git/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 zlib_compression_seen;
  17
  18 static int get_next_char(void)
  19 {
  20         int c;
  21         FILE *f;
  22
  23         c = '\n';
  24         if ((f = config_file) != NULL) {
  25                 c = fgetc(f);
  26                 if (c == '\r') {
  27                         /* DOS like systems */
  28                         c = fgetc(f);
  29                         if (c != '\n') {
  30                                 ungetc(c, f);
  31                                 c = '\r';
  32                         }
  33                 }
  34                 if (c == '\n')
  35                         config_linenr++;
  36                 if (c == EOF) {
  37                         config_file = NULL;
  38                         c = '\n';
  39                 }
  40         }
  41         return c;
  42 }
  43
  44 static char *parse_value(void)
  45 {
  46         static char value[1024];
  47         int quote = 0, comment = 0, len = 0, space = 0;
  48
  49         for (;;) {
  50                 int c = get_next_char();
  51                 if (len >= sizeof(value))
  52                         return NULL;
  53                 if (c == '\n') {
  54                         if (quote)
  55                                 return NULL;
  56                         value[len] = 0;
  57                         return value;
  58                 }
  59                 if (comment)
  60                         continue;
  61                 if (isspace(c) && !quote) {
  62                         space = 1;
  63                         continue;
  64                 }
  65                 if (!quote) {
  66                         if (c == ';' || c == '#') {
  67                                 comment = 1;
  68                                 continue;
  69                         }
  70                 }
  71                 if (space) {
  72                         if (len)
  73                                 value[len++] = ' ';
  74                         space = 0;
  75                 }
  76                 if (c == '\\') {
  77                         c = get_next_char();
  78                         switch (c) {
  79                         case '\n':
  80                                 continue;
  81                         case 't':
  82                                 c = '\t';
  83                                 break;
  84                         case 'b':
  85                                 c = '\b';
  86                                 break;
  87                         case 'n':
  88                                 c = '\n';
  89                                 break;
  90                         /* Some characters escape as themselves */
  91                         case '\\': case '"':
  92                                 break;
  93                         /* Reject unknown escape sequences */
  94                         default:
  95                                 return NULL;
  96                         }
  97                         value[len++] = c;
  98                         continue;
  99                 }
 100                 if (c == '"') {
 101                         quote = 1-quote;
 102                         continue;
 103                 }
 104                 value[len++] = c;
 105         }
 106 }
 107
 108 static inline int iskeychar(int c)
 109 {
 110         return isalnum(c) || c == '-';
 111 }
 112
 113 static int get_value(config_fn_t fn, char *name, unsigned int len)
 114 {
 115         int c;
 116         char *value;
 117
 118         /* Get the full name */
 119         for (;;) {
 120                 c = get_next_char();
 121                 if (c == EOF)
 122                         break;
 123                 if (!iskeychar(c))
 124                         break;
 125                 name[len++] = tolower(c);
 126                 if (len >= MAXNAME)
 127                         return -1;
 128         }
 129         name[len] = 0;
 130         while (c == ' ' || c == '\t')
 131                 c = get_next_char();
 132
 133         value = NULL;
 134         if (c != '\n') {
 135                 if (c != '=')
 136                         return -1;
 137                 value = parse_value();
 138                 if (!value)
 139                         return -1;
 140         }
 141         return fn(name, value);
 142 }
 143
 144 static int get_extended_base_var(char *name, int baselen, int c)
 145 {
 146         do {
 147                 if (c == '\n')
 148                         return -1;
 149                 c = get_next_char();
 150         } while (isspace(c));
 151
 152         /* We require the format to be '[base "extension"]' */
 153         if (c != '"')
 154                 return -1;
 155         name[baselen++] = '.';
 156
 157         for (;;) {
 158                 int c = get_next_char();
 159                 if (c == '\n')
 160                         return -1;
 161                 if (c == '"')
 162                         break;
 163                 if (c == '\\') {
 164                         c = get_next_char();
 165                         if (c == '\n')
 166                                 return -1;
 167                 }
 168                 name[baselen++] = c;
 169                 if (baselen > MAXNAME / 2)
 170                         return -1;
 171         }
 172
 173         /* Final ']' */
 174         if (get_next_char() != ']')
 175                 return -1;
 176         return baselen;
 177 }
 178
 179 static int get_base_var(char *name)
 180 {
 181         int baselen = 0;
 182
 183         for (;;) {
 184                 int c = get_next_char();
 185                 if (c == EOF)
 186                         return -1;
 187                 if (c == ']')
 188                         return baselen;
 189                 if (isspace(c))
 190                         return get_extended_base_var(name, baselen, c);
 191                 if (!iskeychar(c) && c != '.')
