xref: /openbmc/linux/tools/perf/util/config.c (revision 829c6524)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * config.c
4  *
5  * Helper functions for parsing config items.
6  * Originally copied from GIT source.
7  *
8  * Copyright (C) Linus Torvalds, 2005
9  * Copyright (C) Johannes Schindelin, 2005
10  *
11  */
12 #include <errno.h>
13 #include <sys/param.h>
14 #include "cache.h"
15 #include "callchain.h"
16 #include <subcmd/exec-cmd.h>
17 #include "util/event.h"  /* proc_map_timeout */
18 #include "util/hist.h"  /* perf_hist_config */
19 #include "util/llvm-utils.h"   /* perf_llvm_config */
20 #include "util/stat.h"  /* perf_stat__set_big_num */
21 #include "util/evsel.h"  /* evsel__hw_names, evsel__use_bpf_counters */
22 #include "util/srcline.h"  /* addr2line_timeout_ms */
23 #include "build-id.h"
24 #include "debug.h"
25 #include "config.h"
26 #include <sys/types.h>
27 #include <sys/stat.h>
28 #include <stdlib.h>
29 #include <unistd.h>
30 #include <linux/string.h>
31 #include <linux/zalloc.h>
32 #include <linux/ctype.h>
33 
34 #define MAXNAME (256)
35 
36 #define DEBUG_CACHE_DIR ".debug"
37 
38 
39 char buildid_dir[MAXPATHLEN]; /* root dir for buildid, binary cache */
40 
41 static FILE *config_file;
42 static const char *config_file_name;
43 static int config_linenr;
44 static int config_file_eof;
45 static struct perf_config_set *config_set;
46 
47 const char *config_exclusive_filename;
48 
49 static int get_next_char(void)
50 {
51 	int c;
52 	FILE *f;
53 
54 	c = '\n';
55 	if ((f = config_file) != NULL) {
56 		c = fgetc(f);
57 		if (c == '\r') {
58 			/* DOS like systems */
59 			c = fgetc(f);
60 			if (c != '\n') {
61 				ungetc(c, f);
62 				c = '\r';
63 			}
64 		}
65 		if (c == '\n')
66 			config_linenr++;
67 		if (c == EOF) {
68 			config_file_eof = 1;
69 			c = '\n';
70 		}
71 	}
72 	return c;
73 }
74 
75 static char *parse_value(void)
76 {
77 	static char value[1024];
78 	int quote = 0, comment = 0, space = 0;
79 	size_t len = 0;
80 
81 	for (;;) {
82 		int c = get_next_char();
83 
84 		if (len >= sizeof(value) - 1)
85 			return NULL;
86 		if (c == '\n') {
87 			if (quote)
88 				return NULL;
89 			value[len] = 0;
90 			return value;
91 		}
92 		if (comment)
93 			continue;
94 		if (isspace(c) && !quote) {
95 			space = 1;
96 			continue;
97 		}
98 		if (!quote) {
99 			if (c == ';' || c == '#') {
100 				comment = 1;
101 				continue;
102 			}
103 		}
104 		if (space) {
105 			if (len)
106 				value[len++] = ' ';
107 			space = 0;
108 		}
109 		if (c == '\\') {
110 			c = get_next_char();
111 			switch (c) {
112 			case '\n':
113 				continue;
114 			case 't':
115 				c = '\t';
116 				break;
117 			case 'b':
118 				c = '\b';
119 				break;
120 			case 'n':
121 				c = '\n';
122 				break;
123 			/* Some characters escape as themselves */
124 			case '\\': case '"':
125 				break;
126 			/* Reject unknown escape sequences */
127 			default:
128 				return NULL;
129 			}
130 			value[len++] = c;
131 			continue;
132 		}
133 		if (c == '"') {
134 			quote = 1-quote;
135 			continue;
136 		}
137 		value[len++] = c;
138 	}
139 }
140 
141 static inline int iskeychar(int c)
142 {
143 	return isalnum(c) || c == '-' || c == '_';
144 }
145 
146 static int get_value(config_fn_t fn, void *data, char *name, unsigned int len)
