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
  10 #define MAXNAME (256)
  11
  12 static FILE *config_file;
  13 static const char *config_file_name;
  14 static int config_linenr;
  15 static int zlib_compression_seen;
  16
  17 static int get_next_char(void)
  18 {
  19         int c;
  20         FILE *f;
  21
  22         c = '\n';
  23         if ((f = config_file) != NULL) {
  24                 c = fgetc(f);
  25                 if (c == '\r') {
  26                         /* DOS like systems */
  27                         c = fgetc(f);
  28                         if (c != '\n') {
  29                                 ungetc(c, f);
  30                                 c = '\r';
  31                         }
  32                 }
  33                 if (c == '\n')
  34                         config_linenr++;
  35                 if (c == EOF) {
  36                         config_file = NULL;
  37                         c = '\n';
  38                 }
  39         }
  40         return c;
  41 }
  42
  43 static char *parse_value(void)
  44 {
  45         static char value[1024];
  46         int quote = 0, comment = 0, len = 0, space = 0;
  47
  48         for (;;) {
  49                 int c = get_next_char();
  50                 if (len >= sizeof(value))
  51                         return NULL;
  52                 if (c == '\n') {
  53                         if (quote)
  54                                 return NULL;
  55                         value[len] = 0;
  56                         return value;
  57                 }
  58                 if (comment)
  59                         continue;
  60                 if (isspace(c) && !quote) {
  61                         space = 1;
  62                         continue;
  63                 }
  64                 if (!quote) {
  65                         if (c == ';' || c == '#') {
  66                                 comment = 1;
  67                                 continue;
  68                         }
  69                 }
  70                 if (space) {
  71                         if (len)
  72                                 value[len++] = ' ';
  73                         space = 0;
  74                 }
  75                 if (c == '\\') {
  76                         c = get_next_char();
  77                         switch (c) {
  78                         case '\n':
  79                                 continue;
  80                         case 't':
  81                                 c = '\t';
  82                                 break;
  83                         case 'b':
  84                                 c = '\b';
  85                                 break;
  86                         case 'n':
  87                                 c = '\n';
  88                                 break;
  89                         /* Some characters escape as themselves */
  90                         case '\\': case '"':
  91                                 break;
  92                         /* Reject unknown escape sequences */
  93                         default:
  94                                 return NULL;
  95                         }
  96                         value[len++] = c;
  97                         continue;
  98                 }
  99                 if (c == '"') {
 100                         quote = 1-quote;
 101                         continue;
 102                 }
 103                 value[len++] = c;
 104         }
 105 }
 106
 107 static inline int iskeychar(int c)
 108 {
 109         return isalnum(c) || c == '-';
 110 }
 111
 112 static int get_value(config_fn_t fn, char *name, unsigned int len)
 113 {
 114         int c;
 115         char *value;
 116
 117         /* Get the full name */
 118         for (;;) {
 119                 c = get_next_char();
 120                 if (c == EOF)
 121                         break;
 122                 if (!iskeychar(c))
 123                         break;
 124                 name[len++] = tolower(c);
 125                 if (len >= MAXNAME)
 126                         return -1;
 127         }
 128         name[len] = 0;
 129         while (c == ' ' || c == '\t')
 130                 c = get_next_char();
 131
 132         value = NULL;
 133         if (c != '\n') {
 134                 if (c != '=')
 135                         return -1;
 136                 value = parse_value();
 137                 if (!value)
 138                         return -1;
 139         }
 140         return fn(name, value);
 141 }
 142
 143 static int get_extended_base_var(char *name, int baselen, int c)
 144 {
 145         do {
 146                 if (c == '\n')
 147                         return -1;
 148                 c = get_next_char();
 149         } while (isspace(c));
 150
 151         /* We require the format to be '[base "extension"]' */
 152         if (c != '"')
 153                 return -1;
 154         name[baselen++] = '.';
 155
 156         for (;;) {
 157                 int c = get_next_char();
 158                 if (c == '\n')
 159                         return -1;
 160                 if (c == '"')
 161                         break;
 162                 if (c == '\\') {
 163                         c = get_next_char();
 164                         if (c == '\n')
 165                                 return -1;
 166                 }
 167                 name[baselen++] = c;
 168                 if (baselen > MAXNAME / 2)
 169                         return -1;
 170         }
 171
 172         /* Final ']' */
 173         if (get_next_char() != ']')
 174                 return -1;
 175         return baselen;
 176 }
 177
 178 static int get_base_var(char *name)
 179 {
 180         int baselen = 0;
 181
 182         for (;;) {
 183                 int c = get_next_char();
 184                 if (c == EOF)
 185                         return -1;
 186                 if (c == ']')
 187                         return baselen;
 188                 if (isspace(c))
 189                         return get_extended_base_var(name, baselen, c);
 190                 if (!iskeychar(c) && c != '.')
