tree-walk.c

   1 #include "cache.h"
   2 #include "tree-walk.h"
   3 #include "unpack-trees.h"
   4 #include "dir.h"
   5 #include "tree.h"
   6 #include "pathspec.h"
   7
   8 static const char *get_mode(const char *str, unsigned int *modep)
   9 {
  10         unsigned char c;
  11         unsigned int mode = 0;
  12
  13         if (*str == ' ')
  14                 return NULL;
  15
  16         while ((c = *str++) != ' ') {
  17                 if (c < '0' || c > '7')
  18                         return NULL;
  19                 mode = (mode << 3) + (c - '0');
  20         }
  21         *modep = mode;
  22         return str;
  23 }
  24
  25 static int decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned long size, struct strbuf *err)
  26 {
  27         const char *path;
  28         unsigned int mode, len;
  29
  30         if (size < 23 || buf[size - 21]) {
  31                 strbuf_addstr(err, _("too-short tree object"));
  32                 return -1;
  33         }
  34
  35         path = get_mode(buf, &mode);
  36         if (!path) {
  37                 strbuf_addstr(err, _("malformed mode in tree entry"));
  38                 return -1;
  39         }
  40         if (!*path) {
  41                 strbuf_addstr(err, _("empty filename in tree entry"));
  42                 return -1;
  43         }
  44 #ifdef GIT_WINDOWS_NATIVE
  45         if (protect_ntfs && strchr(path, '\\')) {
  46                 strbuf_addf(err, _("filename in tree entry contains backslash: '%s'"), path);
  47                 return -1;
  48         }
  49 #endif
  50         len = strlen(path) + 1;
  51
  52         /* Initialize the descriptor entry */
  53         desc->entry.path = path;
  54         desc->entry.mode = canon_mode(mode);
  55         desc->entry.oid  = (const struct object_id *)(path + len);
  56
  57         return 0;
  58 }
  59
  60 static int init_tree_desc_internal(struct tree_desc *desc, const void *buffer, unsigned long size, struct strbuf *err)
  61 {
  62         desc->buffer = buffer;
  63         desc->size = size;
  64         if (size)
  65                 return decode_tree_entry(desc, buffer, size, err);
  66         return 0;
  67 }
  68
  69 void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
  70 {
  71         struct strbuf err = STRBUF_INIT;
  72         if (init_tree_desc_internal(desc, buffer, size, &err))
  73                 die("%s", err.buf);
  74         strbuf_release(&err);
  75 }
  76
  77 int init_tree_desc_gently(struct tree_desc *desc, const void *buffer, unsigned long size)
  78 {
  79         struct strbuf err = STRBUF_INIT;
  80         int result = init_tree_desc_internal(desc, buffer, size, &err);
  81         if (result)
  82                 error("%s", err.buf);
  83         strbuf_release(&err);
  84         return result;
  85 }
  86
  87 void *fill_tree_descriptor(struct tree_desc *desc, const struct object_id *oid)
  88 {
  89         unsigned long size = 0;
  90         void *buf = NULL;
  91
  92         if (oid) {
  93                 buf = read_object_with_reference(oid, tree_type, &size, NULL);
  94                 if (!buf)
  95                         die("unable to read tree %s", oid_to_hex(oid));
  96         }
  97         init_tree_desc(desc, buf, size);
  98         return buf;
  99 }
 100
 101 static void entry_clear(struct name_entry *a)
 102 {
 103         memset(a, 0, sizeof(*a));
 104 }
 105
 106 static void entry_extract(struct tree_desc *t, struct name_entry *a)
 107 {
 108         *a = t->entry;
 109 }
 110
 111 static int update_tree_entry_internal(struct tree_desc *desc, struct strbuf *err)
 112 {
 113         const void *buf = desc->buffer;
 114         const unsigned char *end = desc->entry.oid->hash + the_hash_algo->rawsz;
 115         unsigned long size = desc->size;
 116         unsigned long len = end - (const unsigned char *)buf;
 117
 118         if (size < len)
 119                 die(_("too-short tree file"));
 120         buf = end;
 121         size -= len;
 122         desc->buffer = buf;
 123         desc->size = size;
 124         if (size)
 125                 return decode_tree_entry(desc, buf, size, err);
 126         return 0;
 127 }
 128
 129 void update_tree_entry(struct tree_desc *desc)
 130 {
 131         struct strbuf err = STRBUF_INIT;
 132         if (update_tree_entry_internal(desc, &err))
 133                 die("%s", err.buf);
 134         strbuf_release(&err);
 135 }
 136
 137 int update_tree_entry_gently(struct tree_desc *desc)
 138 {
 139         struct strbuf err = STRBUF_INIT;
 140         if (update_tree_entry_internal(desc, &err)) {
 141                 error("%s", err.buf);
 142                 strbuf_release(&err);
 143                 /* Stop processing this tree after error */
 144                 desc->size = 0;
 145                 return -1;
 146         }
 147         strbuf_release(&err);
 148         return 0;
 149 }
 150
 151 int tree_entry(struct tree_desc *desc, struct name_entry *entry)
 152 {
 153         if (!desc->size)