 192                         return -1;
 193                 if (baselen > MAXNAME / 2)
 194                         return -1;
 195                 name[baselen++] = tolower(c);
 196         }
 197 }
 198
 199 static int git_parse_file(config_fn_t fn)
 200 {
 201         int comment = 0;
 202         int baselen = 0;
 203         static char var[MAXNAME];
 204
 205         for (;;) {
 206                 int c = get_next_char();
 207                 if (c == '\n') {
 208                         /* EOF? */
 209                         if (!config_file)
 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 unsigned long get_unit_factor(const char *end)
 238 {
 239         if (!*end)
 240                 return 1;
 241         else if (!strcasecmp(end, "k"))
 242                 return 1024;
 243         else if (!strcasecmp(end, "m"))
 244                 return 1024 * 1024;
 245         else if (!strcasecmp(end, "g"))
 246                 return 1024 * 1024 * 1024;
 247         die("unknown unit: '%s'", end);
 248 }
 249
 250 int git_parse_long(const char *value, long *ret)
 251 {
 252         if (value && *value) {
 253                 char *end;
 254                 long val = strtol(value, &end, 0);
 255                 *ret = val * get_unit_factor(end);
 256                 return 1;
 257         }
 258         return 0;
 259 }
 260
 261 int git_parse_ulong(const char *value, unsigned long *ret)
 262 {
 263         if (value && *value) {
 264                 char *end;
 265                 unsigned long val = strtoul(value, &end, 0);
 266                 *ret = val * get_unit_factor(end);
 267                 return 1;
 268         }
 269         return 0;
 270 }
 271
 272 int git_config_int(const char *name, const char *value)
 273 {
 274         long ret;
 275         if (!git_parse_long(value, &ret))
 276                 die("bad config value for '%s' in %s", name, config_file_name);
 277         return ret;
 278 }
 279
 280 unsigned long git_config_ulong(const char *name, const char *value)
 281 {
 282         unsigned long ret;
 283         if (!git_parse_ulong(value, &ret))
 284                 die("bad config value for '%s' in %s", name, config_file_name);
 285         return ret;
 286 }
 287
 288 int git_config_bool(const char *name, const char *value)
 289 {
 290         if (!value)
 291                 return 1;
 292         if (!*value)
 293                 return 0;
 294         if (!strcasecmp(value, "true") || !strcasecmp(value, "yes"))
 295                 return 1;
 296         if (!strcasecmp(value, "false") || !strcasecmp(value, "no"))
 297                 return 0;
 298         return git_config_int(name, value) != 0;
 299 }
 300
 301 int git_default_config(const char *var, const char *value)
 302 {
 303         /* This needs a better name */
 304         if (!strcmp(var, "core.filemode")) {
 305                 trust_executable_bit = git_config_bool(var, value);
 306                 return 0;
 307         }
 308
 309         if (!strcmp(var, "core.quotepath")) {
 310                 quote_path_fully = git_config_bool(var, value);
 311                 return 0;
 312         }
 313
 314         if (!strcmp(var, "core.symlinks")) {
 315                 has_symlinks = git_config_bool(var, value);
 316                 return 0;
 317         }
 318
 319         if (!strcmp(var, "core.bare")) {
 320                 is_bare_repository_cfg = git_config_bool(var, value);
 321                 return 0;
 322         }
 323
 324         if (!strcmp(var, "core.ignorestat")) {
 325                 assume_unchanged = git_config_bool(var, value);
 326                 return 0;
 327         }
 328
 329         if (!strcmp(var, "core.prefersymlinkrefs")) {
 330                 prefer_symlink_refs = git_config_bool(var, value);
 331                 return 0;
 332         }
 333
 334         if (!strcmp(var, "core.logallrefupdates")) {
 335                 log_all_ref_updates = git_config_bool(var, value);
 336                 return 0;
 337         }
 338
 339         if (!strcmp(var, "core.warnambiguousrefs")) {
 340                 warn_ambiguous_refs = git_config_bool(var, value);
 341                 return 0;
 342         }
 343
 344         if (!strcmp(var, "core.loosecompression")) {
