Andrew's git / gitweb.git / config.c
?
config.con commit Mention that git-rm can be an appropriate resolution as well as git-add. (0d81358)
   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
  13static FILE *config_file;
  14static const char *config_file_name;
  15static int config_linenr;
  16static int zlib_compression_seen;
  17
  18static 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
  44static 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
 108static inline int iskeychar(int c)
 109{
 110        return isalnum(c) || c == '-';
 111}
 112
 113static 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
 144static 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
 179static 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
 199static 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
 237static 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
 250int 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
 261int 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
 272int 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
 280unsigned 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
 288int 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
 301int 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        if (!strcmp(var, "core.editor")) {
 431                editor_program = xstrdup(value);
 432                return 0;
 433        }
 434
 435        if (!strcmp(var, "core.excludesfile")) {
 436                if (!value)
 437                        die("core.excludesfile without value");
 438                excludes_file = xstrdup(value);
 439                return 0;
 440        }
 441
 442        /* Add other config variables here and to Documentation/config.txt. */
 443        return 0;
 444}
 445
 446int git_config_from_file(config_fn_t fn, const char *filename)
 447{
 448        int ret;
 449        FILE *f = fopen(filename, "r");
 450
 451        ret = -1;
 452        if (f) {
 453                config_file = f;
 454                config_file_name = filename;
 455                config_linenr = 1;
 456                ret = git_parse_file(fn);
 457                fclose(f);
 458                config_file_name = NULL;
 459        }
 460        return ret;
 461}
 462
 463const char *git_etc_gitconfig(void)
 464{
 465        static const char *system_wide;
 466        if (!system_wide) {
 467                system_wide = ETC_GITCONFIG;
 468                if (!is_absolute_path(system_wide)) {
 469                        /* interpret path relative to exec-dir */
 470                        const char *exec_path = git_exec_path();
 471                        system_wide = prefix_path(exec_path, strlen(exec_path),
 472                                                system_wide);
 473                }
 474        }
 475        return system_wide;
 476}
 477
 478int git_config(config_fn_t fn)
 479{
 480        int ret = 0;
 481        char *repo_config = NULL;
 482        const char *home = NULL, *filename;
 483
 484        /* $GIT_CONFIG makes git read _only_ the given config file,
 485         * $GIT_CONFIG_LOCAL will make it process it in addition to the
 486         * global config file, the same way it would the per-repository
 487         * config file otherwise. */
 488        filename = getenv(CONFIG_ENVIRONMENT);
 489        if (!filename) {
 490                if (!access(git_etc_gitconfig(), R_OK))
 491                        ret += git_config_from_file(fn, git_etc_gitconfig());
 492                home = getenv("HOME");
 493                filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 494                if (!filename)
 495                        filename = repo_config = xstrdup(git_path("config"));
 496        }
 497
 498        if (home) {
 499                char *user_config = xstrdup(mkpath("%s/.gitconfig", home));
 500                if (!access(user_config, R_OK))
 501                        ret = git_config_from_file(fn, user_config);
 502                free(user_config);
 503        }
 504
 505        ret += git_config_from_file(fn, filename);
 506        free(repo_config);
 507        return ret;
 508}
 509
 510/*
 511 * Find all the stuff for git_config_set() below.
 512 */
 513
 514#define MAX_MATCHES 512
 515
 516static struct {
 517        int baselen;
 518        char* key;
 519        int do_not_match;
 520        regex_t* value_regex;
 521        int multi_replace;
 522        size_t offset[MAX_MATCHES];
 523        enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
 524        int seen;
 525} store;
 526
 527static int matches(const char* key, const char* value)
 528{
 529        return !strcmp(key, store.key) &&
 530                (store.value_regex == NULL ||
 531                 (store.do_not_match ^
 532                  !regexec(store.value_regex, value, 0, NULL, 0)));
 533}
 534
 535static int store_aux(const char* key, const char* value)
 536{
 537        const char *ep;
 538        size_t section_len;
 539
 540        switch (store.state) {
 541        case KEY_SEEN:
 542                if (matches(key, value)) {
 543                        if (store.seen == 1 && store.multi_replace == 0) {
 544                                fprintf(stderr,
 545                                        "Warning: %s has multiple values\n",
 546                                        key);
 547                        } else if (store.seen >= MAX_MATCHES) {
 548                                fprintf(stderr, "Too many matches\n");
 549                                return 1;
 550                        }
 551
 552                        store.offset[store.seen] = ftell(config_file);
 553                        store.seen++;
 554                }
 555                break;
 556        case SECTION_SEEN:
 557                /*
 558                 * What we are looking for is in store.key (both
 559                 * section and var), and its section part is baselen
 560                 * long.  We found key (again, both section and var).
