@matheusbsbs / matheus-bagliano / commits / 998330ac2e

read-cache: look for shared index files next to the index, too

When reading a split index git always looks for its referenced shared base index in the gitdir of the current repository, even when reading an alternate index specified via GIT_INDEX_FILE, and even when that alternate index file is the "main" '.git/index' file of an other repository. However, if that split index and its referenced shared index files were written by a git command running entirely in that other repository, then, naturally, the shared index file is written to that other repository's gitdir. Consequently, a git command attempting to read that shared index file while running in a different repository won't be able find it and will error out. I'm not sure in what use case it is necessary to read the index of one repository by a git command running in a different repository, but it is certainly possible to do so, and in fact the test 'bare repository: check that --cached honors index' in 't0003-attributes.sh' does exactly that. If GIT_TEST_SPLIT_INDEX=1 were to split the index in just the right moment [1], then this test would indeed fail, because the referenced shared index file could not be found. Let's look for the referenced shared index file not only in the gitdir of the current directory, but, if the shared index is not there, right next to the split index as well. [1] We haven't seen this issue trigger a failure in t0003 yet, because: - While GIT_TEST_SPLIT_INDEX=1 is supposed to trigger index splitting randomly, the first index write has always been deterministic and it has never split the index. - That alternate index file in the other repository is written only once in the entire test script, so it's never split. However, the next patch will fix GIT_TEST_SPLIT_INDEX, and while doing so it will slightly change its behavior to always split the index already on the first index write, and t0003 would always fail without this patch. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

SZEDER Gábor committed Aug 26, 2021 at 23:00 UTC 998330ac2e7c384d2f73c734177ca21f36c06e48

2 files changed +36 -1

read-cache.c

+13 -1

@@ -2391,9 +2391,21 @@ int read_index_from(struct index_state *istate, const char *path,

2391 base_path = xstrfmt("%s/sharedindex.%s", gitdir, base_oid_hex);

2392 trace2_region_enter_printf("index", "shared/do_read_index",

2393 the_repository, "%s", base_path);

2394 - ret = do_read_index(split_index->base, base_path, 1);

2394 + ret = do_read_index(split_index->base, base_path, 0);

2395 trace2_region_leave_printf("index", "shared/do_read_index",

2396 the_repository, "%s", base_path);

2397 + if (!ret) {

2398 + char *path_copy = xstrdup(path);

2399 + const char *base_path2 = xstrfmt("%s/sharedindex.%s",

2400 + dirname(path_copy),

2401 + base_oid_hex);

2402 + free(path_copy);

2403 + trace2_region_enter_printf("index", "shared/do_read_index",

2404 + the_repository, "%s", base_path2);

2405 + ret = do_read_index(split_index->base, base_path2, 1);

2406 + trace2_region_leave_printf("index", "shared/do_read_index",

2407 + the_repository, "%s", base_path2);

2408 + }

2409 if (!oideq(&split_index->base_oid, &split_index->base->oid))

2410 die(_("broken index, expect %s in %s, got %s"),

2411 base_oid_hex, base_path,

t/t1700-split-index.sh

+23

@@ -510,4 +510,27 @@ test_expect_success 'do not refresh null base index' '

510 )

511 '

512

513 +test_expect_success 'reading split index at alternate location' '

514 + git init reading-alternate-location &&

515 + (

516 + cd reading-alternate-location &&

517 + >file-in-alternate &&

518 + git update-index --split-index --add file-in-alternate

519 + ) &&

520 + echo file-in-alternate >expect &&

521 +

522 + # Should be able to find the shared index both right next to

523 + # the specified split index file ...

524 + GIT_INDEX_FILE=./reading-alternate-location/.git/index \

525 + git ls-files --cached >actual &&

526 + test_cmp expect actual &&

527 +

528 + # ... and, for backwards compatibility, in the current GIT_DIR

529 + # as well.

530 + mv -v ./reading-alternate-location/.git/sharedindex.* .git &&

531 + GIT_INDEX_FILE=./reading-alternate-location/.git/index \

532 + git ls-files --cached >actual &&

533 + test_cmp expect actual

534 +'

535 +

536 test_done