 345                 int level = git_config_int(var, value);
 346                 if (level == -1)
 347                         level = Z_DEFAULT_COMPRESSION;
 348                 else if (level < 0 || level > Z_BEST_COMPRESSION)
 349                         die("bad zlib compression level %d", level);
 350                 zlib_compression_level = level;
 351                 zlib_compression_seen = 1;
 352                 return 0;
 353         }
 354
 355         if (!strcmp(var, "core.compression")) {
 356                 int level = git_config_int(var, value);
 357                 if (level == -1)
 358                         level = Z_DEFAULT_COMPRESSION;
 359                 else if (level < 0 || level > Z_BEST_COMPRESSION)
 360                         die("bad zlib compression level %d", level);
 361                 core_compression_level = level;
 362                 core_compression_seen = 1;
 363                 if (!zlib_compression_seen)
 364                         zlib_compression_level = level;
 365                 return 0;
 366         }
 367
 368         if (!strcmp(var, "core.packedgitwindowsize")) {
 369                 int pgsz_x2 = getpagesize() * 2;
 370                 packed_git_window_size = git_config_int(var, value);
 371
 372                 /* This value must be multiple of (pagesize * 2) */
 373                 packed_git_window_size /= pgsz_x2;
 374                 if (packed_git_window_size < 1)
 375                         packed_git_window_size = 1;
 376                 packed_git_window_size *= pgsz_x2;
 377                 return 0;
 378         }
 379
 380         if (!strcmp(var, "core.packedgitlimit")) {
 381                 packed_git_limit = git_config_int(var, value);
 382                 return 0;
 383         }
 384
 385         if (!strcmp(var, "core.deltabasecachelimit")) {
 386                 delta_base_cache_limit = git_config_int(var, value);
 387                 return 0;
 388         }
 389
 390         if (!strcmp(var, "core.autocrlf")) {
 391                 if (value && !strcasecmp(value, "input")) {
 392                         auto_crlf = -1;
 393                         return 0;
 394                 }
 395                 auto_crlf = git_config_bool(var, value);
 396                 return 0;
 397         }
 398
 399         if (!strcmp(var, "user.name")) {
 400                 strlcpy(git_default_name, value, sizeof(git_default_name));
 401                 return 0;
 402         }
 403
 404         if (!strcmp(var, "user.email")) {
 405                 strlcpy(git_default_email, value, sizeof(git_default_email));
 406                 return 0;
 407         }
 408
 409         if (!strcmp(var, "i18n.commitencoding")) {
 410                 git_commit_encoding = xstrdup(value);
 411                 return 0;
 412         }
 413
 414         if (!strcmp(var, "i18n.logoutputencoding")) {
 415                 git_log_output_encoding = xstrdup(value);
 416                 return 0;
 417         }
 418
 419
 420         if (!strcmp(var, "pager.color") || !strcmp(var, "color.pager")) {
 421                 pager_use_color = git_config_bool(var,value);
 422                 return 0;
 423         }
 424
 425         if (!strcmp(var, "core.pager")) {
 426                 pager_program = xstrdup(value);
 427                 return 0;
 428         }
 429
 430         /* Add other config variables here and to Documentation/config.txt. */
 431         return 0;
 432 }
 433
 434 int git_config_from_file(config_fn_t fn, const char *filename)
 435 {
 436         int ret;
 437         FILE *f = fopen(filename, "r");
 438
 439         ret = -1;
 440         if (f) {
 441                 config_file = f;
 442                 config_file_name = filename;
 443                 config_linenr = 1;
 444                 ret = git_parse_file(fn);
 445                 fclose(f);
 446                 config_file_name = NULL;
 447         }
 448         return ret;
 449 }
 450
 451 const char *git_etc_gitconfig(void)
 452 {
 453         static const char *system_wide;
 454         if (!system_wide) {
 455                 system_wide = ETC_GITCONFIG;
 456                 /* interpret path relative to exec-dir */
 457                 if (system_wide[0] != '/' && system_wide[1] != ':') {
 458                         const char *exec_path = git_exec_path();