 154                 return 0;
 155
 156         *entry = desc->entry;
 157         update_tree_entry(desc);
 158         return 1;
 159 }
 160
 161 int tree_entry_gently(struct tree_desc *desc, struct name_entry *entry)
 162 {
 163         if (!desc->size)
 164                 return 0;
 165
 166         *entry = desc->entry;
 167         if (update_tree_entry_gently(desc))
 168                 return 0;
 169         return 1;
 170 }
 171
 172 void setup_traverse_info(struct traverse_info *info, const char *base)
 173 {
 174         int pathlen = strlen(base);
 175         static struct traverse_info dummy;
 176
 177         memset(info, 0, sizeof(*info));
 178         if (pathlen && base[pathlen-1] == '/')
 179                 pathlen--;
 180         info->pathlen = pathlen ? pathlen + 1 : 0;
 181         info->name.path = base;
 182         info->name.oid = (void *)(base + pathlen + 1);
 183         if (pathlen)
 184                 info->prev = &dummy;
 185 }
 186
 187 char *make_traverse_path(char *path, const struct traverse_info *info, const struct name_entry *n)
 188 {
 189         int len = tree_entry_len(n);
 190         int pathlen = info->pathlen;
 191
 192         path[pathlen + len] = 0;
 193         for (;;) {
 194                 memcpy(path + pathlen, n->path, len);
 195                 if (!pathlen)
 196                         break;
 197                 path[--pathlen] = '/';
 198                 n = &info->name;
 199                 len = tree_entry_len(n);
 200                 info = info->prev;
 201                 pathlen -= len;
 202         }
 203         return path;
 204 }
 205
 206 struct tree_desc_skip {
 207         struct tree_desc_skip *prev;
 208         const void *ptr;
 209 };
 210
 211 struct tree_desc_x {
 212         struct tree_desc d;
 213         struct tree_desc_skip *skip;
 214 };
 215
 216 static int check_entry_match(const char *a, int a_len, const char *b, int b_len)
 217 {
 218         /*
 219          * The caller wants to pick *a* from a tree or nothing.
 220          * We are looking at *b* in a tree.
 221          *
 222          * (0) If a and b are the same name, we are trivially happy.
 223          *
 224          * There are three possibilities where *a* could be hiding
 225          * behind *b*.
 226          *
 227          * (1) *a* == "t",   *b* == "ab"  i.e. *b* sorts earlier than *a* no
 228          *                                matter what.
 229          * (2) *a* == "t",   *b* == "t-2" and "t" is a subtree in the tree;
 230          * (3) *a* == "t-2", *b* == "t"   and "t-2" is a blob in the tree.
 231          *
 232          * Otherwise we know *a* won't appear in the tree without
 233          * scanning further.
 234          */
 235
 236         int cmp = name_compare(a, a_len, b, b_len);
 237
 238         /* Most common case first -- reading sync'd trees */
 239         if (!cmp)
 240                 return cmp;
 241
 242         if (0 < cmp) {
 243                 /* a comes after b; it does not matter if it is case (3)
 244                 if (b_len < a_len && !memcmp(a, b, b_len) && a[b_len] < '/')
 245                         return 1;
 246                 */
 247                 return 1; /* keep looking */
 248         }
 249
 250         /* b comes after a; are we looking at case (2)? */
 251         if (a_len < b_len && !memcmp(a, b, a_len) && b[a_len] < '/')
 252                 return 1; /* keep looking */
 253
 254         return -1; /* a cannot appear in the tree */
 255 }
 256
 257 /*
 258  * From the extended tree_desc, extract the first name entry, while
 259  * paying attention to the candidate "first" name.  Most importantly,
 260  * when looking for an entry, if there are entries that sorts earlier
 261  * in the tree object representation than that name, skip them and
 262  * process the named entry first.  We will remember that we haven't
 263  * processed the first entry yet, and in the later call skip the
 264  * entry we processed early when update_extended_entry() is called.
 265  *
 266  * E.g. if the underlying tree object has these entries:
 267  *
 268  *    blob    "t-1"
 269  *    blob    "t-2"
 270  *    tree    "t"
 271  *    blob    "t=1"
 272  *
 273  * and the "first" asks for "t", remember that we still need to
 274  * process "t-1" and "t-2" but extract "t".  After processing the
 275  * entry "t" from this call, the caller will let us know by calling
 276  * update_extended_entry() that we can remember "t" has been processed
 277  * already.
 278  */
 279
 280 static void extended_entry_extract(struct tree_desc_x *t,
 281                                    struct name_entry *a,
 282                                    const char *first,
 283                                    int first_len)
 284 {
 285         const char *path;
 286         int len;
 287         struct tree_desc probe;
 288         struct tree_desc_skip *skip;
 289
 290         /*
 291          * Extract the first entry from the tree_desc, but skip the
 292          * ones that we already returned in earlier rounds.
