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 get_next_char(void)
  16 {
  17         int c;
  18         FILE *f;
  19
  20         c = '\n';
  21         if ((f = config_file) != NULL) {
  22                 c = fgetc(f);
  23                 if (c == '\r') {
  24                         /* DOS like systems */
  25                         c = fgetc(f);
  26                         if (c != '\n') {
  27                                 ungetc(c, f);
  28                                 c = '\r';
  29                         }
  30                 }
  31                 if (c == '\n')
  32                         config_linenr++;
  33                 if (c == EOF) {
  34                         config_file = NULL;
  35                         c = '\n';
  36                 }
  37         }
  38         return c;
  39 }
  40
  41 static char *parse_value(void)
  42 {
  43         static char value[1024];
  44         int quote = 0, comment = 0, len = 0, space = 0;
  45
  46         for (;;) {
  47                 int c = get_next_char();
  48                 if (len >= sizeof(value))
  49                         return NULL;
  50                 if (c == '\n') {
  51                         if (quote)
  52                                 return NULL;
  53                         value[len] = 0;
  54                         return value;
  55                 }
  56                 if (comment)
  57                         continue;
  58                 if (isspace(c) && !quote) {
  59                         space = 1;
  60                         continue;
  61                 }
  62                 if (!quote) {
  63                         if (c == ';' || c == '#') {
  64                                 comment = 1;
  65                                 continue;
  66                         }
  67                 }
  68                 if (space) {
  69                         if (len)
  70                                 value[len++] = ' ';
  71                         space = 0;
  72                 }
  73                 if (c == '\\') {
  74                         c = get_next_char();
  75                         switch (c) {
  76                         case '\n':
  77                                 continue;
  78                         case 't':
  79                                 c = '\t';
  80                                 break;
  81                         case 'b':
  82                                 c = '\b';
  83                                 break;
  84                         case 'n':
  85                                 c = '\n';
  86                                 break;
  87                         /* Some characters escape as themselves */
  88                         case '\\': case '"':
  89                                 break;
  90                         /* Reject unknown escape sequences */
  91                         default:
  92                                 return NULL;
  93                         }
  94                         value[len++] = c;
  95                         continue;
  96                 }
  97                 if (c == '"') {
  98                         quote = 1-quote;
  99                         continue;
 100                 }
 101                 value[len++] = c;
 102         }
 103 }
 104
 105 static inline int iskeychar(int c)
 106 {
 107         return isalnum(c) || c == '-';
 108 }
 109
 110 static int get_value(config_fn_t fn, char *name, unsigned int len)
 111 {
 112         int c;
 113         char *value;
 114
 115         /* Get the full name */
 116         for (;;) {
 117                 c = get_next_char();
 118                 if (c == EOF)
 119                         break;
 120                 if (!iskeychar(c))
 121                         break;
 122                 name[len++] = tolower(c);
 123                 if (len >= MAXNAME)
 124                         return -1;
 125         }
 126         name[len] = 0;
 127         while (c == ' ' || c == '\t')
 128                 c = get_next_char();
 129
 130         value = NULL;
 131         if (c != '\n') {
 132                 if (c != '=')
 133                         return -1;
 134                 value = parse_value();
 135                 if (!value)
 136                         return -1;
 137         }
 138         return fn(name, value);
 139 }
 140
 141 static int get_extended_base_var(char *name, int baselen, int c)
 142 {
 143         do {
 144                 if (c == '\n')
 145                         return -1;
 146                 c = get_next_char();
 147         } while (isspace(c));
 148
 149         /* We require the format to be '[base "extension"]' */
 150         if (c != '"')
 151                 return -1;
 152         name[baselen++] = '.';
 153
 154         for (;;) {
 155                 int c = get_next_char();
 156                 if (c == '\n')
 157                         return -1;
 158                 if (c == '"')
 159                         break;
 160                 if (c == '\\') {
 161                         c = get_next_char();
 162                         if (c == '\n')
 163                                 return -1;
 164                 }
 165                 name[baselen++] = c;
 166                 if (baselen > MAXNAME / 2)
 167                         return -1;
 168         }
 169
 170         /* Final ']' */
 171         if (get_next_char() != ']')
 172                 return -1;
 173         return baselen;
 174 }
 175
 176 static int get_base_var(char *name)
 177 {
 178         int baselen = 0;
 179
 180         for (;;) {
 181                 int c = get_next_char();
 182                 if (c == EOF)
 183                         return -1;
 184                 if (c == ']')
 185                         return baselen;
 186                 if (isspace(c))
 187                         return get_extended_base_var(name, baselen, c);
 188                 if (!iskeychar(c) && c != '.')