 459                         system_wide = prefix_path(exec_path, strlen(exec_path),
 460                                                 system_wide);
 461                 }
 462         }
 463         return system_wide;
 464 }
 465
 466 int git_config(config_fn_t fn)
 467 {
 468         int ret = 0;
 469         char *repo_config = NULL;
 470         const char *home = NULL, *filename;
 471
 472         /* $GIT_CONFIG makes git read _only_ the given config file,
 473          * $GIT_CONFIG_LOCAL will make it process it in addition to the
 474          * global config file, the same way it would the per-repository
 475          * config file otherwise. */
 476         filename = getenv(CONFIG_ENVIRONMENT);
 477         if (!filename) {
 478                 if (!access(git_etc_gitconfig(), R_OK))
 479                         ret += git_config_from_file(fn, git_etc_gitconfig());
 480                 home = getenv("HOME");
 481                 filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 482                 if (!filename)
 483                         filename = repo_config = xstrdup(git_path("config"));
 484         }
 485
 486         if (home) {
 487                 char *user_config = xstrdup(mkpath("%s/.gitconfig", home));
 488                 if (!access(user_config, R_OK))
 489                         ret = git_config_from_file(fn, user_config);
 490                 free(user_config);
 491         }
 492
 493         ret += git_config_from_file(fn, filename);
 494         free(repo_config);
 495         return ret;
 496 }
 497
 498 /*
 499  * Find all the stuff for git_config_set() below.
 500  */
 501
 502 #define MAX_MATCHES 512
 503
 504 static struct {
 505         int baselen;
 506         char* key;
 507         int do_not_match;
 508         regex_t* value_regex;
 509         int multi_replace;
 510         size_t offset[MAX_MATCHES];
 511         enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
 512         int seen;
 513 } store;
 514
 515 static int matches(const char* key, const char* value)
 516 {
 517         return !strcmp(key, store.key) &&
 518                 (store.value_regex == NULL ||
 519                  (store.do_not_match ^
 520                   !regexec(store.value_regex, value, 0, NULL, 0)));
 521 }
 522
 523 static int store_aux(const char* key, const char* value)
 524 {
 525         const char *ep;
 526         size_t section_len;
 527
 528         switch (store.state) {
 529         case KEY_SEEN:
 530                 if (matches(key, value)) {
 531                         if (store.seen == 1 && store.multi_replace == 0) {
 532                                 fprintf(stderr,
 533                                         "Warning: %s has multiple values\n",
 534                                         key);
 535                         } else if (store.seen >= MAX_MATCHES) {
 536                                 fprintf(stderr, "Too many matches\n");
 537                                 return 1;
 538                         }
 539
 540                         store.offset[store.seen] = ftell(config_file);
 541                         store.seen++;
 542                 }
 543                 break;
 544         case SECTION_SEEN:
 545                 /*
 546                  * What we are looking for is in store.key (both
 547                  * section and var), and its section part is baselen
 548                  * long.  We found key (again, both section and var).
 549                  * We would want to know if this key is in the same
 550                  * section as what we are looking for.  We already
 551                  * know we are in the same section as what should
 552                  * hold store.key.
 553                  */
 554                 ep = strrchr(key, '.');
 555                 section_len = ep - key;
 556
 557                 if ((section_len != store.baselen) ||
 558                     memcmp(key, store.key, section_len+1)) {
 559                         store.state = SECTION_END_SEEN;
 560                         break;
 561                 }
 562
 563                 /*
 564                  * Do not increment matches: this is no match, but we
 565                  * just made sure we are in the desired section.
