tree-walk.c

   1 #include "cache.h"
   2 #include "tree-walk.h"
   3 #include "unpack-trees.h"
   4 #include "dir.h"
   5 #include "object-store.h"
   6 #include "tree.h"
   7 #include "pathspec.h"
   8
   9 static const char *get_mode(const char *str, unsigned int *modep)
  10 {
  11         unsigned char c;
  12         unsigned int mode = 0;
  13
  14         if (*str == ' ')
  15                 return NULL;
  16
  17         while ((c = *str++) != ' ') {
  18                 if (c < '0' || c > '7')
  19                         return NULL;
  20                 mode = (mode << 3) + (c - '0');
  21         }
  22         *modep = mode;
  23         return str;
  24 }
  25
  26 static int decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned long size, struct strbuf *err)
  27 {
  28         const char *path;
  29         unsigned int mode, len;
  30         const unsigned hashsz = the_hash_algo->rawsz;
  31
  32         if (size < hashsz + 3 || buf[size - (hashsz + 1)]) {
  33                 strbuf_addstr(err, _("too-short tree object"));
  34                 return -1;
  35         }
  36
  37         path = get_mode(buf, &mode);
  38         if (!path) {
  39                 strbuf_addstr(err, _("malformed mode in tree entry"));
  40                 return -1;
  41         }
  42         if (!*path) {
  43                 strbuf_addstr(err, _("empty filename in tree entry"));
  44                 return -1;
  45         }
  46         len = strlen(path) + 1;
  47
  48         /* Initialize the descriptor entry */
  49         desc->entry.path = path;
  50         desc->entry.mode = canon_mode(mode);
  51         desc->entry.pathlen = len - 1;
  52         hashcpy(desc->entry.oid.hash, (const unsigned char *)path + len);
  53
  54         return 0;
  55 }
  56
  57 static int init_tree_desc_internal(struct tree_desc *desc, const void *buffer, unsigned long size, struct strbuf *err)
  58 {
  59         desc->buffer = buffer;
  60         desc->size = size;
  61         if (size)
  62                 return decode_tree_entry(desc, buffer, size, err);
  63         return 0;
  64 }
  65
  66 void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
  67 {
  68         struct strbuf err = STRBUF_INIT;
  69         if (init_tree_desc_internal(desc, buffer, size, &err))
  70                 die("%s", err.buf);
  71         strbuf_release(&err);
  72 }
  73
  74 int init_tree_desc_gently(struct tree_desc *desc, const void *buffer, unsigned long size)
  75 {
  76         struct strbuf err = STRBUF_INIT;
  77         int result = init_tree_desc_internal(desc, buffer, size, &err);
  78         if (result)
  79                 error("%s", err.buf);
  80         strbuf_release(&err);
  81         return result;
  82 }
  83
  84 void *fill_tree_descriptor(struct repository *r,
  85                            struct tree_desc *desc,
  86                            const struct object_id *oid)
  87 {
  88         unsigned long size = 0;
  89         void *buf = NULL;
  90
  91         if (oid) {
  92                 buf = read_object_with_reference(r, oid, tree_type, &size, NULL);
  93                 if (!buf)
  94                         die("unable to read tree %s", oid_to_hex(oid));
  95         }
  96         init_tree_desc(desc, buf, size);
  97         return buf;
  98 }
  99
 100 static void entry_clear(struct name_entry *a)
 101 {
 102         memset(a, 0, sizeof(*a));
 103 }
 104
 105 static void entry_extract(struct tree_desc *t, struct name_entry *a)
 106 {
 107         *a = t->entry;
 108 }
 109
 110 static int update_tree_entry_internal(struct tree_desc *desc, struct strbuf *err)
 111 {
 112         const void *buf = desc->buffer;
 113         const unsigned char *end = (const unsigned char *)desc->entry.path + desc->entry.pathlen + 1 + the_hash_algo->rawsz;
 114         unsigned long size = desc->size;
 115         unsigned long len = end - (const unsigned char *)buf;
 116
 117         if (size < len)
 118                 die(_("too-short tree file"));
 119         buf = end;
 120         size -= len;
 121         desc->buffer = buf;
 122         desc->size = size;
 123         if (size)
 124                 return decode_tree_entry(desc, buf, size, err);
 125         return 0;
 126 }
 127
 128 void update_tree_entry(struct tree_desc *desc)
 129 {
 130         struct strbuf err = STRBUF_INIT;
 131         if (update_tree_entry_internal(desc, &err))
 132                 die("%s", err.buf);
 133         strbuf_release(&err);
 134 }
 135
 136 int update_tree_entry_gently(struct tree_desc *desc)
 137 {
 138         struct strbuf err = STRBUF_INIT;
 139         if (update_tree_entry_internal(desc, &err)) {
 140                 error("%s", err.buf);
 141                 strbuf_release(&err);
 142                 /* Stop processing this tree after error */
 143                 desc->size = 0;
 144                 return -1;
 145         }
 146         strbuf_release(&err);
 147         return 0;
 148 }
 149
 150 int tree_entry(struct tree_desc *desc, struct name_entry *entry)
 151 {
 152         if (!desc->size)
 153                 return 0;
 154
 155         *entry = desc->entry;
 156         update_tree_entry(desc);
 157         return 1;
 158 }
 159
 160 int tree_entry_gently(struct tree_desc *desc, struct name_entry *entry)
 161 {
 162         if (!desc->size)
 163                 return 0;
 164
 165         *entry = desc->entry;
 166         if (update_tree_entry_gently(desc))
 167                 return 0;
 168         return 1;
 169 }
 170