 293          */
 294         while (1) {
 295                 if (!t->d.size) {
 296                         entry_clear(a);
 297                         break; /* not found */
 298                 }
 299                 entry_extract(&t->d, a);
 300                 for (skip = t->skip; skip; skip = skip->prev)
 301                         if (a->path == skip->ptr)
 302                                 break; /* found */
 303                 if (!skip)
 304                         break;
 305                 /* We have processed this entry already. */
 306                 update_tree_entry(&t->d);
 307         }
 308
 309         if (!first || !a->path)
 310                 return;
 311
 312         /*
 313          * The caller wants "first" from this tree, or nothing.
 314          */
 315         path = a->path;
 316         len = tree_entry_len(a);
 317         switch (check_entry_match(first, first_len, path, len)) {
 318         case -1:
 319                 entry_clear(a);
 320         case 0:
 321                 return;
 322         default:
 323                 break;
 324         }
 325
 326         /*
 327          * We need to look-ahead -- we suspect that a subtree whose
 328          * name is "first" may be hiding behind the current entry "path".
 329          */
 330         probe = t->d;
 331         while (probe.size) {
 332                 entry_extract(&probe, a);
 333                 path = a->path;
 334                 len = tree_entry_len(a);
 335                 switch (check_entry_match(first, first_len, path, len)) {
 336                 case -1:
 337                         entry_clear(a);
 338                 case 0:
 339                         return;
 340                 default:
 341                         update_tree_entry(&probe);
 342                         break;
 343                 }
 344                 /* keep looking */
 345         }
 346         entry_clear(a);
 347 }
 348
 349 static void update_extended_entry(struct tree_desc_x *t, struct name_entry *a)
 350 {
 351         if (t->d.entry.path == a->path) {
 352                 update_tree_entry(&t->d);
 353         } else {
 354                 /* we have returned this entry early */
 355                 struct tree_desc_skip *skip = xmalloc(sizeof(*skip));
 356                 skip->ptr = a->path;
 357                 skip->prev = t->skip;
 358                 t->skip = skip;
 359         }
 360 }
 361
 362 static void free_extended_entry(struct tree_desc_x *t)
 363 {
 364         struct tree_desc_skip *p, *s;
 365
 366         for (s = t->skip; s; s = p) {
 367                 p = s->prev;
 368                 free(s);
 369         }
 370 }
 371
 372 static inline int prune_traversal(struct name_entry *e,
 373                                   struct traverse_info *info,
 374                                   struct strbuf *base,
 375                                   int still_interesting)
 376 {
 377         if (!info->pathspec || still_interesting == 2)
 378                 return 2;
 379         if (still_interesting < 0)
 380                 return still_interesting;
 381         return tree_entry_interesting(e, base, 0, info->pathspec);
 382 }
 383
 384 int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
 385 {
 386         int error = 0;
 387         struct name_entry *entry = xmalloc(n*sizeof(*entry));
 388         int i;
 389         struct tree_desc_x *tx = xcalloc(n, sizeof(*tx));
 390         struct strbuf base = STRBUF_INIT;
 391         int interesting = 1;
 392         char *traverse_path;
 393
 394         for (i = 0; i < n; i++)
 395                 tx[i].d = t[i];
 396
 397         if (info->prev) {
 398                 strbuf_grow(&base, info->pathlen);
 399                 make_traverse_path(base.buf, info->prev, &info->name);
 400                 base.buf[info->pathlen-1] = '/';
 401                 strbuf_setlen(&base, info->pathlen);
 402                 traverse_path = xstrndup(base.buf, info->pathlen);
 403         } else {
 404                 traverse_path = xstrndup(info->name.path, info->pathlen);
 405         }
 406         info->traverse_path = traverse_path;
 407         for (;;) {
 408                 int trees_used;
 409                 unsigned long mask, dirmask;
 410                 const char *first = NULL;
 411                 int first_len = 0;
 412                 struct name_entry *e = NULL;
 413                 int len;
 414
 415                 for (i = 0; i < n; i++) {
 416                         e = entry + i;
 417                         extended_entry_extract(tx + i, e, NULL, 0);
 418                 }
 419
 420                 /*
 421                  * A tree may have "t-2" at the current location even
 422                  * though it may have "t" that is a subtree behind it,
 423                  * and another tree may return "t".  We want to grab
 424                  * all "t" from all trees to match in such a case.