147 {
148 	int c;
149 	char *value;
150 
151 	/* Get the full name */
152 	for (;;) {
153 		c = get_next_char();
154 		if (config_file_eof)
155 			break;
156 		if (!iskeychar(c))
157 			break;
158 		name[len++] = c;
159 		if (len >= MAXNAME)
160 			return -1;
161 	}
162 	name[len] = 0;
163 	while (c == ' ' || c == '\t')
164 		c = get_next_char();
165 
166 	value = NULL;
167 	if (c != '\n') {
168 		if (c != '=')
169 			return -1;
170 		value = parse_value();
171 		if (!value)
172 			return -1;
173 	}
174 	return fn(name, value, data);
175 }
176 
177 static int get_extended_base_var(char *name, int baselen, int c)
178 {
179 	do {
180 		if (c == '\n')
181 			return -1;
182 		c = get_next_char();
183 	} while (isspace(c));
184 
185 	/* We require the format to be '[base "extension"]' */
186 	if (c != '"')
187 		return -1;
188 	name[baselen++] = '.';
189 
190 	for (;;) {
191 		int ch = get_next_char();
192 
193 		if (ch == '\n')
194 			return -1;
195 		if (ch == '"')
196 			break;
197 		if (ch == '\\') {
198 			ch = get_next_char();
199 			if (ch == '\n')
200 				return -1;
201 		}
202 		name[baselen++] = ch;
203 		if (baselen > MAXNAME / 2)
204 			return -1;
205 	}
206 
207 	/* Final ']' */
208 	if (get_next_char() != ']')
209 		return -1;
210 	return baselen;
211 }
212 
213 static int get_base_var(char *name)
214 {
215 	int baselen = 0;
216 
217 	for (;;) {
218 		int c = get_next_char();
219 		if (config_file_eof)
220 			return -1;
221 		if (c == ']')
222 			return baselen;
223 		if (isspace(c))
224 			return get_extended_base_var(name, baselen, c);
225 		if (!iskeychar(c) && c != '.')
226 			return -1;
227 		if (baselen > MAXNAME / 2)
228 			return -1;
229 		name[baselen++] = tolower(c);
230 	}
231 }
232 
233 static int perf_parse_file(config_fn_t fn, void *data)
234 {
235 	int comment = 0;
236 	int baselen = 0;
237 	static char var[MAXNAME];
238 
239 	/* U+FEFF Byte Order Mark in UTF8 */
240 	static const unsigned char *utf8_bom = (unsigned char *) "\xef\xbb\xbf";
241 	const unsigned char *bomptr = utf8_bom;
242 
243 	for (;;) {
244 		int line, c = get_next_char();
245 
246 		if (bomptr && *bomptr) {
247 			/* We are at the file beginning; skip UTF8-encoded BOM
248 			 * if present. Sane editors won't put this in on their
249 			 * own, but e.g. Windows Notepad will do it happily. */
250 			if ((unsigned char) c == *bomptr) {
251 				bomptr++;
252 				continue;
253 			} else {
254 				/* Do not tolerate partial BOM. */
255 				if (bomptr != utf8_bom)
256 					break;
257 				/* No BOM at file beginning. Cool. */
258 				bomptr = NULL;
259 			}
260 		}
261 		if (c == '\n') {
262 			if (config_file_eof)
263 				return 0;
264 			comment = 0;
265 			continue;
266 		}
267 		if (comment || isspace(c))
268 			continue;
269 		if (c == '#' || c == ';') {
270 			comment = 1;
271 			continue;
272 		}
273 		if (c == '[') {
274 			baselen = get_base_var(var);
275 			if (baselen <= 0)
276 				break;
277 			var[baselen++] = '.';
278 			var[baselen] = 0;
279 			continue;
280 		}
281 		if (!isalpha(c))
282 			break;
283 		var[baselen] = tolower(c);
284 
285 		/*
286 		 * The get_value function might or might not reach the '\n',
287 		 * so saving the current line number for error reporting.
