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 static void do_submodule_path(struct strbuf *buf, const char *path,
 228                               const char *fmt, va_list args)
 229 {
 230         const char *git_dir;
 231
 232         strbuf_addstr(buf, path);
 233         if (buf->len && buf->buf[buf->len - 1] != '/')
 234                 strbuf_addch(buf, '/');
 235         strbuf_addstr(buf, ".git");
 236
 237         git_dir = read_gitfile(buf->buf);
 238         if (git_dir) {
 239                 strbuf_reset(buf);
 240                 strbuf_addstr(buf, git_dir);
 241         }
 242         strbuf_addch(buf, '/');
 243
 244         strbuf_vaddf(buf, fmt, args);
 245         strbuf_cleanup_path(buf);
 246 }
 247
 248 char *git_pathdup_submodule(const char *path, const char *fmt, ...)
 249 {
 250         va_list args;
 251         struct strbuf buf = STRBUF_INIT;
 252         va_start(args, fmt);
 253         do_submodule_path(&buf, path, fmt, args);
 254         va_end(args);
 255         return strbuf_detach(&buf, NULL);
 256 }
 257
 258 void strbuf_git_path_submodule(struct strbuf *buf, const char *path,
 259                                const char *fmt, ...)
 260 {
 261         va_list args;
 262         va_start(args, fmt);
 263         do_submodule_path(buf, path, fmt, args);
 264         va_end(args);
 265 }
 266
 267 int validate_headref(const char *path)
 268 {
 269         struct stat st;
 270         char *buf, buffer[256];
 271         unsigned char sha1[20];
 272         int fd;
 273         ssize_t len;
 274
 275         if (lstat(path, &st) < 0)
 276                 return -1;
 277
 278         /* Make sure it is a "refs/.." symlink */
 279         if (S_ISLNK(st.st_mode)) {
 280                 len = readlink(path, buffer, sizeof(buffer)-1);
 281                 if (len >= 5 && !memcmp("refs/", buffer, 5))
 282                         return 0;
 283                 return -1;
 284         }
 285
 286         /*
 287          * Anything else, just open it and try to see if it is a symbolic ref.
 288          */
 289         fd = open(path, O_RDONLY);
 290         if (fd < 0)
 291                 return -1;
 292         len = read_in_full(fd, buffer, sizeof(buffer)-1);
 293         close(fd);
 294
 295         /*
 296          * Is it a symbolic ref?
 297          */
 298         if (len < 4)
 299                 return -1;
 300         if (!memcmp("ref:", buffer, 4)) {
 301                 buf = buffer + 4;
 302                 len -= 4;
 303                 while (len && isspace(*buf))
 304                         buf++, len--;
 305                 if (len >= 5 && !memcmp("refs/", buf, 5))
 306                         return 0;
 307         }
 308
 309         /*
 310          * Is this a detached HEAD?
 311          */
 312         if (!get_sha1_hex(buffer, sha1))
 313                 return 0;
 314
 315         return -1;
 316 }
 317
 318 static struct passwd *getpw_str(const char *username, size_t len)
 319 {
 320         struct passwd *pw;
 321         char *username_z = xmemdupz(username, len);
 322         pw = getpwnam(username_z);
 323         free(username_z);
 324         return pw;
 325 }
 326
 327 /*
 328  * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 329  * then it is a newly allocated string. Returns NULL on getpw failure or
 330  * if path is NULL.
 331  */
 332 char *expand_user_path(const char *path)
 333 {
 334         struct strbuf user_path = STRBUF_INIT;
 335         const char *to_copy = path;
 336
 337         if (path == NULL)
 338                 goto return_null;
 339         if (path[0] == '~') {
 340                 const char *first_slash = strchrnul(path, '/');
 341                 const char *username = path + 1;
 342                 size_t username_len = first_slash - username;
 343                 if (username_len == 0) {
 344                         const char *home = getenv("HOME");
 345                         if (!home)
 346                                 goto return_null;
 347                         strbuf_addstr(&user_path, home);
 348                 } else {
 349                         struct passwd *pw = getpw_str(username, username_len);
 350                         if (!pw)
 351                                 goto return_null;
 352                         strbuf_addstr(&user_path, pw->pw_dir);
 353                 }
 354                 to_copy = first_slash;
 355         }
 356         strbuf_addstr(&user_path, to_copy);
 357         return strbuf_detach(&user_path, NULL);
 358 return_null:
 359         strbuf_release(&user_path);
 360         return NULL;
 361 }
 362
 363 /*
 364  * First, one directory to try is determined by the following algorithm.
