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         len = strlen(path) + 1;
  45
  46         /* Initialize the descriptor entry */
  47         desc->entry.path = path;
  48         desc->entry.mode = canon_mode(mode);
  49         desc->entry.oid  = (const struct object_id *)(path + len);
  50
  51         return 0;
  52 }
  53
  54 static int init_tree_desc_internal(struct tree_desc *desc, const void *buffer, unsigned long size, struct strbuf *err)
  55 {
  56         desc->buffer = buffer;
  57         desc->size = size;
  58         if (size)
  59                 return decode_tree_entry(desc, buffer, size, err);
  60         return 0;
  61 }
  62
  63 void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
  64 {
  65         struct strbuf err = STRBUF_INIT;
  66         if (init_tree_desc_internal(desc, buffer, size, &err))
  67                 die("%s", err.buf);
  68         strbuf_release(&err);
  69 }
  70
  71 int init_tree_desc_gently(struct tree_desc *desc, const void *buffer, unsigned long size)
  72 {
  73         struct strbuf err = STRBUF_INIT;
  74         int result = init_tree_desc_internal(desc, buffer, size, &err);
  75         if (result)
  76                 error("%s", err.buf);
  77         strbuf_release(&err);
  78         return result;
  79 }
  80
  81 void *fill_tree_descriptor(struct tree_desc *desc, const struct object_id *oid)
  82 {
  83         unsigned long size = 0;
  84         void *buf = NULL;
  85
  86         if (oid) {
  87                 buf = read_object_with_reference(oid->hash, tree_type, &size,
  88                                                  NULL);
  89                 if (!buf)
  90                         die("unable to read tree %s", oid_to_hex(oid));
  91         }
  92         init_tree_desc(desc, buf, size);
  93         return buf;
  94 }
  95
  96 static void entry_clear(struct name_entry *a)
  97 {
  98         memset(a, 0, sizeof(*a));
  99 }
 100
 101 static void entry_extract(struct tree_desc *t, struct name_entry *a)
 102 {
 103         *a = t->entry;
 104 }
 105
 106 static int update_tree_entry_internal(struct tree_desc *desc, struct strbuf *err)
 107 {
 108         const void *buf = desc->buffer;
 109         const unsigned char *end = desc->entry.oid->hash + 20;
 110         unsigned long size = desc->size;
 111         unsigned long len = end - (const unsigned char *)buf;
 112
 113         if (size < len)
 114                 die(_("too-short tree file"));
 115         buf = end;
 116         size -= len;
 117         desc->buffer = buf;
 118         desc->size = size;
 119         if (size)
 120                 return decode_tree_entry(desc, buf, size, err);
 121         return 0;
 122 }
 123
 124 void update_tree_entry(struct tree_desc *desc)
 125 {
 126         struct strbuf err = STRBUF_INIT;
 127         if (update_tree_entry_internal(desc, &err))
 128                 die("%s", err.buf);
 129         strbuf_release(&err);
 130 }
 131
 132 int update_tree_entry_gently(struct tree_desc *desc)
 133 {
 134         struct strbuf err = STRBUF_INIT;
 135         if (update_tree_entry_internal(desc, &err)) {
 136                 error("%s", err.buf);
 137                 strbuf_release(&err);
 138                 /* Stop processing this tree after error */
 139                 desc->size = 0;
 140                 return -1;
 141         }
 142         strbuf_release(&err);
 143         return 0;
 144 }
 145
 146 int tree_entry(struct tree_desc *desc, struct name_entry *entry)
 147 {
 148         if (!desc->size)
 149                 return 0;
 150
 151         *entry = desc->entry;
 152         update_tree_entry(desc);
 153         return 1;
 154 }
 155
 156 int tree_entry_gently(struct tree_desc *desc, struct name_entry *entry)
 157 {
 158         if (!desc->size)
 159                 return 0;
 160
 161         *entry = desc->entry;
 162         if (update_tree_entry_gently(desc))
 163                 return 0;
 164         return 1;
 165 }
 166
 167 void setup_traverse_info(struct traverse_info *info, const char *base)
 168 {
 169         int pathlen = strlen(base);
 170         static struct traverse_info dummy;
 171
 172         memset(info, 0, sizeof(*info));
 173         if (pathlen && base[pathlen-1] == '/')
 174                 pathlen--;
 175         info->pathlen = pathlen ? pathlen + 1 : 0;
 176         info->name.path = base;
 177         info->name.oid = (void *)(base + pathlen + 1);
 178         if (pathlen)
 179                 info->prev = &dummy;
 180 }
 181
 182 char *make_traverse_path(char *path, const struct traverse_info *info, const struct name_entry *n)
 183 {
 184         int len = tree_entry_len(n);
 185         int pathlen = info->pathlen;
 186
 187         path[pathlen + len] = 0;
 188         for (;;) {
 189                 memcpy(path + pathlen, n->path, len);
 190                 if (!pathlen)
 191                         break;
 192                 path[--pathlen] = '/';
 193                 n = &info->name;
 194                 len = tree_entry_len(n);
 195                 info = info->prev;
 196                 pathlen -= len;
 197         }
 198         return path;
 199 }
 200
 201 struct tree_desc_skip {
 202         struct tree_desc_skip *prev;
 203         const void *ptr;
 204 };
 205
 206 struct tree_desc_x {
 207         struct tree_desc d;
 208         struct tree_desc_skip *skip;
 209 };
 210
 211 static int check_entry_match(const char *a, int a_len, const char *b, int b_len)
 212 {
 213         /*
 214          * The caller wants to pick *a* from a tree or nothing.
