summaryrefslogtreecommitdiffstats
path: root/tools/perf/util/config.c
blob: 658170b8dcef73ebeadf91c1f7cfd24a62f14b95 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
// SPDX-License-Identifier: GPL-2.0
/*
 * config.c
 *
 * Helper functions for parsing config items.
 * Originally copied from GIT source.
 *
 * Copyright (C) Linus Torvalds, 2005
 * Copyright (C) Johannes Schindelin, 2005
 *
 */
#include <errno.h>
#include <sys/param.h>
#include "cache.h"
#include "callchain.h"
#include <subcmd/exec-cmd.h>
#include "util/event.h"  /* proc_map_timeout */
#include "util/hist.h"  /* perf_hist_config */
#include "util/llvm-utils.h"   /* perf_llvm_config */
#include "util/stat.h"  /* perf_stat__set_big_num */
#include "util/evsel.h"  /* evsel__hw_names, evsel__use_bpf_counters */
#include "build-id.h"
#include "debug.h"
#include "config.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/string.h>
#include <linux/zalloc.h>
#include <linux/ctype.h>

#define MAXNAME (256)

#define DEBUG_CACHE_DIR ".debug"


char buildid_dir[MAXPATHLEN]; /* root dir for buildid, binary cache */

static FILE *config_file;
static const char *config_file_name;
static int config_linenr;
static int config_file_eof;
static struct perf_config_set *config_set;

const char *config_exclusive_filename;

static int get_next_char(void)
{
	int c;
	FILE *f;

	c = '\n';
	if ((f = config_file) != NULL) {
		c = fgetc(f);
		if (c == '\r') {
			/* DOS like systems */
			c = fgetc(f);
			if (c != '\n') {
				ungetc(c, f);
				c = '\r';
			}
		}
		if (c == '\n')
			config_linenr++;
		if (c == EOF) {
			config_file_eof = 1;
			c = '\n';
		}
	}
	return c;
}

static char *parse_value(void)
{
	static char value[1024];
	int quote = 0, comment = 0, space = 0;
	size_t len = 0;

	for (;;) {
		int c = get_next_char();

		if (len >= sizeof(value) - 1)
			return NULL;
		if (c == '\n') {
			if (quote)
				return NULL;
			value[len] = 0;
			return value;
		}
		if (comment)
			continue;
		if (isspace(c) && !quote) {
			space = 1;
			continue;
		}
		if (!quote) {
			if (c == ';' || c == '#') {
				comment = 1;
				continue;
			}
		}
		if (space) {
			if (len)
				value[len++] = ' ';
			space = 0;
		}
		if (c == '\\') {
			c = get_next_char();
			switch (c) {
			case '\n':
				continue;
			case 't':
				c = '\t';
				break;
			case 'b':
				c = '\b';
				break;
			case 'n':
				c = '\n';
				break;
			/* Some characters escape as themselves */
			case '\\': case '"':
				break;
			/* Reject unknown escape sequences */
			default:
				return NULL;
			}
			value[len++] = c;
			continue;
		}
		if (c == '"') {
			quote = 1-quote;
			continue;
		}
		value[len++] = c;
	}
}

static inline int iskeychar(int c)
{
	return isalnum(c) || c == '-' || c == '_';
}

static int get_value(config_fn_t fn, void *data, char *name, unsigned int len)
{
	int c;
	char *value;

	/* Get the full name */
	for (;;) {
		c = get_next_char();
		if (config_file_eof)
			break;
		if (!iskeychar(c))
			break;
		name[len++] = c;
		if (len >= MAXNAME)
			return -1;
	}
	name[len] = 0;
	while (c == ' ' || c == '\t')
		c = get_next_char();

	value = NULL;
	if (c != '\n') {
		if (c != '=')
			return -1;
		value = parse_value();
		if (!value)
			return -1;
	}
	return fn(name, value, data);
}

static int get_extended_base_var(char *name, int baselen, int c)
{
	do {
		if (c == '\n')
			return -1;
		c = get_next_char();
	} while (isspace(c));

	/* We require the format to be '[base "extension"]' */
	if (c != '"')
		return -1;
	name[baselen++] = '.';

	for (;;) {
		int ch = get_next_char();

		if (ch == '\n')
			return -1;
		if (ch == '"')
			break;
		if (ch == '\\') {
			ch = get_next_char();
			if (ch == '\n')
				return -1;
		}
		name[baselen++] = ch;
		if (baselen > MAXNAME / 2)
			return -1;
	}