 191                         return -1;
 192                 if (baselen > MAXNAME / 2)
 193                         return -1;
 194                 name[baselen++] = tolower(c);
 195         }
 196 }
 197
 198 static int git_parse_file(config_fn_t fn)
 199 {
 200         int comment = 0;
 201         int baselen = 0;
 202         static char var[MAXNAME];
 203
 204         for (;;) {
 205                 int c = get_next_char();
 206                 if (c == '\n') {
 207                         /* EOF? */
 208                         if (!config_file)
 209                                 return 0;
 210                         comment = 0;
 211                         continue;
 212                 }
 213                 if (comment || isspace(c))
 214                         continue;
 215                 if (c == '#' || c == ';') {
 216                         comment = 1;
 217                         continue;
 218                 }
 219                 if (c == '[') {
 220                         baselen = get_base_var(var);
 221                         if (baselen <= 0)
 222                                 break;
 223                         var[baselen++] = '.';
 224                         var[baselen] = 0;
 225                         continue;
 226                 }
 227                 if (!isalpha(c))
 228                         break;
 229                 var[baselen] = tolower(c);
 230                 if (get_value(fn, var, baselen+1) < 0)
 231                         break;
 232         }
 233         die("bad config file line %d in %s", config_linenr, config_file_name);
 234 }
 235
 236 static unsigned long get_unit_factor(const char *end)
 237 {
 238         if (!*end)
 239                 return 1;
 240         else if (!strcasecmp(end, "k"))
 241                 return 1024;
 242         else if (!strcasecmp(end, "m"))
 243                 return 1024 * 1024;
 244         else if (!strcasecmp(end, "g"))
 245                 return 1024 * 1024 * 1024;
 246         die("unknown unit: '%s'", end);
 247 }
 248
 249 int git_parse_long(const char *value, long *ret)
 250 {
 251         if (value && *value) {
 252                 char *end;
 253                 long val = strtol(value, &end, 0);
 254                 *ret = val * get_unit_factor(end);
 255                 return 1;
 256         }
 257         return 0;
 258 }
 259
 260 int git_parse_ulong(const char *value, unsigned long *ret)
 261 {
 262         if (value && *value) {
 263                 char *end;
 264                 unsigned long val = strtoul(value, &end, 0);
 265                 *ret = val * get_unit_factor(end);
 266                 return 1;
 267         }
 268         return 0;
 269 }
 270
 271 int git_config_int(const char *name, const char *value)
 272 {
 273         long ret;
 274         if (!git_parse_long(value, &ret))
 275                 die("bad config value for '%s' in %s", name, config_file_name);
 276         return ret;
 277 }
 278
 279 unsigned long git_config_ulong(const char *name, const char *value)
 280 {
 281         unsigned long ret;
 282         if (!git_parse_ulong(value, &ret))
 283                 die("bad config value for '%s' in %s", name, config_file_name);
 284         return ret;
 285 }
 286
 287 int git_config_bool(const char *name, const char *value)
 288 {
 289         if (!value)
 290                 return 1;
 291         if (!*value)
 292                 return 0;
 293         if (!strcasecmp(value, "true") || !strcasecmp(value, "yes"))
 294                 return 1;
 295         if (!strcasecmp(value, "false") || !strcasecmp(value, "no"))
 296                 return 0;
 297         return git_config_int(name, value) != 0;
 298 }
 299
 300 int git_default_config(const char *var, const char *value)
 301 {
 302         /* This needs a better name */
 303         if (!strcmp(var, "core.filemode")) {
 304                 trust_executable_bit = git_config_bool(var, value);
 305                 return 0;
 306         }
 307
 308         if (!strcmp(var, "core.quotepath")) {
 309                 quote_path_fully = git_config_bool(var, value);
 310                 return 0;
 311         }
 312
 313         if (!strcmp(var, "core.symlinks")) {
 314                 has_symlinks = git_config_bool(var, value);
 315                 return 0;
 316         }
 317
 318         if (!strcmp(var, "core.bare")) {
 319                 is_bare_repository_cfg = git_config_bool(var, value);
 320                 return 0;
 321         }
 322
 323         if (!strcmp(var, "core.ignorestat")) {