 171 void setup_traverse_info(struct traverse_info *info, const char *base)
 172 {
 173         size_t pathlen = strlen(base);
 174         static struct traverse_info dummy;
 175
 176         memset(info, 0, sizeof(*info));
 177         if (pathlen && base[pathlen-1] == '/')
 178                 pathlen--;
 179         info->pathlen = pathlen ? pathlen + 1 : 0;
 180         info->name = base;
 181         info->namelen = pathlen;
 182         if (pathlen)
 183                 info->prev = &dummy;
 184 }
 185
 186 char *make_traverse_path(char *path, size_t pathlen,
 187                          const struct traverse_info *info,
 188                          const char *name, size_t namelen)
 189 {
 190         /* Always points to the end of the name we're about to add */
 191         size_t pos = st_add(info->pathlen, namelen);
 192
 193         if (pos >= pathlen)
 194                 BUG("too small buffer passed to make_traverse_path");
 195
 196         path[pos] = 0;
 197         for (;;) {
 198                 if (pos < namelen)
 199                         BUG("traverse_info pathlen does not match strings");
 200                 pos -= namelen;
 201                 memcpy(path + pos, name, namelen);
 202
 203                 if (!pos)
 204                         break;
 205                 path[--pos] = '/';
 206
 207                 if (!info)
 208                         BUG("traverse_info ran out of list items");
 209                 name = info->name;
 210                 namelen = info->namelen;
 211                 info = info->prev;
 212         }
 213         return path;
 214 }
 215
 216 void strbuf_make_traverse_path(struct strbuf *out,
 217                                const struct traverse_info *info,
 218                                const char *name, size_t namelen)
 219 {
 220         size_t len = traverse_path_len(info, namelen);
 221
 222         strbuf_grow(out, len);
 223         make_traverse_path(out->buf + out->len, out->alloc - out->len,
 224                            info, name, namelen);
 225         strbuf_setlen(out, out->len + len);
 226 }
 227
 228 struct tree_desc_skip {
 229         struct tree_desc_skip *prev;
 230         const void *ptr;
 231 };
 232
 233 struct tree_desc_x {
 234         struct tree_desc d;
 235         struct tree_desc_skip *skip;
 236 };
 237
 238 static int check_entry_match(const char *a, int a_len, const char *b, int b_len)
 239 {
 240         /*
 241          * The caller wants to pick *a* from a tree or nothing.
 242          * We are looking at *b* in a tree.
 243          *
 244          * (0) If a and b are the same name, we are trivially happy.
 245          *
 246          * There are three possibilities where *a* could be hiding
 247          * behind *b*.
 248          *
 249          * (1) *a* == "t",   *b* == "ab"  i.e. *b* sorts earlier than *a* no
 250          *                                matter what.
 251          * (2) *a* == "t",   *b* == "t-2" and "t" is a subtree in the tree;
 252          * (3) *a* == "t-2", *b* == "t"   and "t-2" is a blob in the tree.
 253          *
 254          * Otherwise we know *a* won't appear in the tree without
 255          * scanning further.
 256          */
 257
 258         int cmp = name_compare(a, a_len, b, b_len);
 259
 260         /* Most common case first -- reading sync'd trees */
 261         if (!cmp)
 262                 return cmp;
 263
 264         if (0 < cmp) {
 265                 /* a comes after b; it does not matter if it is case (3)
 266                 if (b_len < a_len && !memcmp(a, b, b_len) && a[b_len] < '/')
 267                         return 1;
 268                 */
 269                 return 1; /* keep looking */
 270         }
 271
 272         /* b comes after a; are we looking at case (2)? */
 273         if (a_len < b_len && !memcmp(a, b, a_len) && b[a_len] < '/')
 274                 return 1; /* keep looking */
 275
 276         return -1; /* a cannot appear in the tree */
 277 }
 278
 279 /*
 280  * From the extended tree_desc, extract the first name entry, while
 281  * paying attention to the candidate "first" name.  Most importantly,
 282  * when looking for an entry, if there are entries that sorts earlier
 283  * in the tree object representation than that name, skip them and
 284  * process the named entry first.  We will remember that we haven't
 285  * processed the first entry yet, and in the later call skip the
 286  * entry we processed early when update_extended_entry() is called.
 287  *
 288  * E.g. if the underlying tree object has these entries:
 289  *
 290  *    blob    "t-1"
 291  *    blob    "t-2"
 292  *    tree    "t"
 293  *    blob    "t=1"
 294  *
 295  * and the "first" asks for "t", remember that we still need to
 296  * process "t-1" and "t-2" but extract "t".  After processing the
 297  * entry "t" from this call, the caller will let us know by calling
 298  * update_extended_entry() that we can remember "t" has been processed
 299  * already.
 300  */
 301
 302 static void extended_entry_extract(struct tree_desc_x *t,
 303                                    struct name_entry *a,
 304                                    const char *first,
 305                                    int first_len)
 306 {
 307         const char *path;
 308         int len;
 309         struct tree_desc probe;
 310         struct tree_desc_skip *skip;
 311
 312         /*
 313          * Extract the first entry from the tree_desc, but skip the
 314          * ones that we already returned in earlier rounds.