 425                  */
 426                 for (i = 0; i < n; i++) {
 427                         e = entry + i;
 428                         if (!e->path)
 429                                 continue;
 430                         len = tree_entry_len(e);
 431                         if (!first) {
 432                                 first = e->path;
 433                                 first_len = len;
 434                                 continue;
 435                         }
 436                         if (name_compare(e->path, len, first, first_len) < 0) {
 437                                 first = e->path;
 438                                 first_len = len;
 439                         }
 440                 }
 441
 442                 if (first) {
 443                         for (i = 0; i < n; i++) {
 444                                 e = entry + i;
 445                                 extended_entry_extract(tx + i, e, first, first_len);
 446                                 /* Cull the ones that are not the earliest */
 447                                 if (!e->path)
 448                                         continue;
 449                                 len = tree_entry_len(e);
 450                                 if (name_compare(e->path, len, first, first_len))
 451                                         entry_clear(e);
 452                         }
 453                 }
 454
 455                 /* Now we have in entry[i] the earliest name from the trees */
 456                 mask = 0;
 457                 dirmask = 0;
 458                 for (i = 0; i < n; i++) {
 459                         if (!entry[i].path)
 460                                 continue;
 461                         mask |= 1ul << i;
 462                         if (S_ISDIR(entry[i].mode))
 463                                 dirmask |= 1ul << i;
 464                         e = &entry[i];
 465                 }
 466                 if (!mask)
 467                         break;
 468                 interesting = prune_traversal(e, info, &base, interesting);
 469                 if (interesting < 0)
 470                         break;
 471                 if (interesting) {
 472                         trees_used = info->fn(n, mask, dirmask, entry, info);
 473                         if (trees_used < 0) {
 474                                 error = trees_used;
 475                                 if (!info->show_all_errors)
 476                                         break;
 477                         }
 478                         mask &= trees_used;
 479                 }
 480                 for (i = 0; i < n; i++)
 481                         if (mask & (1ul << i))
 482                                 update_extended_entry(tx + i, entry + i);
 483         }
 484         free(entry);
 485         for (i = 0; i < n; i++)
 486                 free_extended_entry(tx + i);
 487         free(tx);
 488         free(traverse_path);
 489         info->traverse_path = NULL;
 490         strbuf_release(&base);
 491         return error;
 492 }
 493
 494 struct dir_state {
 495         void *tree;
 496         unsigned long size;
 497         struct object_id oid;
 498 };
 499
 500 static int find_tree_entry(struct tree_desc *t, const char *name, struct object_id *result, unsigned *mode)
 501 {
 502         int namelen = strlen(name);
 503         while (t->size) {
 504                 const char *entry;
 505                 const struct object_id *oid;
 506                 int entrylen, cmp;
 507
 508                 oid = tree_entry_extract(t, &entry, mode);
 509                 entrylen = tree_entry_len(&t->entry);
 510                 update_tree_entry(t);
 511                 if (entrylen > namelen)
 512                         continue;
 513                 cmp = memcmp(name, entry, entrylen);
 514                 if (cmp > 0)
 515                         continue;
 516                 if (cmp < 0)
 517                         break;
 518                 if (entrylen == namelen) {
 519                         oidcpy(result, oid);
 520                         return 0;
 521                 }
 522                 if (name[entrylen] != '/')
 523                         continue;
 524                 if (!S_ISDIR(*mode))
 525                         break;
 526                 if (++entrylen == namelen) {
 527                         oidcpy(result, oid);
 528                         return 0;
 529                 }
 530                 return get_tree_entry(oid, name + entrylen, result, mode);
 531         }
 532         return -1;
 533 }
 534
 535 int get_tree_entry(const struct object_id *tree_oid, const char *name, struct object_id *oid, unsigned *mode)
 536 {
 537         int retval;
 538         void *tree;
 539         unsigned long size;
 540         struct object_id root;
 541
 542         tree = read_object_with_reference(tree_oid, tree_type, &size, &root);
 543         if (!tree)
 544                 return -1;
 545
 546         if (name[0] == '\0') {
 547                 oidcpy(oid, &root);
 548                 free(tree);
 549                 return 0;
 550         }
 551
 552         if (!size) {
 553                 retval = -1;
 554         } else {
 555                 struct tree_desc t;
 556                 init_tree_desc(&t, tree, size);
 557                 retval = find_tree_entry(&t, name, oid, mode);
 558         }
 559         free(tree);
 560         return retval;
 561 }
 562
 563 /*
 564  * This is Linux's built-in max for the number of symlinks to follow.
 565  * That limit, of course, does not affect git, but it's a reasonable
 566  * choice.
 567  */
 568 #define GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS 40
 569
 570 /**
 571  * Find a tree entry by following symlinks in tree_sha (which is
 572  * assumed to be the root of the repository).  In the event that a
 573  * symlink points outside the repository (e.g. a link to /foo or a
 574  * root-level link to ../foo), the portion of the link which is
 575  * outside the repository will be returned in result_path, and *mode
 576  * will be set to 0.  It is assumed that result_path is uninitialized.
 577  * If there are no symlinks, or the end result of the symlink chain
 578  * points to an object inside the repository, result will be filled in
 579  * with the sha1 of the found object, and *mode will hold the mode of
 580  * the object.
 581  *
 582  * See the code for enum follow_symlink_result for a description of
 583  * the return values.