 215          * We are looking at *b* in a tree.
 216          *
 217          * (0) If a and b are the same name, we are trivially happy.
 218          *
 219          * There are three possibilities where *a* could be hiding
 220          * behind *b*.
 221          *
 222          * (1) *a* == "t",   *b* == "ab"  i.e. *b* sorts earlier than *a* no
 223          *                                matter what.
 224          * (2) *a* == "t",   *b* == "t-2" and "t" is a subtree in the tree;
 225          * (3) *a* == "t-2", *b* == "t"   and "t-2" is a blob in the tree.
 226          *
 227          * Otherwise we know *a* won't appear in the tree without
 228          * scanning further.
 229          */
 230
 231         int cmp = name_compare(a, a_len, b, b_len);
 232
 233         /* Most common case first -- reading sync'd trees */
 234         if (!cmp)
 235                 return cmp;
 236
 237         if (0 < cmp) {
 238                 /* a comes after b; it does not matter if it is case (3)
 239                 if (b_len < a_len && !memcmp(a, b, b_len) && a[b_len] < '/')
 240                         return 1;
 241                 */
 242                 return 1; /* keep looking */
 243         }
 244
 245         /* b comes after a; are we looking at case (2)? */
 246         if (a_len < b_len && !memcmp(a, b, a_len) && b[a_len] < '/')
 247                 return 1; /* keep looking */
 248
 249         return -1; /* a cannot appear in the tree */
 250 }
 251
 252 /*
 253  * From the extended tree_desc, extract the first name entry, while
 254  * paying attention to the candidate "first" name.  Most importantly,
 255  * when looking for an entry, if there are entries that sorts earlier
 256  * in the tree object representation than that name, skip them and
 257  * process the named entry first.  We will remember that we haven't
 258  * processed the first entry yet, and in the later call skip the
 259  * entry we processed early when update_extended_entry() is called.
 260  *
 261  * E.g. if the underlying tree object has these entries:
 262  *
 263  *    blob    "t-1"
 264  *    blob    "t-2"
 265  *    tree    "t"
 266  *    blob    "t=1"
 267  *
 268  * and the "first" asks for "t", remember that we still need to
 269  * process "t-1" and "t-2" but extract "t".  After processing the
 270  * entry "t" from this call, the caller will let us know by calling
 271  * update_extended_entry() that we can remember "t" has been processed
 272  * already.
 273  */
 274
 275 static void extended_entry_extract(struct tree_desc_x *t,
 276                                    struct name_entry *a,
 277                                    const char *first,
 278                                    int first_len)
 279 {
 280         const char *path;
 281         int len;
 282         struct tree_desc probe;
 283         struct tree_desc_skip *skip;
 284
 285         /*
 286          * Extract the first entry from the tree_desc, but skip the
 287          * ones that we already returned in earlier rounds.
 288          */
 289         while (1) {
 290                 if (!t->d.size) {
 291                         entry_clear(a);
 292                         break; /* not found */
 293                 }
 294                 entry_extract(&t->d, a);
 295                 for (skip = t->skip; skip; skip = skip->prev)
 296                         if (a->path == skip->ptr)
 297                                 break; /* found */
 298                 if (!skip)
 299                         break;
 300                 /* We have processed this entry already. */
 301                 update_tree_entry(&t->d);
 302         }
 303
 304         if (!first || !a->path)
 305                 return;
 306
 307         /*
 308          * The caller wants "first" from this tree, or nothing.
 309          */
 310         path = a->path;
 311         len = tree_entry_len(a);
 312         switch (check_entry_match(first, first_len, path, len)) {
 313         case -1:
 314                 entry_clear(a);
 315         case 0:
 316                 return;
 317         default:
 318                 break;
 319         }
 320
 321         /*
 322          * We need to look-ahead -- we suspect that a subtree whose
 323          * name is "first" may be hiding behind the current entry "path".
