git.oblomov.eu Git - git/blob - config.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  * Copyright (C) Johannes Schindelin, 2005
   6  *
   7  */
   8 #include "cache.h"
   9 #include "exec_cmd.h"
  10
  11 #define MAXNAME (256)
  12
  13 static FILE *config_file;
  14 static const char *config_file_name;
  15 static int config_linenr;
  16 static int config_file_eof;
  17 static int zlib_compression_seen;
  18
  19 static int get_next_char(void)
  20 {
  21         int c;
  22         FILE *f;
  23
  24         c = '\n';
  25         if ((f = config_file) != NULL) {
  26                 c = fgetc(f);
  27                 if (c == '\r') {
  28                         /* DOS like systems */
  29                         c = fgetc(f);
  30                         if (c != '\n') {
  31                                 ungetc(c, f);
  32                                 c = '\r';
  33                         }
  34                 }
  35                 if (c == '\n')
  36                         config_linenr++;
  37                 if (c == EOF) {
  38                         config_file_eof = 1;
  39                         c = '\n';
  40                 }
  41         }
  42         return c;
  43 }
  44
  45 static char *parse_value(void)
  46 {
  47         static char value[1024];
  48         int quote = 0, comment = 0, len = 0, space = 0;
  49
  50         for (;;) {
  51                 int c = get_next_char();
  52                 if (len >= sizeof(value))
  53                         return NULL;
  54                 if (c == '\n') {
  55                         if (quote)
  56                                 return NULL;
  57                         value[len] = 0;
  58                         return value;
  59                 }
  60                 if (comment)
  61                         continue;
  62                 if (isspace(c) && !quote) {
  63                         space = 1;
  64                         continue;
  65                 }
  66                 if (!quote) {
  67                         if (c == ';' || c == '#') {
  68                                 comment = 1;
  69                                 continue;
  70                         }
  71                 }
  72                 if (space) {
  73                         if (len)
  74                                 value[len++] = ' ';
  75                         space = 0;
  76                 }
  77                 if (c == '\\') {
  78                         c = get_next_char();
  79                         switch (c) {
  80                         case '\n':
  81                                 continue;
  82                         case 't':
  83                                 c = '\t';
  84                                 break;
  85                         case 'b':
  86                                 c = '\b';
  87                                 break;
  88                         case 'n':
  89                                 c = '\n';
  90                                 break;
  91                         /* Some characters escape as themselves */
  92                         case '\\': case '"':
  93                                 break;
  94                         /* Reject unknown escape sequences */
  95                         default:
  96                                 return NULL;
  97                         }
  98                         value[len++] = c;
  99                         continue;
 100                 }
 101                 if (c == '"') {
 102                         quote = 1-quote;
 103                         continue;
 104                 }
 105                 value[len++] = c;
 106         }
 107 }
 108
 109 static inline int iskeychar(int c)
 110 {
 111         return isalnum(c) || c == '-';
 112 }
 113
 114 static int get_value(config_fn_t fn, char *name, unsigned int len)
 115 {
 116         int c;
 117         char *value;
 118
 119         /* Get the full name */
 120         for (;;) {
 121                 c = get_next_char();
 122                 if (config_file_eof)
 123                         break;
 124                 if (!iskeychar(c))
 125                         break;
 126                 name[len++] = tolower(c);
 127                 if (len >= MAXNAME)
 128                         return -1;
 129         }
 130         name[len] = 0;
 131         while (c == ' ' || c == '\t')
 132                 c = get_next_char();
 133
 134         value = NULL;
 135         if (c != '\n') {
 136                 if (c != '=')
 137                         return -1;
 138                 value = parse_value();
 139                 if (!value)
 140                         return -1;
 141         }
 142         return fn(name, value);
 143 }
 144
 145 static int get_extended_base_var(char *name, int baselen, int c)
 146 {
 147         do {
 148                 if (c == '\n')
 149                         return -1;
 150                 c = get_next_char();
 151         } while (isspace(c));
 152
 153         /* We require the format to be '[base "extension"]' */
 154         if (c != '"')
 155                 return -1;
 156         name[baselen++] = '.';
 157
 158         for (;;) {
 159                 int c = get_next_char();
 160                 if (c == '\n')
 161                         return -1;
 162                 if (c == '"')
 163                         break;
 164                 if (c == '\\') {
 165                         c = get_next_char();
 166                         if (c == '\n')
 167                                 return -1;
 168                 }
 169                 name[baselen++] = c;
 170                 if (baselen > MAXNAME / 2)
 171                         return -1;
 172         }
 173
 174         /* Final ']' */
 175         if (get_next_char() != ']')
 176                 return -1;
 177         return baselen;
 178 }
 179
 180 static int get_base_var(char *name)
 181 {
 182         int baselen = 0;
 183
 184         for (;;) {
 185                 int c = get_next_char();
 186                 if (config_file_eof)
 187                         return -1;
 188                 if (c == ']')
 189                         return baselen;
 190                 if (isspace(c))
 191                         return get_extended_base_var(name, baselen, c);
 192                 if (!iskeychar(c) && c != '.')