 315          */
 316         while (1) {
 317                 if (!t->d.size) {
 318                         entry_clear(a);
 319                         break; /* not found */
 320                 }
 321                 entry_extract(&t->d, a);
 322                 for (skip = t->skip; skip; skip = skip->prev)
 323                         if (a->path == skip->ptr)
 324                                 break; /* found */
 325                 if (!skip)
 326                         break;
 327                 /* We have processed this entry already. */
 328                 update_tree_entry(&t->d);
 329         }
 330
 331         if (!first || !a->path)
 332                 return;
 333
 334         /*
 335          * The caller wants "first" from this tree, or nothing.
 336          */
 337         path = a->path;
 338         len = tree_entry_len(a);
 339         switch (check_entry_match(first, first_len, path, len)) {
 340         case -1:
 341                 entry_clear(a);
 342         case 0:
 343                 return;
 344         default:
 345                 break;
 346         }
 347
 348         /*
 349          * We need to look-ahead -- we suspect that a subtree whose
 350          * name is "first" may be hiding behind the current entry "path".
 351          */
 352         probe = t->d;
 353         while (probe.size) {
 354                 entry_extract(&probe, a);
 355                 path = a->path;
 356                 len = tree_entry_len(a);
 357                 switch (check_entry_match(first, first_len, path, len)) {
 358                 case -1:
 359                         entry_clear(a);
 360                 case 0:
 361                         return;
 362                 default:
 363                         update_tree_entry(&probe);
 364                         break;
 365                 }
 366                 /* keep looking */
 367         }
 368         entry_clear(a);
 369 }
 370
 371 static void update_extended_entry(struct tree_desc_x *t, struct name_entry *a)
 372 {
 373         if (t->d.entry.path == a->path) {
 374                 update_tree_entry(&t->d);
 375         } else {
 376                 /* we have returned this entry early */
 377                 struct tree_desc_skip *skip = xmalloc(sizeof(*skip));
 378                 skip->ptr = a->path;
 379                 skip->prev = t->skip;
 380                 t->skip = skip;
 381         }
 382 }
 383
 384 static void free_extended_entry(struct tree_desc_x *t)
 385 {
 386         struct tree_desc_skip *p, *s;
 387
 388         for (s = t->skip; s; s = p) {
 389                 p = s->prev;
 390                 free(s);
 391         }
 392 }
 393
 394 static inline int prune_traversal(struct index_state *istate,
 395                                   struct name_entry *e,
 396                                   struct traverse_info *info,
 397                                   struct strbuf *base,
 398                                   int still_interesting)
 399 {
 400         if (!info->pathspec || still_interesting == 2)
 401                 return 2;
 402         if (still_interesting < 0)
 403                 return still_interesting;
 404         return tree_entry_interesting(istate, e, base,
 405                                       0, info->pathspec);
 406 }
 407
 408 int traverse_trees(struct index_state *istate,
 409                    int n, struct tree_desc *t,
 410                    struct traverse_info *info)
 411 {
 412         int error = 0;
 413         struct name_entry *entry = xmalloc(n*sizeof(*entry));
 414         int i;
 415         struct tree_desc_x *tx = xcalloc(n, sizeof(*tx));
 416         struct strbuf base = STRBUF_INIT;
 417         int interesting = 1;
 418         char *traverse_path;
 419
 420         for (i = 0; i < n; i++)
 421                 tx[i].d = t[i];
 422
 423         if (info->prev) {
 424                 strbuf_make_traverse_path(&base, info->prev,
 425                                           info->name, info->namelen);
 426                 strbuf_addch(&base, '/');
 427                 traverse_path = xstrndup(base.buf, base.len);
 428         } else {
 429                 traverse_path = xstrndup(info->name, info->pathlen);
 430         }
 431         info->traverse_path = traverse_path;
 432         for (;;) {
 433                 int trees_used;
 434                 unsigned long mask, dirmask;
 435                 const char *first = NULL;
 436                 int first_len = 0;
 437                 struct name_entry *e = NULL;
 438                 int len;
 439
 440                 for (i = 0; i < n; i++) {
 441                         e = entry + i;
 442                         extended_entry_extract(tx + i, e, NULL, 0);
 443                 }
 444
 445                 /*
 446                  * A tree may have "t-2" at the current location even
 447                  * though it may have "t" that is a subtree behind it,
 448                  * and another tree may return "t".  We want to grab
 449                  * all "t" from all trees to match in such a case.