 189                         return -1;
 190                 if (baselen > MAXNAME / 2)
 191                         return -1;
 192                 name[baselen++] = tolower(c);
 193         }
 194 }
 195
 196 static int git_parse_file(config_fn_t fn)
 197 {
 198         int comment = 0;
 199         int baselen = 0;
 200         static char var[MAXNAME];
 201
 202         for (;;) {
 203                 int c = get_next_char();
 204                 if (c == '\n') {
 205                         /* EOF? */
 206                         if (!config_file)
 207                                 return 0;
 208                         comment = 0;
 209                         continue;
 210                 }
 211                 if (comment || isspace(c))
 212                         continue;
 213                 if (c == '#' || c == ';') {
 214                         comment = 1;
 215                         continue;
 216                 }
 217                 if (c == '[') {
 218                         baselen = get_base_var(var);
 219                         if (baselen <= 0)
 220                                 break;
 221                         var[baselen++] = '.';
 222                         var[baselen] = 0;
 223                         continue;
 224                 }
 225                 if (!isalpha(c))
 226                         break;
 227                 var[baselen] = tolower(c);
 228                 if (get_value(fn, var, baselen+1) < 0)
 229                         break;
 230         }
 231         die("bad config file line %d in %s", config_linenr, config_file_name);
 232 }
 233
 234 int git_config_int(const char *name, const char *value)
 235 {
 236         if (value && *value) {
 237                 char *end;
 238                 int val = strtol(value, &end, 0);
 239                 if (!*end)
 240                         return val;
 241                 if (!strcasecmp(end, "k"))
 242                         return val * 1024;
 243                 if (!strcasecmp(end, "m"))
 244                         return val * 1024 * 1024;
 245                 if (!strcasecmp(end, "g"))
 246                         return val * 1024 * 1024 * 1024;
 247         }
 248         die("bad config value for '%s' in %s", name, config_file_name);
 249 }
 250
 251 int git_config_bool(const char *name, const char *value)
 252 {
 253         if (!value)
 254                 return 1;
 255         if (!*value)
 256                 return 0;
 257         if (!strcasecmp(value, "true") || !strcasecmp(value, "yes"))
 258                 return 1;
 259         if (!strcasecmp(value, "false") || !strcasecmp(value, "no"))
 260                 return 0;
 261         return git_config_int(name, value) != 0;
 262 }
 263
 264 int git_default_config(const char *var, const char *value)
 265 {
 266         /* This needs a better name */
 267         if (!strcmp(var, "core.filemode")) {
 268                 trust_executable_bit = git_config_bool(var, value);
 269                 return 0;
 270         }
 271
 272         if (!strcmp(var, "core.symlinks")) {
 273                 has_symlinks = git_config_bool(var, value);
 274                 return 0;
 275         }
 276
 277         if (!strcmp(var, "core.bare")) {
 278                 is_bare_repository_cfg = git_config_bool(var, value);
 279                 return 0;
 280         }
 281
 282         if (!strcmp(var, "core.ignorestat")) {
 283                 assume_unchanged = git_config_bool(var, value);
 284                 return 0;
 285         }
 286
 287         if (!strcmp(var, "core.prefersymlinkrefs")) {
 288                 prefer_symlink_refs = git_config_bool(var, value);
 289                 return 0;
 290         }
 291
 292         if (!strcmp(var, "core.logallrefupdates")) {
 293                 log_all_ref_updates = git_config_bool(var, value);
 294                 return 0;
 295         }
 296
 297         if (!strcmp(var, "core.warnambiguousrefs")) {
 298                 warn_ambiguous_refs = git_config_bool(var, value);
 299                 return 0;
 300         }
 301
 302         if (!strcmp(var, "core.legacyheaders")) {
 303                 use_legacy_headers = git_config_bool(var, value);
 304                 return 0;
 305         }
 306
 307         if (!strcmp(var, "core.compression")) {
 308                 int level = git_config_int(var, value);
 309                 if (level == -1)