 561                 * We would want to know if this key is in the same
 562                 * section as what we are looking for.  We already
 563                 * know we are in the same section as what should
 564                 * hold store.key.
 565                 */
 566                ep = strrchr(key, '.');
 567                section_len = ep - key;
 568
 569                if ((section_len != store.baselen) ||
 570                    memcmp(key, store.key, section_len+1)) {
 571                        store.state = SECTION_END_SEEN;
 572                        break;
 573                }
 574
 575                /*
 576                 * Do not increment matches: this is no match, but we
 577                 * just made sure we are in the desired section.
 578                 */
 579                store.offset[store.seen] = ftell(config_file);
 580                /* fallthru */
 581        case SECTION_END_SEEN:
 582        case START:
 583                if (matches(key, value)) {
 584                        store.offset[store.seen] = ftell(config_file);
 585                        store.state = KEY_SEEN;
 586                        store.seen++;
 587                } else {
 588                        if (strrchr(key, '.') - key == store.baselen &&
 589                              !strncmp(key, store.key, store.baselen)) {
 590                                        store.state = SECTION_SEEN;
 591                                        store.offset[store.seen] = ftell(config_file);
 592                        }
 593                }
 594        }
 595        return 0;
 596}
 597
 598static int write_error(void)
 599{
 600        fprintf(stderr, "Failed to write new configuration file\n");
 601
 602        /* Same error code as "failed to rename". */
 603        return 4;
 604}
 605
 606static int store_write_section(int fd, const char* key)
 607{
 608        const char *dot = strchr(key, '.');
 609        int len1 = store.baselen, len2 = -1;
 610
 611        dot = strchr(key, '.');
 612        if (dot) {
 613                int dotlen = dot - key;
 614                if (dotlen < len1) {
 615                        len2 = len1 - dotlen - 1;
 616                        len1 = dotlen;
 617                }
 618        }
 619
 620        if (write_in_full(fd, "[", 1) != 1 ||
 621            write_in_full(fd, key, len1) != len1)
 622                return 0;
 623        if (len2 >= 0) {
 624                if (write_in_full(fd, " \"", 2) != 2)
 625                        return 0;
 626                while (--len2 >= 0) {
 627                        unsigned char c = *++dot;
 628                        if (c == '"')
 629                                if (write_in_full(fd, "\\", 1) != 1)
 630                                        return 0;
 631                        if (write_in_full(fd, &c, 1) != 1)
 632                                return 0;
 633                }
 634                if (write_in_full(fd, "\"", 1) != 1)
 635                        return 0;
 636        }
 637        if (write_in_full(fd, "]\n", 2) != 2)
 638                return 0;
 639
 640        return 1;
 641}
 642
 643static int store_write_pair(int fd, const char* key, const char* value)
 644{
 645        int i;
 646        int length = strlen(key+store.baselen+1);
 647        int quote = 0;
 648
 649        /* Check to see if the value needs to be quoted. */
 650        if (value[0] == ' ')
 651                quote = 1;
 652        for (i = 0; value[i]; i++)
 653                if (value[i] == ';' || value[i] == '#')
 654                        quote = 1;
 655        if (value[i-1] == ' ')
 656                quote = 1;
 657
 658        if (write_in_full(fd, "\t", 1) != 1 ||
 659            write_in_full(fd, key+store.baselen+1, length) != length ||
 660            write_in_full(fd, " = ", 3) != 3)
 661                return 0;
 662        if (quote && write_in_full(fd, "\"", 1) != 1)
 663                return 0;
 664        for (i = 0; value[i]; i++)
 665                switch (value[i]) {
 666                case '\n':
 667                        if (write_in_full(fd, "\\n", 2) != 2)
 668                                return 0;
 669                        break;
 670                case '\t':
 671                        if (write_in_full(fd, "\\t", 2) != 2)
 672                                return 0;
 673                        break;
 674                case '"':
 675                case '\\':
 676                        if (write_in_full(fd, "\\", 1) != 1)
 677                                return 0;
 678                default:
 679                        if (write_in_full(fd, value+i, 1) != 1)
 680                                return 0;
 681                        break;
 682                }
 683        if (quote && write_in_full(fd, "\"", 1) != 1)
 684                return 0;
 685        if (write_in_full(fd, "\n", 1) != 1)
 686                return 0;
 687        return 1;
 688}
 689
 690static ssize_t find_beginning_of_line(const char* contents, size_t size,
 691        size_t offset_, int* found_bracket)
 692{
 693        size_t equal_offset = size, bracket_offset = size;
 694        ssize_t offset;
 695
 696        for (offset = offset_-2; offset > 0
 697                        && contents[offset] != '\n'; offset--)
 698                switch (contents[offset]) {
 699                        case '=': equal_offset = offset; break;
 700                        case ']': bracket_offset = offset; break;
 701                }
 702        if (bracket_offset < equal_offset) {
 703                *found_bracket = 1;
 704                offset = bracket_offset+1;
 705        } else
 706                offset++;
 707
 708        return offset;
 709}
 710
 711int git_config_set(const char* key, const char* value)
 712{
 713        return git_config_set_multivar(key, value, NULL, 0);
 714}
 715
 716/*
 717 * If value==NULL, unset in (remove from) config,
 718 * if value_regex!=NULL, disregard key/value pairs where value does not match.