 450                  */
 451                 for (i = 0; i < n; i++) {
 452                         e = entry + i;
 453                         if (!e->path)
 454                                 continue;
 455                         len = tree_entry_len(e);
 456                         if (!first) {
 457                                 first = e->path;
 458                                 first_len = len;
 459                                 continue;
 460                         }
 461                         if (name_compare(e->path, len, first, first_len) < 0) {
 462                                 first = e->path;
 463                                 first_len = len;
 464                         }
 465                 }
 466
 467                 if (first) {
 468                         for (i = 0; i < n; i++) {
 469                                 e = entry + i;
 470                                 extended_entry_extract(tx + i, e, first, first_len);
 471                                 /* Cull the ones that are not the earliest */
 472                                 if (!e->path)
 473                                         continue;
 474                                 len = tree_entry_len(e);
 475                                 if (name_compare(e->path, len, first, first_len))
 476                                         entry_clear(e);
 477                         }
 478                 }
 479
 480                 /* Now we have in entry[i] the earliest name from the trees */
 481                 mask = 0;
 482                 dirmask = 0;
 483                 for (i = 0; i < n; i++) {
 484                         if (!entry[i].path)
 485                                 continue;
 486                         mask |= 1ul << i;
 487                         if (S_ISDIR(entry[i].mode))
 488                                 dirmask |= 1ul << i;
 489                         e = &entry[i];
 490                 }
 491                 if (!mask)
 492                         break;
 493                 interesting = prune_traversal(istate, e, info, &base, interesting);
 494                 if (interesting < 0)
 495                         break;
 496                 if (interesting) {
 497                         trees_used = info->fn(n, mask, dirmask, entry, info);
 498                         if (trees_used < 0) {
 499                                 error = trees_used;
 500                                 if (!info->show_all_errors)
 501                                         break;
 502                         }
 503                         mask &= trees_used;
 504                 }
 505                 for (i = 0; i < n; i++)
 506                         if (mask & (1ul << i))
 507                                 update_extended_entry(tx + i, entry + i);
 508         }
 509         free(entry);
 510         for (i = 0; i < n; i++)
 511                 free_extended_entry(tx + i);
 512         free(tx);
 513         free(traverse_path);
 514         info->traverse_path = NULL;
 515         strbuf_release(&base);
 516         return error;
 517 }
 518
 519 struct dir_state {
 520         void *tree;
 521         unsigned long size;
 522         struct object_id oid;
 523 };
 524
 525 static int find_tree_entry(struct repository *r, struct tree_desc *t,
 526                            const char *name, struct object_id *result,
 527                            unsigned short *mode)
 528 {
 529         int namelen = strlen(name);
 530         while (t->size) {
 531                 const char *entry;
 532                 struct object_id oid;
 533                 int entrylen, cmp;
 534
 535                 oidcpy(&oid, tree_entry_extract(t, &entry, mode));
 536                 entrylen = tree_entry_len(&t->entry);
 537                 update_tree_entry(t);
 538                 if (entrylen > namelen)
 539                         continue;
 540                 cmp = memcmp(name, entry, entrylen);
 541                 if (cmp > 0)
 542                         continue;
 543                 if (cmp < 0)
 544                         break;
 545                 if (entrylen == namelen) {
 546                         oidcpy(result, &oid);
 547                         return 0;
 548                 }
 549                 if (name[entrylen] != '/')
 550                         continue;
 551                 if (!S_ISDIR(*mode))
 552                         break;
 553                 if (++entrylen == namelen) {
 554                         oidcpy(result, &oid);
 555                         return 0;
 556                 }
 557                 return get_tree_entry(r, &oid, name + entrylen, result, mode);
 558         }
 559         return -1;
 560 }
 561
 562 int get_tree_entry(struct repository *r,
 563                    const struct object_id *tree_oid,
 564                    const char *name,
 565                    struct object_id *oid,
 566                    unsigned short *mode)
 567 {
 568         int retval;
 569         void *tree;
 570         unsigned long size;
 571         struct object_id root;
 572
 573         tree = read_object_with_reference(r, tree_oid, tree_type, &size, &root);
 574         if (!tree)
 575                 return -1;
 576
 577         if (name[0] == '\0') {
 578                 oidcpy(oid, &root);
 579                 free(tree);
 580                 return 0;
 581         }
 582
 583         if (!size) {
 584                 retval = -1;
 585         } else {
 586                 struct tree_desc t;
 587                 init_tree_desc(&t, tree, size);
 588                 retval = find_tree_entry(r, &t, name, oid, mode);
 589         }
 590         free(tree);
 591         return retval;
 592 }
 593
 594 /*
 595  * This is Linux's built-in max for the number of symlinks to follow.
 596  * That limit, of course, does not affect git, but it's a reasonable
 597  * choice.
 598  */
 599 #define GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS 40
 600
 601 /**
 602  * Find a tree entry by following symlinks in tree_sha (which is
 603  * assumed to be the root of the repository).  In the event that a
 604  * symlink points outside the repository (e.g. a link to /foo or a
 605  * root-level link to ../foo), the portion of the link which is
 606  * outside the repository will be returned in result_path, and *mode
 607  * will be set to 0.  It is assumed that result_path is uninitialized.
 608  * If there are no symlinks, or the end result of the symlink chain
 609  * points to an object inside the repository, result will be filled in
 610  * with the sha1 of the found object, and *mode will hold the mode of
 611  * the object.
 612  *
 613  * See the code for enum get_oid_result for a description of
 614  * the return values.