 324          */
 325         probe = t->d;
 326         while (probe.size) {
 327                 entry_extract(&probe, a);
 328                 path = a->path;
 329                 len = tree_entry_len(a);
 330                 switch (check_entry_match(first, first_len, path, len)) {
 331                 case -1:
 332                         entry_clear(a);
 333                 case 0:
 334                         return;
 335                 default:
 336                         update_tree_entry(&probe);
 337                         break;
 338                 }
 339                 /* keep looking */
 340         }
 341         entry_clear(a);
 342 }
 343
 344 static void update_extended_entry(struct tree_desc_x *t, struct name_entry *a)
 345 {
 346         if (t->d.entry.path == a->path) {
 347                 update_tree_entry(&t->d);
 348         } else {
 349                 /* we have returned this entry early */
 350                 struct tree_desc_skip *skip = xmalloc(sizeof(*skip));
 351                 skip->ptr = a->path;
 352                 skip->prev = t->skip;
 353                 t->skip = skip;
 354         }
 355 }
 356
 357 static void free_extended_entry(struct tree_desc_x *t)
 358 {
 359         struct tree_desc_skip *p, *s;
 360
 361         for (s = t->skip; s; s = p) {
 362                 p = s->prev;
 363                 free(s);
 364         }
 365 }
 366
 367 static inline int prune_traversal(struct name_entry *e,
 368                                   struct traverse_info *info,
 369                                   struct strbuf *base,
 370                                   int still_interesting)
 371 {
 372         if (!info->pathspec || still_interesting == 2)
 373                 return 2;
 374         if (still_interesting < 0)
 375                 return still_interesting;
 376         return tree_entry_interesting(e, base, 0, info->pathspec);
 377 }
 378
 379 int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
 380 {
 381         int error = 0;
 382         struct name_entry *entry = xmalloc(n*sizeof(*entry));
 383         int i;
 384         struct tree_desc_x *tx = xcalloc(n, sizeof(*tx));
 385         struct strbuf base = STRBUF_INIT;
 386         int interesting = 1;
 387         char *traverse_path;
 388
 389         for (i = 0; i < n; i++)
 390                 tx[i].d = t[i];
 391
 392         if (info->prev) {
 393                 strbuf_grow(&base, info->pathlen);
 394                 make_traverse_path(base.buf, info->prev, &info->name);
 395                 base.buf[info->pathlen-1] = '/';
 396                 strbuf_setlen(&base, info->pathlen);
 397                 traverse_path = xstrndup(base.buf, info->pathlen);
 398         } else {
 399                 traverse_path = xstrndup(info->name.path, info->pathlen);
 400         }
 401         info->traverse_path = traverse_path;
 402         for (;;) {
 403                 int trees_used;
 404                 unsigned long mask, dirmask;
 405                 const char *first = NULL;
 406                 int first_len = 0;
 407                 struct name_entry *e = NULL;
 408                 int len;
 409
 410                 for (i = 0; i < n; i++) {
 411                         e = entry + i;
 412                         extended_entry_extract(tx + i, e, NULL, 0);
 413                 }
 414
 415                 /*
 416                  * A tree may have "t-2" at the current location even
 417                  * though it may have "t" that is a subtree behind it,
 418                  * and another tree may return "t".  We want to grab
 419                  * all "t" from all trees to match in such a case.
 420                  */
 421                 for (i = 0; i < n; i++) {
 422                         e = entry + i;
 423                         if (!e->path)
 424                                 continue;
 425                         len = tree_entry_len(e);
 426                         if (!first) {
 427                                 first = e->path;
 428                                 first_len = len;
 429                                 continue;
 430                         }
 431                         if (name_compare(e->path, len, first, first_len) < 0) {
 432                                 first = e->path;
 433                                 first_len = len;
 434                         }
 435                 }
 436
 437                 if (first) {
 438                         for (i = 0; i < n; i++) {
 439                                 e = entry + i;
 440                                 extended_entry_extract(tx + i, e, first, first_len);
 441                                 /* Cull the ones that are not the earliest */
 442                                 if (!e->path)
 443                                         continue;
 444                                 len = tree_entry_len(e);
 445                                 if (name_compare(e->path, len, first, first_len))
 446                                         entry_clear(e);
 447                         }
 448                 }
 449
 450                 /* Now we have in entry[i] the earliest name from the trees */
 451                 mask = 0;
 452                 dirmask = 0;
 453                 for (i = 0; i < n; i++) {
 454                         if (!entry[i].path)
 455                                 continue;
 456                         mask |= 1ul << i;
 457                         if (S_ISDIR(entry[i].mode))
 458                                 dirmask |= 1ul << i;
 459                         e = &entry[i];
 460                 }
 461                 if (!mask)
 462                         break;
 463                 interesting = prune_traversal(e, info, &base, interesting);
 464                 if (interesting < 0)
 465                         break;
 466                 if (interesting) {
 467                         trees_used = info->fn(n, mask, dirmask, entry, info);
 468                         if (trees_used < 0) {
 469                                 error = trees_used;
 470                                 if (!info->show_all_errors)
 471                                         break;
 472                         }
 473                         mask &= trees_used;
 474                 }
 475                 for (i = 0; i < n; i++)
 476                         if (mask & (1ul << i))
 477                                 update_extended_entry(tx + i, entry + i);
 478         }
 479         free(entry);
 480         for (i = 0; i < n; i++)