 324                 assume_unchanged = git_config_bool(var, value);
 325                 return 0;
 326         }
 327
 328         if (!strcmp(var, "core.prefersymlinkrefs")) {
 329                 prefer_symlink_refs = git_config_bool(var, value);
 330                 return 0;
 331         }
 332
 333         if (!strcmp(var, "core.logallrefupdates")) {
 334                 log_all_ref_updates = git_config_bool(var, value);
 335                 return 0;
 336         }
 337
 338         if (!strcmp(var, "core.warnambiguousrefs")) {
 339                 warn_ambiguous_refs = git_config_bool(var, value);
 340                 return 0;
 341         }
 342
 343         if (!strcmp(var, "core.loosecompression")) {
 344                 int level = git_config_int(var, value);
 345                 if (level == -1)
 346                         level = Z_DEFAULT_COMPRESSION;
 347                 else if (level < 0 || level > Z_BEST_COMPRESSION)
 348                         die("bad zlib compression level %d", level);
 349                 zlib_compression_level = level;
 350                 zlib_compression_seen = 1;
 351                 return 0;
 352         }
 353
 354         if (!strcmp(var, "core.compression")) {
 355                 int level = git_config_int(var, value);
 356                 if (level == -1)
 357                         level = Z_DEFAULT_COMPRESSION;
 358                 else if (level < 0 || level > Z_BEST_COMPRESSION)
 359                         die("bad zlib compression level %d", level);
 360                 core_compression_level = level;
 361                 core_compression_seen = 1;
 362                 if (!zlib_compression_seen)
 363                         zlib_compression_level = level;
 364                 return 0;
 365         }
 366
 367         if (!strcmp(var, "core.packedgitwindowsize")) {
 368                 int pgsz_x2 = getpagesize() * 2;
 369                 packed_git_window_size = git_config_int(var, value);
 370
 371                 /* This value must be multiple of (pagesize * 2) */
 372                 packed_git_window_size /= pgsz_x2;
 373                 if (packed_git_window_size < 1)
 374                         packed_git_window_size = 1;
 375                 packed_git_window_size *= pgsz_x2;
 376                 return 0;
 377         }
 378
 379         if (!strcmp(var, "core.packedgitlimit")) {
 380                 packed_git_limit = git_config_int(var, value);
 381                 return 0;
 382         }
 383
 384         if (!strcmp(var, "core.deltabasecachelimit")) {
 385                 delta_base_cache_limit = git_config_int(var, value);
 386                 return 0;
 387         }
 388
 389         if (!strcmp(var, "core.autocrlf")) {
 390                 if (value && !strcasecmp(value, "input")) {
 391                         auto_crlf = -1;
 392                         return 0;
 393                 }
 394                 auto_crlf = git_config_bool(var, value);
 395                 return 0;
 396         }
 397
 398         if (!strcmp(var, "user.name")) {
 399                 strlcpy(git_default_name, value, sizeof(git_default_name));
 400                 return 0;
 401         }
 402
 403         if (!strcmp(var, "user.email")) {
 404                 strlcpy(git_default_email, value, sizeof(git_default_email));
 405                 return 0;
 406         }
 407
 408         if (!strcmp(var, "i18n.commitencoding")) {
 409                 git_commit_encoding = xstrdup(value);
 410                 return 0;
 411         }
 412
 413         if (!strcmp(var, "i18n.logoutputencoding")) {
 414                 git_log_output_encoding = xstrdup(value);
 415                 return 0;
 416         }
 417
 418
 419         if (!strcmp(var, "pager.color") || !strcmp(var, "color.pager")) {
 420                 pager_use_color = git_config_bool(var,value);
 421                 return 0;
 422         }
 423
 424         if (!strcmp(var, "core.pager")) {
 425                 pager_program = xstrdup(value);
 426                 return 0;
 427         }
 428
 429         if (!strcmp(var, "core.editor")) {
 430                 editor_program = xstrdup(value);
 431                 return 0;
 432         }
 433
 434         if (!strcmp(var, "core.excludesfile")) {
 435                 if (!value)
 436                         die("core.excludesfile without value");
 437                 excludes_file = xstrdup(value);
 438                 return 0;
 439         }
 440
 441         /* Add other config variables here and to Documentation/config.txt. */