 615  */
 616 enum get_oid_result get_tree_entry_follow_symlinks(struct repository *r,
 617                 struct object_id *tree_oid, const char *name,
 618                 struct object_id *result, struct strbuf *result_path,
 619                 unsigned short *mode)
 620 {
 621         int retval = MISSING_OBJECT;
 622         struct dir_state *parents = NULL;
 623         size_t parents_alloc = 0;
 624         size_t i, parents_nr = 0;
 625         struct object_id current_tree_oid;
 626         struct strbuf namebuf = STRBUF_INIT;
 627         struct tree_desc t;
 628         int follows_remaining = GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS;
 629
 630         init_tree_desc(&t, NULL, 0UL);
 631         strbuf_addstr(&namebuf, name);
 632         oidcpy(&current_tree_oid, tree_oid);
 633
 634         while (1) {
 635                 int find_result;
 636                 char *first_slash;
 637                 char *remainder = NULL;
 638
 639                 if (!t.buffer) {
 640                         void *tree;
 641                         struct object_id root;
 642                         unsigned long size;
 643                         tree = read_object_with_reference(r,
 644                                                           &current_tree_oid,
 645                                                           tree_type, &size,
 646                                                           &root);
 647                         if (!tree)
 648                                 goto done;
 649
 650                         ALLOC_GROW(parents, parents_nr + 1, parents_alloc);
 651                         parents[parents_nr].tree = tree;
 652                         parents[parents_nr].size = size;
 653                         oidcpy(&parents[parents_nr].oid, &root);
 654                         parents_nr++;
 655
 656                         if (namebuf.buf[0] == '\0') {
 657                                 oidcpy(result, &root);
 658                                 retval = FOUND;
 659                                 goto done;
 660                         }
 661
 662                         if (!size)
 663                                 goto done;
 664
 665                         /* descend */
 666                         init_tree_desc(&t, tree, size);
 667                 }
 668
 669                 /* Handle symlinks to e.g. a//b by removing leading slashes */
 670                 while (namebuf.buf[0] == '/') {
 671                         strbuf_remove(&namebuf, 0, 1);
 672                 }
 673
 674                 /* Split namebuf into a first component and a remainder */
 675                 if ((first_slash = strchr(namebuf.buf, '/'))) {
 676                         *first_slash = 0;
 677                         remainder = first_slash + 1;
 678                 }
 679
 680                 if (!strcmp(namebuf.buf, "..")) {
 681                         struct dir_state *parent;
 682                         /*
 683                          * We could end up with .. in the namebuf if it
 684                          * appears in a symlink.
 685                          */
 686
 687                         if (parents_nr == 1) {
 688                                 if (remainder)
 689                                         *first_slash = '/';
 690                                 strbuf_add(result_path, namebuf.buf,
 691                                            namebuf.len);
 692                                 *mode = 0;
 693                                 retval = FOUND;
 694                                 goto done;
 695                         }
 696                         parent = &parents[parents_nr - 1];
 697                         free(parent->tree);
 698                         parents_nr--;
 699                         parent = &parents[parents_nr - 1];
 700                         init_tree_desc(&t, parent->tree, parent->size);
 701                         strbuf_remove(&namebuf, 0, remainder ? 3 : 2);
 702                         continue;
 703                 }
 704
 705                 /* We could end up here via a symlink to dir/.. */
 706                 if (namebuf.buf[0] == '\0') {
 707                         oidcpy(result, &parents[parents_nr - 1].oid);
 708                         retval = FOUND;
 709                         goto done;
 710                 }
 711
 712                 /* Look up the first (or only) path component in the tree. */
 713                 find_result = find_tree_entry(r, &t, namebuf.buf,
 714                                               &current_tree_oid, mode);
 715                 if (find_result) {
 716                         goto done;
 717                 }
 718
 719                 if (S_ISDIR(*mode)) {
 720                         if (!remainder) {
 721                                 oidcpy(result, &current_tree_oid);
 722                                 retval = FOUND;
 723                                 goto done;
 724                         }
 725                         /* Descend the tree */
 726                         t.buffer = NULL;
 727                         strbuf_remove(&namebuf, 0,
 728                                       1 + first_slash - namebuf.buf);
 729                 } else if (S_ISREG(*mode)) {
 730                         if (!remainder) {
 731                                 oidcpy(result, &current_tree_oid);
 732                                 retval = FOUND;
 733                         } else {
 734                                 retval = NOT_DIR;
 735                         }
 736                         goto done;
 737                 } else if (S_ISLNK(*mode)) {
 738                         /* Follow a symlink */
 739                         unsigned long link_len;
 740                         size_t len;
 741                         char *contents, *contents_start;
 742                         struct dir_state *parent;
 743                         enum object_type type;
 744
 745                         if (follows_remaining-- == 0) {
 746                                 /* Too many symlinks followed */
 747                                 retval = SYMLINK_LOOP;
 748                                 goto done;
 749                         }
 750
 751                         /*
 752                          * At this point, we have followed at a least
 753                          * one symlink, so on error we need to report this.
 754                          */
 755                         retval = DANGLING_SYMLINK;
 756
 757                         contents = repo_read_object_file(r,
 758                                                     &current_tree_oid, &type,
 759                                                     &link_len);
 760
 761                         if (!contents)
 762                                 goto done;
 763
 764                         if (contents[0] == '/') {
 765                                 strbuf_addstr(result_path, contents);
 766                                 free(contents);
 767                                 *mode = 0;
 768                                 retval = FOUND;
 769                                 goto done;
 770                         }
 771
 772                         if (remainder)
 773                                 len = first_slash - namebuf.buf;
 774                         else
 775                                 len = namebuf.len;
 776
 777                         contents_start = contents;
 778
 779                         parent = &parents[parents_nr - 1];
 780                         init_tree_desc(&t, parent->tree, parent->size);
 781                         strbuf_splice(&namebuf, 0, len,
 782                                       contents_start, link_len);
 783                         if (remainder)
 784                                 namebuf.buf[link_len] = '/';
 785                         free(contents);
 786                 }
 787         }
 788 done:
 789         for (i = 0; i < parents_nr; i++)
 790                 free(parents[i].tree);
 791         free(parents);
 792
 793         strbuf_release(&namebuf);
 794         return retval;
 795 }
 796
 797 static int match_entry(const struct pathspec_item *item,
 798                        const struct name_entry *entry, int pathlen,
 799                        const char *match, int matchlen,
 800                        enum interesting *never_interesting)
 801 {
 802         int m = -1; /* signals that we haven't called strncmp() */
 803
 804         if (item->magic & PATHSPEC_ICASE)
 805                 /*
 806                  * "Never interesting" trick requires exact
 807                  * matching. We could do something clever with inexact
 808                  * matching, but it's trickier (and not to forget that
 809                  * strcasecmp is locale-dependent, at least in
 810                  * glibc). Just disable it for now. It can't be worse
 811                  * than the wildcard's codepath of '[Tt][Hi][Is][Ss]'
 812                  * pattern.