288 		 */
289 		line = config_linenr;
290 		if (get_value(fn, data, var, baselen+1) < 0) {
291 			config_linenr = line;
292 			break;
293 		}
294 	}
295 	pr_err("bad config file line %d in %s\n", config_linenr, config_file_name);
296 	return -1;
297 }
298 
299 static int parse_unit_factor(const char *end, unsigned long *val)
300 {
301 	if (!*end)
302 		return 1;
303 	else if (!strcasecmp(end, "k")) {
304 		*val *= 1024;
305 		return 1;
306 	}
307 	else if (!strcasecmp(end, "m")) {
308 		*val *= 1024 * 1024;
309 		return 1;
310 	}
311 	else if (!strcasecmp(end, "g")) {
312 		*val *= 1024 * 1024 * 1024;
313 		return 1;
314 	}
315 	return 0;
316 }
317 
318 static int perf_parse_llong(const char *value, long long *ret)
319 {
320 	if (value && *value) {
321 		char *end;
322 		long long val = strtoll(value, &end, 0);
323 		unsigned long factor = 1;
324 
325 		if (!parse_unit_factor(end, &factor))
326 			return 0;
327 		*ret = val * factor;
328 		return 1;
329 	}
330 	return 0;
331 }
332 
333 static int perf_parse_long(const char *value, long *ret)
334 {
335 	if (value && *value) {
336 		char *end;
337 		long val = strtol(value, &end, 0);
338 		unsigned long factor = 1;
339 		if (!parse_unit_factor(end, &factor))
340 			return 0;
341 		*ret = val * factor;
342 		return 1;
343 	}
344 	return 0;
345 }
346 
347 static void bad_config(const char *name)
348 {
349 	if (config_file_name)
350 		pr_warning("bad config value for '%s' in %s, ignoring...\n", name, config_file_name);
351 	else
352 		pr_warning("bad config value for '%s', ignoring...\n", name);
353 }
354 
355 int perf_config_u64(u64 *dest, const char *name, const char *value)
356 {
357 	long long ret = 0;
358 
359 	if (!perf_parse_llong(value, &ret)) {
360 		bad_config(name);
361 		return -1;
362 	}
363 
364 	*dest = ret;
365 	return 0;
366 }
367 
368 int perf_config_int(int *dest, const char *name, const char *value)
369 {
370 	long ret = 0;
371 	if (!perf_parse_long(value, &ret)) {
372 		bad_config(name);
373 		return -1;
374 	}
375 	*dest = ret;
376 	return 0;
377 }
378 
379 int perf_config_u8(u8 *dest, const char *name, const char *value)
380 {
381 	long ret = 0;
382 
383 	if (!perf_parse_long(value, &ret)) {
384 		bad_config(name);
385 		return -1;
386 	}
387 	*dest = ret;
388 	return 0;
389 }
390 
391 static int perf_config_bool_or_int(const char *name, const char *value, int *is_bool)
392 {
393 	int ret;
394 
395 	*is_bool = 1;
396 	if (!value)
397 		return 1;
398 	if (!*value)
399 		return 0;
400 	if (!strcasecmp(value, "true") || !strcasecmp(value, "yes") || !strcasecmp(value, "on"))
401 		return 1;
