Andrew's git / gitweb.git / config.c
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config.con commit Merge branch 'jc/shortlog-e' (cd1bea9)
   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        if (!strcmp(var, "core.whitespace")) {
 443                whitespace_rule_cfg = parse_whitespace_rule(value);
 444                return 0;
 445        }
 446
 447        /* Add other config variables here and to Documentation/config.txt. */
 448        return 0;
 449}
 450
 451int git_config_from_file(config_fn_t fn, const char *filename)
 452{
 453        int ret;
 454        FILE *f = fopen(filename, "r");
 455
 456        ret = -1;
 457        if (f) {
 458                config_file = f;
 459                config_file_name = filename;
 460                config_linenr = 1;
 461                ret = git_parse_file(fn);
 462                fclose(f);
 463                config_file_name = NULL;
 464        }
 465        return ret;
 466}
 467
 468const char *git_etc_gitconfig(void)
 469{
 470        static const char *system_wide;
 471        if (!system_wide) {
 472                system_wide = ETC_GITCONFIG;
 473                if (!is_absolute_path(system_wide)) {
 474                        /* interpret path relative to exec-dir */
 475                        const char *exec_path = git_exec_path();
 476                        system_wide = prefix_path(exec_path, strlen(exec_path),
 477                                                system_wide);
 478                }
 479        }
 480        return system_wide;
 481}
 482
 483int git_config(config_fn_t fn)
 484{
 485        int ret = 0;
 486        char *repo_config = NULL;
 487        const char *home = NULL, *filename;
 488
 489        /* $GIT_CONFIG makes git read _only_ the given config file,
 490         * $GIT_CONFIG_LOCAL will make it process it in addition to the
 491         * global config file, the same way it would the per-repository
 492         * config file otherwise. */
 493        filename = getenv(CONFIG_ENVIRONMENT);
 494        if (!filename) {
 495                if (!access(git_etc_gitconfig(), R_OK))
 496                        ret += git_config_from_file(fn, git_etc_gitconfig());
 497                home = getenv("HOME");
 498                filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 499                if (!filename)
 500                        filename = repo_config = xstrdup(git_path("config"));
 501        }
 502
 503        if (home) {
 504                char *user_config = xstrdup(mkpath("%s/.gitconfig", home));
 505                if (!access(user_config, R_OK))
 506                        ret = git_config_from_file(fn, user_config);
 507                free(user_config);
 508        }
 509
 510        ret += git_config_from_file(fn, filename);
 511        free(repo_config);
 512        return ret;
 513}
 514
 515/*
 516 * Find all the stuff for git_config_set() below.
 517 */
 518
 519#define MAX_MATCHES 512
 520
 521static struct {
 522        int baselen;
 523        char* key;
 524        int do_not_match;
 525        regex_t* value_regex;
 526        int multi_replace;
 527        size_t offset[MAX_MATCHES];
 528        enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
 529        int seen;
 530} store;
 531
 532static int matches(const char* key, const char* value)
 533{
 534        return !strcmp(key, store.key) &&
 535                (store.value_regex == NULL ||
 536                 (store.do_not_match ^
 537                  !regexec(store.value_regex, value, 0, NULL, 0)));
 538}
 539
 540static int store_aux(const char* key, const char* value)
 541{
 542        const char *ep;
 543        size_t section_len;
 544
 545        switch (store.state) {
 546        case KEY_SEEN:
 547                if (matches(key, value)) {
 548                        if (store.seen == 1 && store.multi_replace == 0) {
 549                                fprintf(stderr,
 550                                        "Warning: %s has multiple values\n",
 551                                        key);
 552                        } else if (store.seen >= MAX_MATCHES) {
 553                                fprintf(stderr, "Too many matches\n");
 554                                return 1;
 555                        }
 556
 557                        store.offset[store.seen] = ftell(config_file);
 558                        store.seen++;
 559                }
 560                break;
 561        case SECTION_SEEN:
 562                /*
 563                 * What we are looking for is in store.key (both
 564                 * section and var), and its section part is baselen
 565                 * long.  We found key (again, both section and var).
 566                 * We would want to know if this key is in the same
 567                 * section as what we are looking for.  We already
 568                 * know we are in the same section as what should
 569                 * hold store.key.