 813                  */
 814                 *never_interesting = entry_not_interesting;
 815         else if (*never_interesting != entry_not_interesting) {
 816                 /*
 817                  * We have not seen any match that sorts later
 818                  * than the current path.
 819                  */
 820
 821                 /*
 822                  * Does match sort strictly earlier than path
 823                  * with their common parts?
 824                  */
 825                 m = strncmp(match, entry->path,
 826                             (matchlen < pathlen) ? matchlen : pathlen);
 827                 if (m < 0)
 828                         return 0;
 829
 830                 /*
 831                  * If we come here even once, that means there is at
 832                  * least one pathspec that would sort equal to or
 833                  * later than the path we are currently looking at.
 834                  * In other words, if we have never reached this point
 835                  * after iterating all pathspecs, it means all
 836                  * pathspecs are either outside of base, or inside the
 837                  * base but sorts strictly earlier than the current
 838                  * one.  In either case, they will never match the
 839                  * subsequent entries.  In such a case, we initialized
 840                  * the variable to -1 and that is what will be
 841                  * returned, allowing the caller to terminate early.
 842                  */
 843                 *never_interesting = entry_not_interesting;
 844         }
 845
 846         if (pathlen > matchlen)
 847                 return 0;
 848
 849         if (matchlen > pathlen) {
 850                 if (match[pathlen] != '/')
 851                         return 0;
 852                 if (!S_ISDIR(entry->mode) && !S_ISGITLINK(entry->mode))
 853                         return 0;
 854         }
 855
 856         if (m == -1)
 857                 /*
 858                  * we cheated and did not do strncmp(), so we do
 859                  * that here.
 860                  */
 861                 m = ps_strncmp(item, match, entry->path, pathlen);
 862
 863         /*
 864          * If common part matched earlier then it is a hit,
 865          * because we rejected the case where path is not a
 866          * leading directory and is shorter than match.
 867          */
 868         if (!m)
 869                 /*
 870                  * match_entry does not check if the prefix part is
 871                  * matched case-sensitively. If the entry is a
 872                  * directory and part of prefix, it'll be rematched
 873                  * eventually by basecmp with special treatment for
 874                  * the prefix.
 875                  */
 876                 return 1;
 877
 878         return 0;
 879 }
 880
 881 /* :(icase)-aware string compare */
 882 static int basecmp(const struct pathspec_item *item,
 883                    const char *base, const char *match, int len)
 884 {
 885         if (item->magic & PATHSPEC_ICASE) {
 886                 int ret, n = len > item->prefix ? item->prefix : len;
 887                 ret = strncmp(base, match, n);
 888                 if (ret)
 889                         return ret;
 890                 base += n;
 891                 match += n;
 892                 len -= n;
 893         }
 894         return ps_strncmp(item, base, match, len);
 895 }
 896
 897 static int match_dir_prefix(const struct pathspec_item *item,
 898                             const char *base,
 899                             const char *match, int matchlen)
 900 {
 901         if (basecmp(item, base, match, matchlen))
 902                 return 0;
 903
 904         /*
 905          * If the base is a subdirectory of a path which
 906          * was specified, all of them are interesting.
 907          */
 908         if (!matchlen ||
 909             base[matchlen] == '/' ||
 910             match[matchlen - 1] == '/')
 911                 return 1;
 912
 913         /* Just a random prefix match */
 914         return 0;
 915 }
 916
 917 /*
 918  * Perform matching on the leading non-wildcard part of
 919  * pathspec. item->nowildcard_len must be greater than zero. Return
 920  * non-zero if base is matched.
 921  */
 922 static int match_wildcard_base(const struct pathspec_item *item,
 923                                const char *base, int baselen,
 924                                int *matched)
 925 {
 926         const char *match = item->match;
 927         /* the wildcard part is not considered in this function */
 928         int matchlen = item->nowildcard_len;
 929
 930         if (baselen) {
 931                 int dirlen;
 932                 /*
 933                  * Return early if base is longer than the
 934                  * non-wildcard part but it does not match.
 935                  */
 936                 if (baselen >= matchlen) {
 937                         *matched = matchlen;
 938                         return !basecmp(item, base, match, matchlen);
 939                 }
 940
 941                 dirlen = matchlen;
 942                 while (dirlen && match[dirlen - 1] != '/')
 943                         dirlen--;
 944
 945                 /*
 946                  * Return early if base is shorter than the
 947                  * non-wildcard part but it does not match. Note that
 948                  * base ends with '/' so we are sure it really matches
 949                  * directory
 950                  */
 951                 if (basecmp(item, base, match, baselen))
 952                         return 0;
 953                 *matched = baselen;
 954         } else
 955                 *matched = 0;
 956         /*
 957          * we could have checked entry against the non-wildcard part
 958          * that is not in base and does similar never_interesting
 959          * optimization as in match_entry. For now just be happy with
 960          * base comparison.
 961          */
 962         return entry_interesting;
 963 }
 964
 965 /*
 966  * Is a tree entry interesting given the pathspec we have?
 967  *
 968  * Pre-condition: either baselen == base_offset (i.e. empty path)
 969  * or base[baselen-1] == '/' (i.e. with trailing slash).
