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 unsigned char *sha1)
  82 {
  83         unsigned long size = 0;
  84         void *buf = NULL;
  85
  86         if (sha1) {
  87                 buf = read_object_with_reference(sha1, tree_type, &size, NULL);
  88                 if (!buf)
  89                         die("unable to read tree %s", sha1_to_hex(sha1));
  90         }
  91         init_tree_desc(desc, buf, size);
  92         return buf;
  93 }
  94
  95 static void entry_clear(struct name_entry *a)
  96 {
  97         memset(a, 0, sizeof(*a));
  98 }
  99
 100 static void entry_extract(struct tree_desc *t, struct name_entry *a)
 101 {
 102         *a = t->entry;
 103 }
 104
 105 static int update_tree_entry_internal(struct tree_desc *desc, struct strbuf *err)
 106 {
 107         const void *buf = desc->buffer;
 108         const unsigned char *end = desc->entry.oid->hash + 20;
 109         unsigned long size = desc->size;
 110         unsigned long len = end - (const unsigned char *)buf;
 111
 112         if (size < len)
 113                 die(_("too-short tree file"));
 114         buf = end;
 115         size -= len;
 116         desc->buffer = buf;
 117         desc->size = size;
 118         if (size)
 119                 return decode_tree_entry(desc, buf, size, err);
 120         return 0;
 121 }
 122
 123 void update_tree_entry(struct tree_desc *desc)
 124 {
 125         struct strbuf err = STRBUF_INIT;
 126         if (update_tree_entry_internal(desc, &err))
 127                 die("%s", err.buf);
 128         strbuf_release(&err);
 129 }
 130
 131 int update_tree_entry_gently(struct tree_desc *desc)
 132 {
 133         struct strbuf err = STRBUF_INIT;
 134         if (update_tree_entry_internal(desc, &err)) {
 135                 error("%s", err.buf);
 136                 strbuf_release(&err);
 137                 /* Stop processing this tree after error */
 138                 desc->size = 0;
 139                 return -1;
 140         }
 141         strbuf_release(&err);
 142         return 0;
 143 }
 144
 145 int tree_entry(struct tree_desc *desc, struct name_entry *entry)
 146 {
 147         if (!desc->size)
 148                 return 0;
 149
 150         *entry = desc->entry;
 151         update_tree_entry(desc);
 152         return 1;
 153 }
 154
 155 int tree_entry_gently(struct tree_desc *desc, struct name_entry *entry)
 156 {
 157         if (!desc->size)
 158                 return 0;
 159
 160         *entry = desc->entry;
 161         if (update_tree_entry_gently(desc))
 162                 return 0;
 163         return 1;
 164 }
 165
 166 void setup_traverse_info(struct traverse_info *info, const char *base)
 167 {
 168         int pathlen = strlen(base);
 169         static struct traverse_info dummy;
 170
 171         memset(info, 0, sizeof(*info));
 172         if (pathlen && base[pathlen-1] == '/')
 173                 pathlen--;
 174         info->pathlen = pathlen ? pathlen + 1 : 0;
 175         info->name.path = base;
 176         info->name.oid = (void *)(base + pathlen + 1);
 177         if (pathlen)
 178                 info->prev = &dummy;
 179 }
 180
 181 char *make_traverse_path(char *path, const struct traverse_info *info, const struct name_entry *n)
 182 {
 183         int len = tree_entry_len(n);
 184         int pathlen = info->pathlen;
 185
 186         path[pathlen + len] = 0;
 187         for (;;) {
 188                 memcpy(path + pathlen, n->path, len);
 189                 if (!pathlen)
 190                         break;
 191                 path[--pathlen] = '/';
 192                 n = &info->name;
 193                 len = tree_entry_len(n);
 194                 info = info->prev;
 195                 pathlen -= len;
 196         }
 197         return path;
 198 }
 199
 200 struct tree_desc_skip {
 201         struct tree_desc_skip *prev;
 202         const void *ptr;
 203 };
 204
 205 struct tree_desc_x {
 206         struct tree_desc d;
 207         struct tree_desc_skip *skip;
 208 };
 209
 210 static int check_entry_match(const char *a, int a_len, const char *b, int b_len)
 211 {
 212         /*
 213          * The caller wants to pick *a* from a tree or nothing.
 214          * We are looking at *b* in a tree.
 215          *
 216          * (0) If a and b are the same name, we are trivially happy.
 217          *
 218          * There are three possibilities where *a* could be hiding
 219          * behind *b*.
 220          *
 221          * (1) *a* == "t",   *b* == "ab"  i.e. *b* sorts earlier than *a* no
 222          *                                matter what.
