path.c

   1 /*
   2  * Utilities for paths and pathnames
   3  */
   4 #include "cache.h"
   5 #include "strbuf.h"
   6 #include "string-list.h"
   7 #include "dir.h"
   8
   9 static int get_st_mode_bits(const char *path, int *mode)
  10 {
  11         struct stat st;
  12         if (lstat(path, &st) < 0)
  13                 return -1;
  14         *mode = st.st_mode;
  15         return 0;
  16 }
  17
  18 static char bad_path[] = "/bad-path/";
  19
  20 static struct strbuf *get_pathname(void)
  21 {
  22         static struct strbuf pathname_array[4] = {
  23                 STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
  24         };
  25         static int index;
  26         struct strbuf *sb = &pathname_array[3 & ++index];
  27         strbuf_reset(sb);
  28         return sb;
  29 }
  30
  31 static char *cleanup_path(char *path)
  32 {
  33         /* Clean it up */
  34         if (!memcmp(path, "./", 2)) {
  35                 path += 2;
  36                 while (*path == '/')
  37                         path++;
  38         }
  39         return path;
  40 }
  41
  42 static void strbuf_cleanup_path(struct strbuf *sb)
  43 {
  44         char *path = cleanup_path(sb->buf);
  45         if (path > sb->buf)
  46                 strbuf_remove(sb, 0, path - sb->buf);
  47 }
  48
  49 char *mksnpath(char *buf, size_t n, const char *fmt, ...)
  50 {
  51         va_list args;
  52         unsigned len;
  53
  54         va_start(args, fmt);
  55         len = vsnprintf(buf, n, fmt, args);
  56         va_end(args);
  57         if (len >= n) {
  58                 strlcpy(buf, bad_path, n);
  59                 return buf;
  60         }
  61         return cleanup_path(buf);
  62 }
  63
  64 static int dir_prefix(const char *buf, const char *dir)
  65 {
  66         int len = strlen(dir);
  67         return !strncmp(buf, dir, len) &&
  68                 (is_dir_sep(buf[len]) || buf[len] == '\0');
  69 }
  70
  71 /* $buf =~ m|$dir/+$file| but without regex */
  72 static int is_dir_file(const char *buf, const char *dir, const char *file)
  73 {
  74         int len = strlen(dir);
  75         if (strncmp(buf, dir, len) || !is_dir_sep(buf[len]))
  76                 return 0;
  77         while (is_dir_sep(buf[len]))
  78                 len++;
  79         return !strcmp(buf + len, file);
  80 }
  81
  82 static void replace_dir(struct strbuf *buf, int len, const char *newdir)
  83 {
  84         int newlen = strlen(newdir);
  85         int need_sep = (buf->buf[len] && !is_dir_sep(buf->buf[len])) &&
  86                 !is_dir_sep(newdir[newlen - 1]);
  87         if (need_sep)
  88                 len--;   /* keep one char, to be replaced with '/'  */
  89         strbuf_splice(buf, 0, len, newdir, newlen);
  90         if (need_sep)
  91                 buf->buf[newlen] = '/';
  92 }
  93
  94 static const char *common_list[] = {
  95         "/branches", "/hooks", "/info", "!/logs", "/lost-found",
  96         "/objects", "/refs", "/remotes", "/worktrees", "/rr-cache", "/svn",
  97         "config", "!gc.pid", "packed-refs", "shallow",
  98         NULL
  99 };
 100
 101 static void update_common_dir(struct strbuf *buf, int git_dir_len, const char *common_dir)
 102 {
 103         char *base = buf->buf + git_dir_len;
 104         const char **p;
 105
 106         if (is_dir_file(base, "logs", "HEAD") ||
 107             is_dir_file(base, "info", "sparse-checkout"))
 108                 return; /* keep this in $GIT_DIR */
 109         for (p = common_list; *p; p++) {
 110                 const char *path = *p;
 111                 int is_dir = 0;
 112                 if (*path == '!')
