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