 223          * (2) *a* == "t",   *b* == "t-2" and "t" is a subtree in the tree;
 224          * (3) *a* == "t-2", *b* == "t"   and "t-2" is a blob in the tree.
 225          *
 226          * Otherwise we know *a* won't appear in the tree without
 227          * scanning further.
 228          */
 229
 230         int cmp = name_compare(a, a_len, b, b_len);
 231
 232         /* Most common case first -- reading sync'd trees */
 233         if (!cmp)
 234                 return cmp;
 235
 236         if (0 < cmp) {
 237                 /* a comes after b; it does not matter if it is case (3)
 238                 if (b_len < a_len && !memcmp(a, b, b_len) && a[b_len] < '/')
 239                         return 1;
 240                 */
 241                 return 1; /* keep looking */
 242         }
 243
 244         /* b comes after a; are we looking at case (2)? */
 245         if (a_len < b_len && !memcmp(a, b, a_len) && b[a_len] < '/')
 246                 return 1; /* keep looking */
 247
 248         return -1; /* a cannot appear in the tree */
 249 }
 250
 251 /*
 252  * From the extended tree_desc, extract the first name entry, while
 253  * paying attention to the candidate "first" name.  Most importantly,
 254  * when looking for an entry, if there are entries that sorts earlier
 255  * in the tree object representation than that name, skip them and
 256  * process the named entry first.  We will remember that we haven't
 257  * processed the first entry yet, and in the later call skip the
 258  * entry we processed early when update_extended_entry() is called.
 259  *
 260  * E.g. if the underlying tree object has these entries:
 261  *
 262  *    blob    "t-1"
 263  *    blob    "t-2"
 264  *    tree    "t"
 265  *    blob    "t=1"
 266  *
 267  * and the "first" asks for "t", remember that we still need to
 268  * process "t-1" and "t-2" but extract "t".  After processing the
 269  * entry "t" from this call, the caller will let us know by calling
 270  * update_extended_entry() that we can remember "t" has been processed
 271  * already.
 272  */
 273
 274 static void extended_entry_extract(struct tree_desc_x *t,
 275                                    struct name_entry *a,
 276                                    const char *first,
 277                                    int first_len)
 278 {
 279         const char *path;
 280         int len;
 281         struct tree_desc probe;
 282         struct tree_desc_skip *skip;
 283
 284         /*
 285          * Extract the first entry from the tree_desc, but skip the
 286          * ones that we already returned in earlier rounds.
 287          */
 288         while (1) {
 289                 if (!t->d.size) {
 290                         entry_clear(a);
 291                         break; /* not found */
 292                 }
 293                 entry_extract(&t->d, a);
 294                 for (skip = t->skip; skip; skip = skip->prev)
 295                         if (a->path == skip->ptr)
 296                                 break; /* found */
 297                 if (!skip)
 298                         break;
 299                 /* We have processed this entry already. */
 300                 update_tree_entry(&t->d);
 301         }
 302
 303         if (!first || !a->path)
 304                 return;
 305
 306         /*
 307          * The caller wants "first" from this tree, or nothing.
 308          */
 309         path = a->path;
 310         len = tree_entry_len(a);
 311         switch (check_entry_match(first, first_len, path, len)) {
 312         case -1:
 313                 entry_clear(a);
 314         case 0:
 315                 return;
 316         default:
 317                 break;
 318         }
 319
 320         /*
 321          * We need to look-ahead -- we suspect that a subtree whose
 322          * name is "first" may be hiding behind the current entry "path".