 113                         path++;
 114                 if (*path == '/') {
 115                         path++;
 116                         is_dir = 1;
 117                 }
 118
 119                 if (!common_dir)
 120                         common_dir = get_git_common_dir();
 121
 122                 if (is_dir && dir_prefix(base, path)) {
 123                         replace_dir(buf, git_dir_len, common_dir);
 124                         return;
 125                 }
 126                 if (!is_dir && !strcmp(base, path)) {
 127                         replace_dir(buf, git_dir_len, common_dir);
 128                         return;
 129                 }
 130         }
 131 }
 132
 133 void report_linked_checkout_garbage(void)
 134 {
 135         struct strbuf sb = STRBUF_INIT;
 136         const char **p;
 137         int len;
 138
 139         if (!git_common_dir_env)
 140                 return;
 141         strbuf_addf(&sb, "%s/", get_git_dir());
 142         len = sb.len;
 143         for (p = common_list; *p; p++) {
 144                 const char *path = *p;
 145                 if (*path == '!')
 146                         continue;
 147                 strbuf_setlen(&sb, len);
 148                 strbuf_addstr(&sb, path);
 149                 if (file_exists(sb.buf))
 150                         report_garbage("unused in linked checkout", sb.buf);
 151         }
 152         strbuf_release(&sb);
 153 }
 154
 155 static void adjust_git_path(struct strbuf *buf, int git_dir_len)
 156 {
 157         const char *base = buf->buf + git_dir_len;
 158         if (git_graft_env && is_dir_file(base, "info", "grafts"))
 159                 strbuf_splice(buf, 0, buf->len,
 160                               get_graft_file(), strlen(get_graft_file()));
 161         else if (git_index_env && !strcmp(base, "index"))
 162                 strbuf_splice(buf, 0, buf->len,
 163                               get_index_file(), strlen(get_index_file()));
 164         else if (git_db_env && dir_prefix(base, "objects"))
 165                 replace_dir(buf, git_dir_len + 7, get_object_directory());
 166         else if (git_common_dir_env)
 167                 update_common_dir(buf, git_dir_len, NULL);
 168 }
 169
 170 static void do_git_path(struct strbuf *buf, const char *fmt, va_list args)
 171 {
 172         int gitdir_len;
 173         strbuf_addstr(buf, get_git_dir());
 174         if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 175                 strbuf_addch(buf, '/');
 176         gitdir_len = buf->len;
 177         strbuf_vaddf(buf, fmt, args);
 178         adjust_git_path(buf, gitdir_len);
 179         strbuf_cleanup_path(buf);
 180 }
 181
 182 void strbuf_git_path(struct strbuf *sb, const char *fmt, ...)
 183 {
 184         va_list args;
 185         va_start(args, fmt);
 186         do_git_path(sb, fmt, args);
 187         va_end(args);
 188 }
 189
 190 const char *git_path(const char *fmt, ...)
 191 {
 192         struct strbuf *pathname = get_pathname();
 193         va_list args;
 194         va_start(args, fmt);
 195         do_git_path(pathname, fmt, args);
 196         va_end(args);
 197         return pathname->buf;
 198 }
 199
 200 char *git_pathdup(const char *fmt, ...)
 201 {
 202         struct strbuf path = STRBUF_INIT;
 203         va_list args;
 204         va_start(args, fmt);
 205         do_git_path(&path, fmt, args);
 206         va_end(args);
 207         return strbuf_detach(&path, NULL);
 208 }
 209
 210 char *mkpathdup(const char *fmt, ...)
 211 {
 212         struct strbuf sb = STRBUF_INIT;
 213         va_list args;
 214         va_start(args, fmt);
 215         strbuf_vaddf(&sb, fmt, args);
 216         va_end(args);
 217         strbuf_cleanup_path(&sb);
 218         return strbuf_detach(&sb, NULL);
 219 }
 220
 221 const char *mkpath(const char *fmt, ...)
