(iso8601l_string));
1626		}
1627
1628		if ((channel->flags & ISC_LOG_PRINTLEVEL) != 0 &&
1629		    level_string[0] == '\0')
1630		{
1631			if (level < ISC_LOG_CRITICAL) {
1632				snprintf(level_string, sizeof(level_string),
1633					 "level %d: ", level);
1634			} else if (level > ISC_LOG_DYNAMIC) {
1635				snprintf(level_string, sizeof(level_string),
1636					 "%s %d: ", log_level_strings[0],
1637					 level);
1638			} else {
1639				snprintf(level_string, sizeof(level_string),
1640					 "%s: ", log_level_strings[-level]);
1641			}
1642		}
1643
1644		/*
1645		 * Only format the message once.
1646		 */
1647		if (lctx->buffer[0] == '\0') {
1648			(void)vsnprintf(lctx->buffer, sizeof(lctx->buffer),
1649					format, args);
1650
1651			/*
1652			 * Check for duplicates.
1653			 */
1654			if (write_once) {
1655				isc_logmessage_t *message, *next;
1656				isc_time_t oldest;
1657				isc_interval_t interval;
1658				size_t size;
1659
1660				isc_interval_set(&interval,
1661						 lcfg->duplicate_interval, 0);
1662
1663				/*
1664				 * 'oldest' is the age of the oldest
1665				 * messages which fall within the
1666				 * duplicate_interval range.
1667				 */
1668				TIME_NOW(&oldest);
1669				if (isc_time_subtract(&oldest, &interval,
1670						      &oldest) != ISC_R_SUCCESS)
1671				{
1672					/*
1673					 * Can't effectively do the
1674					 * checking without having a
1675					 * valid time.
1676					 */
1677					message = NULL;
1678				} else {
1679					message = ISC_LIST_HEAD(lctx->messages);
1680				}
1681
1682				while (message != NULL) {
1683					if (isc_time_compare(&message->time,
1684							     &oldest) < 0)
1685					{
1686						/*
1687						 * This message is older
1688						 * than the
1689						 * duplicate_interval,
1690						 * so it should be
1691						 * dropped from the
1692						 * history.
1693						 *
1694						 * Setting the interval
1695						 * to be to be longer
1696						 * will obviously not
1697						 * cause the expired
1698						 * message to spring
1699						 * back into existence.
1700						 */
1701						next = ISC_LIST_NEXT(message,
1702								     link);
1703
1704						ISC_LIST_UNLINK(lctx->messages,
1705								message, link);
1706
1707						isc_mem_put(
1708							lctx->mctx, message,
1709							sizeof(*message) + 1 +
1710								strlen(message->text));
1711
1712						message = next;
1713						continue;
1714					}
1715
1716					/*
1717					 * This message is in the
1718					 * duplicate filtering interval
1719					 * ...
1720					 */
1721					if (strcmp(lctx->buffer,
1722						   message->text) == 0)
1723					{
1724						/*
1725						 * ... and it is a
1726						 * duplicate. Unlock the
1727						 * mutex and get the
1728						 * hell out of Dodge.
1729						 */
1730						goto unlock;
1731					}
1732
1733					message = ISC_LIST_NEXT(message, link);
1734				}
1735
1736				/*
1737				 * It wasn't in the duplicate interval,
1738				 * so add it to the message list.
1739				 */
1740				size = sizeof(isc_logmessage_t) +
1741				       strlen(lctx->buffer) + 1;
1742				message = isc_mem_get(lctx->mctx, size);
1743				message->text = (char *)(message + 1);
1744				size -= sizeof(isc_logmessage_t);
1745				strlcpy(message->text, lctx->buffer, size);
1746				TIME_NOW(&message->time);
1747				ISC_LINK_INIT(message, link);
1748				ISC_LIST_APPEND(lctx->messages, message, link);
1749			}
1750		}
1751
1752		utc = ((channel->flags & ISC_LOG_UTC) != 0);
1753		iso8601 = ((channel->flags & ISC_LOG_ISO8601) != 0);
1754		printtime = ((channel->flags & ISC_LOG_PRINTTIME) != 0);
1755		printtag = ((channel->flags &
1756			     (ISC_LOG_PRINTTAG | ISC_LOG_PRINTPREFIX)) != 0 &&
1757			    lcfg->tag != NULL);
1758		printcolon = ((channel->flags & ISC_LOG_PRINTTAG) != 0 &&
1759			      lcfg->tag != NULL);
1760		printcategory = ((channel->flags & ISC_LOG_PRINTCATEGORY) != 0);
1761		printmodule = ((channel->flags & ISC_LOG_PRINTMODULE) != 0);
1762		printlevel = ((channel->flags & ISC_LOG_PRINTLEVEL) != 0);
1763		buffered = ((channel->flags & ISC_LOG_BUFFERED) != 0);
1764
1765		if (printtime) {
1766			if (iso8601) {
1767				if (utc) {
1768					time_string = iso8601z_string;
1769				} else {
1770					time_string = iso8601l_string;
1771				}
1772			} else {
1773				time_string = local_time;
1774			}
1775		} else {
1776			time_string = "";
1777		}
1778
1779		switch (channel->type) {
1780		case ISC_LOG_TOFILE:
1781			if (FILE_MAXREACHED(channel)) {
1782				/*
1783				 * If the file can be rolled, OR
1784				 * If the file no longer exists, OR
1785				 * If the file is less than the maximum
1786				 * size, (such as if it had been renamed
1787				 * and a new one touched, or it was
1788				 * truncated in place)
1789				 * ... then close it to trigger
1790				 * reopening.