 365  *
 366  * (0) If "strict" is given, the path is used as given and no DWIM is
 367  *     done. Otherwise:
 368  * (1) "~/path" to mean path under the running user's home directory;
 369  * (2) "~user/path" to mean path under named user's home directory;
 370  * (3) "relative/path" to mean cwd relative directory; or
 371  * (4) "/absolute/path" to mean absolute directory.
 372  *
 373  * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 374  * in this order. We select the first one that is a valid git repository, and
 375  * chdir() to it. If none match, or we fail to chdir, we return NULL.
 376  *
 377  * If all goes well, we return the directory we used to chdir() (but
 378  * before ~user is expanded), avoiding getcwd() resolving symbolic
 379  * links.  User relative paths are also returned as they are given,
 380  * except DWIM suffixing.
 381  */
 382 const char *enter_repo(const char *path, int strict)
 383 {
 384         static char used_path[PATH_MAX];
 385         static char validated_path[PATH_MAX];
 386
 387         if (!path)
 388                 return NULL;
 389
 390         if (!strict) {
 391                 static const char *suffix[] = {
 392                         "/.git", "", ".git/.git", ".git", NULL,
 393                 };
 394                 const char *gitfile;
 395                 int len = strlen(path);
 396                 int i;
 397                 while ((1 < len) && (path[len-1] == '/'))
 398                         len--;
 399
 400                 if (PATH_MAX <= len)
 401                         return NULL;
 402                 strncpy(used_path, path, len); used_path[len] = 0 ;
 403                 strcpy(validated_path, used_path);
 404
 405                 if (used_path[0] == '~') {
 406                         char *newpath = expand_user_path(used_path);
 407                         if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 408                                 free(newpath);
 409                                 return NULL;
 410                         }
 411                         /*
 412                          * Copy back into the static buffer. A pity
 413                          * since newpath was not bounded, but other
 414                          * branches of the if are limited by PATH_MAX
 415                          * anyway.
 416                          */
 417                         strcpy(used_path, newpath); free(newpath);
 418                 }
 419                 else if (PATH_MAX - 10 < len)
 420                         return NULL;
 421                 len = strlen(used_path);
 422                 for (i = 0; suffix[i]; i++) {
 423                         struct stat st;
 424                         strcpy(used_path + len, suffix[i]);
 425                         if (!stat(used_path, &st) &&
 426                             (S_ISREG(st.st_mode) ||
 427                             (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 428                                 strcat(validated_path, suffix[i]);
 429                                 break;
 430                         }
 431                 }
 432                 if (!suffix[i])
 433                         return NULL;
 434                 gitfile = read_gitfile(used_path);
 435                 if (gitfile)
 436                         strcpy(used_path, gitfile);
 437                 if (chdir(used_path))
 438                         return NULL;
 439                 path = validated_path;
 440         }
 441         else {
 442                 const char *gitfile = read_gitfile(path);
 443                 if (gitfile)
 444                         path = gitfile;
 445                 if (chdir(path))
 446                         return NULL;
 447         }
 448
 449         if (is_git_directory(".")) {
 450                 set_git_dir(".");
 451                 check_repository_format();
 452                 return path;
 453         }
 454
 455         return NULL;
 456 }
 457
 458 static int calc_shared_perm(int mode)
 459 {
 460         int tweak;
 461
 462         if (shared_repository < 0)
 463                 tweak = -shared_repository;
 464         else
 465                 tweak = shared_repository;
 466
 467         if (!(mode & S_IWUSR))
 468                 tweak &= ~0222;
 469         if (mode & S_IXUSR)
 470                 /* Copy read bits to execute bits */
 471                 tweak |= (tweak & 0444) >> 2;
 472         if (shared_repository < 0)
 473                 mode = (mode & ~0777) | tweak;
 474         else
 475                 mode |= tweak;
 476
 477         return mode;
 478 }
 479
 480
 481 int adjust_shared_perm(const char *path)
 482 {
 483         int old_mode, new_mode;
 484
 485         if (!shared_repository)
 486                 return 0;
 487         if (get_st_mode_bits(path, &old_mode) < 0)