 222 {
 223         va_list args;
 224         struct strbuf *pathname = get_pathname();
 225         va_start(args, fmt);
 226         strbuf_vaddf(pathname, fmt, args);
 227         va_end(args);
 228         return cleanup_path(pathname->buf);
 229 }
 230
 231 static void do_submodule_path(struct strbuf *buf, const char *path,
 232                               const char *fmt, va_list args)
 233 {
 234         const char *git_dir;
 235         struct strbuf git_submodule_common_dir = STRBUF_INIT;
 236         struct strbuf git_submodule_dir = STRBUF_INIT;
 237
 238         strbuf_addstr(buf, path);
 239         if (buf->len && buf->buf[buf->len - 1] != '/')
 240                 strbuf_addch(buf, '/');
 241         strbuf_addstr(buf, ".git");
 242
 243         git_dir = read_gitfile(buf->buf);
 244         if (git_dir) {
 245                 strbuf_reset(buf);
 246                 strbuf_addstr(buf, git_dir);
 247         }
 248         strbuf_addch(buf, '/');
 249         strbuf_addstr(&git_submodule_dir, buf->buf);
 250
 251         strbuf_vaddf(buf, fmt, args);
 252
 253         if (get_common_dir_noenv(&git_submodule_common_dir, git_submodule_dir.buf))
 254                 update_common_dir(buf, git_submodule_dir.len, git_submodule_common_dir.buf);
 255
 256         strbuf_cleanup_path(buf);
 257
 258         strbuf_release(&git_submodule_dir);
 259         strbuf_release(&git_submodule_common_dir);
 260 }
 261
 262 char *git_pathdup_submodule(const char *path, const char *fmt, ...)
 263 {
 264         va_list args;
 265         struct strbuf buf = STRBUF_INIT;
 266         va_start(args, fmt);
 267         do_submodule_path(&buf, path, fmt, args);
 268         va_end(args);
 269         return strbuf_detach(&buf, NULL);
 270 }
 271
 272 void strbuf_git_path_submodule(struct strbuf *buf, const char *path,
 273                                const char *fmt, ...)
 274 {
 275         va_list args;
 276         va_start(args, fmt);
 277         do_submodule_path(buf, path, fmt, args);
 278         va_end(args);
 279 }
 280
 281 int validate_headref(const char *path)
 282 {
 283         struct stat st;
 284         char *buf, buffer[256];
 285         unsigned char sha1[20];
 286         int fd;
 287         ssize_t len;
 288
 289         if (lstat(path, &st) < 0)
 290                 return -1;
 291
 292         /* Make sure it is a "refs/.." symlink */
 293         if (S_ISLNK(st.st_mode)) {
 294                 len = readlink(path, buffer, sizeof(buffer)-1);
 295                 if (len >= 5 && !memcmp("refs/", buffer, 5))
 296                         return 0;
 297                 return -1;
 298         }
 299
 300         /*
 301          * Anything else, just open it and try to see if it is a symbolic ref.
 302          */
 303         fd = open(path, O_RDONLY);
 304         if (fd < 0)
 305                 return -1;
 306         len = read_in_full(fd, buffer, sizeof(buffer)-1);
 307         close(fd);
 308
 309         /*
 310          * Is it a symbolic ref?
 311          */
 312         if (len < 4)
 313                 return -1;
 314         if (!memcmp("ref:", buffer, 4)) {
 315                 buf = buffer + 4;
 316                 len -= 4;
 317                 while (len && isspace(*buf))
 318                         buf++, len--;
 319                 if (len >= 5 && !memcmp("refs/", buf, 5))
 320                         return 0;
 321         }
 322
 323         /*
 324          * Is this a detached HEAD?
 325          */
 326         if (!get_sha1_hex(buffer, sha1))
 327                 return 0;
 328
 329         return -1;
 330 }
 331
 332 static struct passwd *getpw_str(const char *username, size_t len)
 333 {
 334         struct passwd *pw;
 335         char *username_z = xmemdupz(username, len);
 336         pw = getpwnam(username_z);
 337         free(username_z);
 338         return pw;
 339 }
 340
 341 /*
 342  * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 343  * then it is a newly allocated string. Returns NULL on getpw failure or
 344  * if path is NULL.
