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