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