 345  */
 346 char *expand_user_path(const char *path)
 347 {
 348         struct strbuf user_path = STRBUF_INIT;
 349         const char *to_copy = path;
 350
 351         if (path == NULL)
 352                 goto return_null;
 353         if (path[0] == '~') {
 354                 const char *first_slash = strchrnul(path, '/');
 355                 const char *username = path + 1;
 356                 size_t username_len = first_slash - username;
 357                 if (username_len == 0) {
 358                         const char *home = getenv("HOME");
 359                         if (!home)
 360                                 goto return_null;
 361                         strbuf_addstr(&user_path, home);
 362                 } else {
 363                         struct passwd *pw = getpw_str(username, username_len);
 364                         if (!pw)
 365                                 goto return_null;
 366                         strbuf_addstr(&user_path, pw->pw_dir);
 367                 }
 368                 to_copy = first_slash;
 369         }
 370         strbuf_addstr(&user_path, to_copy);
 371         return strbuf_detach(&user_path, NULL);
 372 return_null:
 373         strbuf_release(&user_path);
 374         return NULL;
 375 }
 376
 377 /*
 378  * First, one directory to try is determined by the following algorithm.
 379  *
 380  * (0) If "strict" is given, the path is used as given and no DWIM is
 381  *     done. Otherwise:
 382  * (1) "~/path" to mean path under the running user's home directory;
 383  * (2) "~user/path" to mean path under named user's home directory;
 384  * (3) "relative/path" to mean cwd relative directory; or
 385  * (4) "/absolute/path" to mean absolute directory.
 386  *
 387  * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 388  * in this order. We select the first one that is a valid git repository, and
 389  * chdir() to it. If none match, or we fail to chdir, we return NULL.
 390  *
 391  * If all goes well, we return the directory we used to chdir() (but
 392  * before ~user is expanded), avoiding getcwd() resolving symbolic
 393  * links.  User relative paths are also returned as they are given,
 394  * except DWIM suffixing.
 395  */
 396 const char *enter_repo(const char *path, int strict)
 397 {
 398         static char used_path[PATH_MAX];
 399         static char validated_path[PATH_MAX];
 400
 401         if (!path)
 402                 return NULL;
 403
 404         if (!strict) {
 405                 static const char *suffix[] = {
 406                         "/.git", "", ".git/.git", ".git", NULL,
 407                 };
 408                 const char *gitfile;
 409                 int len = strlen(path);
 410                 int i;
 411                 while ((1 < len) && (path[len-1] == '/'))
 412                         len--;
 413
 414                 if (PATH_MAX <= len)
 415                         return NULL;
 416                 strncpy(used_path, path, len); used_path[len] = 0 ;
 417                 strcpy(validated_path, used_path);
 418
 419                 if (used_path[0] == '~') {
 420                         char *newpath = expand_user_path(used_path);
 421                         if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 422                                 free(newpath);
 423                                 return NULL;
 424                         }
 425                         /*
 426                          * Copy back into the static buffer. A pity
 427                          * since newpath was not bounded, but other
 428                          * branches of the if are limited by PATH_MAX
 429                          * anyway.
 430                          */
 431                         strcpy(used_path, newpath); free(newpath);
 432                 }
 433                 else if (PATH_MAX - 10 < len)
 434                         return NULL;
 435                 len = strlen(used_path);
 436                 for (i = 0; suffix[i]; i++) {
 437                         struct stat st;
 438                         strcpy(used_path + len, suffix[i]);
 439                         if (!stat(used_path, &st) &&
 440                             (S_ISREG(st.st_mode) ||
 441                             (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 442                                 strcat(validated_path, suffix[i]);
 443                                 break;
 444                         }
 445                 }
 446                 if (!suffix[i])
 447                         return NULL;
 448                 gitfile = read_gitfile(used_path) ;
 449                 if (gitfile)
 450                         strcpy(used_path, gitfile);
 451                 if (chdir(used_path))
 452                         return NULL;
 453                 path = validated_path;
 454         }
 455         else if (chdir(path))
 456                 return NULL;
 457
 458         if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 459             validate_headref("HEAD") == 0) {
 460                 set_git_dir(".");
 461                 check_repository_format();
 462                 return path;
 463         }
 464
 465         return NULL;
 466 }
 467
 468 static int calc_shared_perm(int mode)
 469 {
 470         int tweak;
 471
 472         if (shared_repository < 0)
 473                 tweak = -shared_repository;
 474         else
 475                 tweak = shared_repository;
 476