 570                 */
 571                ep = strrchr(key, '.');
 572                section_len = ep - key;
 573
 574                if ((section_len != store.baselen) ||
 575                    memcmp(key, store.key, section_len+1)) {
 576                        store.state = SECTION_END_SEEN;
 577                        break;
 578                }
 579
 580                /*
 581                 * Do not increment matches: this is no match, but we
 582                 * just made sure we are in the desired section.
 583                 */
 584                store.offset[store.seen] = ftell(config_file);
 585                /* fallthru */
 586        case SECTION_END_SEEN:
 587        case START:
 588                if (matches(key, value)) {
 589                        store.offset[store.seen] = ftell(config_file);
 590                        store.state = KEY_SEEN;
 591                        store.seen++;
 592                } else {
 593                        if (strrchr(key, '.') - key == store.baselen &&
 594                              !strncmp(key, store.key, store.baselen)) {
 595                                        store.state = SECTION_SEEN;
 596                                        store.offset[store.seen] = ftell(config_file);
 597                        }
 598                }
 599        }
 600        return 0;
 601}
 602
 603static int write_error(void)
 604{
 605        fprintf(stderr, "Failed to write new configuration file\n");
 606
 607        /* Same error code as "failed to rename". */
 608        return 4;
 609}
 610
 611static int store_write_section(int fd, const char* key)
 612{
 613        const char *dot = strchr(key, '.');
 614        int len1 = store.baselen, len2 = -1;
 615
 616        dot = strchr(key, '.');
 617        if (dot) {
 618                int dotlen = dot - key;
 619                if (dotlen < len1) {
 620                        len2 = len1 - dotlen - 1;
 621                        len1 = dotlen;
 622                }
 623        }
 624
 625        if (write_in_full(fd, "[", 1) != 1 ||
 626            write_in_full(fd, key, len1) != len1)
 627                return 0;
 628        if (len2 >= 0) {
 629                if (write_in_full(fd, " \"", 2) != 2)
 630                        return 0;
 631                while (--len2 >= 0) {
 632                        unsigned char c = *++dot;
 633                        if (c == '"')
 634                                if (write_in_full(fd, "\\", 1) != 1)
 635                                        return 0;
 636                        if (write_in_full(fd, &c, 1) != 1)
 637                                return 0;
 638                }
 639                if (write_in_full(fd, "\"", 1) != 1)
 640                        return 0;
 641        }
 642        if (write_in_full(fd, "]\n", 2) != 2)
 643                return 0;
 644
 645        return 1;
 646}
 647
 648static int store_write_pair(int fd, const char* key, const char* value)
 649{
 650        int i;
 651        int length = strlen(key+store.baselen+1);
 652        int quote = 0;
 653
 654        /*
 655         * Check to see if the value needs to be surrounded with a dq pair.
 656         * Note that problematic characters are always backslash-quoted; this
 657         * check is about not losing leading or trailing SP and strings that
 658         * follow beginning-of-comment characters (i.e. ';' and '#') by the
 659         * configuration parser.
 660         */
 661        if (value[0] == ' ')
 662                quote = 1;
 663        for (i = 0; value[i]; i++)
 664                if (value[i] == ';' || value[i] == '#')
 665                        quote = 1;
 666        if (i && value[i-1] == ' ')
 667                quote = 1;
 668
 669        if (write_in_full(fd, "\t", 1) != 1 ||
 670            write_in_full(fd, key+store.baselen+1, length) != length ||
 671            write_in_full(fd, " = ", 3) != 3)
 672                return 0;
 673        if (quote && write_in_full(fd, "\"", 1) != 1)
 674                return 0;
 675        for (i = 0; value[i]; i++)
 676                switch (value[i]) {
 677                case '\n':
 678                        if (write_in_full(fd, "\\n", 2) != 2)
 679                                return 0;
 680                        break;
 681                case '\t':
 682                        if (write_in_full(fd, "\\t", 2) != 2)
 683                                return 0;
 684                        break;
 685                case '"':
 686                case '\\':
 687                        if (write_in_full(fd, "\\", 1) != 1)
 688                                return 0;
 689                default:
 690                        if (write_in_full(fd, value+i, 1) != 1)
 691                                return 0;
 692                        break;
 693                }
 694        if (quote && write_in_full(fd, "\"", 1) != 1)
 695                return 0;
 696        if (write_in_full(fd, "\n", 1) != 1)
 697                return 0;
 698        return 1;
 699}
 700
 701static ssize_t find_beginning_of_line(const char* contents, size_t size,
 702        size_t offset_, int* found_bracket)
 703{
 704        size_t equal_offset = size, bracket_offset = size;
 705        ssize_t offset;
 706
 707        for (offset = offset_-2; offset > 0
 708                        && contents[offset] != '\n'; offset--)
 709                switch (contents[offset]) {
 710                        case '=': equal_offset = offset; break;
 711                        case ']': bracket_offset = offset; break;
 712                }
 713        if (bracket_offset < equal_offset) {
 714                *found_bracket = 1;
 715                offset = bracket_offset+1;
 716        } else
 717                offset++;
 718
 719        return offset;
 720}
 721
 722int git_config_set(const char* key, const char* value)
 723{
 724        return git_config_set_multivar(key, value, NULL, 0);
 725}
 726
 727/*
 728 * If value==NULL, unset in (remove from) config,
 729 * if value_regex!=NULL, disregard key/value pairs where value does not match.