 310                         level = Z_DEFAULT_COMPRESSION;
 311                 else if (level < 0 || level > Z_BEST_COMPRESSION)
 312                         die("bad zlib compression level %d", level);
 313                 zlib_compression_level = level;
 314                 return 0;
 315         }
 316
 317         if (!strcmp(var, "core.packedgitwindowsize")) {
 318                 int pgsz_x2 = getpagesize() * 2;
 319                 packed_git_window_size = git_config_int(var, value);
 320
 321                 /* This value must be multiple of (pagesize * 2) */
 322                 packed_git_window_size /= pgsz_x2;
 323                 if (packed_git_window_size < 1)
 324                         packed_git_window_size = 1;
 325                 packed_git_window_size *= pgsz_x2;
 326                 return 0;
 327         }
 328
 329         if (!strcmp(var, "core.packedgitlimit")) {
 330                 packed_git_limit = git_config_int(var, value);
 331                 return 0;
 332         }
 333
 334         if (!strcmp(var, "core.deltabasecachelimit")) {
 335                 delta_base_cache_limit = git_config_int(var, value);
 336                 return 0;
 337         }
 338
 339         if (!strcmp(var, "core.autocrlf")) {
 340                 if (value && !strcasecmp(value, "input")) {
 341                         auto_crlf = -1;
 342                         return 0;
 343                 }
 344                 auto_crlf = git_config_bool(var, value);
 345                 return 0;
 346         }
 347
 348         if (!strcmp(var, "user.name")) {
 349                 strlcpy(git_default_name, value, sizeof(git_default_name));
 350                 return 0;
 351         }
 352
 353         if (!strcmp(var, "user.email")) {
 354                 strlcpy(git_default_email, value, sizeof(git_default_email));
 355                 return 0;
 356         }
 357
 358         if (!strcmp(var, "i18n.commitencoding")) {
 359                 git_commit_encoding = xstrdup(value);
 360                 return 0;
 361         }
 362
 363         if (!strcmp(var, "i18n.logoutputencoding")) {
 364                 git_log_output_encoding = xstrdup(value);
 365                 return 0;
 366         }
 367
 368
 369         if (!strcmp(var, "pager.color") || !strcmp(var, "color.pager")) {
 370                 pager_use_color = git_config_bool(var,value);
 371                 return 0;
 372         }
 373
 374         /* Add other config variables here and to Documentation/config.txt. */
 375         return 0;
 376 }
 377
 378 int git_config_from_file(config_fn_t fn, const char *filename)
 379 {
 380         int ret;
 381         FILE *f = fopen(filename, "r");
 382
 383         ret = -1;
 384         if (f) {
 385                 config_file = f;
 386                 config_file_name = filename;
 387                 config_linenr = 1;
 388                 ret = git_parse_file(fn);
 389                 fclose(f);
 390                 config_file_name = NULL;
 391         }
 392         return ret;
 393 }
 394
 395 int git_config(config_fn_t fn)
 396 {
 397         int ret = 0;
 398         char *repo_config = NULL;
 399         const char *home = NULL, *filename;
 400
 401         /* $GIT_CONFIG makes git read _only_ the given config file,
 402          * $GIT_CONFIG_LOCAL will make it process it in addition to the
 403          * global config file, the same way it would the per-repository
 404          * config file otherwise. */
 405         filename = getenv(CONFIG_ENVIRONMENT);
 406         if (!filename) {
 407                 if (!access(ETC_GITCONFIG, R_OK))
 408                         ret += git_config_from_file(fn, ETC_GITCONFIG);
 409                 home = getenv("HOME");
 410                 filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 411                 if (!filename)
 412                         filename = repo_config = xstrdup(git_path("config"));
 413         }
 414
 415         if (home) {
 416                 char *user_config = xstrdup(mkpath("%s/.gitconfig", home));
 417                 if (!access(user_config, R_OK))
 418                         ret = git_config_from_file(fn, user_config);
 419                 free(user_config);
 420         }
 421
 422         ret += git_config_from_file(fn, filename);
 423         free(repo_config);
 424         return ret;
 425 }
 426
 427 /*
 428  * Find all the stuff for git_config_set() below.