 323          */
 324         probe = t->d;
 325         while (probe.size) {
 326                 entry_extract(&probe, a);
 327                 path = a->path;
 328                 len = tree_entry_len(a);
 329                 switch (check_entry_match(first, first_len, path, len)) {
 330                 case -1:
 331                         entry_clear(a);
 332                 case 0:
 333                         return;
 334                 default:
 335                         update_tree_entry(&probe);
 336                         break;
 337                 }
 338                 /* keep looking */
 339         }
 340         entry_clear(a);
 341 }
 342
 343 static void update_extended_entry(struct tree_desc_x *t, struct name_entry *a)
 344 {
 345         if (t->d.entry.path == a->path) {
 346                 update_tree_entry(&t->d);
 347         } else {
 348                 /* we have returned this entry early */
 349                 struct tree_desc_skip *skip = xmalloc(sizeof(*skip));
 350                 skip->ptr = a->path;
 351                 skip->prev = t->skip;
 352                 t->skip = skip;
 353         }
 354 }
 355
 356 static void free_extended_entry(struct tree_desc_x *t)
 357 {
 358         struct tree_desc_skip *p, *s;
 359
 360         for (s = t->skip; s; s = p) {
 361                 p = s->prev;
 362                 free(s);
 363         }
 364 }
 365
 366 static inline int prune_traversal(struct name_entry *e,
 367                                   struct traverse_info *info,
 368                                   struct strbuf *base,
 369                                   int still_interesting)
 370 {
 371         if (!info->pathspec || still_interesting == 2)
 372                 return 2;
 373         if (still_interesting < 0)
 374                 return still_interesting;
 375         return tree_entry_interesting(e, base, 0, info->pathspec);
 376 }
 377
 378 int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
 379 {
 380         int error = 0;
 381         struct name_entry *entry = xmalloc(n*sizeof(*entry));
 382         int i;
 383         struct tree_desc_x *tx = xcalloc(n, sizeof(*tx));
 384         struct strbuf base = STRBUF_INIT;
 385         int interesting = 1;
 386         char *traverse_path;
 387
 388         for (i = 0; i < n; i++)
 389                 tx[i].d = t[i];
 390
 391         if (info->prev) {
 392                 strbuf_grow(&base, info->pathlen);
 393                 make_traverse_path(base.buf, info->prev, &info->name);
 394                 base.buf[info->pathlen-1] = '/';
 395                 strbuf_setlen(&base, info->pathlen);
 396                 traverse_path = xstrndup(base.buf, info->pathlen);
 397         } else {
 398                 traverse_path = xstrndup(info->name.path, info->pathlen);
 399         }
 400         info->traverse_path = traverse_path;
 401         for (;;) {
 402                 int trees_used;
 403                 unsigned long mask, dirmask;
 404                 const char *first = NULL;
 405                 int first_len = 0;
 406                 struct name_entry *e = NULL;
 407                 int len;
 408
 409                 for (i = 0; i < n; i++) {
 410                         e = entry + i;
 411                         extended_entry_extract(tx + i, e, NULL, 0);
 412                 }
 413
 414                 /*
 415                  * A tree may have "t-2" at the current location even
 416                  * though it may have "t" that is a subtree behind it,
 417                  * and another tree may return "t".  We want to grab
 418                  * all "t" from all trees to match in such a case.
 419                  */
 420                 for (i = 0; i < n; i++) {
 421                         e = entry + i;
 422                         if (!e->path)
 423                                 continue;
 424                         len = tree_entry_len(e);
 425                         if (!first) {
 426                                 first = e->path;
 427                                 first_len = len;
 428                                 continue;
 429                         }
 430                         if (name_compare(e->path, len, first, first_len) < 0) {
 431                                 first = e->path;
 432                                 first_len = len;
 433                         }
 434                 }
 435
 436                 if (first) {
 437                         for (i = 0; i < n; i++) {
 438                                 e = entry + i;
 439                                 extended_entry_extract(tx + i, e, first, first_len);
 440                                 /* Cull the ones that are not the earliest */
 441                                 if (!e->path)
 442                                         continue;
 443                                 len = tree_entry_len(e);
 444                                 if (name_compare(e->path, len, first, first_len))
 445                                         entry_clear(e);
 446                         }
 447                 }
 448
 449                 /* Now we have in entry[i] the earliest name from the trees */
 450                 mask = 0;
 451                 dirmask = 0;
 452                 for (i = 0; i < n; i++) {
 453                         if (!entry[i].path)
 454                                 continue;
 455                         mask |= 1ul << i;
 456                         if (S_ISDIR(entry[i].mode))
 457                                 dirmask |= 1ul << i;
 458                         e = &entry[i];
 459                 }
 460                 if (!mask)
 461                         break;
 462                 interesting = prune_traversal(e, info, &base, interesting);
 463                 if (interesting < 0)
 464                         break;
 465                 if (interesting) {
 466                         trees_used = info->fn(n, mask, dirmask, entry, info);
 467                         if (trees_used < 0) {
 468                                 error = trees_used;
 469                                 if (!info->show_all_errors)
 470                                         break;
 471                         }
 472                         mask &= trees_used;
 473                 }
 474                 for (i = 0; i < n; i++)
 475                         if (mask & (1ul << i))
 476                                 update_extended_entry(tx + i, entry + i);
 477         }
 478         free(entry);
 479         for (i = 0; i < n; i++)