	/* Final ']' */
	if (get_next_char() != ']')
		return -1;
	return baselen;
}

static int get_base_var(char *name)
{
	int baselen = 0;

	for (;;) {
		int c = get_next_char();
		if (config_file_eof)
			return -1;
		if (c == ']')
			return baselen;
		if (isspace(c))
			return get_extended_base_var(name, baselen, c);
		if (!iskeychar(c) && c != '.')
			return -1;
		if (baselen > MAXNAME / 2)
			return -1;
		name[baselen++] = tolower(c);
	}
}

static int perf_parse_file(config_fn_t fn, void *data)
{
	int comment = 0;
	int baselen = 0;
	static char var[MAXNAME];

	/* U+FEFF Byte Order Mark in UTF8 */
	static const unsigned char *utf8_bom = (unsigned char *) "\xef\xbb\xbf";
	const unsigned char *bomptr = utf8_bom;

	for (;;) {
		int line, c = get_next_char();

		if (bomptr && *bomptr) {
			/* We are at the file beginning; skip UTF8-encoded BOM
			 * if present. Sane editors won't put this in on their
			 * own, but e.g. Windows Notepad will do it happily. */
			if ((unsigned char) c == *bomptr) {
				bomptr++;
				continue;
			} else {
				/* Do not tolerate partial BOM. */
				if (bomptr != utf8_bom)
					break;
				/* No BOM at file beginning. Cool. */
				bomptr = NULL;
			}
		}
		if (c == '\n') {
			if (config_file_eof)
				return 0;
			comment = 0;
			continue;
		}
		if (comment || isspace(c))
			continue;
		if (c == '#' || c == ';') {
			comment = 1;
			continue;
		}
		if (c == '[') {
			baselen = get_base_var(var);
			if (baselen <= 0)
				break;
			var[baselen++] = '.';
			var[baselen] = 0;
			continue;
		}
		if (!isalpha(c))
			break;
		var[baselen] = tolower(c);

		/*
		 * The get_value function might or might not reach the '\n',
		 * so saving the current line number for error reporting.
		 */
		line = config_linenr;
		if (get_value(fn, data, var, baselen+1) < 0) {
			config_linenr = line;
			break;
		}
	}
	pr_err("bad config file line %d in %s\n", config_linenr, config_file_name);
	return -1;
}

static int parse_unit_factor(const char *end, unsigned long *val)
{
	if (!*end)
		return 1;
	else if (!strcasecmp(end, "k")) {
		*val *= 1024;
		return 1;
	}
	else if (!strcasecmp(end, "m")) {
		*val *= 1024 * 1024;
		return 1;
	}
	else if (!strcasecmp(end, "g")) {
		*val *= 1024 * 1024 * 1024;
		return 1;
	}
	return 0;
}

static int perf_parse_llong(const char *value, long long *ret)
{
	if (value && *value) {
		char *end;
		long long val = strtoll(value, &end, 0);
		unsigned long factor = 1;

		if (!parse_unit_factor(end, &factor))
			return 0;
		*ret = val * factor;
		return 1;
	}
	return 0;
}

static int perf_parse_long(const char *value, long *ret)
{
	if (value && *value) {
		char *end;
		long val = strtol(value, &end, 0);
		unsigned long factor = 1;
		if (!parse_unit_factor(end, &factor))
			return 0;
		*ret = val * factor;
		return 1;
	}
	return 0;
}

static void bad_config(const char *name)
{
	if (config_file_name)
		pr_warning("bad config value for '%s' in %s, ignoring...\n", name, config_file_name);
	else
		pr_warning("bad config value for '%s', ignoring...\n", name);
}

int perf_config_u64(u64 *dest, const char *name, const char *value)
{
	long long ret = 0;

	if (!perf_parse_llong(value, &ret)) {
		bad_config(name);
		return -1;
	}

	*dest = ret;
	return 0;
}

int perf_config_int(int *dest, const char *name, const char *value)
{
	long ret = 0;
	if (!perf_parse_long(value, &ret)) {
		bad_config(name);
		return -1;
	}
	*dest = ret;
	return 0;
}

int perf_config_u8(u8 *dest, const char *name, const char *value)
{
	long ret = 0;

	if (!perf_parse_long(value, &ret)) {
		bad_config(name);
		return -1;
	}
	*dest = ret;
	return 0;
}

static int perf_config_bool_or_int(const char *name, const char *value, int *is_bool)
{
	int ret;