 429  */
 430
 431 #define MAX_MATCHES 512
 432
 433 static struct {
 434         int baselen;
 435         char* key;
 436         int do_not_match;
 437         regex_t* value_regex;
 438         int multi_replace;
 439         size_t offset[MAX_MATCHES];
 440         enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
 441         int seen;
 442 } store;
 443
 444 static int matches(const char* key, const char* value)
 445 {
 446         return !strcmp(key, store.key) &&
 447                 (store.value_regex == NULL ||
 448                  (store.do_not_match ^
 449                   !regexec(store.value_regex, value, 0, NULL, 0)));
 450 }
 451
 452 static int store_aux(const char* key, const char* value)
 453 {
 454         switch (store.state) {
 455         case KEY_SEEN:
 456                 if (matches(key, value)) {
 457                         if (store.seen == 1 && store.multi_replace == 0) {
 458                                 fprintf(stderr,
 459                                         "Warning: %s has multiple values\n",
 460                                         key);
 461                         } else if (store.seen >= MAX_MATCHES) {
 462                                 fprintf(stderr, "Too many matches\n");
 463                                 return 1;
 464                         }
 465
 466                         store.offset[store.seen] = ftell(config_file);
 467                         store.seen++;
 468                 }
 469                 break;
 470         case SECTION_SEEN:
 471                 if (strncmp(key, store.key, store.baselen+1)) {
 472                         store.state = SECTION_END_SEEN;
 473                         break;
 474                 } else
 475                         /* do not increment matches: this is no match */
 476                         store.offset[store.seen] = ftell(config_file);
 477                 /* fallthru */
 478         case SECTION_END_SEEN:
 479         case START:
 480                 if (matches(key, value)) {
 481                         store.offset[store.seen] = ftell(config_file);
 482                         store.state = KEY_SEEN;
 483                         store.seen++;
 484                 } else {
 485                         if (strrchr(key, '.') - key == store.baselen &&
 486                               !strncmp(key, store.key, store.baselen)) {
 487                                         store.state = SECTION_SEEN;
 488                                         store.offset[store.seen] = ftell(config_file);
 489                         }
 490                 }
 491         }
 492         return 0;
 493 }
 494
 495 static int write_error()
 496 {
 497         fprintf(stderr, "Failed to write new configuration file\n");
 498
 499         /* Same error code as "failed to rename". */
 500         return 4;
 501 }
 502
 503 static int store_write_section(int fd, const char* key)
 504 {
 505         const char *dot = strchr(key, '.');
 506         int len1 = store.baselen, len2 = -1;
 507
 508         dot = strchr(key, '.');
 509         if (dot) {
 510                 int dotlen = dot - key;
 511                 if (dotlen < len1) {
 512                         len2 = len1 - dotlen - 1;
 513                         len1 = dotlen;
 514                 }
 515         }
 516
 517         if (write_in_full(fd, "[", 1) != 1 ||
 518             write_in_full(fd, key, len1) != len1)
 519                 return 0;
 520         if (len2 >= 0) {
 521                 if (write_in_full(fd, " \"", 2) != 2)
 522                         return 0;
 523                 while (--len2 >= 0) {
 524                         unsigned char c = *++dot;
 525                         if (c == '"')