 566                  */
 567                 store.offset[store.seen] = ftell(config_file);
 568                 /* fallthru */
 569         case SECTION_END_SEEN:
 570         case START:
 571                 if (matches(key, value)) {
 572                         store.offset[store.seen] = ftell(config_file);
 573                         store.state = KEY_SEEN;
 574                         store.seen++;
 575                 } else {
 576                         if (strrchr(key, '.') - key == store.baselen &&
 577                               !strncmp(key, store.key, store.baselen)) {
 578                                         store.state = SECTION_SEEN;
 579                                         store.offset[store.seen] = ftell(config_file);
 580                         }
 581                 }
 582         }
 583         return 0;
 584 }
 585
 586 static int write_error(void)
 587 {
 588         fprintf(stderr, "Failed to write new configuration file\n");
 589
 590         /* Same error code as "failed to rename". */
 591         return 4;
 592 }
 593
 594 static int store_write_section(int fd, const char* key)
 595 {
 596         const char *dot = strchr(key, '.');
 597         int len1 = store.baselen, len2 = -1;
 598
 599         dot = strchr(key, '.');
 600         if (dot) {
 601                 int dotlen = dot - key;
 602                 if (dotlen < len1) {
 603                         len2 = len1 - dotlen - 1;
 604                         len1 = dotlen;
 605                 }
 606         }
 607
 608         if (write_in_full(fd, "[", 1) != 1 ||
 609             write_in_full(fd, key, len1) != len1)
 610                 return 0;
 611         if (len2 >= 0) {
 612                 if (write_in_full(fd, " \"", 2) != 2)
 613                         return 0;
 614                 while (--len2 >= 0) {
 615                         unsigned char c = *++dot;
 616                         if (c == '"')
 617                                 if (write_in_full(fd, "\\", 1) != 1)
 618                                         return 0;
 619                         if (write_in_full(fd, &c, 1) != 1)
 620                                 return 0;
 621                 }
 622                 if (write_in_full(fd, "\"", 1) != 1)
 623                         return 0;
 624         }
 625         if (write_in_full(fd, "]\n", 2) != 2)
 626                 return 0;
 627
 628         return 1;
 629 }
 630
 631 static int store_write_pair(int fd, const char* key, const char* value)
 632 {
 633         int i;
 634         int length = strlen(key+store.baselen+1);
 635         int quote = 0;
 636
 637         /* Check to see if the value needs to be quoted. */
 638         if (value[0] == ' ')
 639                 quote = 1;
 640         for (i = 0; value[i]; i++)
 641                 if (value[i] == ';' || value[i] == '#')
 642                         quote = 1;
 643         if (value[i-1] == ' ')
 644                 quote = 1;
 645
 646         if (write_in_full(fd, "\t", 1) != 1 ||
 647             write_in_full(fd, key+store.baselen+1, length) != length ||
 648             write_in_full(fd, " = ", 3) != 3)
 649                 return 0;
 650         if (quote && write_in_full(fd, "\"", 1) != 1)
 651                 return 0;
 652         for (i = 0; value[i]; i++)
 653                 switch (value[i]) {
 654                 case '\n':
 655                         if (write_in_full(fd, "\\n", 2) != 2)
 656                                 return 0;
 657                         break;
 658                 case '\t':
 659                         if (write_in_full(fd, "\\t", 2) != 2)
 660                                 return 0;
 661                         break;
 662                 case '"':
 663                 case '\\':
 664                         if (write_in_full(fd, "\\", 1) != 1)
 665                                 return 0;
 666                 default:
 667                         if (write_in_full(fd, value+i, 1) != 1)
 668                                 return 0;
 669                         break;
 670                 }
 671         if (quote && write_in_full(fd, "\"", 1) != 1)
 672                 return 0;
 673         if (write_in_full(fd, "\n", 1) != 1)
 674                 return 0;
 675         return 1;
 676 }
 677
 678 static ssize_t find_beginning_of_line(const char* contents, size_t size,
 679         size_t offset_, int* found_bracket)
 680 {
 681         size_t equal_offset = size, bracket_offset = size;
 682         ssize_t offset;
 683
 684         for (offset = offset_-2; offset > 0
 685                         && contents[offset] != '\n'; offset--)
 686                 switch (contents[offset]) {
 687                         case '=': equal_offset = offset; break;
 688                         case ']': bracket_offset = offset; break;
 689                 }
 690         if (bracket_offset < equal_offset) {
 691                 *found_bracket = 1;
 692                 offset = bracket_offset+1;
 693         } else
 694                 offset++;
 695
 696         return offset;
 697 }
 698
 699 int git_config_set(const char* key, const char* value)
 700 {
 701         return git_config_set_multivar(key, value, NULL, 0);
 702 }
 703
 704 /*
 705  * If value==NULL, unset in (remove from) config,
 706  * if value_regex!=NULL, disregard key/value pairs where value does not match.