 584  */
 585 enum follow_symlinks_result get_tree_entry_follow_symlinks(struct object_id *tree_oid, const char *name, struct object_id *result, struct strbuf *result_path, unsigned *mode)
 586 {
 587         int retval = MISSING_OBJECT;
 588         struct dir_state *parents = NULL;
 589         size_t parents_alloc = 0;
 590         size_t i, parents_nr = 0;
 591         struct object_id current_tree_oid;
 592         struct strbuf namebuf = STRBUF_INIT;
 593         struct tree_desc t;
 594         int follows_remaining = GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS;
 595
 596         init_tree_desc(&t, NULL, 0UL);
 597         strbuf_addstr(&namebuf, name);
 598         oidcpy(&current_tree_oid, tree_oid);
 599
 600         while (1) {
 601                 int find_result;
 602                 char *first_slash;
 603                 char *remainder = NULL;
 604
 605                 if (!t.buffer) {
 606                         void *tree;
 607                         struct object_id root;
 608                         unsigned long size;
 609                         tree = read_object_with_reference(&current_tree_oid,
 610                                                           tree_type, &size,
 611                                                           &root);
 612                         if (!tree)
 613                                 goto done;
 614
 615                         ALLOC_GROW(parents, parents_nr + 1, parents_alloc);
 616                         parents[parents_nr].tree = tree;
 617                         parents[parents_nr].size = size;
 618                         oidcpy(&parents[parents_nr].oid, &root);
 619                         parents_nr++;
 620
 621                         if (namebuf.buf[0] == '\0') {
 622                                 oidcpy(result, &root);
 623                                 retval = FOUND;
 624                                 goto done;
 625                         }
 626
 627                         if (!size)
 628                                 goto done;
 629
 630                         /* descend */
 631                         init_tree_desc(&t, tree, size);
 632                 }
 633
 634                 /* Handle symlinks to e.g. a//b by removing leading slashes */
 635                 while (namebuf.buf[0] == '/') {
 636                         strbuf_remove(&namebuf, 0, 1);
 637                 }
 638
 639                 /* Split namebuf into a first component and a remainder */
 640                 if ((first_slash = strchr(namebuf.buf, '/'))) {
 641                         *first_slash = 0;
 642                         remainder = first_slash + 1;
 643                 }
 644
 645                 if (!strcmp(namebuf.buf, "..")) {
 646                         struct dir_state *parent;
 647                         /*
 648                          * We could end up with .. in the namebuf if it
 649                          * appears in a symlink.
 650                          */
 651
 652                         if (parents_nr == 1) {
 653                                 if (remainder)
 654                                         *first_slash = '/';
 655                                 strbuf_add(result_path, namebuf.buf,
 656                                            namebuf.len);
 657                                 *mode = 0;
 658                                 retval = FOUND;
 659                                 goto done;
 660                         }
 661                         parent = &parents[parents_nr - 1];
 662                         free(parent->tree);
 663                         parents_nr--;
 664                         parent = &parents[parents_nr - 1];
 665                         init_tree_desc(&t, parent->tree, parent->size);
 666                         strbuf_remove(&namebuf, 0, remainder ? 3 : 2);
 667                         continue;
 668                 }
 669
 670                 /* We could end up here via a symlink to dir/.. */
 671                 if (namebuf.buf[0] == '\0') {
 672                         oidcpy(result, &parents[parents_nr - 1].oid);
 673                         retval = FOUND;
 674                         goto done;
 675                 }
 676
 677                 /* Look up the first (or only) path component in the tree. */
 678                 find_result = find_tree_entry(&t, namebuf.buf,
 679                                               &current_tree_oid, mode);
 680                 if (find_result) {
 681                         goto done;
 682                 }
 683
 684                 if (S_ISDIR(*mode)) {
 685                         if (!remainder) {
 686                                 oidcpy(result, &current_tree_oid);
 687                                 retval = FOUND;
 688                                 goto done;
 689                         }
 690                         /* Descend the tree */
 691                         t.buffer = NULL;
 692                         strbuf_remove(&namebuf, 0,
 693                                       1 + first_slash - namebuf.buf);
 694                 } else if (S_ISREG(*mode)) {
 695                         if (!remainder) {
 696                                 oidcpy(result, &current_tree_oid);
 697                                 retval = FOUND;
 698                         } else {
 699                                 retval = NOT_DIR;
 700                         }
 701                         goto done;
 702                 } else if (S_ISLNK(*mode)) {
 703                         /* Follow a symlink */
 704                         unsigned long link_len;
 705                         size_t len;
 706                         char *contents, *contents_start;
 707                         struct dir_state *parent;
 708                         enum object_type type;
 709
 710                         if (follows_remaining-- == 0) {
 711                                 /* Too many symlinks followed */
 712                                 retval = SYMLINK_LOOP;
 713                                 goto done;
 714                         }
 715
 716                         /*
 717                          * At this point, we have followed at a least
 718                          * one symlink, so on error we need to report this.
 719                          */
 720                         retval = DANGLING_SYMLINK;
 721
 722                         contents = read_object_file(&current_tree_oid, &type,
 723                                                     &link_len);
 724
 725                         if (!contents)
 726                                 goto done;
 727
 728                         if (contents[0] == '/') {
 729                                 strbuf_addstr(result_path, contents);
 730                                 free(contents);
 731                                 *mode = 0;
 732                                 retval = FOUND;
 733                                 goto done;
 734                         }
 735
 736                         if (remainder)
 737                                 len = first_slash - namebuf.buf;
 738                         else
 739                                 len = namebuf.len;
 740
 741                         contents_start = contents;
 742
 743                         parent = &parents[parents_nr - 1];
 744                         init_tree_desc(&t, parent->tree, parent->size);
 745                         strbuf_splice(&namebuf, 0, len,
 746                                       contents_start, link_len);
 747                         if (remainder)
 748                                 namebuf.buf[link_len] = '/';
 749                         free(contents);
 750                 }
 751         }
 752 done:
 753         for (i = 0; i < parents_nr; i++)
 754                 free(parents[i].tree);
 755         free(parents);
 756
 757         strbuf_release(&namebuf);
 758         return retval;
 759 }
 760
 761 static int match_entry(const struct pathspec_item *item,
 762                        const struct name_entry *entry, int pathlen,
 763                        const char *match, int matchlen,
 764                        enum interesting *never_interesting)
 765 {
 766         int m = -1; /* signals that we haven't called strncmp() */
 767
 768         if (item->magic & PATHSPEC_ICASE)
 769                 /*
 770                  * "Never interesting" trick requires exact
 771                  * matching. We could do something clever with inexact
 772                  * matching, but it's trickier (and not to forget that
 773                  * strcasecmp is locale-dependent, at least in
 774                  * glibc). Just disable it for now. It can't be worse
 775                  * than the wildcard's codepath of '[Tt][Hi][Is][Ss]'
 776                  * pattern.