 488                 return -1;
 489
 490         new_mode = calc_shared_perm(old_mode);
 491         if (S_ISDIR(old_mode)) {
 492                 /* Copy read bits to execute bits */
 493                 new_mode |= (new_mode & 0444) >> 2;
 494                 new_mode |= FORCE_DIR_SET_GID;
 495         }
 496
 497         if (((old_mode ^ new_mode) & ~S_IFMT) &&
 498                         chmod(path, (new_mode & ~S_IFMT)) < 0)
 499                 return -2;
 500         return 0;
 501 }
 502
 503 static int have_same_root(const char *path1, const char *path2)
 504 {
 505         int is_abs1, is_abs2;
 506
 507         is_abs1 = is_absolute_path(path1);
 508         is_abs2 = is_absolute_path(path2);
 509         return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 510                (!is_abs1 && !is_abs2);
 511 }
 512
 513 /*
 514  * Give path as relative to prefix.
 515  *
 516  * The strbuf may or may not be used, so do not assume it contains the
 517  * returned path.
 518  */
 519 const char *relative_path(const char *in, const char *prefix,
 520                           struct strbuf *sb)
 521 {
 522         int in_len = in ? strlen(in) : 0;
 523         int prefix_len = prefix ? strlen(prefix) : 0;
 524         int in_off = 0;
 525         int prefix_off = 0;
 526         int i = 0, j = 0;
 527
 528         if (!in_len)
 529                 return "./";
 530         else if (!prefix_len)
 531                 return in;
 532
 533         if (have_same_root(in, prefix)) {
 534                 /* bypass dos_drive, for "c:" is identical to "C:" */
 535                 if (has_dos_drive_prefix(in)) {
 536                         i = 2;
 537                         j = 2;
 538                 }
 539         } else {
 540                 return in;
 541         }
 542
 543         while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 544                 if (is_dir_sep(prefix[i])) {
 545                         while (is_dir_sep(prefix[i]))
 546                                 i++;
 547                         while (is_dir_sep(in[j]))
 548                                 j++;
 549                         prefix_off = i;
 550                         in_off = j;
 551                 } else {
 552                         i++;
 553                         j++;
 554                 }
 555         }
 556
 557         if (
 558             /* "prefix" seems like prefix of "in" */
 559             i >= prefix_len &&
 560             /*
 561              * but "/foo" is not a prefix of "/foobar"
 562              * (i.e. prefix not end with '/')
 563              */
 564             prefix_off < prefix_len) {
 565                 if (j >= in_len) {
 566                         /* in="/a/b", prefix="/a/b" */
 567                         in_off = in_len;
 568                 } else if (is_dir_sep(in[j])) {
 569                         /* in="/a/b/c", prefix="/a/b" */
 570                         while (is_dir_sep(in[j]))
 571                                 j++;
 572                         in_off = j;
 573                 } else {
 574                         /* in="/a/bbb/c", prefix="/a/b" */
 575                         i = prefix_off;
 576                 }
 577         } else if (
 578                    /* "in" is short than "prefix" */
 579                    j >= in_len &&
 580                    /* "in" not end with '/' */
 581                    in_off < in_len) {
 582                 if (is_dir_sep(prefix[i])) {
 583                         /* in="/a/b", prefix="/a/b/c/" */
 584                         while (is_dir_sep(prefix[i]))
 585                                 i++;
 586                         in_off = in_len;
 587                 }
 588         }
 589         in += in_off;
 590         in_len -= in_off;
 591
 592         if (i >= prefix_len) {
 593                 if (!in_len)
 594                         return "./";
 595                 else
 596                         return in;
 597         }
 598
 599         strbuf_reset(sb);
 600         strbuf_grow(sb, in_len);
 601
 602         while (i < prefix_len) {
 603                 if (is_dir_sep(prefix[i])) {
 604                         strbuf_addstr(sb, "../");
 605                         while (is_dir_sep(prefix[i]))
 606                                 i++;
 607                         continue;
 608                 }
 609                 i++;
 610         }
 611         if (!is_dir_sep(prefix[prefix_len - 1]))
 612                 strbuf_addstr(sb, "../");
 613
 614         strbuf_addstr(sb, in);
 615
 616         return sb->buf;
 617 }
 618
 619 /*
 620  * A simpler implementation of relative_path
 621  *
 622  * Get relative path by removing "prefix" from "in". This function
 623  * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 624  * to increase performance when traversing the path to work_tree.