 481                 free_extended_entry(tx + i);
 482         free(tx);
 483         free(traverse_path);
 484         info->traverse_path = NULL;
 485         strbuf_release(&base);
 486         return error;
 487 }
 488
 489 struct dir_state {
 490         void *tree;
 491         unsigned long size;
 492         unsigned char sha1[20];
 493 };
 494
 495 static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
 496 {
 497         int namelen = strlen(name);
 498         while (t->size) {
 499                 const char *entry;
 500                 const struct object_id *oid;
 501                 int entrylen, cmp;
 502
 503                 oid = tree_entry_extract(t, &entry, mode);
 504                 entrylen = tree_entry_len(&t->entry);
 505                 update_tree_entry(t);
 506                 if (entrylen > namelen)
 507                         continue;
 508                 cmp = memcmp(name, entry, entrylen);
 509                 if (cmp > 0)
 510                         continue;
 511                 if (cmp < 0)
 512                         break;
 513                 if (entrylen == namelen) {
 514                         hashcpy(result, oid->hash);
 515                         return 0;
 516                 }
 517                 if (name[entrylen] != '/')
 518                         continue;
 519                 if (!S_ISDIR(*mode))
 520                         break;
 521                 if (++entrylen == namelen) {
 522                         hashcpy(result, oid->hash);
 523                         return 0;
 524                 }
 525                 return get_tree_entry(oid->hash, name + entrylen, result, mode);
 526         }
 527         return -1;
 528 }
 529
 530 int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned char *sha1, unsigned *mode)
 531 {
 532         int retval;
 533         void *tree;
 534         unsigned long size;
 535         unsigned char root[20];
 536
 537         tree = read_object_with_reference(tree_sha1, tree_type, &size, root);
 538         if (!tree)
 539                 return -1;
 540
 541         if (name[0] == '\0') {
 542                 hashcpy(sha1, root);
 543                 free(tree);
 544                 return 0;
 545         }
 546
 547         if (!size) {
 548                 retval = -1;
 549         } else {
 550                 struct tree_desc t;
 551                 init_tree_desc(&t, tree, size);
 552                 retval = find_tree_entry(&t, name, sha1, mode);
 553         }
 554         free(tree);
 555         return retval;
 556 }
 557
 558 /*
 559  * This is Linux's built-in max for the number of symlinks to follow.
 560  * That limit, of course, does not affect git, but it's a reasonable
 561  * choice.
 562  */
 563 #define GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS 40
 564
 565 /**
 566  * Find a tree entry by following symlinks in tree_sha (which is
 567  * assumed to be the root of the repository).  In the event that a
 568  * symlink points outside the repository (e.g. a link to /foo or a
 569  * root-level link to ../foo), the portion of the link which is
 570  * outside the repository will be returned in result_path, and *mode
 571  * will be set to 0.  It is assumed that result_path is uninitialized.
 572  * If there are no symlinks, or the end result of the symlink chain
 573  * points to an object inside the repository, result will be filled in
 574  * with the sha1 of the found object, and *mode will hold the mode of
 575  * the object.
 576  *
 577  * See the code for enum follow_symlink_result for a description of
 578  * the return values.
 579  */
 580 enum follow_symlinks_result get_tree_entry_follow_symlinks(unsigned char *tree_sha1, const char *name, unsigned char *result, struct strbuf *result_path, unsigned *mode)
 581 {
 582         int retval = MISSING_OBJECT;
 583         struct dir_state *parents = NULL;
 584         size_t parents_alloc = 0;
 585         size_t i, parents_nr = 0;
 586         unsigned char current_tree_sha1[20];
 587         struct strbuf namebuf = STRBUF_INIT;
 588         struct tree_desc t;
 589         int follows_remaining = GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS;
 590
 591         init_tree_desc(&t, NULL, 0UL);
 592         strbuf_addstr(&namebuf, name);
 593         hashcpy(current_tree_sha1, tree_sha1);
 594
 595         while (1) {
 596                 int find_result;
 597                 char *first_slash;
 598                 char *remainder = NULL;
 599
 600                 if (!t.buffer) {
 601                         void *tree;
 602                         unsigned char root[20];
 603                         unsigned long size;
 604                         tree = read_object_with_reference(current_tree_sha1,
 605                                                           tree_type, &size,
 606                                                           root);
 607                         if (!tree)
 608                                 goto done;
 609
 610                         ALLOC_GROW(parents, parents_nr + 1, parents_alloc);
 611                         parents[parents_nr].tree = tree;
 612                         parents[parents_nr].size = size;
 613                         hashcpy(parents[parents_nr].sha1, root);
 614                         parents_nr++;
 615
 616                         if (namebuf.buf[0] == '\0') {
 617                                 hashcpy(result, root);
 618                                 retval = FOUND;
 619                                 goto done;
 620                         }
 621
 622                         if (!size)
 623                                 goto done;
 624
 625                         /* descend */
 626                         init_tree_desc(&t, tree, size);
 627                 }
 628
 629                 /* Handle symlinks to e.g. a//b by removing leading slashes */
 630                 while (namebuf.buf[0] == '/') {
 631                         strbuf_remove(&namebuf, 0, 1);
 632                 }
 633
 634                 /* Split namebuf into a first component and a remainder */
 635                 if ((first_slash = strchr(namebuf.buf, '/'))) {
 636                         *first_slash = 0;
 637                         remainder = first_slash + 1;
 638                 }
 639
 640                 if (!strcmp(namebuf.buf, "..")) {
 641                         struct dir_state *parent;
 642                         /*
 643                          * We could end up with .. in the namebuf if it
 644                          * appears in a symlink.