 777                  */
 778                 *never_interesting = entry_not_interesting;
 779         else if (*never_interesting != entry_not_interesting) {
 780                 /*
 781                  * We have not seen any match that sorts later
 782                  * than the current path.
 783                  */
 784
 785                 /*
 786                  * Does match sort strictly earlier than path
 787                  * with their common parts?
 788                  */
 789                 m = strncmp(match, entry->path,
 790                             (matchlen < pathlen) ? matchlen : pathlen);
 791                 if (m < 0)
 792                         return 0;
 793
 794                 /*
 795                  * If we come here even once, that means there is at
 796                  * least one pathspec that would sort equal to or
 797                  * later than the path we are currently looking at.
 798                  * In other words, if we have never reached this point
 799                  * after iterating all pathspecs, it means all
 800                  * pathspecs are either outside of base, or inside the
 801                  * base but sorts strictly earlier than the current
 802                  * one.  In either case, they will never match the
 803                  * subsequent entries.  In such a case, we initialized
 804                  * the variable to -1 and that is what will be
 805                  * returned, allowing the caller to terminate early.
 806                  */
 807                 *never_interesting = entry_not_interesting;
 808         }
 809
 810         if (pathlen > matchlen)
 811                 return 0;
 812
 813         if (matchlen > pathlen) {
 814                 if (match[pathlen] != '/')
 815                         return 0;
 816                 if (!S_ISDIR(entry->mode) && !S_ISGITLINK(entry->mode))
 817                         return 0;
 818         }
 819
 820         if (m == -1)
 821                 /*
 822                  * we cheated and did not do strncmp(), so we do
 823                  * that here.
 824                  */
 825                 m = ps_strncmp(item, match, entry->path, pathlen);
 826
 827         /*
 828          * If common part matched earlier then it is a hit,
 829          * because we rejected the case where path is not a
 830          * leading directory and is shorter than match.
 831          */
 832         if (!m)
 833                 /*
 834                  * match_entry does not check if the prefix part is
 835                  * matched case-sensitively. If the entry is a
 836                  * directory and part of prefix, it'll be rematched
 837                  * eventually by basecmp with special treatment for
 838                  * the prefix.
 839                  */
 840                 return 1;
 841
 842         return 0;
 843 }
 844
 845 /* :(icase)-aware string compare */
 846 static int basecmp(const struct pathspec_item *item,
 847                    const char *base, const char *match, int len)
 848 {
 849         if (item->magic & PATHSPEC_ICASE) {
 850                 int ret, n = len > item->prefix ? item->prefix : len;
 851                 ret = strncmp(base, match, n);
 852                 if (ret)
 853                         return ret;
 854                 base += n;
 855                 match += n;
 856                 len -= n;
 857         }
 858         return ps_strncmp(item, base, match, len);
 859 }
 860
 861 static int match_dir_prefix(const struct pathspec_item *item,
 862                             const char *base,
 863                             const char *match, int matchlen)
 864 {
 865         if (basecmp(item, base, match, matchlen))
 866                 return 0;
 867
 868         /*
 869          * If the base is a subdirectory of a path which
 870          * was specified, all of them are interesting.
 871          */
 872         if (!matchlen ||
 873             base[matchlen] == '/' ||
 874             match[matchlen - 1] == '/')
 875                 return 1;
 876
 877         /* Just a random prefix match */
 878         return 0;
 879 }
 880
 881 /*
 882  * Perform matching on the leading non-wildcard part of
 883  * pathspec. item->nowildcard_len must be greater than zero. Return
 884  * non-zero if base is matched.
 885  */
 886 static int match_wildcard_base(const struct pathspec_item *item,
 887                                const char *base, int baselen,
 888                                int *matched)
 889 {
 890         const char *match = item->match;
 891         /* the wildcard part is not considered in this function */
 892         int matchlen = item->nowildcard_len;
 893
 894         if (baselen) {
 895                 int dirlen;
 896                 /*
 897                  * Return early if base is longer than the
 898                  * non-wildcard part but it does not match.