402 	if (!strcasecmp(value, "false") || !strcasecmp(value, "no") || !strcasecmp(value, "off"))
403 		return 0;
404 	*is_bool = 0;
405 	return perf_config_int(&ret, name, value) < 0 ? -1 : ret;
406 }
407 
408 int perf_config_bool(const char *name, const char *value)
409 {
410 	int discard;
411 	return !!perf_config_bool_or_int(name, value, &discard);
412 }
413 
414 static const char *perf_config_dirname(const char *name, const char *value)
415 {
416 	if (!name)
417 		return NULL;
418 	return value;
419 }
420 
421 static int perf_buildid_config(const char *var, const char *value)
422 {
423 	/* same dir for all commands */
424 	if (!strcmp(var, "buildid.dir")) {
425 		const char *dir = perf_config_dirname(var, value);
426 
427 		if (!dir) {
428 			pr_err("Invalid buildid directory!\n");
429 			return -1;
430 		}
431 		strncpy(buildid_dir, dir, MAXPATHLEN-1);
432 		buildid_dir[MAXPATHLEN-1] = '\0';
433 	}
434 
435 	return 0;
436 }
437 
438 static int perf_default_core_config(const char *var, const char *value)
439 {
440 	if (!strcmp(var, "core.proc-map-timeout"))
441 		proc_map_timeout = strtoul(value, NULL, 10);
442 
443 	if (!strcmp(var, "core.addr2line-timeout"))
444 		addr2line_timeout_ms = strtoul(value, NULL, 10);
445 
446 	/* Add other config variables here. */
447 	return 0;
448 }
449 
450 static int perf_ui_config(const char *var, const char *value)
451 {
452 	/* Add other config variables here. */
453 	if (!strcmp(var, "ui.show-headers"))
454 		symbol_conf.show_hist_headers = perf_config_bool(var, value);
455 
456 	return 0;
457 }
458 
459 static int perf_stat_config(const char *var, const char *value)
460 {
461 	if (!strcmp(var, "stat.big-num"))
462 		perf_stat__set_big_num(perf_config_bool(var, value));
463 
464 	if (!strcmp(var, "stat.no-csv-summary"))
465 		perf_stat__set_no_csv_summary(perf_config_bool(var, value));
466 
467 	if (!strcmp(var, "stat.bpf-counter-events"))
468 		evsel__bpf_counter_events = strdup(value);
469 
470 	/* Add other config variables here. */
471 	return 0;
472 }
473 
474 int perf_default_config(const char *var, const char *value,
475 			void *dummy __maybe_unused)
476 {
477 	if (strstarts(var, "core."))
478 		return perf_default_core_config(var, value);
479 
480 	if (strstarts(var, "hist."))
481 		return perf_hist_config(var, value);
482 
483 	if (strstarts(var, "ui."))
484 		return perf_ui_config(var, value);
485 
486 	if (strstarts(var, "call-graph."))
487 		return perf_callchain_config(var, value);
488 
489 	if (strstarts(var, "llvm."))
490 		return perf_llvm_config(var, value);
491 
492 	if (strstarts(var, "buildid."))
493 		return perf_buildid_config(var, value);
494 
495 	if (strstarts(var, "stat."))