 193                         return -1;
 194                 if (baselen > MAXNAME / 2)
 195                         return -1;
 196                 name[baselen++] = tolower(c);
 197         }
 198 }
 199
 200 static int git_parse_file(config_fn_t fn)
 201 {
 202         int comment = 0;
 203         int baselen = 0;
 204         static char var[MAXNAME];
 205
 206         for (;;) {
 207                 int c = get_next_char();
 208                 if (c == '\n') {
 209                         if (config_file_eof)
 210                                 return 0;
 211                         comment = 0;
 212                         continue;
 213                 }
 214                 if (comment || isspace(c))
 215                         continue;
 216                 if (c == '#' || c == ';') {
 217                         comment = 1;
 218                         continue;
 219                 }
 220                 if (c == '[') {
 221                         baselen = get_base_var(var);
 222                         if (baselen <= 0)
 223                                 break;
 224                         var[baselen++] = '.';
 225                         var[baselen] = 0;
 226                         continue;
 227                 }
 228                 if (!isalpha(c))
 229                         break;
 230                 var[baselen] = tolower(c);
 231                 if (get_value(fn, var, baselen+1) < 0)
 232                         break;
 233         }
 234         die("bad config file line %d in %s", config_linenr, config_file_name);
 235 }
 236
 237 static int parse_unit_factor(const char *end, unsigned long *val)
 238 {
 239         if (!*end)
 240                 return 1;
 241         else if (!strcasecmp(end, "k")) {
 242                 *val *= 1024;
 243                 return 1;
 244         }
 245         else if (!strcasecmp(end, "m")) {
 246                 *val *= 1024 * 1024;
 247                 return 1;
 248         }
 249         else if (!strcasecmp(end, "g")) {
 250                 *val *= 1024 * 1024 * 1024;
 251                 return 1;
 252         }
 253         return 0;
 254 }
 255
 256 int git_parse_long(const char *value, long *ret)
 257 {
 258         if (value && *value) {
 259                 char *end;
 260                 long val = strtol(value, &end, 0);
 261                 unsigned long factor = 1;
 262                 if (!parse_unit_factor(end, &factor))
 263                         return 0;
 264                 *ret = val * factor;
 265                 return 1;
 266         }
 267         return 0;
 268 }
 269
 270 int git_parse_ulong(const char *value, unsigned long *ret)
 271 {
 272         if (value && *value) {
 273                 char *end;
 274                 unsigned long val = strtoul(value, &end, 0);
 275                 if (!parse_unit_factor(end, &val))
 276                         return 0;
 277                 *ret = val;
 278                 return 1;
 279         }
 280         return 0;
 281 }
 282
 283 static void die_bad_config(const char *name)
 284 {
 285         if (config_file_name)
 286                 die("bad config value for '%s' in %s", name, config_file_name);
 287         die("bad config value for '%s'", name);
 288 }
 289
 290 int git_config_int(const char *name, const char *value)
 291 {
 292         long ret;
 293         if (!git_parse_long(value, &ret))
 294                 die_bad_config(name);
 295         return ret;
 296 }
 297
 298 unsigned long git_config_ulong(const char *name, const char *value)
 299 {
 300         unsigned long ret;
 301         if (!git_parse_ulong(value, &ret))
 302                 die_bad_config(name);
 303         return ret;
 304 }
 305
 306 int git_config_bool_or_int(const char *name, const char *value, int *is_bool)
 307 {
 308         *is_bool = 1;
 309         if (!value)
 310                 return 1;
 311         if (!*value)
 312                 return 0;
 313         if (!strcasecmp(value, "true") || !strcasecmp(value, "yes"))
 314                 return 1;
 315         if (!strcasecmp(value, "false") || !strcasecmp(value, "no"))
 316                 return 0;
 317         *is_bool = 0;
 318         return git_config_int(name, value);
 319 }
 320
 321 int git_config_bool(const char *name, const char *value)
 322 {
 323         int discard;
 324         return !!git_config_bool_or_int(name, value, &discard);
 325 }
 326
 327 int git_config_string(const char **dest, const char *var, const char *value)
 328 {
 329         if (!value)
 330                 return config_error_nonbool(var);
 331         *dest = xstrdup(value);
 332         return 0;
 333 }