1791				 */
1792				if (FILE_VERSIONS(channel) !=
1793					    ISC_LOG_ROLLNEVER ||
1794				    (stat(FILE_NAME(channel), &statbuf) != 0 &&
1795				     errno == ENOENT) ||
1796				    statbuf.st_size < FILE_MAXSIZE(channel))
1797				{
1798					(void)fclose(FILE_STREAM(channel));
1799					FILE_STREAM(channel) = NULL;
1800					FILE_MAXREACHED(channel) = false;
1801				} else {
1802					/*
1803					 * Eh, skip it.
1804					 */
1805					break;
1806				}
1807			}
1808
1809			if (FILE_STREAM(channel) == NULL) {
1810				result = isc_log_open(channel);
1811				if (result != ISC_R_SUCCESS &&
1812				    result != ISC_R_MAXSIZE &&
1813				    (channel->flags & ISC_LOG_OPENERR) == 0)
1814				{
1815					syslog(LOG_ERR,
1816					       "isc_log_open '%s' "
1817					       "failed: %s",
1818					       FILE_NAME(channel),
1819					       isc_result_totext(result));
1820					channel->flags |= ISC_LOG_OPENERR;
1821				}
1822				if (result != ISC_R_SUCCESS) {
1823					break;
1824				}
1825				channel->flags &= ~ISC_LOG_OPENERR;
1826			}
1827			FALLTHROUGH;
1828
1829		case ISC_LOG_TOFILEDESC:
1830			fprintf(FILE_STREAM(channel), "%s%s%s%s%s%s%s%s%s%s\n",
1831				printtime ? time_string : "",
1832				printtime ? " " : "", printtag ? lcfg->tag : "",
1833				printcolon ? ": " : "",
1834				printcategory ? category->name : "",
1835				printcategory ? ": " : "",
1836				printmodule ? (module != NULL ? module->name
1837							      : "no_module")
1838					    : "",
1839				printmodule ? ": " : "",
1840				printlevel ? level_string : "", lctx->buffer);
1841
1842			if (!buffered) {
1843				fflush(FILE_STREAM(channel));
1844			}
1845
1846			/*
1847			 * If the file now exceeds its maximum size
1848			 * threshold, note it so that it will not be
1849			 * logged to any more.
1850			 */
1851			if (FILE_MAXSIZE(channel) > 0) {
1852				INSIST(channel->type == ISC_LOG_TOFILE);
1853
1854				/* XXXDCL NT fstat/fileno */
1855				/* XXXDCL complain if fstat fails? */
1856				if (fstat(fileno(FILE_STREAM(channel)),
1857					  &statbuf) >= 0 &&
1858				    statbuf.st_size > FILE_MAXSIZE(channel))
1859				{
1860					FILE_MAXREACHED(channel) = true;
1861				}
1862			}
1863
1864			break;
1865
1866		case ISC_LOG_TOSYSLOG:
1867			if (level > 0) {
1868				syslog_level = LOG_DEBUG;
1869			} else if (level < ISC_LOG_CRITICAL) {
1870				syslog_level = LOG_CRIT;
1871			} else {
1872				syslog_level = syslog_map[-level];
1873			}
1874
1875			(void)syslog(
1876				FACILITY(channel) | syslog_level,
1877				"%s%s%s%s%s%s%s%s%s%s",
1878				printtime ? time_string : "",
1879				printtime ? " " : "", printtag ? lcfg->tag : "",
1880				printcolon ? ": " : "",
1881				printcategory ? category->name : "",
1882				printcategory ? ": " : "",
1883				printmodule ? (module != NULL ? module->name
1884							      : "no_module")
1885					    : "",
1886				printmodule ? ": " : "",
1887				printlevel ? level_string : "", lctx->buffer);
1888			break;
1889
1890		case ISC_LOG_TONULL:
1891			break;
1892		}
1893	} while (1);
1894
1895unlock:
1896	UNLOCK(&lctx->lock);
1897	RDUNLOCK(&lctx->lcfg_rwl);
1898}
1899