tools/perf/util/config.c

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