 707  * if multi_replace==0, nothing, or only one matching key/value is replaced,
 708  *     else all matching key/values (regardless how many) are removed,
 709  *     before the new pair is written.
 710  *
 711  * Returns 0 on success.
 712  *
 713  * This function does this:
 714  *
 715  * - it locks the config file by creating ".git/config.lock"
 716  *
 717  * - it then parses the config using store_aux() as validator to find
 718  *   the position on the key/value pair to replace. If it is to be unset,
 719  *   it must be found exactly once.
 720  *
 721  * - the config file is mmap()ed and the part before the match (if any) is
 722  *   written to the lock file, then the changed part and the rest.
 723  *
 724  * - the config file is removed and the lock file rename()d to it.
 725  *
 726  */
 727 int git_config_set_multivar(const char* key, const char* value,
 728         const char* value_regex, int multi_replace)
 729 {
 730         int i, dot;
 731         int fd = -1, in_fd;
 732         int ret;
 733         char* config_filename;
 734         char* lock_file;
 735         const char* last_dot = strrchr(key, '.');
 736
 737         config_filename = getenv(CONFIG_ENVIRONMENT);
 738         if (!config_filename) {
 739                 config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 740                 if (!config_filename)
 741                         config_filename  = git_path("config");
 742         }
 743         config_filename = xstrdup(config_filename);
 744         lock_file = xstrdup(mkpath("%s.lock", config_filename));
 745
 746         /*
 747          * Since "key" actually contains the section name and the real
 748          * key name separated by a dot, we have to know where the dot is.
 749          */
 750
 751         if (last_dot == NULL) {
 752                 fprintf(stderr, "key does not contain a section: %s\n", key);
 753                 ret = 2;
 754                 goto out_free;
 755         }
 756         store.baselen = last_dot - key;
 757
 758         store.multi_replace = multi_replace;
 759
 760         /*
 761          * Validate the key and while at it, lower case it for matching.
 762          */
 763         store.key = xmalloc(strlen(key) + 1);
 764         dot = 0;
 765         for (i = 0; key[i]; i++) {
 766                 unsigned char c = key[i];
 767                 if (c == '.')
 768                         dot = 1;
 769                 /* Leave the extended basename untouched.. */
 770                 if (!dot || i > store.baselen) {
 771                         if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
 772                                 fprintf(stderr, "invalid key: %s\n", key);
 773                                 free(store.key);
 774                                 ret = 1;
 775                                 goto out_free;
 776                         }
 777                         c = tolower(c);
 778                 } else if (c == '\n') {
 779                         fprintf(stderr, "invalid key (newline): %s\n", key);
 780                         free(store.key);
 781                         ret = 1;
 782                         goto out_free;
 783                 }
 784                 store.key[i] = c;
 785         }
 786         store.key[i] = 0;
 787
 788         /*
 789          * The lock_file serves a purpose in addition to locking: the new
 790          * contents of .git/config will be written into it.
 791          */
 792         fd = open(lock_file, O_WRONLY | O_CREAT | O_EXCL, 0666);
 793         if (fd < 0 || adjust_shared_perm(lock_file)) {
 794                 fprintf(stderr, "could not lock config file\n");
 795                 free(store.key);
 796                 ret = -1;
 797                 goto out_free;
 798         }
 799
 800         /*
 801          * If .git/config does not exist yet, write a minimal version.