	*is_bool = 1;
	if (!value)
		return 1;
	if (!*value)
		return 0;
	if (!strcasecmp(value, "true") || !strcasecmp(value, "yes") || !strcasecmp(value, "on"))
		return 1;
	if (!strcasecmp(value, "false") || !strcasecmp(value, "no") || !strcasecmp(value, "off"))
		return 0;
	*is_bool = 0;
	return perf_config_int(&ret, name, value) < 0 ? -1 : ret;
}

int perf_config_bool(const char *name, const char *value)
{
	int discard;
	return !!perf_config_bool_or_int(name, value, &discard);
}

static const char *perf_config_dirname(const char *name, const char *value)
{
	if (!name)
		return NULL;
	return value;
}

static int perf_buildid_config(const char *var, const char *value)
{
	/* same dir for all commands */
	if (!strcmp(var, "buildid.dir")) {
		const char *dir = perf_config_dirname(var, value);

		if (!dir) {
			pr_err("Invalid buildid directory!\n");
			return -1;
		}
		strncpy(buildid_dir, dir, MAXPATHLEN-1);
		buildid_dir[MAXPATHLEN-1] = '\0';
	}

	return 0;
}

static int perf_default_core_config(const char *var __maybe_unused,
				    const char *value __maybe_unused)
{
	if (!strcmp(var, "core.proc-map-timeout"))
		proc_map_timeout = strtoul(value, NULL, 10);

	/* Add other config variables here. */
	return 0;
}

static int perf_ui_config(const char *var, const char *value)
{
	/* Add other config variables here. */
	if (!strcmp(var, "ui.show-headers"))
		symbol_conf.show_hist_headers = perf_config_bool(var, value);

	return 0;
}

static int perf_stat_config(const char *var, const char *value)
{
	if (!strcmp(var, "stat.big-num"))
		perf_stat__set_big_num(perf_config_bool(var, value));

	if (!strcmp(var, "stat.no-csv-summary"))
		perf_stat__set_no_csv_summary(perf_config_bool(var, value));

	if (!strcmp(var, "stat.bpf-counter-events"))
		evsel__bpf_counter_events = strdup(value);

	/* Add other config variables here. */
	return 0;
}

int perf_default_config(const char *var, const char *value,
			void *dummy __maybe_unused)
{
	if (strstarts(var, "core."))
		return perf_default_core_config(var, value);

	if (strstarts(var, "hist."))
		return perf_hist_config(var, value);

	if (strstarts(var, "ui."))
		return perf_ui_config(var, value);

	if (strstarts(var, "call-graph."))
		return perf_callchain_config(var, value);

	if (strstarts(var, "llvm."))
		return perf_llvm_config(var, value);

	if (strstarts(var, "buildid."))
		return perf_buildid_config(var, value);

	if (strstarts(var, "stat."))
		return perf_stat_config(var, value);

	/* Add other config variables here. */
	return 0;
}

static int perf_config_from_file(config_fn_t fn, const char *filename, void *data)
{
	int ret;
	FILE *f = fopen(filename, "r");

	ret = -1;
	if (f) {
		config_file = f;
		config_file_name = filename;
		config_linenr = 1;
		config_file_eof = 0;
		ret = perf_parse_file(fn, data);
		fclose(f);
		config_file_name = NULL;
	}
	return ret;
}

const char *perf_etc_perfconfig(void)
{
	static const char *system_wide;
	if (!system_wide)
		system_wide = system_path(ETC_PERFCONFIG);
	return system_wide;
}

static int perf_env_bool(const char *k, int def)
{
	const char *v = getenv(k);
	return v ? perf_config_bool(k, v) : def;
}

int perf_config_system(void)
{
	return !perf_env_bool("PERF_CONFIG_NOSYSTEM", 0);
}

int perf_config_global(void)
{
	return !perf_env_bool("PERF_CONFIG_NOGLOBAL", 0);
}

static char *home_perfconfig(void)
{
	const char *home = NULL;
	char *config;
	struct stat st;

	home = getenv("HOME");