 480                 free_extended_entry(tx + i);
 481         free(tx);
 482         free(traverse_path);
 483         info->traverse_path = NULL;
 484         strbuf_release(&base);
 485         return error;
 486 }
 487
 488 struct dir_state {
 489         void *tree;
 490         unsigned long size;
 491         unsigned char sha1[20];
 492 };
 493
 494 static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
 495 {
 496         int namelen = strlen(name);
 497         while (t->size) {
 498                 const char *entry;
 499                 const struct object_id *oid;
 500                 int entrylen, cmp;
 501
 502                 oid = tree_entry_extract(t, &entry, mode);
 503                 entrylen = tree_entry_len(&t->entry);
 504                 update_tree_entry(t);
 505                 if (entrylen > namelen)
 506                         continue;
 507                 cmp = memcmp(name, entry, entrylen);
 508                 if (cmp > 0)
 509                         continue;
 510                 if (cmp < 0)
 511                         break;
 512                 if (entrylen == namelen) {
 513                         hashcpy(result, oid->hash);
 514                         return 0;
 515                 }
 516                 if (name[entrylen] != '/')
 517                         continue;
 518                 if (!S_ISDIR(*mode))
 519                         break;
 520                 if (++entrylen == namelen) {
 521                         hashcpy(result, oid->hash);
 522                         return 0;
 523                 }
 524                 return get_tree_entry(oid->hash, name + entrylen, result, mode);
 525         }
 526         return -1;
 527 }
 528
 529 int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned char *sha1, unsigned *mode)
 530 {
 531         int retval;
 532         void *tree;
 533         unsigned long size;
 534         unsigned char root[20];
 535
 536         tree = read_object_with_reference(tree_sha1, tree_type, &size, root);
 537         if (!tree)
 538                 return -1;
 539
 540         if (name[0] == '\0') {
 541                 hashcpy(sha1, root);
 542                 free(tree);
 543                 return 0;
 544         }
 545
 546         if (!size) {
 547                 retval = -1;
 548         } else {
 549                 struct tree_desc t;
 550                 init_tree_desc(&t, tree, size);
 551                 retval = find_tree_entry(&t, name, sha1, mode);
 552         }
 553         free(tree);
 554         return retval;
 555 }
 556
 557 /*
 558  * This is Linux's built-in max for the number of symlinks to follow.
 559  * That limit, of course, does not affect git, but it's a reasonable
 560  * choice.
 561  */
 562 #define GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS 40
 563
 564 /**
 565  * Find a tree entry by following symlinks in tree_sha (which is
 566  * assumed to be the root of the repository).  In the event that a
 567  * symlink points outside the repository (e.g. a link to /foo or a
 568  * root-level link to ../foo), the portion of the link which is
 569  * outside the repository will be returned in result_path, and *mode
 570  * will be set to 0.  It is assumed that result_path is uninitialized.
 571  * If there are no symlinks, or the end result of the symlink chain
 572  * points to an object inside the repository, result will be filled in
 573  * with the sha1 of the found object, and *mode will hold the mode of
 574  * the object.
 575  *
 576  * See the code for enum follow_symlink_result for a description of
 577  * the return values.
 578  */
 579 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)
 580 {
 581         int retval = MISSING_OBJECT;
 582         struct dir_state *parents = NULL;
 583         size_t parents_alloc = 0;
 584         ssize_t parents_nr = 0;
 585         unsigned char current_tree_sha1[20];
 586         struct strbuf namebuf = STRBUF_INIT;
 587         struct tree_desc t;
 588         int follows_remaining = GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS;
 589         int i;
 590
 591         init_tree_desc(&t, NULL, 0UL);
 592         strbuf_init(result_path, 0);
 593         strbuf_addstr(&namebuf, name);
 594         hashcpy(current_tree_sha1, tree_sha1);
 595
 596         while (1) {
 597                 int find_result;
 598                 char *first_slash;
 599                 char *remainder = NULL;
 600
 601                 if (!t.buffer) {
 602                         void *tree;
 603                         unsigned char root[20];
 604                         unsigned long size;
 605                         tree = read_object_with_reference(current_tree_sha1,
 606                                                           tree_type, &size,
 607                                                           root);
 608                         if (!tree)
 609                                 goto done;
 610
 611                         ALLOC_GROW(parents, parents_nr + 1, parents_alloc);
 612                         parents[parents_nr].tree = tree;
 613                         parents[parents_nr].size = size;
 614                         hashcpy(parents[parents_nr].sha1, root);
 615                         parents_nr++;
 616
 617                         if (namebuf.buf[0] == '\0') {
 618                                 hashcpy(result, root);
 619                                 retval = FOUND;
 620                                 goto done;
 621                         }
 622
 623                         if (!size)
 624                                 goto done;
 625
 626                         /* descend */
 627                         init_tree_desc(&t, tree, size);
 628                 }
 629
 630                 /* Handle symlinks to e.g. a//b by removing leading slashes */
 631                 while (namebuf.buf[0] == '/') {
 632                         strbuf_remove(&namebuf, 0, 1);
 633                 }
 634
 635                 /* Split namebuf into a first component and a remainder */
 636                 if ((first_slash = strchr(namebuf.buf, '/'))) {
 637                         *first_slash = 0;
 638                         remainder = first_slash + 1;
 639                 }
 640
 641                 if (!strcmp(namebuf.buf, "..")) {
 642                         struct dir_state *parent;
 643                         /*
 644                          * We could end up with .. in the namebuf if it
 645                          * appears in a symlink.