496 		return perf_stat_config(var, value);
497 
498 	/* Add other config variables here. */
499 	return 0;
500 }
501 
502 static int perf_config_from_file(config_fn_t fn, const char *filename, void *data)
503 {
504 	int ret;
505 	FILE *f = fopen(filename, "r");
506 
507 	ret = -1;
508 	if (f) {
509 		config_file = f;
510 		config_file_name = filename;
511 		config_linenr = 1;
512 		config_file_eof = 0;
513 		ret = perf_parse_file(fn, data);
514 		fclose(f);
515 		config_file_name = NULL;
516 	}
517 	return ret;
518 }
519 
520 const char *perf_etc_perfconfig(void)
521 {
522 	static const char *system_wide;
523 	if (!system_wide)
524 		system_wide = system_path(ETC_PERFCONFIG);
525 	return system_wide;
526 }
527 
528 static int perf_env_bool(const char *k, int def)
529 {
530 	const char *v = getenv(k);
531 	return v ? perf_config_bool(k, v) : def;
532 }
533 
534 int perf_config_system(void)
535 {
536 	return !perf_env_bool("PERF_CONFIG_NOSYSTEM", 0);
537 }
538 
539 int perf_config_global(void)
540 {
541 	return !perf_env_bool("PERF_CONFIG_NOGLOBAL", 0);
542 }
543 
544 static char *home_perfconfig(void)
545 {
546 	const char *home = NULL;
547 	char *config;
548 	struct stat st;
549 	char path[PATH_MAX];
550 
551 	home = getenv("HOME");
552 
553 	/*
554 	 * Skip reading user config if:
555 	 *   - there is no place to read it from (HOME)
556 	 *   - we are asked not to (PERF_CONFIG_NOGLOBAL=1)
557 	 */
558 	if (!home || !*home || !perf_config_global())
559 		return NULL;
560 
561 	config = strdup(mkpath(path, sizeof(path), "%s/.perfconfig", home));
562 	if (config == NULL) {
563 		pr_warning("Not enough memory to process %s/.perfconfig, ignoring it.\n", home);
564 		return NULL;
565 	}
566 
567 	if (stat(config, &st) < 0)
568 		goto out_free;
569 
570 	if (st.st_uid && (st.st_uid != geteuid())) {
571 		pr_warning("File %s not owned by current user or root, ignoring it.\n", config);
572 		goto out_free;
573 	}
574 
575 	if (st.st_size)
576 		return config;
577 
578 out_free:
579 	free(config);
580 	return NULL;
581 }
582 
583 const char *perf_home_perfconfig(void)
584 {
585 	static const char *config;
586 	static bool failed;
587 
588 	if (failed || config)
589 		return config;
590 
591 	config = home_perfconfig();
592 	if (!config)
593 		failed = true;
594 
595 	return config;
596 }
597 
598 static struct perf_config_section *find_section(struct list_head *sections,
599 						const char *section_name)
600 {
601 	struct perf_config_section *section;
602 
603 	list_for_each_entry(section, sections, node)
604 		if (!strcmp(section->name, section_name))
605 			return section;
606 
607 	return NULL;
608 }
609 
610 static struct perf_config_item *find_config_item(const char *name,
611 						 struct perf_config_section *section)
612 {
613 	struct perf_config_item *item;
614 
615 	list_for_each_entry(item, &section->items, node)
616 		if (!strcmp(item->name, name))
617 			return item;
618 
619 	return NULL;
620 }
621 
622 static struct perf_config_section *add_section(struct list_head *sections,
623 					       const char *section_name)
624 {
625 	struct perf_config_section *section = zalloc(sizeof(*section));
626 
627 	if (!section)
628 		return NULL;
629 
630 	INIT_LIST_HEAD(&section->items);
631 	section->name = strdup(section_name);
632 	if (!section->name) {
633 		pr_debug("%s: strdup failed\n", __func__);
634 		free(section);
635 		return NULL;
636 	}
637 
638 	list_add_tail(&section->node, sections);
639 	return section;
640 }
641 
642 static struct perf_config_item *add_config_item(struct perf_config_section *section,
643 						const char *name)
644 {
645 	struct perf_config_item *item = zalloc(sizeof(*item));
646 
647 	if (!item)
648 		return NULL;
649 
650 	item->name = strdup(name);
651 	if (!item->name) {
652 		pr_debug("%s: strdup failed\n", __func__);
653 		free(item);
654 		return NULL;
655 	}
656 
657 	list_add_tail(&item->node, &section->items);
658 	return item;
659 }
660 
661 static int set_value(struct perf_config_item *item, const char *value)
662 {
663 	char *val = strdup(value);
664 
665 	if (!val)
666 		return -1;
667 
668 	zfree(&item->value);
669 	item->value = val;
670 	return 0;
671 }
672 
673 static int collect_config(const char *var, const char *value,
674 			  void *perf_config_set)
675 {
676 	int ret = -1;
677 	char *ptr, *key;
678 	char *section_name, *name;
679 	struct perf_config_section *section = NULL;
680 	struct perf_config_item *item = NULL;
681 	struct perf_config_set *set = perf_config_set;
682 	struct list_head *sections;
683 
684 	if (set == NULL)
685 		return -1;
686 
687 	sections = &set->sections;
688 	key = ptr = strdup(var);
689 	if (!key) {
690 		pr_debug("%s: strdup failed\n", __func__);
691 		return -1;
692 	}
693 
694 	section_name = strsep(&ptr, ".");
695 	name = ptr;
696 	if (name == NULL || value == NULL)
697 		goto out_free;
698 
699 	section = find_section(sections, section_name);
700 	if (!section) {
701 		section = add_section(sections, section_name);
702 		if (!section)
703 			goto out_free;
704 	}
705 
706 	item = find_config_item(name, section);
707 	if (!item) {
708 		item = add_config_item(section, name);
709 		if (!item)
710 			goto out_free;
711 	}
712 
713 	/* perf_config_set can contain both user and system config items.