 645                          */
 646
 647                         if (parents_nr == 1) {
 648                                 if (remainder)
 649                                         *first_slash = '/';
 650                                 strbuf_add(result_path, namebuf.buf,
 651                                            namebuf.len);
 652                                 *mode = 0;
 653                                 retval = FOUND;
 654                                 goto done;
 655                         }
 656                         parent = &parents[parents_nr - 1];
 657                         free(parent->tree);
 658                         parents_nr--;
 659                         parent = &parents[parents_nr - 1];
 660                         init_tree_desc(&t, parent->tree, parent->size);
 661                         strbuf_remove(&namebuf, 0, remainder ? 3 : 2);
 662                         continue;
 663                 }
 664
 665                 /* We could end up here via a symlink to dir/.. */
 666                 if (namebuf.buf[0] == '\0') {
 667                         hashcpy(result, parents[parents_nr - 1].sha1);
 668                         retval = FOUND;
 669                         goto done;
 670                 }
 671
 672                 /* Look up the first (or only) path component in the tree. */
 673                 find_result = find_tree_entry(&t, namebuf.buf,
 674                                               current_tree_sha1, mode);
 675                 if (find_result) {
 676                         goto done;
 677                 }
 678
 679                 if (S_ISDIR(*mode)) {
 680                         if (!remainder) {
 681                                 hashcpy(result, current_tree_sha1);
 682                                 retval = FOUND;
 683                                 goto done;
 684                         }
 685                         /* Descend the tree */
 686                         t.buffer = NULL;
 687                         strbuf_remove(&namebuf, 0,
 688                                       1 + first_slash - namebuf.buf);
 689                 } else if (S_ISREG(*mode)) {
 690                         if (!remainder) {
 691                                 hashcpy(result, current_tree_sha1);
 692                                 retval = FOUND;
 693                         } else {
 694                                 retval = NOT_DIR;
 695                         }
 696                         goto done;
 697                 } else if (S_ISLNK(*mode)) {
 698                         /* Follow a symlink */
 699                         unsigned long link_len;
 700                         size_t len;
 701                         char *contents, *contents_start;
 702                         struct dir_state *parent;
 703                         enum object_type type;
 704
 705                         if (follows_remaining-- == 0) {
 706                                 /* Too many symlinks followed */
 707                                 retval = SYMLINK_LOOP;
 708                                 goto done;
 709                         }
 710
 711                         /*
 712                          * At this point, we have followed at a least
 713                          * one symlink, so on error we need to report this.
 714                          */
 715                         retval = DANGLING_SYMLINK;
 716
 717                         contents = read_sha1_file(current_tree_sha1, &type,
 718                                                   &link_len);
 719
 720                         if (!contents)
 721                                 goto done;
 722
 723                         if (contents[0] == '/') {
 724                                 strbuf_addstr(result_path, contents);
 725                                 free(contents);
 726                                 *mode = 0;
 727                                 retval = FOUND;
 728                                 goto done;
 729                         }
 730
 731                         if (remainder)
 732                                 len = first_slash - namebuf.buf;
 733                         else
 734                                 len = namebuf.len;
 735
 736                         contents_start = contents;
 737
 738                         parent = &parents[parents_nr - 1];
 739                         init_tree_desc(&t, parent->tree, parent->size);
 740                         strbuf_splice(&namebuf, 0, len,
 741                                       contents_start, link_len);
 742                         if (remainder)
 743                                 namebuf.buf[link_len] = '/';
 744                         free(contents);
 745                 }
 746         }
 747 done:
 748         for (i = 0; i < parents_nr; i++)
 749                 free(parents[i].tree);
 750         free(parents);
 751
 752         strbuf_release(&namebuf);
 753         return retval;
 754 }
 755
 756 static int match_entry(const struct pathspec_item *item,
 757                        const struct name_entry *entry, int pathlen,
 758                        const char *match, int matchlen,
 759                        enum interesting *never_interesting)
 760 {
 761         int m = -1; /* signals that we haven't called strncmp() */
 762
 763         if (item->magic & PATHSPEC_ICASE)
 764                 /*
 765                  * "Never interesting" trick requires exact
 766                  * matching. We could do something clever with inexact
 767                  * matching, but it's trickier (and not to forget that
 768                  * strcasecmp is locale-dependent, at least in
 769                  * glibc). Just disable it for now. It can't be worse
 770                  * than the wildcard's codepath of '[Tt][Hi][Is][Ss]'
 771                  * pattern.