 442         return 0;
 443 }
 444
 445 int git_config_from_file(config_fn_t fn, const char *filename)
 446 {
 447         int ret;
 448         FILE *f = fopen(filename, "r");
 449
 450         ret = -1;
 451         if (f) {
 452                 config_file = f;
 453                 config_file_name = filename;
 454                 config_linenr = 1;
 455                 ret = git_parse_file(fn);
 456                 fclose(f);
 457                 config_file_name = NULL;
 458         }
 459         return ret;
 460 }
 461
 462 int git_config(config_fn_t fn)
 463 {
 464         int ret = 0;
 465         char *repo_config = NULL;
 466         const char *home = NULL, *filename;
 467
 468         /* $GIT_CONFIG makes git read _only_ the given config file,
 469          * $GIT_CONFIG_LOCAL will make it process it in addition to the
 470          * global config file, the same way it would the per-repository
 471          * config file otherwise. */
 472         filename = getenv(CONFIG_ENVIRONMENT);
 473         if (!filename) {
 474                 if (!access(ETC_GITCONFIG, R_OK))
 475                         ret += git_config_from_file(fn, ETC_GITCONFIG);
 476                 home = getenv("HOME");
 477                 filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 478                 if (!filename)
 479                         filename = repo_config = xstrdup(git_path("config"));
 480         }
 481
 482         if (home) {
 483                 char *user_config = xstrdup(mkpath("%s/.gitconfig", home));
 484                 if (!access(user_config, R_OK))
 485                         ret = git_config_from_file(fn, user_config);
 486                 free(user_config);
 487         }
 488
 489         ret += git_config_from_file(fn, filename);
 490         free(repo_config);
 491         return ret;
 492 }
 493
 494 /*
 495  * Find all the stuff for git_config_set() below.
 496  */
 497
 498 #define MAX_MATCHES 512
 499
 500 static struct {
 501         int baselen;
 502         char* key;
 503         int do_not_match;
 504         regex_t* value_regex;
 505         int multi_replace;
 506         size_t offset[MAX_MATCHES];
 507         enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
 508         int seen;
 509 } store;
 510
 511 static int matches(const char* key, const char* value)
 512 {
 513         return !strcmp(key, store.key) &&
 514                 (store.value_regex == NULL ||
 515                  (store.do_not_match ^
 516                   !regexec(store.value_regex, value, 0, NULL, 0)));
 517 }
 518
 519 static int store_aux(const char* key, const char* value)
 520 {
 521         const char *ep;
 522         size_t section_len;
 523
 524         switch (store.state) {
 525         case KEY_SEEN:
 526                 if (matches(key, value)) {
 527                         if (store.seen == 1 && store.multi_replace == 0) {
 528                                 fprintf(stderr,
 529                                         "Warning: %s has multiple values\n",
 530                                         key);
 531                         } else if (store.seen >= MAX_MATCHES) {
 532                                 fprintf(stderr, "Too many matches\n");
 533                                 return 1;
 534                         }
 535
 536                         store.offset[store.seen] = ftell(config_file);
 537                         store.seen++;
 538                 }
 539                 break;
 540         case SECTION_SEEN:
 541                 /*
 542                  * What we are looking for is in store.key (both
 543                  * section and var), and its section part is baselen
 544                  * long.  We found key (again, both section and var).
 545                  * We would want to know if this key is in the same
 546                  * section as what we are looking for.  We already
 547                  * know we are in the same section as what should
 548                  * hold store.key.
 549                  */
 550                 ep = strrchr(key, '.');
 551                 section_len = ep - key;
 552
 553                 if ((section_len != store.baselen) ||
 554                     memcmp(key, store.key, section_len+1)) {
 555                         store.state = SECTION_END_SEEN;
 556                         break;
 557                 }
 558
 559                 /*
 560                  * Do not increment matches: this is no match, but we
 561                  * just made sure we are in the desired section.