 730 * if multi_replace==0, nothing, or only one matching key/value is replaced,
 731 *     else all matching key/values (regardless how many) are removed,
 732 *     before the new pair is written.
 733 *
 734 * Returns 0 on success.
 735 *
 736 * This function does this:
 737 *
 738 * - it locks the config file by creating ".git/config.lock"
 739 *
 740 * - it then parses the config using store_aux() as validator to find
 741 *   the position on the key/value pair to replace. If it is to be unset,
 742 *   it must be found exactly once.
 743 *
 744 * - the config file is mmap()ed and the part before the match (if any) is
 745 *   written to the lock file, then the changed part and the rest.
 746 *
 747 * - the config file is removed and the lock file rename()d to it.
 748 *
 749 */
 750int git_config_set_multivar(const char* key, const char* value,
 751        const char* value_regex, int multi_replace)
 752{
 753        int i, dot;
 754        int fd = -1, in_fd;
 755        int ret;
 756        char* config_filename;
 757        struct lock_file *lock = NULL;
 758        const char* last_dot = strrchr(key, '.');
 759
 760        config_filename = getenv(CONFIG_ENVIRONMENT);
 761        if (!config_filename) {
 762                config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
 763                if (!config_filename)
 764                        config_filename  = git_path("config");
 765        }
 766        config_filename = xstrdup(config_filename);
 767
 768        /*
 769         * Since "key" actually contains the section name and the real
 770         * key name separated by a dot, we have to know where the dot is.
 771         */
 772
 773        if (last_dot == NULL) {
 774                fprintf(stderr, "key does not contain a section: %s\n", key);
 775                ret = 2;
 776                goto out_free;
 777        }
 778        store.baselen = last_dot - key;
 779
 780        store.multi_replace = multi_replace;
 781
 782        /*
 783         * Validate the key and while at it, lower case it for matching.
 784         */
 785        store.key = xmalloc(strlen(key) + 1);
 786        dot = 0;
 787        for (i = 0; key[i]; i++) {
 788                unsigned char c = key[i];
 789                if (c == '.')
 790                        dot = 1;
 791                /* Leave the extended basename untouched.. */
 792                if (!dot || i > store.baselen) {
 793                        if (!iskeychar(c) || (i == store.baselen+1 && !isalpha(c))) {
 794                                fprintf(stderr, "invalid key: %s\n", key);
 795                                free(store.key);
 796                                ret = 1;
 797                                goto out_free;
 798                        }
 799                        c = tolower(c);
 800                } else if (c == '\n') {
 801                        fprintf(stderr, "invalid key (newline): %s\n", key);
 802                        free(store.key);
 803                        ret = 1;
 804                        goto out_free;
 805                }
 806                store.key[i] = c;
 807        }
 808        store.key[i] = 0;
 809
 810        /*
 811         * The lock serves a purpose in addition to locking: the new
 812         * contents of .git/config will be written into it.
 813         */
 814        lock = xcalloc(sizeof(struct lock_file), 1);
 815        fd = hold_lock_file_for_update(lock, config_filename, 0);
 816        if (fd < 0) {
 817                fprintf(stderr, "could not lock config file\n");
 818                free(store.key);
 819                ret = -1;
 820                goto out_free;
 821        }
 822
 823        /*
 824         * If .git/config does not exist yet, write a minimal version.