 477         if (!(mode & S_IWUSR))
 478                 tweak &= ~0222;
 479         if (mode & S_IXUSR)
 480                 /* Copy read bits to execute bits */
 481                 tweak |= (tweak & 0444) >> 2;
 482         if (shared_repository < 0)
 483                 mode = (mode & ~0777) | tweak;
 484         else
 485                 mode |= tweak;
 486
 487         return mode;
 488 }
 489
 490
 491 int adjust_shared_perm(const char *path)
 492 {
 493         int old_mode, new_mode;
 494
 495         if (!shared_repository)
 496                 return 0;
 497         if (get_st_mode_bits(path, &old_mode) < 0)
 498                 return -1;
 499
 500         new_mode = calc_shared_perm(old_mode);
 501         if (S_ISDIR(old_mode)) {
 502                 /* Copy read bits to execute bits */
 503                 new_mode |= (new_mode & 0444) >> 2;
 504                 new_mode |= FORCE_DIR_SET_GID;
 505         }
 506
 507         if (((old_mode ^ new_mode) & ~S_IFMT) &&
 508                         chmod(path, (new_mode & ~S_IFMT)) < 0)
 509                 return -2;
 510         return 0;
 511 }
 512
 513 static int have_same_root(const char *path1, const char *path2)
 514 {
 515         int is_abs1, is_abs2;
 516
 517         is_abs1 = is_absolute_path(path1);
 518         is_abs2 = is_absolute_path(path2);
 519         return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 520                (!is_abs1 && !is_abs2);
 521 }
 522
 523 /*
 524  * Give path as relative to prefix.
 525  *
 526  * The strbuf may or may not be used, so do not assume it contains the
 527  * returned path.
 528  */
 529 const char *relative_path(const char *in, const char *prefix,
 530                           struct strbuf *sb)
 531 {
 532         int in_len = in ? strlen(in) : 0;
 533         int prefix_len = prefix ? strlen(prefix) : 0;
 534         int in_off = 0;
 535         int prefix_off = 0;
 536         int i = 0, j = 0;
 537
 538         if (!in_len)
 539                 return "./";
 540         else if (!prefix_len)
 541                 return in;
 542
 543         if (have_same_root(in, prefix)) {
 544                 /* bypass dos_drive, for "c:" is identical to "C:" */
 545                 if (has_dos_drive_prefix(in)) {
 546                         i = 2;
 547                         j = 2;
 548                 }
 549         } else {
 550                 return in;
 551         }
 552
 553         while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 554                 if (is_dir_sep(prefix[i])) {
 555                         while (is_dir_sep(prefix[i]))
 556                                 i++;
 557                         while (is_dir_sep(in[j]))
 558                                 j++;
 559                         prefix_off = i;
 560                         in_off = j;
 561                 } else {
 562                         i++;
 563                         j++;
 564                 }
 565         }
 566
 567         if (
 568             /* "prefix" seems like prefix of "in" */
 569             i >= prefix_len &&
 570             /*
 571              * but "/foo" is not a prefix of "/foobar"
 572              * (i.e. prefix not end with '/')
 573              */
 574             prefix_off < prefix_len) {
 575                 if (j >= in_len) {
 576                         /* in="/a/b", prefix="/a/b" */
 577                         in_off = in_len;
 578                 } else if (is_dir_sep(in[j])) {
 579                         /* in="/a/b/c", prefix="/a/b" */
 580                         while (is_dir_sep(in[j]))
 581                                 j++;
 582                         in_off = j;
 583                 } else {
 584                         /* in="/a/bbb/c", prefix="/a/b" */
 585                         i = prefix_off;
 586                 }
 587         } else if (
 588                    /* "in" is short than "prefix" */
 589                    j >= in_len &&
 590                    /* "in" not end with '/' */
 591                    in_off < in_len) {
 592                 if (is_dir_sep(prefix[i])) {
 593                         /* in="/a/b", prefix="/a/b/c/" */
 594                         while (is_dir_sep(prefix[i]))
 595                                 i++;
 596                         in_off = in_len;
 597                 }
 598         }
 599         in += in_off;
 600         in_len -= in_off;
 601
 602         if (i >= prefix_len) {
 603                 if (!in_len)
 604                         return "./";
 605                 else
 606                         return in;
 607         }
 608
 609         strbuf_reset(sb);
 610         strbuf_grow(sb, in_len);
 611
 612         while (i < prefix_len) {
 613                 if (is_dir_sep(prefix[i])) {
 614                         strbuf_addstr(sb, "../");
 615                         while (is_dir_sep(prefix[i]))
 616                                 i++;
 617                         continue;
 618                 }
 619                 i++;
 620         }
 621         if (!is_dir_sep(prefix[prefix_len - 1]))
 622                 strbuf_addstr(sb, "../");
 623
 624         strbuf_addstr(sb, in);
 625
 626         return sb->buf;
 627 }
 628
 629 /*
 630  * A simpler implementation of relative_path
 631  *
 632  * Get relative path by removing "prefix" from "in". This function
 633  * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 634  * to increase performance when traversing the path to work_tree.
