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unpack-trees.c: look ahead in the index

This makes the traversal of index be in sync with the tree traversal. When unpack_callback() is fed a set of tree entries from trees, it inspects the name of the entry and checks if the an index entry with the same name could be hiding behind the current index entry, and (1) if the name appears in the index as a leaf node, it is also fed to the n_way_merge() callback function; (2) if the name is a directory in the index, i.e. there are entries in that are underneath it, then nothing is fed to the n_way_merge() callback function; (3) otherwise, if the name comes before the first eligible entry in the index, the index entry is first unpacked alone. When traverse_trees_recursive() descends into a subdirectory, the cache_bottom pointer is moved to walk index entries within that directory. All of these are omitted for diff-index, which does not even want to be fed an index entry and a tree entry with D/F conflicts. This fixes 3-way read-tree and exposes a bug in other parts of the system in t6035, test #5. The test prepares these three trees: O = HEAD^ 100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 a/b-2/c/d 100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 a/b/c/d 100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 a/x A = HEAD 100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 a/b-2/c/d 100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 a/b/c/d 100644 blob 587be6b4c3f93f93c489c0111bba5596147a26cb a/x B = master 120000 blob a36b77384451ea1de7bd340ffca868249626bc52 a/b 100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 a/b-2/c/d 100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 a/x With a clean index that matches HEAD, running git read-tree -m -u --aggressive $O $A $B now yields 120000 a36b77384451ea1de7bd340ffca868249626bc52 3 a/b 100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0 a/b-2/c/d 100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 1 a/b/c/d 100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 2 a/b/c/d 100644 587be6b4c3f93f93c489c0111bba5596147a26cb 0 a/x which is correct. "master" created "a/b" symlink that did not exist, and removed "a/b/c/d" while HEAD did not do touch either path. Before this series, read-tree did not notice the situation and resolved addition of "a/b" and removal of "a/b/c/d" independently. If A = HEAD had another path "a/b/c/e" added, this merge should conflict but instead it silently resolved "a/b" and then immediately overwrote it to add "a/b/c/e", which was quite bogus. Tests in t1012 start to work with this. Signed-off-by: Junio C Hamano <gitster@pobox.com>

Junio C Hamano committed Sep 20, 2009 at 00:03 UTC 730f72840cc50c523fe4cdd796ea2d2fc4571a28

5 files changed +140 -7

diff-lib.c

@@ -425,6 +425,7 @@ int run_diff_index(struct rev_info *revs, int cached)

425 exit(128);

426

427 diff_set_mnemonic_prefix(&revs->diffopt, "c/", cached ? "i/" : "w/");

428 + diffcore_fix_diff_index(&revs->diffopt);

429 diffcore_std(&revs->diffopt);

430 diff_flush(&revs->diffopt);

431 return 0;

diff.c

+17

@@ -3628,6 +3628,23 @@ static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)

3628 *q = outq;

3629 }

3630

3631 +static int diffnamecmp(const void *a_, const void *b_)

3632 +{

3633 + const struct diff_filepair *a = *((const struct diff_filepair **)a_);

3634 + const struct diff_filepair *b = *((const struct diff_filepair **)b_);

3635 + const char *name_a, *name_b;

3636 +

3637 + name_a = a->one ? a->one->path : a->two->path;

3638 + name_b = b->one ? b->one->path : b->two->path;

3639 + return strcmp(name_a, name_b);

3640 +}

3641 +

3642 +void diffcore_fix_diff_index(struct diff_options *options)

3643 +{

3644 + struct diff_queue_struct *q = &diff_queued_diff;

3645 + qsort(q->queue, q->nr, sizeof(q->queue[0]), diffnamecmp);

3646 +}

3647 +

3648 void diffcore_std(struct diff_options *options)

3649 {

3650 if (options->skip_stat_unmatch)

diff.h

@@ -208,6 +208,7 @@ extern int diff_setup_done(struct diff_options *);

208 #define DIFF_PICKAXE_REGEX 2

209

210 extern void diffcore_std(struct diff_options *);

211 +extern void diffcore_fix_diff_index(struct diff_options *);

212

213 #define COMMON_DIFF_OPTIONS_HELP \

214 "\ncommon diff options:\n" \

t/t1012-read-tree-df.sh

+4 -4

@@ -51,7 +51,7 @@ test_expect_success setup '

51 :

52 '

54 -test_expect_failure '3-way (1)' '

54 +test_expect_success '3-way (1)' '

55 settree A-000 &&

56 git read-tree -m -u O-000 A-000 B-000 &&

57 checkindex <<-EOF

@@ -63,7 +63,7 @@ test_expect_failure '3-way (1)' '

63 EOF

64 '

66 -test_expect_failure '3-way (2)' '

66 +test_expect_success '3-way (2)' '

67 settree A-001 &&

68 git read-tree -m -u O-000 A-001 B-000 &&

69 checkindex <<-EOF

@@ -76,7 +76,7 @@ test_expect_failure '3-way (2)' '

76 EOF

77 '

79 -test_expect_failure '3-way (3)' '

79 +test_expect_success '3-way (3)' '

80 settree A-010 &&

81 git read-tree -m -u O-010 A-010 B-010 &&

82 checkindex <<-EOF

@@ -90,7 +90,7 @@ test_expect_failure '3-way (3)' '

90 EOF

91 '