 825         */
 826        in_fd = open(config_filename, O_RDONLY);
 827        if ( in_fd < 0 ) {
 828                free(store.key);
 829
 830                if ( ENOENT != errno ) {
 831                        error("opening %s: %s", config_filename,
 832                              strerror(errno));
 833                        ret = 3; /* same as "invalid config file" */
 834                        goto out_free;
 835                }
 836                /* if nothing to unset, error out */
 837                if (value == NULL) {
 838                        ret = 5;
 839                        goto out_free;
 840                }
 841
 842                store.key = (char*)key;
 843                if (!store_write_section(fd, key) ||
 844                    !store_write_pair(fd, key, value))
 845                        goto write_err_out;
 846        } else {
 847                struct stat st;
 848                char* contents;
 849                size_t contents_sz, copy_begin, copy_end;
 850                int i, new_line = 0;
 851
 852                if (value_regex == NULL)
 853                        store.value_regex = NULL;
 854                else {
 855                        if (value_regex[0] == '!') {
 856                                store.do_not_match = 1;
 857                                value_regex++;
 858                        } else
 859                                store.do_not_match = 0;
 860
 861                        store.value_regex = (regex_t*)xmalloc(sizeof(regex_t));
 862                        if (regcomp(store.value_regex, value_regex,
 863                                        REG_EXTENDED)) {
 864                                fprintf(stderr, "Invalid pattern: %s\n",
 865                                        value_regex);
 866                                free(store.value_regex);
 867                                ret = 6;
 868                                goto out_free;
 869                        }
 870                }
 871
 872                store.offset[0] = 0;
 873                store.state = START;
 874                store.seen = 0;
 875
 876                /*
 877                 * After this, store.offset will contain the *end* offset
 878                 * of the last match, or remain at 0 if no match was found.
 879                 * As a side effect, we make sure to transform only a valid
 880                 * existing config file.
 881                 */
 882                if (git_config_from_file(store_aux, config_filename)) {
 883                        fprintf(stderr, "invalid config file\n");
 884                        free(store.key);
 885                        if (store.value_regex != NULL) {
 886                                regfree(store.value_regex);
 887                                free(store.value_regex);
 888                        }
 889                        ret = 3;
 890                        goto out_free;
 891                }
 892
 893                free(store.key);
 894                if (store.value_regex != NULL) {
 895                        regfree(store.value_regex);
 896                        free(store.value_regex);
 897                }
 898
 899                /* if nothing to unset, or too many matches, error out */
 900                if ((store.seen == 0 && value == NULL) ||
 901                                (store.seen > 1 && multi_replace == 0)) {
 902                        ret = 5;
 903                        goto out_free;
 904                }
 905
 906                fstat(in_fd, &st);
 907                contents_sz = xsize_t(st.st_size);
 908                contents = xmmap(NULL, contents_sz, PROT_READ,
 909                        MAP_PRIVATE, in_fd, 0);
 910                close(in_fd);
 911
 912                if (store.seen == 0)
 913                        store.seen = 1;
 914
 915                for (i = 0, copy_begin = 0; i < store.seen; i++) {
 916                        if (store.offset[i] == 0) {
 917                                store.offset[i] = copy_end = contents_sz;
 918                        } else if (store.state != KEY_SEEN) {
 919                                copy_end = store.offset[i];
 920                        } else
 921                                copy_end = find_beginning_of_line(
 922                                        contents, contents_sz,
 923                                        store.offset[i]-2, &new_line);
 924
 925                        /* write the first part of the config */
 926                        if (copy_end > copy_begin) {
 927                                if (write_in_full(fd, contents + copy_begin,
 928                                                  copy_end - copy_begin) <
 929                                    copy_end - copy_begin)
 930                                        goto write_err_out;
 931                                if (new_line &&
 932                                    write_in_full(fd, "\n", 1) != 1)
 933                                        goto write_err_out;
 934                        }
 935                        copy_begin = store.offset[i];
 936                }
 937
 938                /* write the pair (value == NULL means unset) */
 939                if (value != NULL) {
 940                        if (store.state == START) {
 941                                if (!store_write_section(fd, key))
 942                                        goto write_err_out;
 943                        }
 944                        if (!store_write_pair(fd, key, value))
 945                                goto write_err_out;
 946                }
 947
 948                /* write the rest of the config */
 949                if (copy_begin < contents_sz)
 950                        if (write_in_full(fd, contents + copy_begin,
 951                                          contents_sz - copy_begin) <
 952                            contents_sz - copy_begin)
 953                                goto write_err_out;
 954
 955                munmap(contents, contents_sz);
 956        }
 957
 958        if (close(fd) || commit_lock_file(lock) < 0) {
 959                fprintf(stderr, "Cannot commit config file!\n");
 960                ret = 4;
 961                goto out_free;
 962        }
 963
 964        /* fd is closed, so don't try to close it below. */
 965        fd = -1;
 966        /*
 967         * lock is committed, so don't try to roll it back below.