 526                                 if (write_in_full(fd, "\\", 1) != 1)
 527                                         return 0;
 528                         if (write_in_full(fd, &c, 1) != 1)
 529                                 return 0;
 530                 }
 531                 if (write_in_full(fd, "\"", 1) != 1)
 532                         return 0;
 533         }
 534         if (write_in_full(fd, "]\n", 2) != 2)
 535                 return 0;
 536
 537         return 1;
 538 }
 539
 540 static int store_write_pair(int fd, const char* key, const char* value)
 541 {
 542         int i;
 543         int length = strlen(key+store.baselen+1);
 544         int quote = 0;
 545
 546         /* Check to see if the value needs to be quoted. */
 547         if (value[0] == ' ')
 548                 quote = 1;
 549         for (i = 0; value[i]; i++)
 550                 if (value[i] == ';' || value[i] == '#')
 551                         quote = 1;
 552         if (value[i-1] == ' ')
 553                 quote = 1;
 554
 555         if (write_in_full(fd, "\t", 1) != 1 ||
 556             write_in_full(fd, key+store.baselen+1, length) != length ||
 557             write_in_full(fd, " = ", 3) != 3)
 558                 return 0;
 559         if (quote && write_in_full(fd, "\"", 1) != 1)
 560                 return 0;
 561         for (i = 0; value[i]; i++)
 562                 switch (value[i]) {
 563                 case '\n':
 564                         if (write_in_full(fd, "\\n", 2) != 2)
 565                                 return 0;
 566                         break;
 567                 case '\t':
 568                         if (write_in_full(fd, "\\t", 2) != 2)
 569                                 return 0;
 570                         break;
 571                 case '"':
 572                 case '\\':
 573                         if (write_in_full(fd, "\\", 1) != 1)
 574                                 return 0;
 575                 default:
 576                         if (write_in_full(fd, value+i, 1) != 1)
 577                                 return 0;
 578                         break;
 579                 }
 580         if (quote && write_in_full(fd, "\"", 1) != 1)
 581                 return 0;
 582         if (write_in_full(fd, "\n", 1) != 1)
 583                 return 0;
 584         return 1;
 585 }
 586
 587 static ssize_t find_beginning_of_line(const char* contents, size_t size,
 588         size_t offset_, int* found_bracket)
 589 {
 590         size_t equal_offset = size, bracket_offset = size;
 591         ssize_t offset;
 592
 593         for (offset = offset_-2; offset > 0
 594                         && contents[offset] != '\n'; offset--)
 595                 switch (contents[offset]) {
 596                         case '=': equal_offset = offset; break;
 597                         case ']': bracket_offset = offset; break;
 598                 }
 599         if (bracket_offset < equal_offset) {
 600                 *found_bracket = 1;
 601                 offset = bracket_offset+1;
 602         } else
 603                 offset++;
 604
 605         return offset;
 606 }
 607
 608 int git_config_set(const char* key, const char* value)
 609 {
 610         return git_config_set_multivar(key, value, NULL, 0);
 611 }
 612
 613 /*
 614  * If value==NULL, unset in (remove from) config,
 615  * if value_regex!=NULL, disregard key/value pairs where value does not match.
 616  * if multi_replace==0, nothing, or only one matching key/value is replaced,
 617  *     else all matching key/values (regardless how many) are removed,
 618  *     before the new pair is written.
 619  *
 620  * Returns 0 on success.