 562                  */
 563                 store.offset[store.seen] = ftell(config_file);
 564                 /* fallthru */
 565         case SECTION_END_SEEN:
 566         case START:
 567                 if (matches(key, value)) {
 568                         store.offset[store.seen] = ftell(config_file);
 569                         store.state = KEY_SEEN;
 570                         store.seen++;
 571                 } else {
 572                         if (strrchr(key, '.') - key == store.baselen &&
 573                               !strncmp(key, store.key, store.baselen)) {
 574                                         store.state = SECTION_SEEN;
 575                                         store.offset[store.seen] = ftell(config_file);
 576                         }
 577                 }
 578         }
 579         return 0;
 580 }
 581
 582 static int write_error(void)
 583 {
 584         fprintf(stderr, "Failed to write new configuration file\n");
 585
 586         /* Same error code as "failed to rename". */
 587         return 4;
 588 }
 589
 590 static int store_write_section(int fd, const char* key)
 591 {
 592         const char *dot = strchr(key, '.');
 593         int len1 = store.baselen, len2 = -1;
 594
 595         dot = strchr(key, '.');
 596         if (dot) {
 597                 int dotlen = dot - key;
 598                 if (dotlen < len1) {
 599                         len2 = len1 - dotlen - 1;
 600                         len1 = dotlen;
 601                 }
 602         }
 603
 604         if (write_in_full(fd, "[", 1) != 1 ||
 605             write_in_full(fd, key, len1) != len1)
 606                 return 0;
 607         if (len2 >= 0) {
 608                 if (write_in_full(fd, " \"", 2) != 2)
 609                         return 0;
 610                 while (--len2 >= 0) {
 611                         unsigned char c = *++dot;
 612                         if (c == '"')
 613                                 if (write_in_full(fd, "\\", 1) != 1)
 614                                         return 0;
 615                         if (write_in_full(fd, &c, 1) != 1)
 616                                 return 0;
 617                 }
 618                 if (write_in_full(fd, "\"", 1) != 1)
 619                         return 0;
 620         }
 621         if (write_in_full(fd, "]\n", 2) != 2)
 622                 return 0;
 623
 624         return 1;
 625 }
 626
 627 static int store_write_pair(int fd, const char* key, const char* value)
 628 {
 629         int i;
 630         int length = strlen(key+store.baselen+1);
 631         int quote = 0;
 632
 633         /*
 634          * Check to see if the value needs to be surrounded with a dq pair.
 635          * Note that problematic characters are always backslash-quoted; this
 636          * check is about not losing leading or trailing SP and strings that
 637          * follow beginning-of-comment characters (i.e. ';' and '#') by the
 638          * configuration parser.
 639          */
 640         if (value[0] == ' ')
 641                 quote = 1;
 642         for (i = 0; value[i]; i++)
 643                 if (value[i] == ';' || value[i] == '#')
 644                         quote = 1;
 645         if (i && value[i-1] == ' ')
 646                 quote = 1;
 647
 648         if (write_in_full(fd, "\t", 1) != 1 ||
 649             write_in_full(fd, key+store.baselen+1, length) != length ||
 650             write_in_full(fd, " = ", 3) != 3)
 651                 return 0;
 652         if (quote && write_in_full(fd, "\"", 1) != 1)
 653                 return 0;
 654         for (i = 0; value[i]; i++)
 655                 switch (value[i]) {
 656                 case '\n':
 657                         if (write_in_full(fd, "\\n", 2) != 2)
 658                                 return 0;
 659                         break;
 660                 case '\t':
 661                         if (write_in_full(fd, "\\t", 2) != 2)
 662                                 return 0;
 663                         break;
 664                 case '"':
 665                 case '\\':
 666                         if (write_in_full(fd, "\\", 1) != 1)
 667                                 return 0;
 668                 default:
 669                         if (write_in_full(fd, value+i, 1) != 1)
 670                                 return 0;
 671                         break;
 672                 }
 673         if (quote && write_in_full(fd, "\"", 1) != 1)
 674                 return 0;
 675         if (write_in_full(fd, "\n", 1) != 1)
 676                 return 0;
 677         return 1;
 678 }
 679
 680 static ssize_t find_beginning_of_line(const char* contents, size_t size,
 681         size_t offset_, int* found_bracket)
 682 {
 683         size_t equal_offset = size, bracket_offset = size;
 684         ssize_t offset;
 685
 686         for (offset = offset_-2; offset > 0
 687                         && contents[offset] != '\n'; offset--)
 688                 switch (contents[offset]) {
 689                         case '=': equal_offset = offset; break;
 690                         case ']': bracket_offset = offset; break;
 691                 }
 692         if (bracket_offset < equal_offset) {
 693                 *found_bracket = 1;
 694                 offset = bracket_offset+1;
 695         } else
 696                 offset++;
 697
 698         return offset;
 699 }
 700
 701 int git_config_set(const char* key, const char* value)
 702 {
 703         return git_config_set_multivar(key, value, NULL, 0);
 704 }
 705
 706 /*
 707  * If value==NULL, unset in (remove from) config,
 708  * if value_regex!=NULL, disregard key/value pairs where value does not match.