 719 * if multi_replace==0, nothing, or only one matching key/value is replaced,
 720 *     else all matching key/values (regardless how many) are removed,
 721 *     before the new pair is written.
 722 *
 723 * Returns 0 on success.
 724 *
 725 * This function does this:
 726 *
 727 * - it locks the config file by creating ".git/config.lock"
 728 *
 729 * - it then parses the config using store_aux() as validator to find
 730 *   the position on the key/value pair to replace. If it is to be unset,
 731 *   it must be found exactly once.
 732 *
 733 * - the config file is mmap()ed and the part before the match (if any) is
 734 *   written to the lock file, then the changed part and the rest.
 735 *
 736 * - the config file is removed and the lock file rename()d to it.
 737 *
 738 */
 739int git_config_set_multivar(const char* key, const char* value,
 740        const char* value_regex, int multi_replace)
 741{
 742        int i, dot;
 743        int fd = -1, in_fd;
 744        int ret;
 745        char* config_filename;
 746        struct lock_file *lock = NULL;
 747        const char* last_dot = strrchr(key, '.');
 748
 749        config_filename = getenv(CONFIG_ENVIRONMENT);
 750        if (!config_filename) {
 751                config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 752                if (!config_filename)
 753                        config_filename  = git_path("config");
 754        }
 755        config_filename = xstrdup(config_filename);
 756
 757        /*
 758         * Since "key" actually contains the section name and the real
 759         * key name separated by a dot, we have to know where the dot is.
 760         */
 761
 762        if (last_dot == NULL) {
 763                fprintf(stderr, "key does not contain a section: %s\n", key);
 764                ret = 2;
 765                goto out_free;
 766        }
 767        store.baselen = last_dot - key;
 768
 769        store.multi_replace = multi_replace;
 770
 771        /*
 772         * Validate the key and while at it, lower case it for matching.
 773         */
 774        store.key = xmalloc(strlen(key) + 1);
 775        dot = 0;
 776        for (i = 0; key[i]; i++) {
 777                unsigned char c = key[i];
 778                if (c == '.')
 779                        dot = 1;
 780                /* Leave the extended basename untouched.. */
 781                if (!dot || i > store.baselen) {
 782                        if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
 783                                fprintf(stderr, "invalid key: %s\n", key);
 784                                free(store.key);
 785                                ret = 1;
 786                                goto out_free;
 787                        }
 788                        c = tolower(c);
 789                } else if (c == '\n') {
 790                        fprintf(stderr, "invalid key (newline): %s\n", key);
 791                        free(store.key);
 792                        ret = 1;
 793                        goto out_free;
 794                }
 795                store.key[i] = c;
 796        }
 797        store.key[i] = 0;
 798
 799        /*
 800         * The lock serves a purpose in addition to locking: the new
 801         * contents of .git/config will be written into it.
 802         */
 803        lock = xcalloc(sizeof(struct lock_file), 1);
 804        fd = hold_lock_file_for_update(lock, config_filename, 0);
 805        if (fd < 0) {
 806                fprintf(stderr, "could not lock config file\n");
 807                free(store.key);
 808                ret = -1;
 809                goto out_free;
 810        }
 811
 812        /*
 813         * If .git/config does not exist yet, write a minimal version.