 635  */
 636 const char *remove_leading_path(const char *in, const char *prefix)
 637 {
 638         static char buf[PATH_MAX + 1];
 639         int i = 0, j = 0;
 640
 641         if (!prefix || !prefix[0])
 642                 return in;
 643         while (prefix[i]) {
 644                 if (is_dir_sep(prefix[i])) {
 645                         if (!is_dir_sep(in[j]))
 646                                 return in;
 647                         while (is_dir_sep(prefix[i]))
 648                                 i++;
 649                         while (is_dir_sep(in[j]))
 650                                 j++;
 651                         continue;
 652                 } else if (in[j] != prefix[i]) {
 653                         return in;
 654                 }
 655                 i++;
 656                 j++;
 657         }
 658         if (
 659             /* "/foo" is a prefix of "/foo" */
 660             in[j] &&
 661             /* "/foo" is not a prefix of "/foobar" */
 662             !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 663            )
 664                 return in;
 665         while (is_dir_sep(in[j]))
 666                 j++;
 667         if (!in[j])
 668                 strcpy(buf, ".");
 669         else
 670                 strcpy(buf, in + j);
 671         return buf;
 672 }
 673
 674 /*
 675  * It is okay if dst == src, but they should not overlap otherwise.
 676  *
 677  * Performs the following normalizations on src, storing the result in dst:
 678  * - Ensures that components are separated by '/' (Windows only)
 679  * - Squashes sequences of '/'.
 680  * - Removes "." components.
 681  * - Removes ".." components, and the components the precede them.
 682  * Returns failure (non-zero) if a ".." component appears as first path
 683  * component anytime during the normalization. Otherwise, returns success (0).
 684  *
 685  * Note that this function is purely textual.  It does not follow symlinks,
 686  * verify the existence of the path, or make any system calls.
 687  *
 688  * prefix_len != NULL is for a specific case of prefix_pathspec():
 689  * assume that src == dst and src[0..prefix_len-1] is already
 690  * normalized, any time "../" eats up to the prefix_len part,
 691  * prefix_len is reduced. In the end prefix_len is the remaining
 692  * prefix that has not been overridden by user pathspec.
 693  *
 694  * NEEDSWORK: This function doesn't perform normalization w.r.t. trailing '/'.
 695  * For everything but the root folder itself, the normalized path should not
 696  * end with a '/', then the callers need to be fixed up accordingly.
 697  *
 698  */
 699 int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 700 {
 701         char *dst0;
 702
 703         if (has_dos_drive_prefix(src)) {
 704                 *dst++ = *src++;
 705                 *dst++ = *src++;
 706         }
 707         dst0 = dst;
 708
 709         if (is_dir_sep(*src)) {
 710                 *dst++ = '/';
 711                 while (is_dir_sep(*src))
 712                         src++;
 713         }
 714
 715         for (;;) {
 716                 char c = *src;
 717
 718                 /*
 719                  * A path component that begins with . could be
 720                  * special:
 721                  * (1) "." and ends   -- ignore and terminate.
 722                  * (2) "./"           -- ignore them, eat slash and continue.
 723                  * (3) ".." and ends  -- strip one and terminate.