 970  */
 971 static enum interesting do_match(struct index_state *istate,
 972                                  const struct name_entry *entry,
 973                                  struct strbuf *base, int base_offset,
 974                                  const struct pathspec *ps,
 975                                  int exclude)
 976 {
 977         int i;
 978         int pathlen, baselen = base->len - base_offset;
 979         enum interesting never_interesting = ps->has_wildcard ?
 980                 entry_not_interesting : all_entries_not_interesting;
 981
 982         GUARD_PATHSPEC(ps,
 983                        PATHSPEC_FROMTOP |
 984                        PATHSPEC_MAXDEPTH |
 985                        PATHSPEC_LITERAL |
 986                        PATHSPEC_GLOB |
 987                        PATHSPEC_ICASE |
 988                        PATHSPEC_EXCLUDE |
 989                        PATHSPEC_ATTR);
 990
 991         if (!ps->nr) {
 992                 if (!ps->recursive ||
 993                     !(ps->magic & PATHSPEC_MAXDEPTH) ||
 994                     ps->max_depth == -1)
 995                         return all_entries_interesting;
 996                 return within_depth(base->buf + base_offset, baselen,
 997                                     !!S_ISDIR(entry->mode),
 998                                     ps->max_depth) ?
 999                         entry_interesting : entry_not_interesting;
1000         }
1001
1002         pathlen = tree_entry_len(entry);
1003
1004         for (i = ps->nr - 1; i >= 0; i--) {
1005                 const struct pathspec_item *item = ps->items+i;
1006                 const char *match = item->match;
1007                 const char *base_str = base->buf + base_offset;
1008                 int matchlen = item->len, matched = 0;
1009
1010                 if ((!exclude &&   item->magic & PATHSPEC_EXCLUDE) ||
1011                     ( exclude && !(item->magic & PATHSPEC_EXCLUDE)))
1012                         continue;
1013
1014                 if (baselen >= matchlen) {
1015                         /* If it doesn't match, move along... */
1016                         if (!match_dir_prefix(item, base_str, match, matchlen))
1017                                 goto match_wildcards;
1018
1019                         if (!ps->recursive ||
1020                             !(ps->magic & PATHSPEC_MAXDEPTH) ||
1021                             ps->max_depth == -1) {
1022                                 if (!item->attr_match_nr)
1023                                         return all_entries_interesting;
1024                                 else
1025                                         goto interesting;
1026                         }
1027
1028                         if (within_depth(base_str + matchlen + 1,
1029                                          baselen - matchlen - 1,
1030                                          !!S_ISDIR(entry->mode),
1031                                          ps->max_depth))
1032                                 goto interesting;
1033                         else
1034                                 return entry_not_interesting;
1035                 }
1036
1037                 /* Either there must be no base, or the base must match. */
1038                 if (baselen == 0 || !basecmp(item, base_str, match, baselen)) {
1039                         if (match_entry(item, entry, pathlen,
1040                                         match + baselen, matchlen - baselen,
1041                                         &never_interesting))
1042                                 goto interesting;
1043
1044                         if (item->nowildcard_len < item->len) {
1045                                 if (!git_fnmatch(item, match + baselen, entry->path,
1046                                                  item->nowildcard_len - baselen))
1047                                         goto interesting;
1048
1049                                 /*
1050                                  * Match all directories. We'll try to
1051                                  * match files later on.
1052                                  */
1053                                 if (ps->recursive && S_ISDIR(entry->mode))
1054                                         return entry_interesting;
1055
1056                                 /*
1057                                  * When matching against submodules with
1058                                  * wildcard characters, ensure that the entry
1059                                  * at least matches up to the first wild
1060                                  * character.  More accurate matching can then
1061                                  * be performed in the submodule itself.
1062                                  */
1063                                 if (ps->recurse_submodules &&
1064                                     S_ISGITLINK(entry->mode) &&
1065                                     !ps_strncmp(item, match + baselen,
1066                                                 entry->path,
1067                                                 item->nowildcard_len - baselen))
1068                                         goto interesting;
1069                         }
1070
1071                         continue;
1072                 }
1073
1074 match_wildcards:
1075                 if (item->nowildcard_len == item->len)
1076                         continue;
1077
1078                 if (item->nowildcard_len &&
1079                     !match_wildcard_base(item, base_str, baselen, &matched))
1080                         continue;
1081
1082                 /*
1083                  * Concatenate base and entry->path into one and do
1084                  * fnmatch() on it.
1085                  *
1086                  * While we could avoid concatenation in certain cases
1087                  * [1], which saves a memcpy and potentially a
1088                  * realloc, it turns out not worth it. Measurement on
1089                  * linux-2.6 does not show any clear improvements,
1090                  * partly because of the nowildcard_len optimization
1091                  * in git_fnmatch(). Avoid micro-optimizations here.
1092                  *
1093                  * [1] if match_wildcard_base() says the base
1094                  * directory is already matched, we only need to match
1095                  * the rest, which is shorter so _in theory_ faster.
1096                  */
1097
1098                 strbuf_add(base, entry->path, pathlen);
1099
1100                 if (!git_fnmatch(item, match, base->buf + base_offset,
1101                                  item->nowildcard_len)) {
1102                         strbuf_setlen(base, base_offset + baselen);
1103                         goto interesting;
1104                 }
1105
1106                 /*
1107                  * When matching against submodules with
1108                  * wildcard characters, ensure that the entry
1109                  * at least matches up to the first wild
1110                  * character.  More accurate matching can then
1111                  * be performed in the submodule itself.
