git/split-index.c, branch v2.40.2

treewide: always have a valid "index_state.repo" member

2023-01-17T22:32:06Z

When the "repo" member was added to "the_index" in [1] the repo_read_index() was made to populate it, but the unpopulated "the_index" variable didn't get the same treatment. Let's do that in initialize_the_repository() when we set it up, and likewise for all of the current callers initialized an empty "struct index_state". This simplifies code that needs to deal with "the_index" or a custom "struct index_state", we no longer need to second-guess this part of the "index_state" deep in the stack. A recent example of such second-guessing is the "istate->repo ? istate->repo : the_repository" code in [2]. We can now simply use "istate->repo". We're doing this by making use of the INDEX_STATE_INIT() macro (and corresponding function) added in [3], which now have mandatory "repo" arguments. Because we now call index_state_init() in repository.c's initialize_the_repository() we don't need to handle the case where we have a "repo->index" whose "repo" member doesn't match the "repo" we're setting up, i.e. the "Complete the double-reference" code in repo_read_index() being altered here. That logic was originally added in [1], and was working around the lack of what we now have in initialize_the_repository(). For "fsmonitor-settings.c" we can remove the initialization of a NULL "r" argument to "the_repository". This was added back in [4], and was needed at the time for callers that would pass us the "r" from an "istate->repo". Before this change such a change to "fsmonitor-settings.c" would segfault all over the test suite (e.g. in t0002-gitfile.sh). This change has wider eventual implications for "fsmonitor-settings.c". The reason the other lazy loading behavior in it is required (starting with "if (!r->settings.fsmonitor) ..." is because of the previously passed "r" being "NULL". I have other local changes on top of this which move its configuration reading to "prepare_repo_settings()" in "repo-settings.c", as we could now start to rely on it being called for our "r". But let's leave all of that for now, and narrowly remove this particular part of the lazy-loading. 1. 1fd9ae517c4 (repository: add repo reference to index_state, 2021-01-23) 2. ee1f0c242ef (read-cache: add index.skipHash config option, 2023-01-06) 3. 2f6b1eb794e (cache API: add a "INDEX_STATE_INIT" macro/function, add release_index(), 2023-01-12) 4. 1e0ea5c4316 (fsmonitor: config settings are repository-specific, 2022-03-25) Signed-off-by: Ævar Arnfjörð Bjarmason Acked-by: Derrick Stolee Signed-off-by: Junio C Hamano

cache API: add a "INDEX_STATE_INIT" macro/function, add release_index()

2023-01-16T18:46:58Z

Hopefully in some not so distant future, we'll get advantages from always initializing the "repo" member of the "struct index_state". To make that easier let's introduce an initialization macro & function. The various ad-hoc initialization of the structure can then be changed over to it, and we can remove the various "0" assignments in discard_index() in favor of calling index_state_init() at the end. While not strictly necessary, let's also change the CALLOC_ARRAY() of various "struct index_state *" to use an ALLOC_ARRAY() followed by index_state_init() instead. We're then adding the release_index() function and converting some callers (including some of these allocations) over to it if they either won't need to use their "struct index_state" again, or are just about to call index_state_init(). Signed-off-by: Ævar Arnfjörð Bjarmason Acked-by: Derrick Stolee Signed-off-by: Junio C Hamano

split-index: it really is incompatible with the sparse index

2022-01-24T01:06:23Z

... at least for now. So let's error out if we are even trying to initialize the split index when the index is sparse, or when trying to write the split index extension for a sparse index. Signed-off-by: Johannes Schindelin Reviewed-by: Elijah Newren Signed-off-by: Junio C Hamano