 646                          */
 647
 648                         if (parents_nr == 1) {
 649                                 if (remainder)
 650                                         *first_slash = '/';
 651                                 strbuf_add(result_path, namebuf.buf,
 652                                            namebuf.len);
 653                                 *mode = 0;
 654                                 retval = FOUND;
 655                                 goto done;
 656                         }
 657                         parent = &parents[parents_nr - 1];
 658                         free(parent->tree);
 659                         parents_nr--;
 660                         parent = &parents[parents_nr - 1];
 661                         init_tree_desc(&t, parent->tree, parent->size);
 662                         strbuf_remove(&namebuf, 0, remainder ? 3 : 2);
 663                         continue;
 664                 }
 665
 666                 /* We could end up here via a symlink to dir/.. */
 667                 if (namebuf.buf[0] == '\0') {
 668                         hashcpy(result, parents[parents_nr - 1].sha1);
 669                         retval = FOUND;
 670                         goto done;
 671                 }
 672
 673                 /* Look up the first (or only) path component in the tree. */
 674                 find_result = find_tree_entry(&t, namebuf.buf,
 675                                               current_tree_sha1, mode);
 676                 if (find_result) {
 677                         goto done;
 678                 }
 679
 680                 if (S_ISDIR(*mode)) {
 681                         if (!remainder) {
 682                                 hashcpy(result, current_tree_sha1);
 683                                 retval = FOUND;
 684                                 goto done;
 685                         }
 686                         /* Descend the tree */
 687                         t.buffer = NULL;
 688                         strbuf_remove(&namebuf, 0,
 689                                       1 + first_slash - namebuf.buf);
 690                 } else if (S_ISREG(*mode)) {
 691                         if (!remainder) {
 692                                 hashcpy(result, current_tree_sha1);
 693                                 retval = FOUND;
 694                         } else {
 695                                 retval = NOT_DIR;
 696                         }
 697                         goto done;
 698                 } else if (S_ISLNK(*mode)) {
 699                         /* Follow a symlink */
 700                         unsigned long link_len;
 701                         size_t len;
 702                         char *contents, *contents_start;
 703                         struct dir_state *parent;
 704                         enum object_type type;
 705
 706                         if (follows_remaining-- == 0) {
 707                                 /* Too many symlinks followed */
 708                                 retval = SYMLINK_LOOP;
 709                                 goto done;
 710                         }
 711
 712                         /*
 713                          * At this point, we have followed at a least
 714                          * one symlink, so on error we need to report this.
 715                          */
 716                         retval = DANGLING_SYMLINK;
 717
 718                         contents = read_sha1_file(current_tree_sha1, &type,
 719                                                   &link_len);
 720
 721                         if (!contents)
 722                                 goto done;
 723
 724                         if (contents[0] == '/') {
 725                                 strbuf_addstr(result_path, contents);
 726                                 free(contents);
 727                                 *mode = 0;
 728                                 retval = FOUND;
 729                                 goto done;
 730                         }
 731
 732                         if (remainder)
 733                                 len = first_slash - namebuf.buf;
 734                         else
 735                                 len = namebuf.len;
 736
 737                         contents_start = contents;
 738
 739                         parent = &parents[parents_nr - 1];
 740                         init_tree_desc(&t, parent->tree, parent->size);
 741                         strbuf_splice(&namebuf, 0, len,
 742                                       contents_start, link_len);
 743                         if (remainder)
 744                                 namebuf.buf[link_len] = '/';
 745                         free(contents);
 746                 }
 747         }
 748 done:
 749         for (i = 0; i < parents_nr; i++)
 750                 free(parents[i].tree);
 751         free(parents);
 752
 753         strbuf_release(&namebuf);
 754         return retval;
 755 }
 756
 757 static int match_entry(const struct pathspec_item *item,
 758                        const struct name_entry *entry, int pathlen,
 759                        const char *match, int matchlen,
 760                        enum interesting *never_interesting)
 761 {
 762         int m = -1; /* signals that we haven't called strncmp() */
 763
 764         if (item->magic & PATHSPEC_ICASE)
 765                 /*
 766                  * "Never interesting" trick requires exact
 767                  * matching. We could do something clever with inexact
 768                  * matching, but it's trickier (and not to forget that
 769                  * strcasecmp is locale-dependent, at least in
 770                  * glibc). Just disable it for now. It can't be worse
 771                  * than the wildcard's codepath of '[Tt][Hi][Is][Ss]'
 772                  * pattern.