 968         * NOTE: Since lockfile.c keeps a linked list of all created
 969         * lock_file structures, it isn't safe to free(lock).  It's
 970         * better to just leave it hanging around.
 971         */
 972        lock = NULL;
 973        ret = 0;
 974
 975out_free:
 976        if (0 <= fd)
 977                close(fd);
 978        if (lock)
 979                rollback_lock_file(lock);
 980        free(config_filename);
 981        return ret;
 982
 983write_err_out:
 984        ret = write_error();
 985        goto out_free;
 986
 987}
 988
 989static int section_name_match (const char *buf, const char *name)
 990{
 991        int i = 0, j = 0, dot = 0;
 992        for (; buf[i] && buf[i] != ']'; i++) {
 993                if (!dot && isspace(buf[i])) {
 994                        dot = 1;
 995                        if (name[j++] != '.')
 996                                break;
 997                        for (i++; isspace(buf[i]); i++)
 998                                ; /* do nothing */
 999                        if (buf[i] != '"')
1000                                break;
1001                        continue;
1002                }
1003                if (buf[i] == '\\' && dot)
1004                        i++;
1005                else if (buf[i] == '"' && dot) {
1006                        for (i++; isspace(buf[i]); i++)
1007                                ; /* do_nothing */
1008                        break;
1009                }
1010                if (buf[i] != name[j++])
1011                        break;
1012        }
1013        return (buf[i] == ']' && name[j] == 0);
1014}
1015
1016/* if new_name == NULL, the section is removed instead */
1017int git_config_rename_section(const char *old_name, const char *new_name)
1018{
1019        int ret = 0, remove = 0;
1020        char *config_filename;
1021        struct lock_file *lock = xcalloc(sizeof(struct lock_file), 1);
1022        int out_fd;
1023        char buf[1024];
1024
1025        config_filename = getenv(CONFIG_ENVIRONMENT);
1026        if (!config_filename) {
1027                config_filename = getenv(CONFIG_LOCAL_ENVIRONMENT);
1028                if (!config_filename)
1029                        config_filename  = git_path("config");
1030        }
1031        config_filename = xstrdup(config_filename);
1032        out_fd = hold_lock_file_for_update(lock, config_filename, 0);
1033        if (out_fd < 0) {
1034                ret = error("Could not lock config file!");
1035                goto out;
1036        }
1037
1038        if (!(config_file = fopen(config_filename, "rb"))) {
1039                /* no config file means nothing to rename, no error */
1040                goto unlock_and_out;
1041        }
1042
1043        while (fgets(buf, sizeof(buf), config_file)) {
1044                int i;
1045                int length;
1046                for (i = 0; buf[i] && isspace(buf[i]); i++)
1047                        ; /* do nothing */
1048                if (buf[i] == '[') {
1049                        /* it's a section */
1050                        if (section_name_match (&buf[i+1], old_name)) {
1051                                ret++;
1052                                if (new_name == NULL) {
1053                                        remove = 1;
1054                                        continue;
1055                                }
1056                                store.baselen = strlen(new_name);
1057                                if (!store_write_section(out_fd, new_name)) {
1058                                        ret = write_error();
1059                                        goto out;
1060                                }
1061                                continue;
1062                        }
1063                        remove = 0;
1064                }
1065                if (remove)
1066                        continue;
1067                length = strlen(buf);
1068                if (write_in_full(out_fd, buf, length) != length) {
1069                        ret = write_error();
1070                        goto out;
1071                }
1072        }
1073        fclose(config_file);
1074 unlock_and_out:
1075        if (close(out_fd) || commit_lock_file(lock) < 0)
1076                        ret = error("Cannot commit config file!");
1077 out:
1078        free(config_filename);
1079        return ret;
1080}