 899                  */
 900                 if (baselen >= matchlen) {
 901                         *matched = matchlen;
 902                         return !basecmp(item, base, match, matchlen);
 903                 }
 904
 905                 dirlen = matchlen;
 906                 while (dirlen && match[dirlen - 1] != '/')
 907                         dirlen--;
 908
 909                 /*
 910                  * Return early if base is shorter than the
 911                  * non-wildcard part but it does not match. Note that
 912                  * base ends with '/' so we are sure it really matches
 913                  * directory
 914                  */
 915                 if (basecmp(item, base, match, baselen))
 916                         return 0;
 917                 *matched = baselen;
 918         } else
 919                 *matched = 0;
 920         /*
 921          * we could have checked entry against the non-wildcard part
 922          * that is not in base and does similar never_interesting
 923          * optimization as in match_entry. For now just be happy with
 924          * base comparison.
 925          */
 926         return entry_interesting;
 927 }
 928
 929 /*
 930  * Is a tree entry interesting given the pathspec we have?
 931  *
 932  * Pre-condition: either baselen == base_offset (i.e. empty path)
 933  * or base[baselen-1] == '/' (i.e. with trailing slash).
 934  */
 935 static enum interesting do_match(const struct name_entry *entry,
 936                                  struct strbuf *base, int base_offset,
 937                                  const struct pathspec *ps,
 938                                  int exclude)
 939 {
 940         int i;
 941         int pathlen, baselen = base->len - base_offset;
 942         enum interesting never_interesting = ps->has_wildcard ?
 943                 entry_not_interesting : all_entries_not_interesting;
 944
 945         GUARD_PATHSPEC(ps,
 946                        PATHSPEC_FROMTOP |
 947                        PATHSPEC_MAXDEPTH |
 948                        PATHSPEC_LITERAL |
 949                        PATHSPEC_GLOB |
 950                        PATHSPEC_ICASE |
 951                        PATHSPEC_EXCLUDE);
 952
 953         if (!ps->nr) {
 954                 if (!ps->recursive ||
 955                     !(ps->magic & PATHSPEC_MAXDEPTH) ||
 956                     ps->max_depth == -1)
 957                         return all_entries_interesting;
 958                 return within_depth(base->buf + base_offset, baselen,
 959                                     !!S_ISDIR(entry->mode),
 960                                     ps->max_depth) ?
 961                         entry_interesting : entry_not_interesting;
 962         }
 963
 964         pathlen = tree_entry_len(entry);
 965
 966         for (i = ps->nr - 1; i >= 0; i--) {
 967                 const struct pathspec_item *item = ps->items+i;
 968                 const char *match = item->match;
 969                 const char *base_str = base->buf + base_offset;
 970                 int matchlen = item->len, matched = 0;
 971
 972                 if ((!exclude &&   item->magic & PATHSPEC_EXCLUDE) ||
 973                     ( exclude && !(item->magic & PATHSPEC_EXCLUDE)))
 974                         continue;
 975
 976                 if (baselen >= matchlen) {
 977                         /* If it doesn't match, move along... */
 978                         if (!match_dir_prefix(item, base_str, match, matchlen))
 979                                 goto match_wildcards;
 980
 981                         if (!ps->recursive ||
 982                             !(ps->magic & PATHSPEC_MAXDEPTH) ||
 983                             ps->max_depth == -1)
 984                                 return all_entries_interesting;
 985
 986                         return within_depth(base_str + matchlen + 1,
 987                                             baselen - matchlen - 1,
 988                                             !!S_ISDIR(entry->mode),
 989                                             ps->max_depth) ?
 990                                 entry_interesting : entry_not_interesting;
 991                 }
 992
 993                 /* Either there must be no base, or the base must match. */
 994                 if (baselen == 0 || !basecmp(item, base_str, match, baselen)) {
 995                         if (match_entry(item, entry, pathlen,
 996                                         match + baselen, matchlen - baselen,
 997                                         &never_interesting))
 998                                 return entry_interesting;
 999
1000                         if (item->nowildcard_len < item->len) {
1001                                 if (!git_fnmatch(item, match + baselen, entry->path,
1002                                                  item->nowildcard_len - baselen))
1003                                         return entry_interesting;
1004
1005                                 /*
1006                                  * Match all directories. We'll try to
1007                                  * match files later on.
1008                                  */
1009                                 if (ps->recursive && S_ISDIR(entry->mode))
1010                                         return entry_interesting;
1011
1012                                 /*
1013                                  * When matching against submodules with
1014                                  * wildcard characters, ensure that the entry
1015                                  * at least matches up to the first wild
1016                                  * character.  More accurate matching can then
1017                                  * be performed in the submodule itself.
1018                                  */
1019                                 if (ps->recurse_submodules &&
1020                                     S_ISGITLINK(entry->mode) &&
1021                                     !ps_strncmp(item, match + baselen,
1022                                                 entry->path,
1023                                                 item->nowildcard_len - baselen))
1024                                         return entry_interesting;
1025                         }
1026
1027                         continue;
1028                 }
1029
1030 match_wildcards:
1031                 if (item->nowildcard_len == item->len)
1032                         continue;
1033
1034                 if (item->nowildcard_len &&
1035                     !match_wildcard_base(item, base_str, baselen, &matched))
1036                         continue;
1037
1038                 /*
1039                  * Concatenate base and entry->path into one and do
1040                  * fnmatch() on it.