 773                  */
 774                 *never_interesting = entry_not_interesting;
 775         else if (*never_interesting != entry_not_interesting) {
 776                 /*
 777                  * We have not seen any match that sorts later
 778                  * than the current path.
 779                  */
 780
 781                 /*
 782                  * Does match sort strictly earlier than path
 783                  * with their common parts?
 784                  */
 785                 m = strncmp(match, entry->path,
 786                             (matchlen < pathlen) ? matchlen : pathlen);
 787                 if (m < 0)
 788                         return 0;
 789
 790                 /*
 791                  * If we come here even once, that means there is at
 792                  * least one pathspec that would sort equal to or
 793                  * later than the path we are currently looking at.
 794                  * In other words, if we have never reached this point
 795                  * after iterating all pathspecs, it means all
 796                  * pathspecs are either outside of base, or inside the
 797                  * base but sorts strictly earlier than the current
 798                  * one.  In either case, they will never match the
 799                  * subsequent entries.  In such a case, we initialized
 800                  * the variable to -1 and that is what will be
 801                  * returned, allowing the caller to terminate early.
 802                  */
 803                 *never_interesting = entry_not_interesting;
 804         }
 805
 806         if (pathlen > matchlen)
 807                 return 0;
 808
 809         if (matchlen > pathlen) {
 810                 if (match[pathlen] != '/')
 811                         return 0;
 812                 if (!S_ISDIR(entry->mode) && !S_ISGITLINK(entry->mode))
 813                         return 0;
 814         }
 815
 816         if (m == -1)
 817                 /*
 818                  * we cheated and did not do strncmp(), so we do
 819                  * that here.
 820                  */
 821                 m = ps_strncmp(item, match, entry->path, pathlen);
 822
 823         /*
 824          * If common part matched earlier then it is a hit,
 825          * because we rejected the case where path is not a
 826          * leading directory and is shorter than match.
 827          */
 828         if (!m)
 829                 /*
 830                  * match_entry does not check if the prefix part is
 831                  * matched case-sensitively. If the entry is a
 832                  * directory and part of prefix, it'll be rematched
 833                  * eventually by basecmp with special treatment for
 834                  * the prefix.
 835                  */
 836                 return 1;
 837
 838         return 0;
 839 }
 840
 841 /* :(icase)-aware string compare */
 842 static int basecmp(const struct pathspec_item *item,
 843                    const char *base, const char *match, int len)
 844 {
 845         if (item->magic & PATHSPEC_ICASE) {
 846                 int ret, n = len > item->prefix ? item->prefix : len;
 847                 ret = strncmp(base, match, n);
 848                 if (ret)
 849                         return ret;
 850                 base += n;
 851                 match += n;
 852                 len -= n;
 853         }
 854         return ps_strncmp(item, base, match, len);
 855 }
 856
 857 static int match_dir_prefix(const struct pathspec_item *item,
 858                             const char *base,
 859                             const char *match, int matchlen)
 860 {
 861         if (basecmp(item, base, match, matchlen))
 862                 return 0;
 863
 864         /*
 865          * If the base is a subdirectory of a path which
 866          * was specified, all of them are interesting.
 867          */
 868         if (!matchlen ||
 869             base[matchlen] == '/' ||
 870             match[matchlen - 1] == '/')
 871                 return 1;
 872
 873         /* Just a random prefix match */
 874         return 0;
 875 }
 876
 877 /*
 878  * Perform matching on the leading non-wildcard part of
 879  * pathspec. item->nowildcard_len must be greater than zero. Return
 880  * non-zero if base is matched.
 881  */
 882 static int match_wildcard_base(const struct pathspec_item *item,
 883                                const char *base, int baselen,
 884                                int *matched)
 885 {
 886         const char *match = item->match;
 887         /* the wildcard part is not considered in this function */
 888         int matchlen = item->nowildcard_len;
 889
 890         if (baselen) {
 891                 int dirlen;
 892                 /*
 893                  * Return early if base is longer than the
 894                  * non-wildcard part but it does not match.