 814         */
 815        in_fd = open(config_filename, O_RDONLY);
 816        if ( in_fd < 0 ) {
 817                free(store.key);
 818
 819                if ( ENOENT != errno ) {
 820                        error("opening %s: %s", config_filename,
 821                              strerror(errno));
 822                        ret = 3; /* same as "invalid config file" */
 823                        goto out_free;
 824                }
 825                /* if nothing to unset, error out */
 826                if (value == NULL) {
 827                        ret = 5;
 828                        goto out_free;
 829                }
 830
 831                store.key = (char*)key;
 832                if (!store_write_section(fd, key) ||
 833                    !store_write_pair(fd, key, value))
 834                        goto write_err_out;
 835        } else {
 836                struct stat st;
 837                char* contents;
 838                size_t contents_sz, copy_begin, copy_end;
 839                int i, new_line = 0;
 840
 841                if (value_regex == NULL)
 842                        store.value_regex = NULL;
 843                else {
 844                        if (value_regex[0] == '!') {
 845                                store.do_not_match = 1;
 846                                value_regex++;
 847                        } else
 848                                store.do_not_match = 0;
 849
 850                        store.value_regex = (regex_t*)xmalloc(sizeof(regex_t));
 851                        if (regcomp(store.value_regex, value_regex,
 852                                        REG_EXTENDED)) {
 853                                fprintf(stderr, "Invalid pattern: %s\n",
 854                                        value_regex);
 855                                free(store.value_regex);
 856                                ret = 6;
 857                                goto out_free;
 858                        }
 859                }
 860
 861                store.offset[0] = 0;
 862                store.state = START;
 863                store.seen = 0;
 864
 865                /*
 866                 * After this, store.offset will contain the *end* offset
 867                 * of the last match, or remain at 0 if no match was found.
 868                 * As a side effect, we make sure to transform only a valid
 869                 * existing config file.
 870                 */
 871                if (git_config_from_file(store_aux, config_filename)) {
 872                        fprintf(stderr, "invalid config file\n");
 873                        free(store.key);
 874                        if (store.value_regex != NULL) {
 875                                regfree(store.value_regex);
 876                                free(store.value_regex);
 877                        }
 878                        ret = 3;
 879                        goto out_free;
 880                }
 881
 882                free(store.key);
 883                if (store.value_regex != NULL) {
 884                        regfree(store.value_regex);
 885                        free(store.value_regex);
 886                }
 887
 888                /* if nothing to unset, or too many matches, error out */
 889                if ((store.seen == 0 && value == NULL) ||
 890                                (store.seen > 1 && multi_replace == 0)) {
 891                        ret = 5;
 892                        goto out_free;
 893                }
 894
 895                fstat(in_fd, &st);
 896                contents_sz = xsize_t(st.st_size);
 897                contents = xmmap(NULL, contents_sz, PROT_READ,
 898                        MAP_PRIVATE, in_fd, 0);
 899                close(in_fd);
 900
 901                if (store.seen == 0)
 902                        store.seen = 1;
 903
 904                for (i = 0, copy_begin = 0; i < store.seen; i++) {
 905                        if (store.offset[i] == 0) {
 906                                store.offset[i] = copy_end = contents_sz;
 907                        } else if (store.state != KEY_SEEN) {
 908                                copy_end = store.offset[i];
 909                        } else
 910                                copy_end = find_beginning_of_line(
 911                                        contents, contents_sz,
 912                                        store.offset[i]-2, &new_line);
 913
 914                        /* write the first part of the config */
 915                        if (copy_end > copy_begin) {
 916                                if (write_in_full(fd, contents + copy_begin,
 917                                                  copy_end - copy_begin) <
 918                                    copy_end - copy_begin)
 919                                        goto write_err_out;
 920                                if (new_line &&
 921                                    write_in_full(fd, "\n", 1) != 1)
 922                                        goto write_err_out;
 923                        }
 924                        copy_begin = store.offset[i];
 925                }
 926
 927                /* write the pair (value == NULL means unset) */
 928                if (value != NULL) {
 929                        if (store.state == START) {
 930                                if (!store_write_section(fd, key))
 931                                        goto write_err_out;
 932                        }
 933                        if (!store_write_pair(fd, key, value))
 934                                goto write_err_out;
 935                }
 936
 937                /* write the rest of the config */
 938                if (copy_begin < contents_sz)
 939                        if (write_in_full(fd, contents + copy_begin,
 940                                          contents_sz - copy_begin) <
 941                            contents_sz - copy_begin)
 942                                goto write_err_out;
 943
 944                munmap(contents, contents_sz);
 945        }
 946
 947        if (close(fd) || commit_lock_file(lock) < 0) {
 948                fprintf(stderr, "Cannot commit config file!\n");
 949                ret = 4;
 950                goto out_free;
 951        }
 952
 953        /* fd is closed, so don't try to close it below. */
 954        fd = -1;
 955        /*
 956         * lock is committed, so don't try to roll it back below.