	/*
	 * Skip reading user config if:
	 *   - there is no place to read it from (HOME)
	 *   - we are asked not to (PERF_CONFIG_NOGLOBAL=1)
	 */
	if (!home || !*home || !perf_config_global())
		return NULL;

	config = strdup(mkpath("%s/.perfconfig", home));
	if (config == NULL) {
		pr_warning("Not enough memory to process %s/.perfconfig, ignoring it.\n", home);
		return NULL;
	}

	if (stat(config, &st) < 0)
		goto out_free;

	if (st.st_uid && (st.st_uid != geteuid())) {
		pr_warning("File %s not owned by current user or root, ignoring it.\n", config);
		goto out_free;
	}

	if (st.st_size)
		return config;

out_free:
	free(config);
	return NULL;
}

const char *perf_home_perfconfig(void)
{
	static const char *config;
	static bool failed;

	if (failed || config)
		return config;

	config = home_perfconfig();
	if (!config)
		failed = true;

	return config;
}

static struct perf_config_section *find_section(struct list_head *sections,
						const char *section_name)
{
	struct perf_config_section *section;

	list_for_each_entry(section, sections, node)
		if (!strcmp(section->name, section_name))
			return section;

	return NULL;
}

static struct perf_config_item *find_config_item(const char *name,
						 struct perf_config_section *section)
{
	struct perf_config_item *item;

	list_for_each_entry(item, &section->items, node)
		if (!strcmp(item->name, name))
			return item;

	return NULL;
}

static struct perf_config_section *add_section(struct list_head *sections,
					       const char *section_name)
{
	struct perf_config_section *section = zalloc(sizeof(*section));

	if (!section)
		return NULL;

	INIT_LIST_HEAD(&section->items);
	section->name = strdup(section_name);
	if (!section->name) {
		pr_debug("%s: strdup failed\n", __func__);
		free(section);
		return NULL;
	}

	list_add_tail(&section->node, sections);
	return section;
}

static struct perf_config_item *add_config_item(struct perf_config_section *section,
						const char *name)
{
	struct perf_config_item *item = zalloc(sizeof(*item));

	if (!item)
		return NULL;

	item->name = strdup(name);
	if (!item->name) {
		pr_debug("%s: strdup failed\n", __func__);
		free(item);
		return NULL;
	}

	list_add_tail(&item->node, &section->items);
	return item;
}

static int set_value(struct perf_config_item *item, const char *value)
{
	char *val = strdup(value);

	if (!val)
		return -1;

	zfree(&item->value);
	item->value = val;
	return 0;
}

static int collect_config(const char *var, const char *value,
			  void *perf_config_set)
{
	int ret = -1;
	char *ptr, *key;
	char *section_name, *name;
	struct perf_config_section *section = NULL;
	struct perf_config_item *item = NULL;
	struct perf_config_set *set = perf_config_set;
	struct list_head *sections;

	if (set == NULL)
		return -1;

	sections = &set->sections;
	key = ptr = strdup(var);
	if (!key) {
		pr_debug("%s: strdup failed\n", __func__);
		return -1;
	}

	section_name = strsep(&ptr, ".");
	name = ptr;
	if (name == NULL || value == NULL)
		goto out_free;

	section = find_section(sections, section_name);
	if (!section) {
		section = add_section(sections, section_name);
		if (!section)
			goto out_free;
	}

	item = find_config_item(name, section);
	if (!item) {
		item = add_config_item(section, name);
		if (!item)
			goto out_free;
	}

	/* perf_config_set can contain both user and system config items.
	 * So we should know where each value is from.
	 * The classification would be needed when a particular config file
	 * is overwritten by setting feature i.e. set_config().
	 */
	if (strcmp(config_file_name, perf_etc_perfconfig()) == 0) {
		section->from_system_config = true;
		item->from_system_config = true;
	} else {
		section->from_system_config = false;
		item->from_system_config = false;
	}

	ret = set_value(item, value);

out_free:
	free(key);
	return ret;
}

int perf_config_set__collect(struct perf_config_set *set, const char *file_name,
			     const char *var, const char *value)
{
	config_file_name = file_name;
	return collect_config(var, value, set);
}

static int perf_config_set__init(struct perf_config_set *set)
{
	int ret = -1;