 895                  */
 896                 if (baselen >= matchlen) {
 897                         *matched = matchlen;
 898                         return !basecmp(item, base, match, matchlen);
 899                 }
 900
 901                 dirlen = matchlen;
 902                 while (dirlen && match[dirlen - 1] != '/')
 903                         dirlen--;
 904
 905                 /*
 906                  * Return early if base is shorter than the
 907                  * non-wildcard part but it does not match. Note that
 908                  * base ends with '/' so we are sure it really matches
 909                  * directory
 910                  */
 911                 if (basecmp(item, base, match, baselen))
 912                         return 0;
 913                 *matched = baselen;
 914         } else
 915                 *matched = 0;
 916         /*
 917          * we could have checked entry against the non-wildcard part
 918          * that is not in base and does similar never_interesting
 919          * optimization as in match_entry. For now just be happy with
 920          * base comparison.
 921          */
 922         return entry_interesting;
 923 }
 924
 925 /*
 926  * Is a tree entry interesting given the pathspec we have?
 927  *
 928  * Pre-condition: either baselen == base_offset (i.e. empty path)
 929  * or base[baselen-1] == '/' (i.e. with trailing slash).
 930  */
 931 static enum interesting do_match(const struct name_entry *entry,
 932                                  struct strbuf *base, int base_offset,
 933                                  const struct pathspec *ps,
 934                                  int exclude)
 935 {
 936         int i;
 937         int pathlen, baselen = base->len - base_offset;
 938         enum interesting never_interesting = ps->has_wildcard ?
 939                 entry_not_interesting : all_entries_not_interesting;
 940
 941         GUARD_PATHSPEC(ps,
 942                        PATHSPEC_FROMTOP |
 943                        PATHSPEC_MAXDEPTH |
 944                        PATHSPEC_LITERAL |
 945                        PATHSPEC_GLOB |
 946                        PATHSPEC_ICASE |
 947                        PATHSPEC_EXCLUDE);
 948
 949         if (!ps->nr) {
 950                 if (!ps->recursive ||
 951                     !(ps->magic & PATHSPEC_MAXDEPTH) ||
 952                     ps->max_depth == -1)
 953                         return all_entries_interesting;
 954                 return within_depth(base->buf + base_offset, baselen,
 955                                     !!S_ISDIR(entry->mode),
 956                                     ps->max_depth) ?
 957                         entry_interesting : entry_not_interesting;
 958         }
 959
 960         pathlen = tree_entry_len(entry);
 961
 962         for (i = ps->nr - 1; i >= 0; i--) {
 963                 const struct pathspec_item *item = ps->items+i;
 964                 const char *match = item->match;
 965                 const char *base_str = base->buf + base_offset;
 966                 int matchlen = item->len, matched = 0;
 967
 968                 if ((!exclude &&   item->magic & PATHSPEC_EXCLUDE) ||
 969                     ( exclude && !(item->magic & PATHSPEC_EXCLUDE)))
 970                         continue;
 971
 972                 if (baselen >= matchlen) {
 973                         /* If it doesn't match, move along... */
 974                         if (!match_dir_prefix(item, base_str, match, matchlen))
 975                                 goto match_wildcards;
 976
 977                         if (!ps->recursive ||
 978                             !(ps->magic & PATHSPEC_MAXDEPTH) ||
 979                             ps->max_depth == -1)
 980                                 return all_entries_interesting;
 981
 982                         return within_depth(base_str + matchlen + 1,
 983                                             baselen - matchlen - 1,
 984                                             !!S_ISDIR(entry->mode),
 985                                             ps->max_depth) ?
 986                                 entry_interesting : entry_not_interesting;
 987                 }
 988
 989                 /* Either there must be no base, or the base must match. */
 990                 if (baselen == 0 || !basecmp(item, base_str, match, baselen)) {
 991                         if (match_entry(item, entry, pathlen,
 992                                         match + baselen, matchlen - baselen,
 993                                         &never_interesting))
 994                                 return entry_interesting;
 995
 996                         if (item->nowildcard_len < item->len) {
 997                                 if (!git_fnmatch(item, match + baselen, entry->path,
 998                                                  item->nowildcard_len - baselen))
 999                                         return entry_interesting;
1000
1001                                 /*
1002                                  * Match all directories. We'll try to
1003                                  * match files later on.
1004                                  */
1005                                 if (ps->recursive && S_ISDIR(entry->mode))
1006                                         return entry_interesting;
1007                         }
1008
1009                         continue;
1010                 }
1011
1012 match_wildcards:
1013                 if (item->nowildcard_len == item->len)
1014                         continue;
1015
1016                 if (item->nowildcard_len &&
1017                     !match_wildcard_base(item, base_str, baselen, &matched))
1018                         continue;
1019
1020                 /*
1021                  * Concatenate base and entry->path into one and do
1022                  * fnmatch() on it.