 772                  */
 773                 *never_interesting = entry_not_interesting;
 774         else if (*never_interesting != entry_not_interesting) {
 775                 /*
 776                  * We have not seen any match that sorts later
 777                  * than the current path.
 778                  */
 779
 780                 /*
 781                  * Does match sort strictly earlier than path
 782                  * with their common parts?
 783                  */
 784                 m = strncmp(match, entry->path,
 785                             (matchlen < pathlen) ? matchlen : pathlen);
 786                 if (m < 0)
 787                         return 0;
 788
 789                 /*
 790                  * If we come here even once, that means there is at
 791                  * least one pathspec that would sort equal to or
 792                  * later than the path we are currently looking at.
 793                  * In other words, if we have never reached this point
 794                  * after iterating all pathspecs, it means all
 795                  * pathspecs are either outside of base, or inside the
 796                  * base but sorts strictly earlier than the current
 797                  * one.  In either case, they will never match the
 798                  * subsequent entries.  In such a case, we initialized
 799                  * the variable to -1 and that is what will be
 800                  * returned, allowing the caller to terminate early.
 801                  */
 802                 *never_interesting = entry_not_interesting;
 803         }
 804
 805         if (pathlen > matchlen)
 806                 return 0;
 807
 808         if (matchlen > pathlen) {
 809                 if (match[pathlen] != '/')
 810                         return 0;
 811                 if (!S_ISDIR(entry->mode) && !S_ISGITLINK(entry->mode))
 812                         return 0;
 813         }
 814
 815         if (m == -1)
 816                 /*
 817                  * we cheated and did not do strncmp(), so we do
 818                  * that here.
 819                  */
 820                 m = ps_strncmp(item, match, entry->path, pathlen);
 821
 822         /*
 823          * If common part matched earlier then it is a hit,
 824          * because we rejected the case where path is not a
 825          * leading directory and is shorter than match.
 826          */
 827         if (!m)
 828                 /*
 829                  * match_entry does not check if the prefix part is
 830                  * matched case-sensitively. If the entry is a
 831                  * directory and part of prefix, it'll be rematched
 832                  * eventually by basecmp with special treatment for
 833                  * the prefix.
 834                  */
 835                 return 1;
 836
 837         return 0;
 838 }
 839
 840 /* :(icase)-aware string compare */
 841 static int basecmp(const struct pathspec_item *item,
 842                    const char *base, const char *match, int len)
 843 {
 844         if (item->magic & PATHSPEC_ICASE) {
 845                 int ret, n = len > item->prefix ? item->prefix : len;
 846                 ret = strncmp(base, match, n);
 847                 if (ret)
 848                         return ret;
 849                 base += n;
 850                 match += n;
 851                 len -= n;
 852         }
 853         return ps_strncmp(item, base, match, len);
 854 }
 855
 856 static int match_dir_prefix(const struct pathspec_item *item,
 857                             const char *base,
 858                             const char *match, int matchlen)
 859 {
 860         if (basecmp(item, base, match, matchlen))
 861                 return 0;
 862
 863         /*
 864          * If the base is a subdirectory of a path which
 865          * was specified, all of them are interesting.
 866          */
 867         if (!matchlen ||
 868             base[matchlen] == '/' ||
 869             match[matchlen - 1] == '/')
 870                 return 1;
 871
 872         /* Just a random prefix match */
 873         return 0;
 874 }
 875
 876 /*
 877  * Perform matching on the leading non-wildcard part of
 878  * pathspec. item->nowildcard_len must be greater than zero. Return
 879  * non-zero if base is matched.
 880  */
 881 static int match_wildcard_base(const struct pathspec_item *item,
 882                                const char *base, int baselen,
 883                                int *matched)
 884 {
 885         const char *match = item->match;
 886         /* the wildcard part is not considered in this function */
 887         int matchlen = item->nowildcard_len;
 888
 889         if (baselen) {
 890                 int dirlen;
 891                 /*
 892                  * Return early if base is longer than the
 893                  * non-wildcard part but it does not match.
 894                  */
 895                 if (baselen >= matchlen) {
 896                         *matched = matchlen;
 897                         return !basecmp(item, base, match, matchlen);
 898                 }
 899
 900                 dirlen = matchlen;
 901                 while (dirlen && match[dirlen - 1] != '/')
 902                         dirlen--;
 903
 904                 /*
 905                  * Return early if base is shorter than the
 906                  * non-wildcard part but it does not match. Note that
 907                  * base ends with '/' so we are sure it really matches
 908                  * directory
 909                  */
 910                 if (basecmp(item, base, match, baselen))
 911                         return 0;
 912                 *matched = baselen;
 913         } else
 914                 *matched = 0;
 915         /*
 916          * we could have checked entry against the non-wildcard part
 917          * that is not in base and does similar never_interesting
 918          * optimization as in match_entry. For now just be happy with
 919          * base comparison.