 724                  * (4) "../"          -- strip one, eat slash and continue.
 725                  */
 726                 if (c == '.') {
 727                         if (!src[1]) {
 728                                 /* (1) */
 729                                 src++;
 730                         } else if (is_dir_sep(src[1])) {
 731                                 /* (2) */
 732                                 src += 2;
 733                                 while (is_dir_sep(*src))
 734                                         src++;
 735                                 continue;
 736                         } else if (src[1] == '.') {
 737                                 if (!src[2]) {
 738                                         /* (3) */
 739                                         src += 2;
 740                                         goto up_one;
 741                                 } else if (is_dir_sep(src[2])) {
 742                                         /* (4) */
 743                                         src += 3;
 744                                         while (is_dir_sep(*src))
 745                                                 src++;
 746                                         goto up_one;
 747                                 }
 748                         }
 749                 }
 750
 751                 /* copy up to the next '/', and eat all '/' */
 752                 while ((c = *src++) != '\0' && !is_dir_sep(c))
 753                         *dst++ = c;
 754                 if (is_dir_sep(c)) {
 755                         *dst++ = '/';
 756                         while (is_dir_sep(c))
 757                                 c = *src++;
 758                         src--;
 759                 } else if (!c)
 760                         break;
 761                 continue;
 762
 763         up_one:
 764                 /*
 765                  * dst0..dst is prefix portion, and dst[-1] is '/';
 766                  * go up one level.
 767                  */
 768                 dst--;  /* go to trailing '/' */
 769                 if (dst <= dst0)
 770                         return -1;
 771                 /* Windows: dst[-1] cannot be backslash anymore */
 772                 while (dst0 < dst && dst[-1] != '/')
 773                         dst--;
 774                 if (prefix_len && *prefix_len > dst - dst0)
 775                         *prefix_len = dst - dst0;
 776         }
 777         *dst = '\0';
 778         return 0;
 779 }
 780
 781 int normalize_path_copy(char *dst, const char *src)
 782 {
 783         return normalize_path_copy_len(dst, src, NULL);
 784 }
 785
 786 /*
 787  * path = Canonical absolute path
 788  * prefixes = string_list containing normalized, absolute paths without
 789  * trailing slashes (except for the root directory, which is denoted by "/").
 790  *
 791  * Determines, for each path in prefixes, whether the "prefix"
 792  * is an ancestor directory of path.  Returns the length of the longest
 793  * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 794  * is an ancestor.  (Note that this means 0 is returned if prefixes is
 795  * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 796  * are not considered to be their own ancestors.  path must be in a
 797  * canonical form: empty components, or "." or ".." components are not
 798  * allowed.
 799  */
 800 int longest_ancestor_length(const char *path, struct string_list *prefixes)
 801 {
 802         int i, max_len = -1;
 803
 804         if (!strcmp(path, "/"))
 805                 return -1;
 806
 807         for (i = 0; i < prefixes->nr; i++) {
 808                 const char *ceil = prefixes->items[i].string;
 809                 int len = strlen(ceil);
 810
 811                 if (len == 1 && ceil[0] == '/')
 812                         len = 0; /* root matches anything, with length 0 */
 813                 else if (!strncmp(path, ceil, len) && path[len] == '/')
 814                         ; /* match of length len */
 815                 else
 816                         continue; /* no match */
 817
 818                 if (len > max_len)
 819                         max_len = len;
 820         }
 821
 822         return max_len;
 823 }
 824
 825 /* strip arbitrary amount of directory separators at end of path */
 826 static inline int chomp_trailing_dir_sep(const char *path, int len)
 827 {
 828         while (len && is_dir_sep(path[len - 1]))
 829                 len--;
 830         return len;
 831 }
 832
 833 /*
 834  * If path ends with suffix (complete path components), returns the
 835  * part before suffix (sans trailing directory separators).
 836  * Otherwise returns NULL.