 957         * NOTE: Since lockfile.c keeps a linked list of all created
 958         * lock_file structures, it isn't safe to free(lock).  It's
 959         * better to just leave it hanging around.
 960         */
 961        lock = NULL;
 962        ret = 0;
 963
 964out_free:
 965        if (0 <= fd)
 966                close(fd);
 967        if (lock)
 968                rollback_lock_file(lock);
 969        free(config_filename);
 970        return ret;
 971
 972write_err_out:
 973        ret = write_error();
 974        goto out_free;
 975
 976}
 977
 978static int section_name_match (const char *buf, const char *name)
 979{
 980        int i = 0, j = 0, dot = 0;
 981        for (; buf[i] && buf[i] != ']'; i++) {
 982                if (!dot && isspace(buf[i])) {
 983                        dot = 1;
 984                        if (name[j++] != '.')
 985                                break;
 986                        for (i++; isspace(buf[i]); i++)
 987                                ; /* do nothing */
 988                        if (buf[i] != '"')
 989                                break;
 990                        continue;
 991                }
 992                if (buf[i] == '\\' && dot)
 993                        i++;
 994                else if (buf[i] == '"' && dot) {
 995                        for (i++; isspace(buf[i]); i++)
 996                                ; /* do_nothing */
 997                        break;
 998                }
 999                if (buf[i] != name[j++])
1000                        break;
1001        }
1002        return (buf[i] == ']' && name[j] == 0);
1003}
1004
1005/* if new_name == NULL, the section is removed instead */
1006int git_config_rename_section(const char *old_name, const char *new_name)
1007{
1008        int ret = 0, remove = 0;
1009        char *config_filename;
1010        struct lock_file *lock = xcalloc(sizeof(struct lock_file), 1);
1011        int out_fd;
1012        char buf[1024];
1013
1014        config_filename = getenv(CONFIG_ENVIRONMENT);
1015        if (!config_filename) {
1016                config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
1017                if (!config_filename)
1018                        config_filename  = git_path("config");
1019        }
1020        config_filename = xstrdup(config_filename);
1021        out_fd = hold_lock_file_for_update(lock, config_filename, 0);
1022        if (out_fd < 0) {
1023                ret = error("Could not lock config file!");
1024                goto out;
1025        }
1026
1027        if (!(config_file = fopen(config_filename, "rb"))) {
1028                /* no config file means nothing to rename, no error */
1029                goto unlock_and_out;
1030        }
1031
1032        while (fgets(buf, sizeof(buf), config_file)) {
1033                int i;
1034                int length;
1035                for (i = 0; buf[i] && isspace(buf[i]); i++)
1036                        ; /* do nothing */
1037                if (buf[i] == '[') {
1038                        /* it's a section */
1039                        if (section_name_match (&buf[i+1], old_name)) {
1040                                ret++;
1041                                if (new_name == NULL) {
1042                                        remove = 1;
1043                                        continue;
1044                                }
1045                                store.baselen = strlen(new_name);
1046                                if (!store_write_section(out_fd, new_name)) {
1047                                        ret = write_error();
1048                                        goto out;
1049                                }
1050                                continue;
1051                        }
1052                        remove = 0;
1053                }
1054                if (remove)
1055                        continue;
1056                length = strlen(buf);
1057                if (write_in_full(out_fd, buf, length) != length) {
1058                        ret = write_error();
1059                        goto out;
1060                }
1061        }
1062        fclose(config_file);
1063 unlock_and_out:
1064        if (close(out_fd) || commit_lock_file(lock) < 0)
1065                        ret = error("Cannot commit config file!");
1066 out:
1067        free(config_filename);
1068        return ret;
1069}