	/* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
	if (config_exclusive_filename)
		return perf_config_from_file(collect_config, config_exclusive_filename, set);
	if (perf_config_system() && !access(perf_etc_perfconfig(), R_OK)) {
		if (perf_config_from_file(collect_config, perf_etc_perfconfig(), set) < 0)
			goto out;
	}
	if (perf_config_global() && perf_home_perfconfig()) {
		if (perf_config_from_file(collect_config, perf_home_perfconfig(), set) < 0)
			goto out;
	}

out:
	return ret;
}

struct perf_config_set *perf_config_set__new(void)
{
	struct perf_config_set *set = zalloc(sizeof(*set));

	if (set) {
		INIT_LIST_HEAD(&set->sections);
		perf_config_set__init(set);
	}

	return set;
}

struct perf_config_set *perf_config_set__load_file(const char *file)
{
	struct perf_config_set *set = zalloc(sizeof(*set));

	if (set) {
		INIT_LIST_HEAD(&set->sections);
		perf_config_from_file(collect_config, file, set);
	}

	return set;
}

static int perf_config__init(void)
{
	if (config_set == NULL)
		config_set = perf_config_set__new();

	return config_set == NULL;
}

int perf_config_set(struct perf_config_set *set,
		    config_fn_t fn, void *data)
{
	int ret = 0;
	char key[BUFSIZ];
	struct perf_config_section *section;
	struct perf_config_item *item;

	perf_config_set__for_each_entry(set, section, item) {
		char *value = item->value;

		if (value) {
			scnprintf(key, sizeof(key), "%s.%s",
				  section->name, item->name);
			ret = fn(key, value, data);
			if (ret < 0) {
				pr_err("Error in the given config file: wrong config key-value pair %s=%s\n",
				       key, value);
				/*
				 * Can't be just a 'break', as perf_config_set__for_each_entry()
				 * expands to two nested for() loops.
				 */
				goto out;
			}
		}
	}
out:
	return ret;
}

int perf_config(config_fn_t fn, void *data)
{
	if (config_set == NULL && perf_config__init())
		return -1;

	return perf_config_set(config_set, fn, data);
}

void perf_config__exit(void)
{
	perf_config_set__delete(config_set);
	config_set = NULL;
}

void perf_config__refresh(void)
{
	perf_config__exit();
	perf_config__init();
}

static void perf_config_item__delete(struct perf_config_item *item)
{
	zfree(&item->name);
	zfree(&item->value);
	free(item);
}

static void perf_config_section__purge(struct perf_config_section *section)
{
	struct perf_config_item *item, *tmp;

	list_for_each_entry_safe(item, tmp, &section->items, node) {
		list_del_init(&item->node);
		perf_config_item__delete(item);
	}
}

static void perf_config_section__delete(struct perf_config_section *section)
{
	perf_config_section__purge(section);
	zfree(&section->name);
	free(section);
}

static void perf_config_set__purge(struct perf_config_set *set)
{
	struct perf_config_section *section, *tmp;

	list_for_each_entry_safe(section, tmp, &set->sections, node) {
		list_del_init(&section->node);
		perf_config_section__delete(section);
	}
}

void perf_config_set__delete(struct perf_config_set *set)
{
	if (set == NULL)
		return;

	perf_config_set__purge(set);
	free(set);
}

/*
 * Call this to report error for your variable that should not
 * get a boolean value (i.e. "[my] var" means "true").
 */
int config_error_nonbool(const char *var)
{
	pr_err("Missing value for '%s'", var);
	return -1;
}

void set_buildid_dir(const char *dir)
{
	if (dir)
		scnprintf(buildid_dir, MAXPATHLEN, "%s", dir);

	/* default to $HOME/.debug */
	if (buildid_dir[0] == '\0') {
		char *home = getenv("HOME");

		if (home) {
			snprintf(buildid_dir, MAXPATHLEN, "%s/%s",
				 home, DEBUG_CACHE_DIR);
		} else {
			strncpy(buildid_dir, DEBUG_CACHE_DIR, MAXPATHLEN-1);
		}
		buildid_dir[MAXPATHLEN-1] = '\0';
	}
	/* for communicating with external commands */
	setenv("PERF_BUILDID_DIR", buildid_dir, 1);
}

struct perf_config_scan_data {
	const char *name;
	const char *fmt;
	va_list args;
	int ret;
};

static int perf_config_scan_cb(const char *var, const char *value, void *data)
{
	struct perf_config_scan_data *d = data;

	if (!strcmp(var, d->name))
		d->ret = vsscanf(value, d->fmt, d->args);

	return 0;
}

int perf_config_scan(const char *name, const char *fmt, ...)
{
	struct perf_config_scan_data d = {
		.name = name,
		.fmt = fmt,
	};

	va_start(d.args, fmt);
	perf_config(perf_config_scan_cb, &d);
	va_end(d.args);

	return d.ret;
}