 334
 335 int git_default_config(const char *var, const char *value)
 336 {
 337         /* This needs a better name */
 338         if (!strcmp(var, "core.filemode")) {
 339                 trust_executable_bit = git_config_bool(var, value);
 340                 return 0;
 341         }
 342
 343         if (!strcmp(var, "core.quotepath")) {
 344                 quote_path_fully = git_config_bool(var, value);
 345                 return 0;
 346         }
 347
 348         if (!strcmp(var, "core.symlinks")) {
 349                 has_symlinks = git_config_bool(var, value);
 350                 return 0;
 351         }
 352
 353         if (!strcmp(var, "core.bare")) {
 354                 is_bare_repository_cfg = git_config_bool(var, value);
 355                 return 0;
 356         }
 357
 358         if (!strcmp(var, "core.ignorestat")) {
 359                 assume_unchanged = git_config_bool(var, value);
 360                 return 0;
 361         }
 362
 363         if (!strcmp(var, "core.prefersymlinkrefs")) {
 364                 prefer_symlink_refs = git_config_bool(var, value);
 365                 return 0;
 366         }
 367
 368         if (!strcmp(var, "core.logallrefupdates")) {
 369                 log_all_ref_updates = git_config_bool(var, value);
 370                 return 0;
 371         }
 372
 373         if (!strcmp(var, "core.warnambiguousrefs")) {
 374                 warn_ambiguous_refs = git_config_bool(var, value);
 375                 return 0;
 376         }
 377
 378         if (!strcmp(var, "core.loosecompression")) {
 379                 int level = git_config_int(var, value);
 380                 if (level == -1)
 381                         level = Z_DEFAULT_COMPRESSION;
 382                 else if (level < 0 || level > Z_BEST_COMPRESSION)
 383                         die("bad zlib compression level %d", level);
 384                 zlib_compression_level = level;
 385                 zlib_compression_seen = 1;
 386                 return 0;
 387         }
 388
 389         if (!strcmp(var, "core.compression")) {
 390                 int level = git_config_int(var, value);
 391                 if (level == -1)
 392                         level = Z_DEFAULT_COMPRESSION;
 393                 else if (level < 0 || level > Z_BEST_COMPRESSION)
 394                         die("bad zlib compression level %d", level);
 395                 core_compression_level = level;
 396                 core_compression_seen = 1;
 397                 if (!zlib_compression_seen)
 398                         zlib_compression_level = level;
 399                 return 0;
 400         }
 401
 402         if (!strcmp(var, "core.packedgitwindowsize")) {
 403                 int pgsz_x2 = getpagesize() * 2;
 404                 packed_git_window_size = git_config_int(var, value);
 405
 406                 /* This value must be multiple of (pagesize * 2) */
 407                 packed_git_window_size /= pgsz_x2;
 408                 if (packed_git_window_size < 1)
 409                         packed_git_window_size = 1;
 410                 packed_git_window_size *= pgsz_x2;
 411                 return 0;
 412         }
 413
 414         if (!strcmp(var, "core.packedgitlimit")) {
 415                 packed_git_limit = git_config_int(var, value);
 416                 return 0;
 417         }
 418
 419         if (!strcmp(var, "core.deltabasecachelimit")) {
 420                 delta_base_cache_limit = git_config_int(var, value);
 421                 return 0;
 422         }
 423
 424         if (!strcmp(var, "core.autocrlf")) {
 425                 if (value && !strcasecmp(value, "input")) {
 426                         auto_crlf = -1;
 427                         return 0;
 428                 }
 429                 auto_crlf = git_config_bool(var, value);
 430                 return 0;
 431         }
 432
 433         if (!strcmp(var, "core.safecrlf")) {
 434                 if (value && !strcasecmp(value, "warn")) {
 435                         safe_crlf = SAFE_CRLF_WARN;
 436                         return 0;
 437                 }
 438                 safe_crlf = git_config_bool(var, value);
 439                 return 0;
 440         }
 441
 442         if (!strcmp(var, "user.name")) {
 443                 if (!value)
 444                         return config_error_nonbool(var);
 445                 strlcpy(git_default_name, value, sizeof(git_default_name));
 446                 if (git_default_email[0])
 447                         user_ident_explicitly_given = 1;
 448                 return 0;
 449         }
 450
 451         if (!strcmp(var, "user.email")) {