714 	 * So we should know where each value is from.
715 	 * The classification would be needed when a particular config file
716 	 * is overwritten by setting feature i.e. set_config().
717 	 */
718 	if (strcmp(config_file_name, perf_etc_perfconfig()) == 0) {
719 		section->from_system_config = true;
720 		item->from_system_config = true;
721 	} else {
722 		section->from_system_config = false;
723 		item->from_system_config = false;
724 	}
725 
726 	ret = set_value(item, value);
727 
728 out_free:
729 	free(key);
730 	return ret;
731 }
732 
733 int perf_config_set__collect(struct perf_config_set *set, const char *file_name,
734 			     const char *var, const char *value)
735 {
736 	config_file_name = file_name;
737 	return collect_config(var, value, set);
738 }
739 
740 static int perf_config_set__init(struct perf_config_set *set)
741 {
742 	int ret = -1;
743 
744 	/* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
745 	if (config_exclusive_filename)
746 		return perf_config_from_file(collect_config, config_exclusive_filename, set);
747 	if (perf_config_system() && !access(perf_etc_perfconfig(), R_OK)) {
748 		if (perf_config_from_file(collect_config, perf_etc_perfconfig(), set) < 0)
749 			goto out;
750 	}
751 	if (perf_config_global() && perf_home_perfconfig()) {
752 		if (perf_config_from_file(collect_config, perf_home_perfconfig(), set) < 0)
753 			goto out;
754 	}
755 
756 out:
757 	return ret;
758 }
759 
760 struct perf_config_set *perf_config_set__new(void)
761 {
762 	struct perf_config_set *set = zalloc(sizeof(*set));
763 
764 	if (set) {
765 		INIT_LIST_HEAD(&set->sections);
766 		perf_config_set__init(set);
767 	}
768 
769 	return set;
770 }
771 
772 struct perf_config_set *perf_config_set__load_file(const char *file)
773 {
774 	struct perf_config_set *set = zalloc(sizeof(*set));
775 
776 	if (set) {
777 		INIT_LIST_HEAD(&set->sections);
778 		perf_config_from_file(collect_config, file, set);
779 	}
780 
781 	return set;
782 }
783 
784 static int perf_config__init(void)
785 {
786 	if (config_set == NULL)
787 		config_set = perf_config_set__new();
788 
789 	return config_set == NULL;
790 }
791 
792 int perf_config_set(struct perf_config_set *set,
793 		    config_fn_t fn, void *data)
794 {
795 	int ret = 0;
796 	char key[BUFSIZ];
797 	struct perf_config_section *section;
798 	struct perf_config_item *item;
799 
800 	perf_config_set__for_each_entry(set, section, item) {
801 		char *value = item->value;
802 
803 		if (value) {
804 			scnprintf(key, sizeof(key), "%s.%s",
805 				  section->name, item->name);
806 			ret = fn(key, value, data);
807 			if (ret < 0) {
808 				pr_err("Error in the given config file: wrong config key-value pair %s=%s\n",
809 				       key, value);
810 				/*
811 				 * Can't be just a 'break', as perf_config_set__for_each_entry()
812 				 * expands to two nested for() loops.