1023                  *
1024                  * While we could avoid concatenation in certain cases
1025                  * [1], which saves a memcpy and potentially a
1026                  * realloc, it turns out not worth it. Measurement on
1027                  * linux-2.6 does not show any clear improvements,
1028                  * partly because of the nowildcard_len optimization
1029                  * in git_fnmatch(). Avoid micro-optimizations here.
1030                  *
1031                  * [1] if match_wildcard_base() says the base
1032                  * directory is already matched, we only need to match
1033                  * the rest, which is shorter so _in theory_ faster.
1034                  */
1035
1036                 strbuf_add(base, entry->path, pathlen);
1037
1038                 if (!git_fnmatch(item, match, base->buf + base_offset,
1039                                  item->nowildcard_len)) {
1040                         strbuf_setlen(base, base_offset + baselen);
1041                         return entry_interesting;
1042                 }
1043                 strbuf_setlen(base, base_offset + baselen);
1044
1045                 /*
1046                  * Match all directories. We'll try to match files
1047                  * later on.
1048                  * max_depth is ignored but we may consider support it
1049                  * in future, see
1050                  * http://thread.gmane.org/gmane.comp.version-control.git/163757/focus=163840
1051                  */
1052                 if (ps->recursive && S_ISDIR(entry->mode))
1053                         return entry_interesting;
1054         }
1055         return never_interesting; /* No matches */
1056 }
1057
1058 /*
1059  * Is a tree entry interesting given the pathspec we have?
1060  *
1061  * Pre-condition: either baselen == base_offset (i.e. empty path)
1062  * or base[baselen-1] == '/' (i.e. with trailing slash).
1063  */
1064 enum interesting tree_entry_interesting(const struct name_entry *entry,
1065                                         struct strbuf *base, int base_offset,
1066                                         const struct pathspec *ps)
1067 {
1068         enum interesting positive, negative;
1069         positive = do_match(entry, base, base_offset, ps, 0);
1070
1071         /*
1072          * case | entry | positive | negative | result
1073          * -----+-------+----------+----------+-------
1074          *   1  |  file |   -1     |  -1..2   |  -1
1075          *   2  |  file |    0     |  -1..2   |   0
1076          *   3  |  file |    1     |   -1     |   1
1077          *   4  |  file |    1     |    0     |   1
1078          *   5  |  file |    1     |    1     |   0
1079          *   6  |  file |    1     |    2     |   0
1080          *   7  |  file |    2     |   -1     |   2
1081          *   8  |  file |    2     |    0     |   2
1082          *   9  |  file |    2     |    1     |   0
1083          *  10  |  file |    2     |    2     |  -1
1084          * -----+-------+----------+----------+-------
1085          *  11  |  dir  |   -1     |  -1..2   |  -1
1086          *  12  |  dir  |    0     |  -1..2   |   0
1087          *  13  |  dir  |    1     |   -1     |   1
1088          *  14  |  dir  |    1     |    0     |   1
1089          *  15  |  dir  |    1     |    1     |   1 (*)
1090          *  16  |  dir  |    1     |    2     |   0
1091          *  17  |  dir  |    2     |   -1     |   2
1092          *  18  |  dir  |    2     |    0     |   2
1093          *  19  |  dir  |    2     |    1     |   1 (*)
1094          *  20  |  dir  |    2     |    2     |  -1
1095          *
1096          * (*) An exclude pattern interested in a directory does not
1097          * necessarily mean it will exclude all of the directory. In
1098          * wildcard case, it can't decide until looking at individual
1099          * files inside. So don't write such directories off yet.
1100          */
1101
1102         if (!(ps->magic & PATHSPEC_EXCLUDE) ||
1103             positive <= entry_not_interesting) /* #1, #2, #11, #12 */
1104                 return positive;
1105
1106         negative = do_match(entry, base, base_offset, ps, 1);
1107
1108         /* #3, #4, #7, #8, #13, #14, #17, #18 */
1109         if (negative <= entry_not_interesting)
1110                 return positive;
1111
1112         /* #15, #19 */
1113         if (S_ISDIR(entry->mode) &&
1114             positive >= entry_interesting &&
1115             negative == entry_interesting)
1116                 return entry_interesting;
1117
1118         if ((positive == entry_interesting &&
1119              negative >= entry_interesting) || /* #5, #6, #16 */
1120             (positive == all_entries_interesting &&
1121              negative == entry_interesting)) /* #9 */
1122                 return entry_not_interesting;
1123
1124         return all_entries_not_interesting; /* #10, #20 */
1125 }