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