 920          */
 921         return entry_interesting;
 922 }
 923
 924 /*
 925  * Is a tree entry interesting given the pathspec we have?
 926  *
 927  * Pre-condition: either baselen == base_offset (i.e. empty path)
 928  * or base[baselen-1] == '/' (i.e. with trailing slash).
 929  */
 930 static enum interesting do_match(const struct name_entry *entry,
 931                                  struct strbuf *base, int base_offset,
 932                                  const struct pathspec *ps,
 933                                  int exclude)
 934 {
 935         int i;
 936         int pathlen, baselen = base->len - base_offset;
 937         enum interesting never_interesting = ps->has_wildcard ?
 938                 entry_not_interesting : all_entries_not_interesting;
 939
 940         GUARD_PATHSPEC(ps,
 941                        PATHSPEC_FROMTOP |
 942                        PATHSPEC_MAXDEPTH |
 943                        PATHSPEC_LITERAL |
 944                        PATHSPEC_GLOB |
 945                        PATHSPEC_ICASE |
 946                        PATHSPEC_EXCLUDE);
 947
 948         if (!ps->nr) {
 949                 if (!ps->recursive ||
 950                     !(ps->magic & PATHSPEC_MAXDEPTH) ||
 951                     ps->max_depth == -1)
 952                         return all_entries_interesting;
 953                 return within_depth(base->buf + base_offset, baselen,
 954                                     !!S_ISDIR(entry->mode),
 955                                     ps->max_depth) ?
 956                         entry_interesting : entry_not_interesting;
 957         }
 958
 959         pathlen = tree_entry_len(entry);
 960
 961         for (i = ps->nr - 1; i >= 0; i--) {
 962                 const struct pathspec_item *item = ps->items+i;
 963                 const char *match = item->match;
 964                 const char *base_str = base->buf + base_offset;
 965                 int matchlen = item->len, matched = 0;
 966
 967                 if ((!exclude &&   item->magic & PATHSPEC_EXCLUDE) ||
 968                     ( exclude && !(item->magic & PATHSPEC_EXCLUDE)))
 969                         continue;
 970
 971                 if (baselen >= matchlen) {
 972                         /* If it doesn't match, move along... */
 973                         if (!match_dir_prefix(item, base_str, match, matchlen))
 974                                 goto match_wildcards;
 975
 976                         if (!ps->recursive ||
 977                             !(ps->magic & PATHSPEC_MAXDEPTH) ||
 978                             ps->max_depth == -1)
 979                                 return all_entries_interesting;
 980
 981                         return within_depth(base_str + matchlen + 1,
 982                                             baselen - matchlen - 1,
 983                                             !!S_ISDIR(entry->mode),
 984                                             ps->max_depth) ?
 985                                 entry_interesting : entry_not_interesting;
 986                 }
 987
 988                 /* Either there must be no base, or the base must match. */
 989                 if (baselen == 0 || !basecmp(item, base_str, match, baselen)) {
 990                         if (match_entry(item, entry, pathlen,
 991                                         match + baselen, matchlen - baselen,
 992                                         &never_interesting))
 993                                 return entry_interesting;
 994
 995                         if (item->nowildcard_len < item->len) {
 996                                 if (!git_fnmatch(item, match + baselen, entry->path,
 997                                                  item->nowildcard_len - baselen))
 998                                         return entry_interesting;
 999
1000                                 /*
1001                                  * Match all directories. We'll try to
1002                                  * match files later on.
1003                                  */
1004                                 if (ps->recursive && S_ISDIR(entry->mode))
1005                                         return entry_interesting;
1006
1007                                 /*
1008                                  * When matching against submodules with
1009                                  * wildcard characters, ensure that the entry
1010                                  * at least matches up to the first wild
1011                                  * character.  More accurate matching can then
1012                                  * be performed in the submodule itself.
1013                                  */
1014                                 if (ps->recurse_submodules &&
1015                                     S_ISGITLINK(entry->mode) &&
1016                                     !ps_strncmp(item, match + baselen,
1017                                                 entry->path,
1018                                                 item->nowildcard_len - baselen))
1019                                         return entry_interesting;
1020                         }
1021
1022                         continue;
1023                 }
1024
1025 match_wildcards:
1026                 if (item->nowildcard_len == item->len)
1027                         continue;
1028
1029                 if (item->nowildcard_len &&
1030                     !match_wildcard_base(item, base_str, baselen, &matched))
1031                         continue;
1032
1033                 /*
1034                  * Concatenate base and entry->path into one and do
1035                  * fnmatch() on it.
1036                  *
1037                  * While we could avoid concatenation in certain cases
1038                  * [1], which saves a memcpy and potentially a
1039                  * realloc, it turns out not worth it. Measurement on
1040                  * linux-2.6 does not show any clear improvements,
1041                  * partly because of the nowildcard_len optimization
1042                  * in git_fnmatch(). Avoid micro-optimizations here.