 709  * if multi_replace==0, nothing, or only one matching key/value is replaced,
 710  *     else all matching key/values (regardless how many) are removed,
 711  *     before the new pair is written.
 712  *
 713  * Returns 0 on success.
 714  *
 715  * This function does this:
 716  *
 717  * - it locks the config file by creating ".git/config.lock"
 718  *
 719  * - it then parses the config using store_aux() as validator to find
 720  *   the position on the key/value pair to replace. If it is to be unset,
 721  *   it must be found exactly once.
 722  *
 723  * - the config file is mmap()ed and the part before the match (if any) is
 724  *   written to the lock file, then the changed part and the rest.
 725  *
 726  * - the config file is removed and the lock file rename()d to it.
 727  *
 728  */
 729 int git_config_set_multivar(const char* key, const char* value,
 730         const char* value_regex, int multi_replace)
 731 {
 732         int i, dot;
 733         int fd = -1, in_fd;
 734         int ret;
 735         char* config_filename;
 736         struct lock_file *lock = NULL;
 737         const char* last_dot = strrchr(key, '.');
 738
 739         config_filename = getenv(CONFIG_ENVIRONMENT);
 740         if (!config_filename) {
 741                 config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 742                 if (!config_filename)
 743                         config_filename  = git_path("config");
 744         }
 745         config_filename = xstrdup(config_filename);
 746
 747         /*
 748          * Since "key" actually contains the section name and the real
 749          * key name separated by a dot, we have to know where the dot is.
 750          */
 751
 752         if (last_dot == NULL) {
 753                 fprintf(stderr, "key does not contain a section: %s\n", key);
 754                 ret = 2;
 755                 goto out_free;
 756         }
 757         store.baselen = last_dot - key;
 758
 759         store.multi_replace = multi_replace;
 760
 761         /*
 762          * Validate the key and while at it, lower case it for matching.
 763          */
 764         store.key = xmalloc(strlen(key) + 1);
 765         dot = 0;
 766         for (i = 0; key[i]; i++) {
 767                 unsigned char c = key[i];
 768                 if (c == '.')
 769                         dot = 1;
 770                 /* Leave the extended basename untouched.. */
 771                 if (!dot || i > store.baselen) {
 772                         if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
 773                                 fprintf(stderr, "invalid key: %s\n", key);
 774                                 free(store.key);
 775                                 ret = 1;
 776                                 goto out_free;
 777                         }
 778                         c = tolower(c);
 779                 } else if (c == '\n') {
 780                         fprintf(stderr, "invalid key (newline): %s\n", key);
 781                         free(store.key);
 782                         ret = 1;
 783                         goto out_free;
 784                 }
 785                 store.key[i] = c;
 786         }
 787         store.key[i] = 0;
 788
 789         /*
 790          * The lock serves a purpose in addition to locking: the new
 791          * contents of .git/config will be written into it.
 792          */
 793         lock = xcalloc(sizeof(struct lock_file), 1);
 794         fd = hold_lock_file_for_update(lock, config_filename, 0);
 795         if (fd < 0) {
 796                 fprintf(stderr, "could not lock config file\n");
 797                 free(store.key);
 798                 ret = -1;
 799                 goto out_free;
 800         }
 801
 802         /*
 803          * If .git/config does not exist yet, write a minimal version.