 837  */
 838 char *strip_path_suffix(const char *path, const char *suffix)
 839 {
 840         int path_len = strlen(path), suffix_len = strlen(suffix);
 841
 842         while (suffix_len) {
 843                 if (!path_len)
 844                         return NULL;
 845
 846                 if (is_dir_sep(path[path_len - 1])) {
 847                         if (!is_dir_sep(suffix[suffix_len - 1]))
 848                                 return NULL;
 849                         path_len = chomp_trailing_dir_sep(path, path_len);
 850                         suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 851                 }
 852                 else if (path[--path_len] != suffix[--suffix_len])
 853                         return NULL;
 854         }
 855
 856         if (path_len && !is_dir_sep(path[path_len - 1]))
 857                 return NULL;
 858         return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 859 }
 860
 861 int daemon_avoid_alias(const char *p)
 862 {
 863         int sl, ndot;
 864
 865         /*
 866          * This resurrects the belts and suspenders paranoia check by HPA
 867          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 868          * does not do getcwd() based path canonicalization.
 869          *
 870          * sl becomes true immediately after seeing '/' and continues to
 871          * be true as long as dots continue after that without intervening
 872          * non-dot character.
 873          */
 874         if (!p || (*p != '/' && *p != '~'))
 875                 return -1;
 876         sl = 1; ndot = 0;
 877         p++;
 878
 879         while (1) {
 880                 char ch = *p++;
 881                 if (sl) {
 882                         if (ch == '.')
 883                                 ndot++;
 884                         else if (ch == '/') {
 885                                 if (ndot < 3)
 886                                         /* reject //, /./ and /../ */
 887                                         return -1;
 888                                 ndot = 0;
 889                         }
 890                         else if (ch == 0) {
 891                                 if (0 < ndot && ndot < 3)
 892                                         /* reject /.$ and /..$ */
 893                                         return -1;
 894                                 return 0;
 895                         }
 896                         else
 897                                 sl = ndot = 0;
 898                 }
 899                 else if (ch == 0)
 900                         return 0;
 901                 else if (ch == '/') {
 902                         sl = 1;
 903                         ndot = 0;
 904                 }
 905         }
 906 }
 907
 908 static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
 909 {
 910         if (len < skip)
 911                 return 0;
 912         len -= skip;
 913         path += skip;
 914         while (len-- > 0) {
 915                 char c = *(path++);
 916                 if (c != ' ' && c != '.')
 917                         return 0;
 918         }
 919         return 1;
 920 }
 921
 922 int is_ntfs_dotgit(const char *name)
 923 {
 924         int len;
 925
 926         for (len = 0; ; len++)
 927                 if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
 928                         if (only_spaces_and_periods(name, len, 4) &&
 929                                         !strncasecmp(name, ".git", 4))
 930                                 return 1;
 931                         if (only_spaces_and_periods(name, len, 5) &&
 932                                         !strncasecmp(name, "git~1", 5))
 933                                 return 1;
 934                         if (name[len] != '\\')
 935                                 return 0;
 936                         name += len + 1;
 937                         len = -1;
 938                 }
 939 }
 940
 941 char *xdg_config_home(const char *filename)
 942 {
 943         const char *home, *config_home;
 944
 945         assert(filename);
 946         config_home = getenv("XDG_CONFIG_HOME");
 947         if (config_home && *config_home)
 948                 return mkpathdup("%s/git/%s", config_home, filename);
 949
 950         home = getenv("HOME");
 951         if (home)
 952                 return mkpathdup("%s/.config/git/%s", home, filename);
 953         return NULL;
 954 }
 955
 956 GIT_PATH_FUNC(git_path_cherry_pick_head, "CHERRY_PICK_HEAD")
 957 GIT_PATH_FUNC(git_path_revert_head, "REVERT_HEAD")
 958 GIT_PATH_FUNC(git_path_squash_msg, "SQUASH_MSG")
 959 GIT_PATH_FUNC(git_path_merge_msg, "MERGE_MSG")
 960 GIT_PATH_FUNC(git_path_merge_rr, "MERGE_RR")
 961 GIT_PATH_FUNC(git_path_merge_mode, "MERGE_MODE")
 962 GIT_PATH_FUNC(git_path_merge_head, "MERGE_HEAD")
 963 GIT_PATH_FUNC(git_path_fetch_head, "FETCH_HEAD")
 964 GIT_PATH_FUNC(git_path_shallow, "shallow")