 621  *
 622  * This function does this:
 623  *
 624  * - it locks the config file by creating ".git/config.lock"
 625  *
 626  * - it then parses the config using store_aux() as validator to find
 627  *   the position on the key/value pair to replace. If it is to be unset,
 628  *   it must be found exactly once.
 629  *
 630  * - the config file is mmap()ed and the part before the match (if any) is
 631  *   written to the lock file, then the changed part and the rest.
 632  *
 633  * - the config file is removed and the lock file rename()d to it.
 634  *
 635  */
 636 int git_config_set_multivar(const char* key, const char* value,
 637         const char* value_regex, int multi_replace)
 638 {
 639         int i, dot;
 640         int fd = -1, in_fd;
 641         int ret;
 642         char* config_filename;
 643         char* lock_file;
 644         const char* last_dot = strrchr(key, '.');
 645
 646         config_filename = getenv(CONFIG_ENVIRONMENT);
 647         if (!config_filename) {
 648                 config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 649                 if (!config_filename)
 650                         config_filename  = git_path("config");
 651         }
 652         config_filename = xstrdup(config_filename);
 653         lock_file = xstrdup(mkpath("%s.lock", config_filename));
 654
 655         /*
 656          * Since "key" actually contains the section name and the real
 657          * key name separated by a dot, we have to know where the dot is.
 658          */
 659
 660         if (last_dot == NULL) {
 661                 fprintf(stderr, "key does not contain a section: %s\n", key);
 662                 ret = 2;
 663                 goto out_free;
 664         }
 665         store.baselen = last_dot - key;
 666
 667         store.multi_replace = multi_replace;
 668
 669         /*
 670          * Validate the key and while at it, lower case it for matching.
 671          */
 672         store.key = xmalloc(strlen(key) + 1);
 673         dot = 0;
 674         for (i = 0; key[i]; i++) {
 675                 unsigned char c = key[i];
 676                 if (c == '.')
 677                         dot = 1;
 678                 /* Leave the extended basename untouched.. */
 679                 if (!dot || i > store.baselen) {
 680                         if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
 681                                 fprintf(stderr, "invalid key: %s\n", key);
 682                                 free(store.key);
 683                                 ret = 1;
 684                                 goto out_free;
 685                         }
 686                         c = tolower(c);
 687                 } else if (c == '\n') {
 688                         fprintf(stderr, "invalid key (newline): %s\n", key);
 689                         free(store.key);
 690                         ret = 1;
 691                         goto out_free;
 692                 }
 693                 store.key[i] = c;
 694         }
 695         store.key[i] = 0;
 696
 697         /*
 698          * The lock_file serves a purpose in addition to locking: the new
 699          * contents of .git/config will be written into it.
 700          */
 701         fd = open(lock_file, O_WRONLY | O_CREAT | O_EXCL, 0666);
 702         if (fd < 0 || adjust_shared_perm(lock_file)) {
 703                 fprintf(stderr, "could not lock config file\n");
 704                 free(store.key);
 705                 ret = -1;
 706                 goto out_free;
 707         }
 708
 709         /*
 710          * If .git/config does not exist yet, write a minimal version.