 804          */
 805         in_fd = open(config_filename, O_RDONLY);
 806         if ( in_fd < 0 ) {
 807                 free(store.key);
 808
 809                 if ( ENOENT != errno ) {
 810                         error("opening %s: %s", config_filename,
 811                               strerror(errno));
 812                         ret = 3; /* same as "invalid config file" */
 813                         goto out_free;
 814                 }
 815                 /* if nothing to unset, error out */
 816                 if (value == NULL) {
 817                         ret = 5;
 818                         goto out_free;
 819                 }
 820
 821                 store.key = (char*)key;
 822                 if (!store_write_section(fd, key) ||
 823                     !store_write_pair(fd, key, value))
 824                         goto write_err_out;
 825         } else {
 826                 struct stat st;
 827                 char* contents;
 828                 size_t contents_sz, copy_begin, copy_end;
 829                 int i, new_line = 0;
 830
 831                 if (value_regex == NULL)
 832                         store.value_regex = NULL;
 833                 else {
 834                         if (value_regex[0] == '!') {
 835                                 store.do_not_match = 1;
 836                                 value_regex++;
 837                         } else
 838                                 store.do_not_match = 0;
 839
 840                         store.value_regex = (regex_t*)xmalloc(sizeof(regex_t));
 841                         if (regcomp(store.value_regex, value_regex,
 842                                         REG_EXTENDED)) {
 843                                 fprintf(stderr, "Invalid pattern: %s\n",
 844                                         value_regex);
 845                                 free(store.value_regex);
 846                                 ret = 6;
 847                                 goto out_free;
 848                         }
 849                 }
 850
 851                 store.offset[0] = 0;
 852                 store.state = START;
 853                 store.seen = 0;
 854
 855                 /*
 856                  * After this, store.offset will contain the *end* offset
 857                  * of the last match, or remain at 0 if no match was found.
 858                  * As a side effect, we make sure to transform only a valid
 859                  * existing config file.
 860                  */
 861                 if (git_config_from_file(store_aux, config_filename)) {
 862                         fprintf(stderr, "invalid config file\n");
 863                         free(store.key);
 864                         if (store.value_regex != NULL) {
 865                                 regfree(store.value_regex);
 866                                 free(store.value_regex);
 867                         }
 868                         ret = 3;
 869                         goto out_free;
 870                 }
 871
 872                 free(store.key);
 873                 if (store.value_regex != NULL) {
 874                         regfree(store.value_regex);
 875                         free(store.value_regex);
 876                 }
 877
 878                 /* if nothing to unset, or too many matches, error out */
 879                 if ((store.seen == 0 && value == NULL) ||
 880                                 (store.seen > 1 && multi_replace == 0)) {
 881                         ret = 5;
 882                         goto out_free;
 883                 }
 884
 885                 fstat(in_fd, &st);
 886                 contents_sz = xsize_t(st.st_size);
 887                 contents = xmmap(NULL, contents_sz, PROT_READ,
 888                         MAP_PRIVATE, in_fd, 0);
 889                 close(in_fd);
 890
 891                 if (store.seen == 0)
 892                         store.seen = 1;
 893
 894                 for (i = 0, copy_begin = 0; i < store.seen; i++) {
 895                         if (store.offset[i] == 0) {
 896                                 store.offset[i] = copy_end = contents_sz;
 897                         } else if (store.state != KEY_SEEN) {
 898                                 copy_end = store.offset[i];
 899                         } else
 900                                 copy_end = find_beginning_of_line(
 901                                         contents, contents_sz,
 902                                         store.offset[i]-2, &new_line);
 903
 904                         /* write the first part of the config */
 905                         if (copy_end > copy_begin) {
 906                                 if (write_in_full(fd, contents + copy_begin,
 907                                                   copy_end - copy_begin) <
 908                                     copy_end - copy_begin)
 909                                         goto write_err_out;
 910                                 if (new_line &&
 911                                     write_in_full(fd, "\n", 1) != 1)
 912                                         goto write_err_out;
 913                         }
 914                         copy_begin = store.offset[i];
 915                 }
 916
 917                 /* write the pair (value == NULL means unset) */
 918                 if (value != NULL) {
 919                         if (store.state == START) {
 920                                 if (!store_write_section(fd, key))
 921                                         goto write_err_out;
 922                         }
 923                         if (!store_write_pair(fd, key, value))
 924                                 goto write_err_out;
 925                 }
 926
 927                 /* write the rest of the config */
 928                 if (copy_begin < contents_sz)
 929                         if (write_in_full(fd, contents + copy_begin,
 930                                           contents_sz - copy_begin) <
 931                             contents_sz - copy_begin)
 932                                 goto write_err_out;
 933
 934                 munmap(contents, contents_sz);
 935         }
 936
 937         if (close(fd) || commit_lock_file(lock) < 0) {
 938                 fprintf(stderr, "Cannot commit config file!\n");
 939                 ret = 4;
 940                 goto out_free;
 941         }
 942
 943         /* fd is closed, so don't try to close it below. */
 944         fd = -1;
 945         /*
 946          * lock is committed, so don't try to roll it back below.