1043                  *
1044                  * [1] if match_wildcard_base() says the base
1045                  * directory is already matched, we only need to match
1046                  * the rest, which is shorter so _in theory_ faster.
1047                  */
1048
1049                 strbuf_add(base, entry->path, pathlen);
1050
1051                 if (!git_fnmatch(item, match, base->buf + base_offset,
1052                                  item->nowildcard_len)) {
1053                         strbuf_setlen(base, base_offset + baselen);
1054                         return entry_interesting;
1055                 }
1056
1057                 /*
1058                  * When matching against submodules with
1059                  * wildcard characters, ensure that the entry
1060                  * at least matches up to the first wild
1061                  * character.  More accurate matching can then
1062                  * be performed in the submodule itself.
1063                  */
1064                 if (ps->recurse_submodules && S_ISGITLINK(entry->mode) &&
1065                     !ps_strncmp(item, match, base->buf + base_offset,
1066                                 item->nowildcard_len)) {
1067                         strbuf_setlen(base, base_offset + baselen);
1068                         return entry_interesting;
1069                 }
1070
1071                 strbuf_setlen(base, base_offset + baselen);
1072
1073                 /*
1074                  * Match all directories. We'll try to match files
1075                  * later on.
1076                  * max_depth is ignored but we may consider support it
1077                  * in future, see
1078                  * https://public-inbox.org/git/7vmxo5l2g4.fsf@alter.siamese.dyndns.org/
1079                  */
1080                 if (ps->recursive && S_ISDIR(entry->mode))
1081                         return entry_interesting;
1082         }
1083         return never_interesting; /* No matches */
1084 }
1085
1086 /*
1087  * Is a tree entry interesting given the pathspec we have?
1088  *
1089  * Pre-condition: either baselen == base_offset (i.e. empty path)
1090  * or base[baselen-1] == '/' (i.e. with trailing slash).
1091  */
1092 enum interesting tree_entry_interesting(const struct name_entry *entry,
1093                                         struct strbuf *base, int base_offset,
1094                                         const struct pathspec *ps)
1095 {
1096         enum interesting positive, negative;
1097         positive = do_match(entry, base, base_offset, ps, 0);
1098
1099         /*
1100          * case | entry | positive | negative | result
1101          * -----+-------+----------+----------+-------
1102          *   1  |  file |   -1     |  -1..2   |  -1
1103          *   2  |  file |    0     |  -1..2   |   0
1104          *   3  |  file |    1     |   -1     |   1
1105          *   4  |  file |    1     |    0     |   1
1106          *   5  |  file |    1     |    1     |   0
1107          *   6  |  file |    1     |    2     |   0
1108          *   7  |  file |    2     |   -1     |   2
1109          *   8  |  file |    2     |    0     |   2
1110          *   9  |  file |    2     |    1     |   0
1111          *  10  |  file |    2     |    2     |  -1
1112          * -----+-------+----------+----------+-------
1113          *  11  |  dir  |   -1     |  -1..2   |  -1
1114          *  12  |  dir  |    0     |  -1..2   |   0
1115          *  13  |  dir  |    1     |   -1     |   1
1116          *  14  |  dir  |    1     |    0     |   1
1117          *  15  |  dir  |    1     |    1     |   1 (*)
1118          *  16  |  dir  |    1     |    2     |   0
1119          *  17  |  dir  |    2     |   -1     |   2
1120          *  18  |  dir  |    2     |    0     |   2
1121          *  19  |  dir  |    2     |    1     |   1 (*)
1122          *  20  |  dir  |    2     |    2     |  -1
1123          *
1124          * (*) An exclude pattern interested in a directory does not
1125          * necessarily mean it will exclude all of the directory. In
1126          * wildcard case, it can't decide until looking at individual
1127          * files inside. So don't write such directories off yet.
1128          */
1129
1130         if (!(ps->magic & PATHSPEC_EXCLUDE) ||
1131             positive <= entry_not_interesting) /* #1, #2, #11, #12 */
1132                 return positive;
1133
1134         negative = do_match(entry, base, base_offset, ps, 1);
1135
1136         /* #3, #4, #7, #8, #13, #14, #17, #18 */
1137         if (negative <= entry_not_interesting)
1138                 return positive;
1139
1140         /* #15, #19 */
1141         if (S_ISDIR(entry->mode) &&
1142             positive >= entry_interesting &&
1143             negative == entry_interesting)
1144                 return entry_interesting;
1145
1146         if ((positive == entry_interesting &&
1147              negative >= entry_interesting) || /* #5, #6, #16 */
1148             (positive == all_entries_interesting &&
1149              negative == entry_interesting)) /* #9 */
1150                 return entry_not_interesting;
1151
1152         return all_entries_not_interesting; /* #10, #20 */
1153 }