 711          */
 712         in_fd = open(config_filename, O_RDONLY);
 713         if ( in_fd < 0 ) {
 714                 free(store.key);
 715
 716                 if ( ENOENT != errno ) {
 717                         error("opening %s: %s", config_filename,
 718                               strerror(errno));
 719                         ret = 3; /* same as "invalid config file" */
 720                         goto out_free;
 721                 }
 722                 /* if nothing to unset, error out */
 723                 if (value == NULL) {
 724                         ret = 5;
 725                         goto out_free;
 726                 }
 727
 728                 store.key = (char*)key;
 729                 if (!store_write_section(fd, key) ||
 730                     !store_write_pair(fd, key, value))
 731                         goto write_err_out;
 732         } else {
 733                 struct stat st;
 734                 char* contents;
 735                 size_t contents_sz, copy_begin, copy_end;
 736                 int i, new_line = 0;
 737
 738                 if (value_regex == NULL)
 739                         store.value_regex = NULL;
 740                 else {
 741                         if (value_regex[0] == '!') {
 742                                 store.do_not_match = 1;
 743                                 value_regex++;
 744                         } else
 745                                 store.do_not_match = 0;
 746
 747                         store.value_regex = (regex_t*)xmalloc(sizeof(regex_t));
 748                         if (regcomp(store.value_regex, value_regex,
 749                                         REG_EXTENDED)) {
 750                                 fprintf(stderr, "Invalid pattern: %s\n",
 751                                         value_regex);
 752                                 free(store.value_regex);
 753                                 ret = 6;
 754                                 goto out_free;
 755                         }
 756                 }
 757
 758                 store.offset[0] = 0;
 759                 store.state = START;
 760                 store.seen = 0;
 761
 762                 /*
 763                  * After this, store.offset will contain the *end* offset
 764                  * of the last match, or remain at 0 if no match was found.
 765                  * As a side effect, we make sure to transform only a valid
 766                  * existing config file.
 767                  */
 768                 if (git_config_from_file(store_aux, config_filename)) {
 769                         fprintf(stderr, "invalid config file\n");
 770                         free(store.key);
 771                         if (store.value_regex != NULL) {
 772                                 regfree(store.value_regex);
 773                                 free(store.value_regex);
 774                         }
 775                         ret = 3;
 776                         goto out_free;
 777                 }
 778
 779                 free(store.key);
 780                 if (store.value_regex != NULL) {
 781                         regfree(store.value_regex);
 782                         free(store.value_regex);
 783                 }
 784
 785                 /* if nothing to unset, or too many matches, error out */
 786                 if ((store.seen == 0 && value == NULL) ||
 787                                 (store.seen > 1 && multi_replace == 0)) {
 788                         ret = 5;
 789                         goto out_free;
 790                 }
 791
 792                 fstat(in_fd, &st);
 793                 contents_sz = xsize_t(st.st_size);
 794                 contents = xmmap(NULL, contents_sz, PROT_READ,
 795                         MAP_PRIVATE, in_fd, 0);
 796                 close(in_fd);
 797
 798                 if (store.seen == 0)
 799                         store.seen = 1;
 800
 801                 for (i = 0, copy_begin = 0; i < store.seen; i++) {
 802                         if (store.offset[i] == 0) {
 803                                 store.offset[i] = copy_end = contents_sz;
 804                         } else if (store.state != KEY_SEEN) {
 805                                 copy_end = store.offset[i];
 806                         } else
 807                                 copy_end = find_beginning_of_line(
 808                                         contents, contents_sz,
 809                                         store.offset[i]-2, &new_line);
 810
 811                         /* write the first part of the config */
 812                         if (copy_end > copy_begin) {
 813                                 if (write_in_full(fd, contents + copy_begin,
 814                                                   copy_end - copy_begin) <
 815                                     copy_end - copy_begin)
 816                                         goto write_err_out;
 817                                 if (new_line &&
 818                                     write_in_full(fd, "\n", 1) != 1)
 819                                         goto write_err_out;
 820                         }
 821                         copy_begin = store.offset[i];
 822                 }
 823
 824                 /* write the pair (value == NULL means unset) */
 825                 if (value != NULL) {
 826                         if (store.state == START) {
 827                                 if (!store_write_section(fd, key))
 828                                         goto write_err_out;
 829                         }
 830                         if (!store_write_pair(fd, key, value))
 831                                 goto write_err_out;
 832                 }
 833
 834                 /* write the rest of the config */
 835                 if (copy_begin < contents_sz)
 836                         if (write_in_full(fd, contents + copy_begin,
 837                                           contents_sz - copy_begin) <
 838                             contents_sz - copy_begin)
 839                                 goto write_err_out;
 840
 841                 munmap(contents, contents_sz);
 842                 unlink(config_filename);
 843         }
 844
 845         if (rename(lock_file, config_filename) < 0) {
 846                 fprintf(stderr, "Could not rename the lock file?\n");
 847                 ret = 4;
 848                 goto out_free;
 849         }
 850
 851         ret = 0;
 852
 853 out_free:
 854         if (0 <= fd)
 855                 close(fd);
 856         free(config_filename);
 857         if (lock_file) {
 858                 unlink(lock_file);
 859                 free(lock_file);
 860         }
 861         return ret;
 862
 863 write_err_out:
 864         ret = write_error();
 865         goto out_free;
 866
 867 }
 868
 869 static int section_name_match (const char *buf, const char *name)
 870 {
 871         int i = 0, j = 0, dot = 0;
 872         for (; buf[i] && buf[i] != ']'; i++) {
 873                 if (!dot && isspace(buf[i])) {
 874                         dot = 1;
 875                         if (name[j++] != '.')