split-index: use oideq instead of memcmp to compare object_id's

2021-06-15T03:07:56Z

cache_entry contains an object_id, and compare_ce_content() would include that field when calling memcmp on a subset of the cache_entry. Depending on which hashing algorithm is being used, only part of object_id.hash is actually being used, therefore including it in a memcmp() is incorrect. Instead we choose to exclude the object_id when calling memcmp(), and call oideq() separately. This issue was found when running t1700-split-index with MSAN, see MSAN output below (on my machine, offset 76 corresponds to 4 bytes after the start of object_id.hash). Uninitialized bytes in MemcmpInterceptorCommon at offset 76 inside [0x7f60e7c00118, 92) ==27914==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x4524ee in memcmp /home/abuild/rpmbuild/BUILD/llvm-11.0.0.src/build/../projects/compiler-rt/lib/msan/../sanitizer_common/sanitizer_common_interceptors.inc:873:10 #1 0xc867ae in compare_ce_content /home/ahunt/git/git/split-index.c:208:8 #2 0xc859fb in prepare_to_write_split_index /home/ahunt/git/git/split-index.c:336:9 #3 0xb4bbca in write_split_index /home/ahunt/git/git/read-cache.c:3107:2 #4 0xb42b4d in write_locked_index /home/ahunt/git/git/read-cache.c:3295:8 #5 0x638058 in try_merge_strategy /home/ahunt/git/git/builtin/merge.c:758:7 #6 0x63057f in cmd_merge /home/ahunt/git/git/builtin/merge.c:1663:9 #7 0x4a1e76 in run_builtin /home/ahunt/git/git/git.c:461:11 #8 0x49e1e7 in handle_builtin /home/ahunt/git/git/git.c:714:3 #9 0x4a0c08 in run_argv /home/ahunt/git/git/git.c:781:4 #10 0x49d5a8 in cmd_main /home/ahunt/git/git/git.c:912:19 #11 0x7974da in main /home/ahunt/git/git/common-main.c:52:11 #12 0x7f60e928e349 in __libc_start_main (/lib64/libc.so.6+0x24349) #13 0x421bd9 in _start /home/abuild/rpmbuild/BUILD/glibc-2.26/csu/../sysdeps/x86_64/start.S:120 Uninitialized value was stored to memory at #0 0x447eb9 in __msan_memcpy /home/abuild/rpmbuild/BUILD/llvm-11.0.0.src/build/../projects/compiler-rt/lib/msan/msan_interceptors.cpp:1558:3 #1 0xb4d1e6 in dup_cache_entry /home/ahunt/git/git/read-cache.c:3457:2 #2 0xd214fa in add_entry /home/ahunt/git/git/unpack-trees.c:215:18 #3 0xd1fae0 in keep_entry /home/ahunt/git/git/unpack-trees.c:2276:2 #4 0xd1ff9e in twoway_merge /home/ahunt/git/git/unpack-trees.c:2504:11 #5 0xd27028 in call_unpack_fn /home/ahunt/git/git/unpack-trees.c:593:12 #6 0xd2443d in unpack_nondirectories /home/ahunt/git/git/unpack-trees.c:1106:12 #7 0xd19435 in unpack_callback /home/ahunt/git/git/unpack-trees.c:1306:6 #8 0xd0d7ff in traverse_trees /home/ahunt/git/git/tree-walk.c:532:17 #9 0xd1773a in unpack_trees /home/ahunt/git/git/unpack-trees.c:1683:9 #10 0xdc6370 in checkout /home/ahunt/git/git/merge-ort.c:3590:8 #11 0xdc51c3 in merge_switch_to_result /home/ahunt/git/git/merge-ort.c:3728:7 #12 0xa195a9 in merge_ort_recursive /home/ahunt/git/git/merge-ort-wrappers.c:58:2 #13 0x637fff in try_merge_strategy /home/ahunt/git/git/builtin/merge.c:751:12 #14 0x63057f in cmd_merge /home/ahunt/git/git/builtin/merge.c:1663:9 #15 0x4a1e76 in run_builtin /home/ahunt/git/git/git.c:461:11 #16 0x49e1e7 in handle_builtin /home/ahunt/git/git/git.c:714:3 #17 0x4a0c08 in run_argv /home/ahunt/git/git/git.c:781:4 #18 0x49d5a8 in cmd_main /home/ahunt/git/git/git.c:912:19 #19 0x7974da in main /home/ahunt/git/git/common-main.c:52:11 Uninitialized value was created by a heap allocation #0 0x44e73d in malloc /home/abuild/rpmbuild/BUILD/llvm-11.0.0.src/build/../projects/compiler-rt/lib/msan/msan_interceptors.cpp:901:3 #1 0xd592f6 in do_xmalloc /home/ahunt/git/git/wrapper.c:41:8 #2 0xd59248 in xmalloc /home/ahunt/git/git/wrapper.c:62:9 #3 0xa17088 in mem_pool_alloc_block /home/ahunt/git/git/mem-pool.c:22:6 #4 0xa16f78 in mem_pool_init /home/ahunt/git/git/mem-pool.c:44:3 #5 0xb481b8 in load_all_cache_entries /home/ahunt/git/git/read-cache.c #6 0xb44d40 in do_read_index /home/ahunt/git/git/read-cache.c:2298:17 #7 0xb48a1b in read_index_from /home/ahunt/git/git/read-cache.c:2389:8 #8 0xbd5a0b in repo_read_index /home/ahunt/git/git/repository.c:276:8 #9 0xb4bcaf in repo_read_index_unmerged /home/ahunt/git/git/read-cache.c:3326:2 #10 0x62ed26 in cmd_merge /home/ahunt/git/git/builtin/merge.c:1362:6 #11 0x4a1e76 in run_builtin /home/ahunt/git/git/git.c:461:11 #12 0x49e1e7 in handle_builtin /home/ahunt/git/git/git.c:714:3 #13 0x4a0c08 in run_argv /home/ahunt/git/git/git.c:781:4 #14 0x49d5a8 in cmd_main /home/ahunt/git/git/git.c:912:19 #15 0x7974da in main /home/ahunt/git/git/common-main.c:52:11 #16 0x7f60e928e349 in __libc_start_main (/lib64/libc.so.6+0x24349) SUMMARY: MemorySanitizer: use-of-uninitialized-value /home/abuild/rpmbuild/BUILD/llvm-11.0.0.src/build/../projects/compiler-rt/lib/msan/../sanitizer_common/sanitizer_common_interceptors.inc:873:10 in memcmp Exiting Signed-off-by: Andrzej Hunt Signed-off-by: Junio C Hamano