 802          */
 803         in_fd = open(config_filename, O_RDONLY);
 804         if ( in_fd < 0 ) {
 805                 free(store.key);
 806
 807                 if ( ENOENT != errno ) {
 808                         error("opening %s: %s", config_filename,
 809                               strerror(errno));
 810                         ret = 3; /* same as "invalid config file" */
 811                         goto out_free;
 812                 }
 813                 /* if nothing to unset, error out */
 814                 if (value == NULL) {
 815                         ret = 5;
 816                         goto out_free;
 817                 }
 818
 819                 store.key = (char*)key;
 820                 if (!store_write_section(fd, key) ||
 821                     !store_write_pair(fd, key, value))
 822                         goto write_err_out;
 823         } else {
 824                 struct stat st;
 825                 char* contents;
 826                 size_t contents_sz, copy_begin, copy_end;
 827                 int i, new_line = 0;
 828
 829                 if (value_regex == NULL)
 830                         store.value_regex = NULL;
 831                 else {
 832                         if (value_regex[0] == '!') {
 833                                 store.do_not_match = 1;
 834                                 value_regex++;
 835                         } else
 836                                 store.do_not_match = 0;
 837
 838                         store.value_regex = (regex_t*)xmalloc(sizeof(regex_t));
 839                         if (regcomp(store.value_regex, value_regex,
 840                                         REG_EXTENDED)) {
 841                                 fprintf(stderr, "Invalid pattern: %s\n",
 842                                         value_regex);
 843                                 free(store.value_regex);
 844                                 ret = 6;
 845                                 goto out_free;
 846                         }
 847                 }
 848
 849                 store.offset[0] = 0;
 850                 store.state = START;
 851                 store.seen = 0;
 852
 853                 /*
 854                  * After this, store.offset will contain the *end* offset
 855                  * of the last match, or remain at 0 if no match was found.
 856                  * As a side effect, we make sure to transform only a valid
 857                  * existing config file.
 858                  */
 859                 if (git_config_from_file(store_aux, config_filename)) {
 860                         fprintf(stderr, "invalid config file\n");
 861                         free(store.key);
 862                         if (store.value_regex != NULL) {
 863                                 regfree(store.value_regex);
 864                                 free(store.value_regex);
 865                         }
 866                         ret = 3;
 867                         goto out_free;
 868                 }
 869
 870                 free(store.key);
 871                 if (store.value_regex != NULL) {
 872                         regfree(store.value_regex);
 873                         free(store.value_regex);
 874                 }
 875
 876                 /* if nothing to unset, or too many matches, error out */
 877                 if ((store.seen == 0 && value == NULL) ||
 878                                 (store.seen > 1 && multi_replace == 0)) {
 879                         ret = 5;
 880                         goto out_free;
 881                 }
 882
 883                 fstat(in_fd, &st);
 884                 contents_sz = xsize_t(st.st_size);
 885                 contents = xmmap(NULL, contents_sz, PROT_READ,
 886                         MAP_PRIVATE, in_fd, 0);
 887                 close(in_fd);
 888
 889                 if (store.seen == 0)
 890                         store.seen = 1;
 891
 892                 for (i = 0, copy_begin = 0; i < store.seen; i++) {
 893                         if (store.offset[i] == 0) {
 894                                 store.offset[i] = copy_end = contents_sz;
 895                         } else if (store.state != KEY_SEEN) {
 896                                 copy_end = store.offset[i];
 897                         } else
 898                                 copy_end = find_beginning_of_line(
 899                                         contents, contents_sz,
 900                                         store.offset[i]-2, &new_line);
 901
 902                         /* write the first part of the config */
 903                         if (copy_end > copy_begin) {
 904                                 if (write_in_full(fd, contents + copy_begin,
 905                                                   copy_end - copy_begin) <
 906                                     copy_end - copy_begin)
 907                                         goto write_err_out;
 908                                 if (new_line &&
 909                                     write_in_full(fd, "\n", 1) != 1)
 910                                         goto write_err_out;
 911                         }
 912                         copy_begin = store.offset[i];
 913                 }
 914
 915                 /* write the pair (value == NULL means unset) */
 916                 if (value != NULL) {
 917                         if (store.state == START) {