1041                  *
1042                  * While we could avoid concatenation in certain cases
1043                  * [1], which saves a memcpy and potentially a
1044                  * realloc, it turns out not worth it. Measurement on
1045                  * linux-2.6 does not show any clear improvements,
1046                  * partly because of the nowildcard_len optimization
1047                  * in git_fnmatch(). Avoid micro-optimizations here.
1048                  *
1049                  * [1] if match_wildcard_base() says the base
1050                  * directory is already matched, we only need to match
1051                  * the rest, which is shorter so _in theory_ faster.
1052                  */
1053
1054                 strbuf_add(base, entry->path, pathlen);
1055
1056                 if (!git_fnmatch(item, match, base->buf + base_offset,
1057                                  item->nowildcard_len)) {
1058                         strbuf_setlen(base, base_offset + baselen);
1059                         return entry_interesting;
1060                 }
1061
1062                 /*
1063                  * When matching against submodules with
1064                  * wildcard characters, ensure that the entry
1065                  * at least matches up to the first wild
1066                  * character.  More accurate matching can then
1067                  * be performed in the submodule itself.
1068                  */
1069                 if (ps->recurse_submodules && S_ISGITLINK(entry->mode) &&
1070                     !ps_strncmp(item, match, base->buf + base_offset,
1071                                 item->nowildcard_len)) {
1072                         strbuf_setlen(base, base_offset + baselen);
1073                         return entry_interesting;
1074                 }
1075
1076                 strbuf_setlen(base, base_offset + baselen);
1077
1078                 /*
1079                  * Match all directories. We'll try to match files
1080                  * later on.
1081                  * max_depth is ignored but we may consider support it
1082                  * in future, see
1083                  * https://public-inbox.org/git/7vmxo5l2g4.fsf@alter.siamese.dyndns.org/
1084                  */
1085                 if (ps->recursive && S_ISDIR(entry->mode))
1086                         return entry_interesting;
1087         }
1088         return never_interesting; /* No matches */
1089 }
1090
1091 /*
1092  * Is a tree entry interesting given the pathspec we have?
1093  *
1094  * Pre-condition: either baselen == base_offset (i.e. empty path)
1095  * or base[baselen-1] == '/' (i.e. with trailing slash).
1096  */
1097 enum interesting tree_entry_interesting(const struct name_entry *entry,
1098                                         struct strbuf *base, int base_offset,
1099                                         const struct pathspec *ps)
1100 {
1101         enum interesting positive, negative;
1102         positive = do_match(entry, base, base_offset, ps, 0);
1103
1104         /*
1105          * case | entry | positive | negative | result
1106          * -----+-------+----------+----------+-------
1107          *   1  |  file |   -1     |  -1..2   |  -1
1108          *   2  |  file |    0     |  -1..2   |   0
1109          *   3  |  file |    1     |   -1     |   1
1110          *   4  |  file |    1     |    0     |   1
1111          *   5  |  file |    1     |    1     |   0
1112          *   6  |  file |    1     |    2     |   0
1113          *   7  |  file |    2     |   -1     |   2
1114          *   8  |  file |    2     |    0     |   2
1115          *   9  |  file |    2     |    1     |   0
1116          *  10  |  file |    2     |    2     |  -1
1117          * -----+-------+----------+----------+-------
1118          *  11  |  dir  |   -1     |  -1..2   |  -1
1119          *  12  |  dir  |    0     |  -1..2   |   0
1120          *  13  |  dir  |    1     |   -1     |   1
1121          *  14  |  dir  |    1     |    0     |   1
1122          *  15  |  dir  |    1     |    1     |   1 (*)
1123          *  16  |  dir  |    1     |    2     |   0
1124          *  17  |  dir  |    2     |   -1     |   2
1125          *  18  |  dir  |    2     |    0     |   2
1126          *  19  |  dir  |    2     |    1     |   1 (*)
1127          *  20  |  dir  |    2     |    2     |  -1
1128          *
1129          * (*) An exclude pattern interested in a directory does not
1130          * necessarily mean it will exclude all of the directory. In
1131          * wildcard case, it can't decide until looking at individual
1132          * files inside. So don't write such directories off yet.
1133          */
1134
1135         if (!(ps->magic & PATHSPEC_EXCLUDE) ||
1136             positive <= entry_not_interesting) /* #1, #2, #11, #12 */
1137                 return positive;
1138
1139         negative = do_match(entry, base, base_offset, ps, 1);
1140
1141         /* #3, #4, #7, #8, #13, #14, #17, #18 */
1142         if (negative <= entry_not_interesting)
1143                 return positive;
1144
1145         /* #15, #19 */
1146         if (S_ISDIR(entry->mode) &&
1147             positive >= entry_interesting &&
1148             negative == entry_interesting)
1149                 return entry_interesting;
1150
1151         if ((positive == entry_interesting &&
1152              negative >= entry_interesting) || /* #5, #6, #16 */
1153             (positive == all_entries_interesting &&
1154              negative == entry_interesting)) /* #9 */
1155                 return entry_not_interesting;
1156
1157         return all_entries_not_interesting; /* #10, #20 */
1158 }