813 				 */
814 				goto out;
815 			}
816 		}
817 	}
818 out:
819 	return ret;
820 }
821 
822 int perf_config(config_fn_t fn, void *data)
823 {
824 	if (config_set == NULL && perf_config__init())
825 		return -1;
826 
827 	return perf_config_set(config_set, fn, data);
828 }
829 
830 void perf_config__exit(void)
831 {
832 	perf_config_set__delete(config_set);
833 	config_set = NULL;
834 }
835 
836 void perf_config__refresh(void)
837 {
838 	perf_config__exit();
839 	perf_config__init();
840 }
841 
842 static void perf_config_item__delete(struct perf_config_item *item)
843 {
844 	zfree(&item->name);
845 	zfree(&item->value);
846 	free(item);
847 }
848 
849 static void perf_config_section__purge(struct perf_config_section *section)
850 {
851 	struct perf_config_item *item, *tmp;
852 
853 	list_for_each_entry_safe(item, tmp, &section->items, node) {
854 		list_del_init(&item->node);
855 		perf_config_item__delete(item);
856 	}
857 }
858 
859 static void perf_config_section__delete(struct perf_config_section *section)
860 {
861 	perf_config_section__purge(section);
862 	zfree(&section->name);
863 	free(section);
864 }
865 
866 static void perf_config_set__purge(struct perf_config_set *set)
867 {
868 	struct perf_config_section *section, *tmp;
869 
870 	list_for_each_entry_safe(section, tmp, &set->sections, node) {
871 		list_del_init(&section->node);
872 		perf_config_section__delete(section);
873 	}
874 }
875 
876 void perf_config_set__delete(struct perf_config_set *set)
877 {
878 	if (set == NULL)
879 		return;
880 
881 	perf_config_set__purge(set);
882 	free(set);
883 }
884 
885 /*
886  * Call this to report error for your variable that should not
887  * get a boolean value (i.e. "[my] var" means "true").
888  */
889 int config_error_nonbool(const char *var)
890 {
891 	pr_err("Missing value for '%s'", var);
892 	return -1;
893 }
894 
895 void set_buildid_dir(const char *dir)
896 {
897 	if (dir)
898 		scnprintf(buildid_dir, MAXPATHLEN, "%s", dir);
899 
900 	/* default to $HOME/.debug */
901 	if (buildid_dir[0] == '\0') {
902 		char *home = getenv("HOME");
903 
904 		if (home) {
905 			snprintf(buildid_dir, MAXPATHLEN, "%s/%s",
906 				 home, DEBUG_CACHE_DIR);
907 		} else {
908 			strncpy(buildid_dir, DEBUG_CACHE_DIR, MAXPATHLEN-1);
909 		}
910 		buildid_dir[MAXPATHLEN-1] = '\0';
911 	}
912 	/* for communicating with external commands */
913 	setenv("PERF_BUILDID_DIR", buildid_dir, 1);
914 }
915 
916 struct perf_config_scan_data {
917 	const char *name;
918 	const char *fmt;
919 	va_list args;
920 	int ret;
921 };
922 
923 static int perf_config_scan_cb(const char *var, const char *value, void *data)
924 {
925 	struct perf_config_scan_data *d = data;
926 
927 	if (!strcmp(var, d->name))
928 		d->ret = vsscanf(value, d->fmt, d->args);
929 
930 	return 0;
931 }
932 
933 int perf_config_scan(const char *name, const char *fmt, ...)
934 {
935 	struct perf_config_scan_data d = {
936 		.name = name,
937 		.fmt = fmt,
938 	};
939 
940 	va_start(d.args, fmt);
941 	perf_config(perf_config_scan_cb, &d);
942 	va_end(d.args);
943 
944 	return d.ret;
945 }
946