 452                 if (!value)
 453                         return config_error_nonbool(var);
 454                 strlcpy(git_default_email, value, sizeof(git_default_email));
 455                 if (git_default_name[0])
 456                         user_ident_explicitly_given = 1;
 457                 return 0;
 458         }
 459
 460         if (!strcmp(var, "i18n.commitencoding"))
 461                 return git_config_string(&git_commit_encoding, var, value);
 462
 463         if (!strcmp(var, "i18n.logoutputencoding"))
 464                 return git_config_string(&git_log_output_encoding, var, value);
 465
 466         if (!strcmp(var, "pager.color") || !strcmp(var, "color.pager")) {
 467                 pager_use_color = git_config_bool(var,value);
 468                 return 0;
 469         }
 470
 471         if (!strcmp(var, "core.pager"))
 472                 return git_config_string(&pager_program, var, value);
 473
 474         if (!strcmp(var, "core.editor"))
 475                 return git_config_string(&editor_program, var, value);
 476
 477         if (!strcmp(var, "core.excludesfile"))
 478                 return git_config_string(&excludes_file, var, value);
 479
 480         if (!strcmp(var, "core.whitespace")) {
 481                 if (!value)
 482                         return config_error_nonbool(var);
 483                 whitespace_rule_cfg = parse_whitespace_rule(value);
 484                 return 0;
 485         }
 486         if (!strcmp(var, "branch.autosetupmerge")) {
 487                 if (value && !strcasecmp(value, "always")) {
 488                         git_branch_track = BRANCH_TRACK_ALWAYS;
 489                         return 0;
 490                 }
 491                 git_branch_track = git_config_bool(var, value);
 492                 return 0;
 493         }
 494
 495         /* Add other config variables here and to Documentation/config.txt. */
 496         return 0;
 497 }
 498
 499 int git_config_from_file(config_fn_t fn, const char *filename)
 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 = git_parse_file(fn);
 511                 fclose(f);
 512                 config_file_name = NULL;
 513         }
 514         return ret;
 515 }
 516
 517 const char *git_etc_gitconfig(void)
 518 {
 519         static const char *system_wide;
 520         if (!system_wide) {
 521                 system_wide = ETC_GITCONFIG;
 522                 if (!is_absolute_path(system_wide)) {
 523                         /* interpret path relative to exec-dir */
 524                         struct strbuf d = STRBUF_INIT;
 525                         strbuf_addf(&d, "%s/%s", git_exec_path(), system_wide);
 526                         system_wide = strbuf_detach(&d, NULL);
 527                 }
 528         }
 529         return system_wide;
 530 }
 531
 532 int git_env_bool(const char *k, int def)
 533 {
 534         const char *v = getenv(k);
 535         return v ? git_config_bool(k, v) : def;
 536 }
 537
 538 int git_config_system(void)
 539 {
 540         return !git_env_bool("GIT_CONFIG_NOSYSTEM", 0);
 541 }
 542
 543 int git_config_global(void)
 544 {
 545         return !git_env_bool("GIT_CONFIG_NOGLOBAL", 0);
 546 }
 547
 548 int git_config(config_fn_t fn)
 549 {
 550         int ret = 0;
 551         char *repo_config = NULL;
 552         const char *home = NULL, *filename;
 553
 554         /* $GIT_CONFIG makes git read _only_ the given config file,
 555          * $GIT_CONFIG_LOCAL will make it process it in addition to the
 556          * global config file, the same way it would the per-repository
 557          * config file otherwise. */
 558         filename = getenv(CONFIG_ENVIRONMENT);
 559         if (!filename) {
 560                 if (git_config_system() && !access(git_etc_gitconfig(), R_OK))
 561                         ret += git_config_from_file(fn, git_etc_gitconfig());
 562                 home = getenv("HOME");
 563                 filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 564                 if (!filename)
 565                         filename = repo_config = xstrdup(git_path("config"));
 566         }
 567
 568         if (git_config_global() && home) {
 569                 char *user_config = xstrdup(mkpath("%s/.gitconfig", home));
 570                 if (!access(user_config, R_OK))
 571                         ret = git_config_from_file(fn, user_config);
 572                 free(user_config);
 573         }
 574
 575         ret += git_config_from_file(fn, filename);
 576         free(repo_config);
 577         return ret;
 578 }
 579
 580 /*
 581  * Find all the stuff for git_config_set() below.