 625  */
 626 const char *remove_leading_path(const char *in, const char *prefix)
 627 {
 628         static char buf[PATH_MAX + 1];
 629         int i = 0, j = 0;
 630
 631         if (!prefix || !prefix[0])
 632                 return in;
 633         while (prefix[i]) {
 634                 if (is_dir_sep(prefix[i])) {
 635                         if (!is_dir_sep(in[j]))
 636                                 return in;
 637                         while (is_dir_sep(prefix[i]))
 638                                 i++;
 639                         while (is_dir_sep(in[j]))
 640                                 j++;
 641                         continue;
 642                 } else if (in[j] != prefix[i]) {
 643                         return in;
 644                 }
 645                 i++;
 646                 j++;
 647         }
 648         if (
 649             /* "/foo" is a prefix of "/foo" */
 650             in[j] &&
 651             /* "/foo" is not a prefix of "/foobar" */
 652             !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 653            )
 654                 return in;
 655         while (is_dir_sep(in[j]))
 656                 j++;
 657         if (!in[j])
 658                 strcpy(buf, ".");
 659         else
 660                 strcpy(buf, in + j);
 661         return buf;
 662 }
 663
 664 /*
 665  * It is okay if dst == src, but they should not overlap otherwise.
 666  *
 667  * Performs the following normalizations on src, storing the result in dst:
 668  * - Ensures that components are separated by '/' (Windows only)
 669  * - Squashes sequences of '/'.
 670  * - Removes "." components.
 671  * - Removes ".." components, and the components the precede them.
 672  * Returns failure (non-zero) if a ".." component appears as first path
 673  * component anytime during the normalization. Otherwise, returns success (0).
 674  *
 675  * Note that this function is purely textual.  It does not follow symlinks,
 676  * verify the existence of the path, or make any system calls.
 677  *
 678  * prefix_len != NULL is for a specific case of prefix_pathspec():
 679  * assume that src == dst and src[0..prefix_len-1] is already
 680  * normalized, any time "../" eats up to the prefix_len part,
 681  * prefix_len is reduced. In the end prefix_len is the remaining
 682  * prefix that has not been overridden by user pathspec.
 683  */
 684 int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 685 {
 686         char *dst0;
 687
 688         if (has_dos_drive_prefix(src)) {
 689                 *dst++ = *src++;
 690                 *dst++ = *src++;
 691         }
 692         dst0 = dst;
 693
 694         if (is_dir_sep(*src)) {
 695                 *dst++ = '/';
 696                 while (is_dir_sep(*src))
 697                         src++;
 698         }
 699
 700         for (;;) {
 701                 char c = *src;
 702
 703                 /*
 704                  * A path component that begins with . could be
 705                  * special:
 706                  * (1) "." and ends   -- ignore and terminate.
 707                  * (2) "./"           -- ignore them, eat slash and continue.
 708                  * (3) ".." and ends  -- strip one and terminate.
 709                  * (4) "../"          -- strip one, eat slash and continue.