93 -test_expect_failure '2-way (1)' '

93 +test_expect_success '2-way (1)' '

94 settree O-020 &&

95 git read-tree -m -u O-020 A-020 &&

96 checkindex <<-EOF

unpack-trees.c

+117 -3

@@ -231,9 +231,37 @@ static int unpack_index_entry(struct cache_entry *ce,

231 return ret;

232 }

233

234 +static int find_cache_pos(struct traverse_info *, const struct name_entry *);

235 +

236 +static void restore_cache_bottom(struct traverse_info *info, int bottom)

237 +{

238 + struct unpack_trees_options *o = info->data;

239 +

240 + if (o->diff_index_cached)

241 + return;

242 + o->cache_bottom = bottom;

243 +}

244 +

245 +static int switch_cache_bottom(struct traverse_info *info)

246 +{

247 + struct unpack_trees_options *o = info->data;

248 + int ret, pos;

249 +

250 + if (o->diff_index_cached)

251 + return 0;

252 + ret = o->cache_bottom;

253 + pos = find_cache_pos(info->prev, &info->name);

254 +

255 + if (pos < -1)

256 + o->cache_bottom = -2 - pos;

257 + else if (pos < 0)

258 + o->cache_bottom = o->src_index->cache_nr;

259 + return ret;

260 +}

261 +

262 static int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)

263 {

236 - int i;

264 + int i, ret, bottom;

265 struct tree_desc t[MAX_UNPACK_TREES];

266 struct traverse_info newinfo;

267 struct name_entry *p;

@@ -254,7 +282,11 @@ static int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long

282 sha1 = names[i].sha1;

283 fill_tree_descriptor(t+i, sha1);

284 }

257 - return traverse_trees(n, t, &newinfo);

285 +

286 + bottom = switch_cache_bottom(&newinfo);

287 + ret = traverse_trees(n, t, &newinfo);

288 + restore_cache_bottom(&newinfo, bottom);

289 + return ret;

290 }

291

292 /*

@@ -393,6 +425,82 @@ static int unpack_failed(struct unpack_trees_options *o, const char *message)

425 return -1;

426 }

427

428 +/* NEEDSWORK: give this a better name and share with tree-walk.c */

429 +static int name_compare(const char *a, int a_len,

430 + const char *b, int b_len)

431 +{

432 + int len = (a_len < b_len) ? a_len : b_len;

433 + int cmp = memcmp(a, b, len);

434 + if (cmp)

435 + return cmp;

436 + return (a_len - b_len);

437 +}

438 +

439 +/*

440 + * The tree traversal is looking at name p. If we have a matching entry,

441 + * return it. If name p is a directory in the index, do not return

442 + * anything, as we will want to match it when the traversal descends into

443 + * the directory.

444 + */

445 +static int find_cache_pos(struct traverse_info *info,

446 + const struct name_entry *p)

447 +{

448 + int pos;

449 + struct unpack_trees_options *o = info->data;

450 + struct index_state *index = o->src_index;

451 + int pfxlen = info->pathlen;

452 + int p_len = tree_entry_len(p->path, p->sha1);

453 +

454 + for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {

455 + struct cache_entry *ce = index->cache[pos];

456 + const char *ce_name, *ce_slash;

457 + int cmp, ce_len;

458 +

459 + if (!ce_in_traverse_path(ce, info))

460 + continue;

461 + if (ce->ce_flags & CE_UNPACKED)

462 + continue;

463 + ce_name = ce->name + pfxlen;

464 + ce_slash = strchr(ce_name, '/');

465 + if (ce_slash)

466 + ce_len = ce_slash - ce_name;

467 + else

468 + ce_len = ce_namelen(ce) - pfxlen;

469 + cmp = name_compare(p->path, p_len, ce_name, ce_len);

470 + /*

471 + * Exact match; if we have a directory we need to

472 + * delay returning it.

473 + */

474 + if (!cmp)

475 + return ce_slash ? -2 - pos : pos;

476 + if (0 < cmp)

477 + continue; /* keep looking */

478 + /*

479 + * ce_name sorts after p->path; could it be that we

480 + * have files under p->path directory in the index?

481 + * E.g. ce_name == "t-i", and p->path == "t"; we may

482 + * have "t/a" in the index.

483 + */

484 + if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&

485 + ce_name[p_len] < '/')

486 + continue; /* keep looking */

487 + break;

488 + }

489 + return -1;

490 +}

491 +

492 +static struct cache_entry *find_cache_entry(struct traverse_info *info,

493 + const struct name_entry *p)

494 +{

495 + int pos = find_cache_pos(info, p);

496 + struct unpack_trees_options *o = info->data;

497 +

498 + if (0 <= pos)

499 + return o->src_index->cache[pos];

500 + else

501 + return NULL;

502 +}

503 +

504 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)

505 {

506 struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };

@@ -406,8 +514,14 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str

514 /* Are we supposed to look at the index too? */

515 if (o->merge) {

516 while (1) {

409 - struct cache_entry *ce = next_cache_entry(o);

517 int cmp;

518 + struct cache_entry *ce;

519 +

520 + if (o->diff_index_cached)

521 + ce = next_cache_entry(o);

522 + else

523 + ce = find_cache_entry(info, p);

524 +

525 if (!ce)

526 break;

527 cmp = compare_entry(ce, info, p);