 582  */
 583
 584 #define MAX_MATCHES 512
 585
 586 static struct {
 587         int baselen;
 588         char* key;
 589         int do_not_match;
 590         regex_t* value_regex;
 591         int multi_replace;
 592         size_t offset[MAX_MATCHES];
 593         enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
 594         int seen;
 595 } store;
 596
 597 static int matches(const char* key, const char* value)
 598 {
 599         return !strcmp(key, store.key) &&
 600                 (store.value_regex == NULL ||
 601                  (store.do_not_match ^
 602                   !regexec(store.value_regex, value, 0, NULL, 0)));
 603 }
 604
 605 static int store_aux(const char* key, const char* value)
 606 {
 607         const char *ep;
 608         size_t section_len;
 609
 610         switch (store.state) {
 611         case KEY_SEEN:
 612                 if (matches(key, value)) {
 613                         if (store.seen == 1 && store.multi_replace == 0) {
 614                                 fprintf(stderr,
 615                                         "Warning: %s has multiple values\n",
 616                                         key);
 617                         } else if (store.seen >= MAX_MATCHES) {
 618                                 fprintf(stderr, "Too many matches\n");
 619                                 return 1;
 620                         }
 621
 622                         store.offset[store.seen] = ftell(config_file);
 623                         store.seen++;
 624                 }
 625                 break;
 626         case SECTION_SEEN:
 627                 /*
 628                  * What we are looking for is in store.key (both
 629                  * section and var), and its section part is baselen
 630                  * long.  We found key (again, both section and var).
 631                  * We would want to know if this key is in the same
 632                  * section as what we are looking for.  We already
 633                  * know we are in the same section as what should
 634                  * hold store.key.
 635                  */
 636                 ep = strrchr(key, '.');
 637                 section_len = ep - key;
 638
 639                 if ((section_len != store.baselen) ||
 640                     memcmp(key, store.key, section_len+1)) {
 641                         store.state = SECTION_END_SEEN;
 642                         break;
 643                 }
 644
 645                 /*
 646                  * Do not increment matches: this is no match, but we
 647                  * just made sure we are in the desired section.
 648                  */
 649                 store.offset[store.seen] = ftell(config_file);
 650                 /* fallthru */
 651         case SECTION_END_SEEN:
 652         case START:
 653                 if (matches(key, value)) {
 654                         store.offset[store.seen] = ftell(config_file);
 655                         store.state = KEY_SEEN;
 656                         store.seen++;
 657                 } else {
 658                         if (strrchr(key, '.') - key == store.baselen &&
 659                               !strncmp(key, store.key, store.baselen)) {
 660                                         store.state = SECTION_SEEN;
 661                                         store.offset[store.seen] = ftell(config_file);
 662                         }
 663                 }
 664         }
 665         return 0;
 666 }
 667
 668 static int write_error(void)
 669 {
 670         fprintf(stderr, "Failed to write new configuration file\n");
 671
 672         /* Same error code as "failed to rename". */
 673         return 4;
 674 }
 675
 676 static int store_write_section(int fd, const char* key)
 677 {
 678         const char *dot;
 679         int i, success;
 680         struct strbuf sb;
 681
 682         strbuf_init(&sb, 0);
 683         dot = memchr(key, '.', store.baselen);
 684         if (dot) {
 685                 strbuf_addf(&sb, "[%.*s \"", (int)(dot - key), key);
 686                 for (i = dot - key + 1; i < store.baselen; i++) {
 687                         if (key[i] == '"')
 688                                 strbuf_addch(&sb, '\\');
 689                         strbuf_addch(&sb, key[i]);
 690                 }
 691                 strbuf_addstr(&sb, "\"]\n");
 692         } else {
 693                 strbuf_addf(&sb, "[%.*s]\n", store.baselen, key);
 694         }
 695
 696         success = write_in_full(fd, sb.buf, sb.len) == sb.len;
 697         strbuf_release(&sb);
 698
 699         return success;
 700 }
 701
 702 static int store_write_pair(int fd, const char* key, const char* value)
 703 {
 704         int i, success;
 705         int length = strlen(key + store.baselen + 1);
 706         const char *quote = "";
 707         struct strbuf sb;
 708
 709         /*
 710          * Check to see if the value needs to be surrounded with a dq pair.
 711          * Note that problematic characters are always backslash-quoted; this
 712          * check is about not losing leading or trailing SP and strings that
 713          * follow beginning-of-comment characters (i.e. ';' and '#') by the
 714          * configuration parser.
