grep/sparse-integration-v1.3 #9
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Add a --sparse option to `git-grep`. This option is mainly used to: If searching in the index (using --cached): With --sparse, proceed the action when the current cache_entry is marked with SKIP_WORKTREE bit (the default is to skip this kind of entry). Before this patch, --cached itself can realize this action. Adding --sparse here grants the user finer control over sparse entries. If the user only wants to peak into the index without caring about sparse entries, --cached should suffice; if the user wants to peak into the index _and_ care about sparse entries, combining --sparse with --cached can address this need. Suggested-by: Victoria Dye <[email protected]> Signed-off-by: Shaoxuan Yuan <[email protected]>
This patch only turns on sparse-index, without actually modifying any functionalities. This change is preparing for the next patch[es], where sparse-index should be on. Signed-off-by: Shaoxuan Yuan <[email protected]>
Originally, `git-grep` always expands a sparse-index. Change it to only expands the index when using --sparse switch and the pathspec needs a expanded index. Signed-off-by: Shaoxuan Yuan <[email protected]>
ffyuanda
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Aug 26, 2022
Since commit fcc07e9 (is_promisor_object(): free tree buffer after parsing, 2021-04-13), we'll always free the buffers attached to a "struct tree" after searching them for promisor links. But there's an important case where we don't want to do so: if somebody else is already using the tree! This can happen during a "rev-list --missing=allow-promisor" traversal in a partial clone that is missing one or more trees or blobs. The backtrace for the free looks like this: #1 free_tree_buffer tree.c:147 #2 add_promisor_object packfile.c:2250 #3 for_each_object_in_pack packfile.c:2190 #4 for_each_packed_object packfile.c:2215 #5 is_promisor_object packfile.c:2272 #6 finish_object__ma builtin/rev-list.c:245 #7 finish_object builtin/rev-list.c:261 #8 show_object builtin/rev-list.c:274 #9 process_blob list-objects.c:63 git#10 process_tree_contents list-objects.c:145 git#11 process_tree list-objects.c:201 git#12 traverse_trees_and_blobs list-objects.c:344 [...] We're in the middle of walking through the entries of a tree object via process_tree_contents(). We see a blob (or it could even be another tree entry) that we don't have, so we call is_promisor_object() to check it. That function loops over all of the objects in the promisor packfile, including the tree we're currently walking. When we're done with it there, we free the tree buffer. But as we return to the walk in process_tree_contents(), it's still holding on to a pointer to that buffer, via its tree_desc iterator, and it accesses the freed memory. Even a trivial use of "--missing=allow-promisor" triggers this problem, as the included test demonstrates (it's just a vanilla --blob:none clone). We can detect this case by only freeing the tree buffer if it was allocated on our behalf. This is a little tricky since that happens inside parse_object(), and it doesn't tell us whether the object was already parsed, or whether it allocated the buffer itself. But by checking for an already-parsed tree beforehand, we can distinguish the two cases. That feels a little hacky, and does incur an extra lookup in the object-hash table. But that cost is fairly minimal compared to actually loading objects (and since we're iterating the whole pack here, we're likely to be loading most objects, rather than reusing cached results). It may also be a good direction for this function in general, as there are other possible optimizations that rely on doing some analysis before parsing: - we could detect blobs and avoid reading their contents; they can't link to other objects, but parse_object() doesn't know that we don't care about checking their hashes. - we could avoid allocating object structs entirely for most objects (since we really only need them in the oidset), which would save some memory. - promisor commits could use the commit-graph rather than loading the object from disk This commit doesn't do any of those optimizations, but I think it argues that this direction is reasonable, rather than relying on parse_object() and trying to teach it to give us more information about whether it parsed. The included test fails reliably under SANITIZE=address just when running "rev-list --missing=allow-promisor". Checking the output isn't strictly necessary to detect the bug, but it seems like a reasonable addition given the general lack of coverage for "allow-promisor" in the test suite. Reported-by: Andrew Olsen <[email protected]> Signed-off-by: Jeff King <[email protected]> Signed-off-by: Junio C Hamano <[email protected]>
ffyuanda
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Sep 1, 2022
Fix a memory leak occuring in case of pathspec copy in preload_index.
Direct leak of 8 byte(s) in 8 object(s) allocated from:
#0 0x7f0a353ead47 in __interceptor_malloc (/usr/lib/gcc/x86_64-pc-linux-gnu/11.3.0/libasan.so.6+0xb5d47)
#1 0x55750995e840 in do_xmalloc /home/anthony/src/c/git/wrapper.c:51
#2 0x55750995e840 in xmalloc /home/anthony/src/c/git/wrapper.c:72
#3 0x55750970f824 in copy_pathspec /home/anthony/src/c/git/pathspec.c:684
#4 0x557509717278 in preload_index /home/anthony/src/c/git/preload-index.c:135
#5 0x55750975f21e in refresh_index /home/anthony/src/c/git/read-cache.c:1633
#6 0x55750915b926 in cmd_status builtin/commit.c:1547
#7 0x5575090e1680 in run_builtin /home/anthony/src/c/git/git.c:466
#8 0x5575090e1680 in handle_builtin /home/anthony/src/c/git/git.c:720
#9 0x5575090e284a in run_argv /home/anthony/src/c/git/git.c:787
git#10 0x5575090e284a in cmd_main /home/anthony/src/c/git/git.c:920
git#11 0x5575090dbf82 in main /home/anthony/src/c/git/common-main.c:56
git#12 0x7f0a348230ab (/lib64/libc.so.6+0x290ab)
Signed-off-by: Anthony Delannoy <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
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