1112                  */
1113                 if (ps->recurse_submodules && S_ISGITLINK(entry->mode) &&
1114                     !ps_strncmp(item, match, base->buf + base_offset,
1115                                 item->nowildcard_len)) {
1116                         strbuf_setlen(base, base_offset + baselen);
1117                         goto interesting;
1118                 }
1119
1120                 strbuf_setlen(base, base_offset + baselen);
1121
1122                 /*
1123                  * Match all directories. We'll try to match files
1124                  * later on.
1125                  * max_depth is ignored but we may consider support it
1126                  * in future, see
1127                  * https://lore.kernel.org/git/7vmxo5l2g4.fsf@alter.siamese.dyndns.org/
1128                  */
1129                 if (ps->recursive && S_ISDIR(entry->mode))
1130                         return entry_interesting;
1131                 continue;
1132 interesting:
1133                 if (item->attr_match_nr) {
1134                         int ret;
1135
1136                         /*
1137                          * Must not return all_entries_not_interesting
1138                          * prematurely. We do not know if all entries do not
1139                          * match some attributes with current attr API.
1140                          */
1141                         never_interesting = entry_not_interesting;
1142
1143                         /*
1144                          * Consider all directories interesting (because some
1145                          * of those files inside may match some attributes
1146                          * even though the parent dir does not)
1147                          *
1148                          * FIXME: attributes _can_ match directories and we
1149                          * can probably return all_entries_interesting or
1150                          * all_entries_not_interesting here if matched.
1151                          */
1152                         if (S_ISDIR(entry->mode))
1153                                 return entry_interesting;
1154
1155                         strbuf_add(base, entry->path, pathlen);
1156                         ret = match_pathspec_attrs(istate, base->buf + base_offset,
1157                                                    base->len - base_offset, item);
1158                         strbuf_setlen(base, base_offset + baselen);
1159                         if (!ret)
1160                                 continue;
1161                 }
1162                 return entry_interesting;
1163         }
1164         return never_interesting; /* No matches */
1165 }
1166
1167 /*
1168  * Is a tree entry interesting given the pathspec we have?
1169  *
1170  * Pre-condition: either baselen == base_offset (i.e. empty path)
1171  * or base[baselen-1] == '/' (i.e. with trailing slash).
1172  */
1173 enum interesting tree_entry_interesting(struct index_state *istate,
1174                                         const struct name_entry *entry,
1175                                         struct strbuf *base, int base_offset,
1176                                         const struct pathspec *ps)
1177 {
1178         enum interesting positive, negative;
1179         positive = do_match(istate, entry, base, base_offset, ps, 0);
1180
1181         /*
1182          * case | entry | positive | negative | result
1183          * -----+-------+----------+----------+-------
1184          *   1  |  file |   -1     |  -1..2   |  -1
1185          *   2  |  file |    0     |  -1..2   |   0
1186          *   3  |  file |    1     |   -1     |   1
1187          *   4  |  file |    1     |    0     |   1
1188          *   5  |  file |    1     |    1     |   0
1189          *   6  |  file |    1     |    2     |   0
1190          *   7  |  file |    2     |   -1     |   2
1191          *   8  |  file |    2     |    0     |   1
1192          *   9  |  file |    2     |    1     |   0
1193          *  10  |  file |    2     |    2     |  -1
1194          * -----+-------+----------+----------+-------
1195          *  11  |  dir  |   -1     |  -1..2   |  -1
1196          *  12  |  dir  |    0     |  -1..2   |   0
1197          *  13  |  dir  |    1     |   -1     |   1
1198          *  14  |  dir  |    1     |    0     |   1
1199          *  15  |  dir  |    1     |    1     |   1 (*)
1200          *  16  |  dir  |    1     |    2     |   0
1201          *  17  |  dir  |    2     |   -1     |   2
1202          *  18  |  dir  |    2     |    0     |   1
1203          *  19  |  dir  |    2     |    1     |   1 (*)
1204          *  20  |  dir  |    2     |    2     |  -1
1205          *
1206          * (*) An exclude pattern interested in a directory does not
1207          * necessarily mean it will exclude all of the directory. In
1208          * wildcard case, it can't decide until looking at individual
1209          * files inside. So don't write such directories off yet.
1210          */
1211
1212         if (!(ps->magic & PATHSPEC_EXCLUDE) ||
1213             positive <= entry_not_interesting) /* #1, #2, #11, #12 */
1214                 return positive;
1215
1216         negative = do_match(istate, entry, base, base_offset, ps, 1);
1217
1218         /* #8, #18 */
1219         if (positive == all_entries_interesting &&
1220             negative == entry_not_interesting)
1221                 return entry_interesting;
1222
1223         /* #3, #4, #7, #13, #14, #17 */
1224         if (negative <= entry_not_interesting)
1225                 return positive;
1226
1227         /* #15, #19 */
1228         if (S_ISDIR(entry->mode) &&
1229             positive >= entry_interesting &&
1230             negative == entry_interesting)
1231                 return entry_interesting;
1232
1233         if ((positive == entry_interesting &&
1234              negative >= entry_interesting) || /* #5, #6, #16 */
1235             (positive == all_entries_interesting &&
1236              negative == entry_interesting)) /* #9 */
1237                 return entry_not_interesting;
1238
1239         return all_entries_not_interesting; /* #10, #20 */
1240 }