 715          */
 716         if (value[0] == ' ')
 717                 quote = "\"";
 718         for (i = 0; value[i]; i++)
 719                 if (value[i] == ';' || value[i] == '#')
 720                         quote = "\"";
 721         if (i && value[i - 1] == ' ')
 722                 quote = "\"";
 723
 724         strbuf_init(&sb, 0);
 725         strbuf_addf(&sb, "\t%.*s = %s",
 726                     length, key + store.baselen + 1, quote);
 727
 728         for (i = 0; value[i]; i++)
 729                 switch (value[i]) {
 730                 case '\n':
 731                         strbuf_addstr(&sb, "\\n");
 732                         break;
 733                 case '\t':
 734                         strbuf_addstr(&sb, "\\t");
 735                         break;
 736                 case '"':
 737                 case '\\':
 738                         strbuf_addch(&sb, '\\');
 739                 default:
 740                         strbuf_addch(&sb, value[i]);
 741                         break;
 742                 }
 743         strbuf_addf(&sb, "%s\n", quote);
 744
 745         success = write_in_full(fd, sb.buf, sb.len) == sb.len;
 746         strbuf_release(&sb);
 747
 748         return success;
 749 }
 750
 751 static ssize_t find_beginning_of_line(const char* contents, size_t size,
 752         size_t offset_, int* found_bracket)
 753 {
 754         size_t equal_offset = size, bracket_offset = size;
 755         ssize_t offset;
 756
 757 contline:
 758         for (offset = offset_-2; offset > 0
 759                         && contents[offset] != '\n'; offset--)
 760                 switch (contents[offset]) {
 761                         case '=': equal_offset = offset; break;
 762                         case ']': bracket_offset = offset; break;
 763                 }
 764         if (offset > 0 && contents[offset-1] == '\\') {
 765                 offset_ = offset;
 766                 goto contline;
 767         }
 768         if (bracket_offset < equal_offset) {
 769                 *found_bracket = 1;
 770                 offset = bracket_offset+1;
 771         } else
 772                 offset++;
 773
 774         return offset;
 775 }
 776
 777 int git_config_set(const char* key, const char* value)
 778 {
 779         return git_config_set_multivar(key, value, NULL, 0);
 780 }
 781
 782 /*
 783  * If value==NULL, unset in (remove from) config,
 784  * if value_regex!=NULL, disregard key/value pairs where value does not match.
 785  * if multi_replace==0, nothing, or only one matching key/value is replaced,
 786  *     else all matching key/values (regardless how many) are removed,
 787  *     before the new pair is written.
 788  *
 789  * Returns 0 on success.
 790  *
 791  * This function does this:
 792  *
 793  * - it locks the config file by creating ".git/config.lock"
 794  *
 795  * - it then parses the config using store_aux() as validator to find
 796  *   the position on the key/value pair to replace. If it is to be unset,
 797  *   it must be found exactly once.
 798  *
 799  * - the config file is mmap()ed and the part before the match (if any) is
 800  *   written to the lock file, then the changed part and the rest.
 801  *
 802  * - the config file is removed and the lock file rename()d to it.
 803  *
 804  */
 805 int git_config_set_multivar(const char* key, const char* value,
 806         const char* value_regex, int multi_replace)
 807 {
 808         int i, dot;
 809         int fd = -1, in_fd;
 810         int ret;
 811         char* config_filename;
 812         struct lock_file *lock = NULL;
 813         const char* last_dot = strrchr(key, '.');
 814
 815         config_filename = getenv(CONFIG_ENVIRONMENT);
 816         if (!config_filename) {
 817                 config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 818                 if (!config_filename)
 819                         config_filename  = git_path("config");
 820         }
 821         config_filename = xstrdup(config_filename);
 822
 823         /*
 824          * Since "key" actually contains the section name and the real
 825          * key name separated by a dot, we have to know where the dot is.
 826          */
 827
 828         if (last_dot == NULL) {
 829                 fprintf(stderr, "key does not contain a section: %s\n", key);
 830                 ret = 2;
 831                 goto out_free;
 832         }
 833         store.baselen = last_dot - key;
 834
 835         store.multi_replace = multi_replace;
 836
 837         /*
 838          * Validate the key and while at it, lower case it for matching.
 839          */
 840         store.key = xmalloc(strlen(key) + 1);
 841         dot = 0;
 842         for (i = 0; key[i]; i++) {
 843                 unsigned char c = key[i];
 844                 if (c == '.')
 845                         dot = 1;
 846                 /* Leave the extended basename untouched.. */
 847                 if (!dot || i > store.baselen) {
 848                         if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
 849                                 fprintf(stderr, "invalid key: %s\n", key);
 850                                 free(store.key);
 851                                 ret = 1;
 852                                 goto out_free;
 853                         }
 854                         c = tolower(c);
 855                 } else if (c == '\n') {
 856                         fprintf(stderr, "invalid key (newline): %s\n", key);
 857                         free(store.key);
 858                         ret = 1;
 859                         goto out_free;
 860                 }
 861                 store.key[i] = c;
 862         }
 863         store.key[i] = 0;
 864
 865         /*
 866          * The lock serves a purpose in addition to locking: the new
 867          * contents of .git/config will be written into it.