Always use oidread to read into struct object_id

2021-04-27T07:31:38Z

In the future, we'll want oidread to automatically set the hash algorithm member for an object ID we read into it, so ensure we use oidread instead of hashcpy everywhere we're copying a hash value into a struct object_id. Signed-off-by: brian m. carlson Signed-off-by: Junio C Hamano

use CALLOC_ARRAY

2021-03-14T00:00:09Z

Add and apply a semantic patch for converting code that open-codes CALLOC_ARRAY to use it instead. It shortens the code and infers the element size automatically. Signed-off-by: René Scharfe Signed-off-by: Junio C Hamano

mem-pool: use more standard initialization and finalization

2020-08-18T19:16:06Z

A typical memory type, such as strbuf, hashmap, or string_list can be stored on the stack or embedded within another structure. mem_pool cannot be, because of how mem_pool_init() and mem_pool_discard() are written. mem_pool_init() does essentially the following (simplified for purposes of explanation here): void mem_pool_init(struct mem_pool **pool...) { *pool = xcalloc(1, sizeof(*pool)); It seems weird to require that mem_pools can only be accessed through a pointer. It also seems slightly dangerous: unlike strbuf_release() or strbuf_reset() or string_list_clear(), all of which put the data structure into a state where it can be re-used after the call, mem_pool_discard(pool) will leave pool pointing at free'd memory. read-cache (and split-index) are the only current users of mem_pools, and they haven't fallen into a use-after-free mistake here, but it seems likely to be problematic for future users especially since several of the current callers of mem_pool_init() will only call it when the mem_pool* is not already allocated (i.e. is NULL). This type of mechanism also prevents finding synchronization points where one can free existing memory and then resume more operations. It would be natural at such points to run something like mem_pool_discard(pool...); and, if necessary, mem_pool_init(&pool...); and then carry on continuing to use the pool. However, this fails badly if several objects had a copy of the value of pool from before these commands; in such a case, those objects won't get the updated value of pool that mem_pool_init() overwrites pool with and they'll all instead be reading and writing from free'd memory. Modify mem_pool_init()/mem_pool_discard() to behave more like strbuf_init()/strbuf_release() or string_list_init()/string_list_clear() In particular: (1) make mem_pool_init() just take a mem_pool* and have it only worry about allocating struct mp_blocks, not the struct mem_pool itself, (2) make mem_pool_discard() free the memory that the pool was responsible for, but leave it in a state where it can be used to allocate more memory afterward (without the need to call mem_pool_init() again). Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano

Merge branch 'nd/split-index-null-base-fix'

2019-03-07T00:59:56Z

Split-index fix. * nd/split-index-null-base-fix: read-cache.c: fix writing "link" index ext with null base oid

read-cache.c: fix writing "link" index ext with null base oid

2019-02-13T20:52:48Z

Since commit 7db118303a (unpack_trees: fix breakage when o->src_index != o->dst_index - 2018-04-23) and changes in merge code to use separate index_state for source and destination, when doing a merge with split index activated, we may run into this line in unpack_trees(): o->result.split_index = init_split_index(&o->result); This is by itself not wrong. But this split index information is not fully populated (and it's only so when move_cache_to_base_index() is called, aka force splitting the index, or loading index_state from a file). Both "base_oid" and "base" in this case remain null. So when writing the main index down, we link to this index with null oid (default value after init_split_index()), which also means "no split index" internally. This triggers an incorrect base index refresh: warning: could not freshen shared index '.../sharedindex.0{40}' This patch makes sure we will not refresh null base_oid (because the file is never there). It also makes sure not to write "link" extension with null base_oid in the first place (no point having it at all). Read code already has protection against null base_oid. There is also another side fix in remove_split_index() that causes a crash when doing "git update-index --no-split-index" when base_oid in the index file is null. In this case we will not load istate->split_index->base but we dereference it anyway and are rewarded with a segfault. This should not happen anymore, but it's still wrong to dereference a potential NULL pointer, especially when we do check for NULL pointer in the next code. Reported-by: Luke Diamand Signed-off-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano

read-cache: add invalidate parameter to remove_marked_cache_entries

2019-01-02T23:28:05Z

When marking cache entries for removal, and later removing them all at once using 'remove_marked_cache_entries()', cache entries currently have to be invalidated manually in the cache tree and in the untracked cache. Add an invalidate flag to the function. With the flag set, the function will take care of invalidating the path in the cache tree and in the untracked cache. Note that the current callsites already do the invalidation properly in other places, so we're just passing 0 from there to keep the status quo. This will be useful in a subsequent commit. Signed-off-by: Thomas Gummerer Signed-off-by: Junio C Hamano