 876                                 break;
 877                         for (i++; isspace(buf[i]); i++)
 878                                 ; /* do nothing */
 879                         if (buf[i] != '"')
 880                                 break;
 881                         continue;
 882                 }
 883                 if (buf[i] == '\\' && dot)
 884                         i++;
 885                 else if (buf[i] == '"' && dot) {
 886                         for (i++; isspace(buf[i]); i++)
 887                                 ; /* do_nothing */
 888                         break;
 889                 }
 890                 if (buf[i] != name[j++])
 891                         break;
 892         }
 893         return (buf[i] == ']' && name[j] == 0);
 894 }
 895
 896 /* if new_name == NULL, the section is removed instead */
 897 int git_config_rename_section(const char *old_name, const char *new_name)
 898 {
 899         int ret = 0, remove = 0;
 900         char *config_filename;
 901         struct lock_file *lock = xcalloc(sizeof(struct lock_file), 1);
 902         int out_fd;
 903         char buf[1024];
 904
 905         config_filename = getenv(CONFIG_ENVIRONMENT);
 906         if (!config_filename) {
 907                 config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 908                 if (!config_filename)
 909                         config_filename  = git_path("config");
 910         }
 911         config_filename = xstrdup(config_filename);
 912         out_fd = hold_lock_file_for_update(lock, config_filename, 0);
 913         if (out_fd < 0) {
 914                 ret = error("Could not lock config file!");
 915                 goto out;
 916         }
 917
 918         if (!(config_file = fopen(config_filename, "rb"))) {
 919                 /* no config file means nothing to rename, no error */
 920                 goto unlock_and_out;
 921         }
 922
 923         while (fgets(buf, sizeof(buf), config_file)) {
 924                 int i;
 925                 int length;
 926                 for (i = 0; buf[i] && isspace(buf[i]); i++)
 927                         ; /* do nothing */
 928                 if (buf[i] == '[') {
 929                         /* it's a section */
 930                         if (section_name_match (&buf[i+1], old_name)) {
 931                                 ret++;
 932                                 if (new_name == NULL) {
 933                                         remove = 1;
 934                                         continue;
 935                                 }
 936                                 store.baselen = strlen(new_name);
 937                                 if (!store_write_section(out_fd, new_name)) {
 938                                         ret = write_error();
 939                                         goto out;
 940                                 }
 941                                 continue;
 942                         }
 943                         remove = 0;
 944                 }
 945                 if (remove)
 946                         continue;
 947                 length = strlen(buf);
 948                 if (write_in_full(out_fd, buf, length) != length) {
 949                         ret = write_error();
 950                         goto out;
 951                 }
 952         }
 953         fclose(config_file);
 954  unlock_and_out:
 955         if (close(out_fd) || commit_lock_file(lock) < 0)
 956                         ret = error("Cannot commit config file!");
 957  out:
 958         free(config_filename);
 959         return ret;
 960 }
 961