 947          * NOTE: Since lockfile.c keeps a linked list of all created
 948          * lock_file structures, it isn't safe to free(lock).  It's
 949          * better to just leave it hanging around.
 950          */
 951         lock = NULL;
 952         ret = 0;
 953
 954 out_free:
 955         if (0 <= fd)
 956                 close(fd);
 957         if (lock)
 958                 rollback_lock_file(lock);
 959         free(config_filename);
 960         return ret;
 961
 962 write_err_out:
 963         ret = write_error();
 964         goto out_free;
 965
 966 }
 967
 968 static int section_name_match (const char *buf, const char *name)
 969 {
 970         int i = 0, j = 0, dot = 0;
 971         for (; buf[i] && buf[i] != ']'; i++) {
 972                 if (!dot && isspace(buf[i])) {
 973                         dot = 1;
 974                         if (name[j++] != '.')
 975                                 break;
 976                         for (i++; isspace(buf[i]); i++)
 977                                 ; /* do nothing */
 978                         if (buf[i] != '"')
 979                                 break;
 980                         continue;
 981                 }
 982                 if (buf[i] == '\\' && dot)
 983                         i++;
 984                 else if (buf[i] == '"' && dot) {
 985                         for (i++; isspace(buf[i]); i++)
 986                                 ; /* do_nothing */
 987                         break;
 988                 }
 989                 if (buf[i] != name[j++])
 990                         break;
 991         }
 992         return (buf[i] == ']' && name[j] == 0);
 993 }
 994
 995 /* if new_name == NULL, the section is removed instead */
 996 int git_config_rename_section(const char *old_name, const char *new_name)
 997 {
 998         int ret = 0, remove = 0;
 999         char *config_filename;
1000         struct lock_file *lock = xcalloc(sizeof(struct lock_file), 1);
1001         int out_fd;
1002         char buf[1024];
1003
1004         config_filename = getenv(CONFIG_ENVIRONMENT);
1005         if (!config_filename) {
1006                 config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
1007                 if (!config_filename)
1008                         config_filename  = git_path("config");
1009         }
1010         config_filename = xstrdup(config_filename);
1011         out_fd = hold_lock_file_for_update(lock, config_filename, 0);
1012         if (out_fd < 0) {
1013                 ret = error("Could not lock config file!");
1014                 goto out;
1015         }
1016
1017         if (!(config_file = fopen(config_filename, "rb"))) {
1018                 /* no config file means nothing to rename, no error */
1019                 goto unlock_and_out;
1020         }
1021
1022         while (fgets(buf, sizeof(buf), config_file)) {
1023                 int i;
1024                 int length;
1025                 for (i = 0; buf[i] && isspace(buf[i]); i++)
1026                         ; /* do nothing */
1027                 if (buf[i] == '[') {
1028                         /* it's a section */
1029                         if (section_name_match (&buf[i+1], old_name)) {
1030                                 ret++;
1031                                 if (new_name == NULL) {
1032                                         remove = 1;
1033                                         continue;
1034                                 }
1035                                 store.baselen = strlen(new_name);
1036                                 if (!store_write_section(out_fd, new_name)) {
1037                                         ret = write_error();
1038                                         goto out;
1039                                 }
1040                                 continue;
1041                         }
1042                         remove = 0;
1043                 }
1044                 if (remove)
1045                         continue;
1046                 length = strlen(buf);
1047                 if (write_in_full(out_fd, buf, length) != length) {
1048                         ret = write_error();
1049                         goto out;
1050                 }
1051         }
1052         fclose(config_file);
1053  unlock_and_out:
1054         if (close(out_fd) || commit_lock_file(lock) < 0)
1055                         ret = error("Cannot commit config file!");
1056  out:
1057         free(config_filename);
1058         return ret;
1059 }