 710                  */
 711                 if (c == '.') {
 712                         if (!src[1]) {
 713                                 /* (1) */
 714                                 src++;
 715                         } else if (is_dir_sep(src[1])) {
 716                                 /* (2) */
 717                                 src += 2;
 718                                 while (is_dir_sep(*src))
 719                                         src++;
 720                                 continue;
 721                         } else if (src[1] == '.') {
 722                                 if (!src[2]) {
 723                                         /* (3) */
 724                                         src += 2;
 725                                         goto up_one;
 726                                 } else if (is_dir_sep(src[2])) {
 727                                         /* (4) */
 728                                         src += 3;
 729                                         while (is_dir_sep(*src))
 730                                                 src++;
 731                                         goto up_one;
 732                                 }
 733                         }
 734                 }
 735
 736                 /* copy up to the next '/', and eat all '/' */
 737                 while ((c = *src++) != '\0' && !is_dir_sep(c))
 738                         *dst++ = c;
 739                 if (is_dir_sep(c)) {
 740                         *dst++ = '/';
 741                         while (is_dir_sep(c))
 742                                 c = *src++;
 743                         src--;
 744                 } else if (!c)
 745                         break;
 746                 continue;
 747
 748         up_one:
 749                 /*
 750                  * dst0..dst is prefix portion, and dst[-1] is '/';
 751                  * go up one level.
 752                  */
 753                 dst--;  /* go to trailing '/' */
 754                 if (dst <= dst0)
 755                         return -1;
 756                 /* Windows: dst[-1] cannot be backslash anymore */
 757                 while (dst0 < dst && dst[-1] != '/')
 758                         dst--;
 759                 if (prefix_len && *prefix_len > dst - dst0)
 760                         *prefix_len = dst - dst0;
 761         }
 762         *dst = '\0';
 763         return 0;
 764 }
 765
 766 int normalize_path_copy(char *dst, const char *src)
 767 {
 768         return normalize_path_copy_len(dst, src, NULL);
 769 }
 770
 771 /*
 772  * path = Canonical absolute path
 773  * prefixes = string_list containing normalized, absolute paths without
 774  * trailing slashes (except for the root directory, which is denoted by "/").
 775  *
 776  * Determines, for each path in prefixes, whether the "prefix"
 777  * is an ancestor directory of path.  Returns the length of the longest
 778  * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 779  * is an ancestor.  (Note that this means 0 is returned if prefixes is
 780  * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 781  * are not considered to be their own ancestors.  path must be in a
 782  * canonical form: empty components, or "." or ".." components are not
 783  * allowed.
 784  */
 785 int longest_ancestor_length(const char *path, struct string_list *prefixes)
 786 {
 787         int i, max_len = -1;
 788
 789         if (!strcmp(path, "/"))
 790                 return -1;
 791
 792         for (i = 0; i < prefixes->nr; i++) {
 793                 const char *ceil = prefixes->items[i].string;
 794                 int len = strlen(ceil);
 795
 796                 if (len == 1 && ceil[0] == '/')
 797                         len = 0; /* root matches anything, with length 0 */
 798                 else if (!strncmp(path, ceil, len) && path[len] == '/')
 799                         ; /* match of length len */
 800                 else
 801                         continue; /* no match */
 802
 803                 if (len > max_len)
 804                         max_len = len;
 805         }
 806
 807         return max_len;
 808 }
 809
 810 /* strip arbitrary amount of directory separators at end of path */
 811 static inline int chomp_trailing_dir_sep(const char *path, int len)
 812 {
 813         while (len && is_dir_sep(path[len - 1]))
 814                 len--;
 815         return len;
 816 }
 817
 818 /*
 819  * If path ends with suffix (complete path components), returns the
 820  * part before suffix (sans trailing directory separators).
 821  * Otherwise returns NULL.