 918                                 if (!store_write_section(fd, key))
 919                                         goto write_err_out;
 920                         }
 921                         if (!store_write_pair(fd, key, value))
 922                                 goto write_err_out;
 923                 }
 924
 925                 /* write the rest of the config */
 926                 if (copy_begin < contents_sz)
 927                         if (write_in_full(fd, contents + copy_begin,
 928                                           contents_sz - copy_begin) <
 929                             contents_sz - copy_begin)
 930                                 goto write_err_out;
 931
 932                 munmap(contents, contents_sz);
 933                 unlink(config_filename);
 934         }
 935
 936         close(fd);
 937         fd = -1;
 938         if (rename(lock_file, config_filename) < 0) {
 939                 fprintf(stderr, "Could not rename the lock file?\n");
 940                 ret = 4;
 941                 goto out_free;
 942         }
 943
 944         ret = 0;
 945
 946 out_free:
 947         if (0 <= fd)
 948                 close(fd);
 949         free(config_filename);
 950         if (lock_file) {
 951                 unlink(lock_file);
 952                 free(lock_file);
 953         }
 954         return ret;
 955
 956 write_err_out:
 957         ret = write_error();
 958         goto out_free;
 959
 960 }
 961
 962 static int section_name_match (const char *buf, const char *name)
 963 {
 964         int i = 0, j = 0, dot = 0;
 965         for (; buf[i] && buf[i] != ']'; i++) {
 966                 if (!dot && isspace(buf[i])) {
 967                         dot = 1;
 968                         if (name[j++] != '.')
 969                                 break;
 970                         for (i++; isspace(buf[i]); i++)
 971                                 ; /* do nothing */
 972                         if (buf[i] != '"')
 973                                 break;
 974                         continue;
 975                 }
 976                 if (buf[i] == '\\' && dot)
 977                         i++;
 978                 else if (buf[i] == '"' && dot) {
 979                         for (i++; isspace(buf[i]); i++)
 980                                 ; /* do_nothing */
 981                         break;
 982                 }
 983                 if (buf[i] != name[j++])
 984                         break;
 985         }
 986         return (buf[i] == ']' && name[j] == 0);
 987 }
 988
 989 /* if new_name == NULL, the section is removed instead */
 990 int git_config_rename_section(const char *old_name, const char *new_name)
 991 {
 992         int ret = 0, remove = 0;
 993         char *config_filename;
 994         struct lock_file *lock = xcalloc(sizeof(struct lock_file), 1);
 995         int out_fd;
 996         char buf[1024];
 997
 998         config_filename = getenv(CONFIG_ENVIRONMENT);
 999         if (!config_filename) {
1000                 config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
1001                 if (!config_filename)
1002                         config_filename  = git_path("config");
1003         }
1004         config_filename = xstrdup(config_filename);
1005         out_fd = hold_lock_file_for_update(lock, config_filename, 0);
1006         if (out_fd < 0) {
1007                 ret = error("Could not lock config file!");
1008                 goto out;
1009         }
1010
1011         if (!(config_file = fopen(config_filename, "rb"))) {
1012                 /* no config file means nothing to rename, no error */
1013                 goto unlock_and_out;
1014         }
1015
1016         while (fgets(buf, sizeof(buf), config_file)) {
1017                 int i;
1018                 int length;
1019                 for (i = 0; buf[i] && isspace(buf[i]); i++)
1020                         ; /* do nothing */
1021                 if (buf[i] == '[') {
1022                         /* it's a section */
1023                         if (section_name_match (&buf[i+1], old_name)) {
1024                                 ret++;
1025                                 if (new_name == NULL) {
1026                                         remove = 1;
1027                                         continue;
1028                                 }
1029                                 store.baselen = strlen(new_name);
1030                                 if (!store_write_section(out_fd, new_name)) {
1031                                         ret = write_error();
1032                                         goto out;
1033                                 }
1034                                 continue;
1035                         }
1036                         remove = 0;
1037                 }
1038                 if (remove)
1039                         continue;
1040                 length = strlen(buf);
1041                 if (write_in_full(out_fd, buf, length) != length) {
1042                         ret = write_error();
1043                         goto out;
1044                 }
1045         }
1046         fclose(config_file);
1047  unlock_and_out:
1048         if (close(out_fd) || commit_lock_file(lock) < 0)
1049                         ret = error("Cannot commit config file!");
1050  out:
1051         free(config_filename);
1052         return ret;
1053 }