 868          */
 869         lock = xcalloc(sizeof(struct lock_file), 1);
 870         fd = hold_lock_file_for_update(lock, config_filename, 0);
 871         if (fd < 0) {
 872                 fprintf(stderr, "could not lock config file\n");
 873                 free(store.key);
 874                 ret = -1;
 875                 goto out_free;
 876         }
 877
 878         /*
 879          * If .git/config does not exist yet, write a minimal version.
 880          */
 881         in_fd = open(config_filename, O_RDONLY);
 882         if ( in_fd < 0 ) {
 883                 free(store.key);
 884
 885                 if ( ENOENT != errno ) {
 886                         error("opening %s: %s", config_filename,
 887                               strerror(errno));
 888                         ret = 3; /* same as "invalid config file" */
 889                         goto out_free;
 890                 }
 891                 /* if nothing to unset, error out */
 892                 if (value == NULL) {
 893                         ret = 5;
 894                         goto out_free;
 895                 }
 896
 897                 store.key = (char*)key;
 898                 if (!store_write_section(fd, key) ||
 899                     !store_write_pair(fd, key, value))
 900                         goto write_err_out;
 901         } else {
 902                 struct stat st;
 903                 char* contents;
 904                 size_t contents_sz, copy_begin, copy_end;
 905                 int i, new_line = 0;
 906
 907                 if (value_regex == NULL)
 908                         store.value_regex = NULL;
 909                 else {
 910                         if (value_regex[0] == '!') {
 911                                 store.do_not_match = 1;
 912                                 value_regex++;
 913                         } else
 914                                 store.do_not_match = 0;
 915
 916                         store.value_regex = (regex_t*)xmalloc(sizeof(regex_t));
 917                         if (regcomp(store.value_regex, value_regex,
 918                                         REG_EXTENDED)) {
 919                                 fprintf(stderr, "Invalid pattern: %s\n",
 920                                         value_regex);
 921                                 free(store.value_regex);
 922                                 ret = 6;
 923                                 goto out_free;
 924                         }
 925                 }
 926
 927                 store.offset[0] = 0;
 928                 store.state = START;
 929                 store.seen = 0;
 930
 931                 /*
 932                  * After this, store.offset will contain the *end* offset
 933                  * of the last match, or remain at 0 if no match was found.
 934                  * As a side effect, we make sure to transform only a valid
 935                  * existing config file.
 936                  */
 937                 if (git_config_from_file(store_aux, config_filename)) {
 938                         fprintf(stderr, "invalid config file\n");
 939                         free(store.key);
 940                         if (store.value_regex != NULL) {
 941                                 regfree(store.value_regex);
 942                                 free(store.value_regex);
 943                         }
 944                         ret = 3;
 945                         goto out_free;
 946                 }
 947
 948                 free(store.key);
 949                 if (store.value_regex != NULL) {
 950                         regfree(store.value_regex);
 951                         free(store.value_regex);
 952                 }
 953
 954                 /* if nothing to unset, or too many matches, error out */
 955                 if ((store.seen == 0 && value == NULL) ||
 956                                 (store.seen > 1 && multi_replace == 0)) {
 957                         ret = 5;
 958                         goto out_free;
 959                 }
 960
 961                 fstat(in_fd, &st);
 962                 contents_sz = xsize_t(st.st_size);
 963                 contents = xmmap(NULL, contents_sz, PROT_READ,
 964                         MAP_PRIVATE, in_fd, 0);
 965                 close(in_fd);
 966
 967                 if (store.seen == 0)
 968                         store.seen = 1;
 969
 970                 for (i = 0, copy_begin = 0; i < store.seen; i++) {
 971                         if (store.offset[i] == 0) {
 972                                 store.offset[i] = copy_end = contents_sz;
 973                         } else if (store.state != KEY_SEEN) {
 974                                 copy_end = store.offset[i];
 975                         } else
 976                                 copy_end = find_beginning_of_line(
 977                                         contents, contents_sz,
 978                                         store.offset[i]-2, &new_line);
 979
 980                         if (copy_end > 0 && contents[copy_end-1] != '\n')
 981                                 new_line = 1;
 982
 983                         /* write the first part of the config */
 984                         if (copy_end > copy_begin) {
 985                                 if (write_in_full(fd, contents + copy_begin,
 986                                                   copy_end - copy_begin) <
 987                                     copy_end - copy_begin)
 988                                         goto write_err_out;
 989                                 if (new_line &&
 990                                     write_in_full(fd, "\n", 1) != 1)
 991                                         goto write_err_out;
 992                         }
 993                         copy_begin = store.offset[i];
 994                 }
 995
 996                 /* write the pair (value == NULL means unset) */
 997                 if (value != NULL) {
 998                         if (store.state == START) {
 999                                 if (!store_write_section(fd, key))
1000                                         goto write_err_out;
1001                         }
1002                         if (!store_write_pair(fd, key, value))
1003                                 goto write_err_out;
1004                 }
1005
1006                 /* write the rest of the config */
1007                 if (copy_begin < contents_sz)
1008                         if (write_in_full(fd, contents + copy_begin,
1009                                           contents_sz - copy_begin) <
1010                             contents_sz - copy_begin)
1011                                 goto write_err_out;
1012
1013                 munmap(contents, contents_sz);
1014         }
1015
1016         if (commit_lock_file(lock) < 0) {
1017                 fprintf(stderr, "Cannot commit config file!\n");
1018                 ret = 4;
1019                 goto out_free;
1020         }
1021
1022         /*
1023          * lock is committed, so don't try to roll it back below.