 822  */
 823 char *strip_path_suffix(const char *path, const char *suffix)
 824 {
 825         int path_len = strlen(path), suffix_len = strlen(suffix);
 826
 827         while (suffix_len) {
 828                 if (!path_len)
 829                         return NULL;
 830
 831                 if (is_dir_sep(path[path_len - 1])) {
 832                         if (!is_dir_sep(suffix[suffix_len - 1]))
 833                                 return NULL;
 834                         path_len = chomp_trailing_dir_sep(path, path_len);
 835                         suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 836                 }
 837                 else if (path[--path_len] != suffix[--suffix_len])
 838                         return NULL;
 839         }
 840
 841         if (path_len && !is_dir_sep(path[path_len - 1]))
 842                 return NULL;
 843         return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 844 }
 845
 846 int daemon_avoid_alias(const char *p)
 847 {
 848         int sl, ndot;
 849
 850         /*
 851          * This resurrects the belts and suspenders paranoia check by HPA
 852          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 853          * does not do getcwd() based path canonicalization.
 854          *
 855          * sl becomes true immediately after seeing '/' and continues to
 856          * be true as long as dots continue after that without intervening
 857          * non-dot character.
 858          */
 859         if (!p || (*p != '/' && *p != '~'))
 860                 return -1;
 861         sl = 1; ndot = 0;
 862         p++;
 863
 864         while (1) {
 865                 char ch = *p++;
 866                 if (sl) {
 867                         if (ch == '.')
 868                                 ndot++;
 869                         else if (ch == '/') {
 870                                 if (ndot < 3)
 871                                         /* reject //, /./ and /../ */
 872                                         return -1;
 873                                 ndot = 0;
 874                         }
 875                         else if (ch == 0) {
 876                                 if (0 < ndot && ndot < 3)
 877                                         /* reject /.$ and /..$ */
 878                                         return -1;
 879                                 return 0;
 880                         }
 881                         else
 882                                 sl = ndot = 0;
 883                 }
 884                 else if (ch == 0)
 885                         return 0;
 886                 else if (ch == '/') {
 887                         sl = 1;
 888                         ndot = 0;
 889                 }
 890         }
 891 }
 892
 893 static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
 894 {
 895         if (len < skip)
 896                 return 0;
 897         len -= skip;
 898         path += skip;
 899         while (len-- > 0) {
 900                 char c = *(path++);
 901                 if (c != ' ' && c != '.')
 902                         return 0;
 903         }
 904         return 1;
 905 }
 906
 907 int is_ntfs_dotgit(const char *name)
 908 {
 909         int len;
 910
 911         for (len = 0; ; len++)
 912                 if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
 913                         if (only_spaces_and_periods(name, len, 4) &&
 914                                         !strncasecmp(name, ".git", 4))
 915                                 return 1;
 916                         if (only_spaces_and_periods(name, len, 5) &&
 917                                         !strncasecmp(name, "git~1", 5))
 918                                 return 1;
 919                         if (name[len] != '\\')
 920                                 return 0;
 921                         name += len + 1;
 922                         len = -1;
 923                 }
 924 }
 925
 926 char *xdg_config_home(const char *filename)
 927 {
 928         const char *home, *config_home;
 929
 930         assert(filename);
 931         config_home = getenv("XDG_CONFIG_HOME");
 932         if (config_home && *config_home)
 933                 return mkpathdup("%s/git/%s", config_home, filename);
 934
 935         home = getenv("HOME");
 936         if (home)
 937                 return mkpathdup("%s/.config/git/%s", home, filename);
 938         return NULL;
 939 }
 940
 941 GIT_PATH_FUNC(git_path_cherry_pick_head, "CHERRY_PICK_HEAD")
 942 GIT_PATH_FUNC(git_path_revert_head, "REVERT_HEAD")
 943 GIT_PATH_FUNC(git_path_squash_msg, "SQUASH_MSG")
 944 GIT_PATH_FUNC(git_path_merge_msg, "MERGE_MSG")
 945 GIT_PATH_FUNC(git_path_merge_rr, "MERGE_RR")
 946 GIT_PATH_FUNC(git_path_merge_mode, "MERGE_MODE")
 947 GIT_PATH_FUNC(git_path_merge_head, "MERGE_HEAD")
 948 GIT_PATH_FUNC(git_path_fetch_head, "FETCH_HEAD")
 949 GIT_PATH_FUNC(git_path_shallow, "shallow")