1024          * NOTE: Since lockfile.c keeps a linked list of all created
1025          * lock_file structures, it isn't safe to free(lock).  It's
1026          * better to just leave it hanging around.
1027          */
1028         lock = NULL;
1029         ret = 0;
1030
1031 out_free:
1032         if (lock)
1033                 rollback_lock_file(lock);
1034         free(config_filename);
1035         return ret;
1036
1037 write_err_out:
1038         ret = write_error();
1039         goto out_free;
1040
1041 }
1042
1043 static int section_name_match (const char *buf, const char *name)
1044 {
1045         int i = 0, j = 0, dot = 0;
1046         for (; buf[i] && buf[i] != ']'; i++) {
1047                 if (!dot && isspace(buf[i])) {
1048                         dot = 1;
1049                         if (name[j++] != '.')
1050                                 break;
1051                         for (i++; isspace(buf[i]); i++)
1052                                 ; /* do nothing */
1053                         if (buf[i] != '"')
1054                                 break;
1055                         continue;
1056                 }
1057                 if (buf[i] == '\\' && dot)
1058                         i++;
1059                 else if (buf[i] == '"' && dot) {
1060                         for (i++; isspace(buf[i]); i++)
1061                                 ; /* do_nothing */
1062                         break;
1063                 }
1064                 if (buf[i] != name[j++])
1065                         break;
1066         }
1067         return (buf[i] == ']' && name[j] == 0);
1068 }
1069
1070 /* if new_name == NULL, the section is removed instead */
1071 int git_config_rename_section(const char *old_name, const char *new_name)
1072 {
1073         int ret = 0, remove = 0;
1074         char *config_filename;
1075         struct lock_file *lock = xcalloc(sizeof(struct lock_file), 1);
1076         int out_fd;
1077         char buf[1024];
1078
1079         config_filename = getenv(CONFIG_ENVIRONMENT);
1080         if (!config_filename) {
1081                 config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
1082                 if (!config_filename)
1083                         config_filename  = git_path("config");
1084         }
1085         config_filename = xstrdup(config_filename);
1086         out_fd = hold_lock_file_for_update(lock, config_filename, 0);
1087         if (out_fd < 0) {
1088                 ret = error("Could not lock config file!");
1089                 goto out;
1090         }
1091
1092         if (!(config_file = fopen(config_filename, "rb"))) {
1093                 /* no config file means nothing to rename, no error */
1094                 goto unlock_and_out;
1095         }
1096
1097         while (fgets(buf, sizeof(buf), config_file)) {
1098                 int i;
1099                 int length;
1100                 for (i = 0; buf[i] && isspace(buf[i]); i++)
1101                         ; /* do nothing */
1102                 if (buf[i] == '[') {
1103                         /* it's a section */
1104                         if (section_name_match (&buf[i+1], old_name)) {
1105                                 ret++;
1106                                 if (new_name == NULL) {
1107                                         remove = 1;
1108                                         continue;
1109                                 }
1110                                 store.baselen = strlen(new_name);
1111                                 if (!store_write_section(out_fd, new_name)) {
1112                                         ret = write_error();
1113                                         goto out;
1114                                 }
1115                                 continue;
1116                         }
1117                         remove = 0;
1118                 }
1119                 if (remove)
1120                         continue;
1121                 length = strlen(buf);
1122                 if (write_in_full(out_fd, buf, length) != length) {
1123                         ret = write_error();
1124                         goto out;
1125                 }
1126         }
1127         fclose(config_file);
1128  unlock_and_out:
1129         if (commit_lock_file(lock) < 0)
1130                         ret = error("Cannot commit config file!");
1131  out:
1132         free(config_filename);
1133         return ret;
1134 }
1135
1136 /*
1137  * Call this to report error for your variable that should not
1138  * get a boolean value (i.e. "[my] var" means "true").
1139  */
1140 int config_error_nonbool(const char *var)
1141 {
1142         return error("Missing value for '%s'", var);
1143 }