git-commit-vandalism/t/t9304-fast-import-marks.sh

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fast-import: fix over-allocation of marks storage Fast-import stores its marks in a trie-like structure made of mark_set structs. Each struct has a fixed size (1024). If our id number is too large to fit in the struct, then we allocate a new struct which shifts the id number by 10 bits. Our original struct becomes a child node of this new layer, and the new struct becomes the top level of the trie. This scheme was broken by ddddf8d7e2 (fast-import: permit reading multiple marks files, 2020-02-22). Before then, we had a top-level "marks" pointer, and the push-down worked by assigning the new top-level struct to "marks". But after that commit, insert_mark() takes a pointer to the mark_set, rather than using the global "marks". It continued to assign to the global "marks" variable during the push down, which was wrong for two reasons: - we added a call in option_rewrite_submodules() which uses a separate mark set; pushing down on "marks" is outright wrong here. We'd corrupt the "marks" set, and we'd fail to correctly store any submodule mappings with an id over 1024. - the other callers passed "marks", but the push-down was still wrong. In read_mark_file(), we take the pointer to the mark_set as a parameter. So even though insert_mark() was updating the global "marks", the local pointer we had in read_mark_file() was not updated. As a result, we'd add a new level when needed, but then the next call to insert_mark() wouldn't see it! It would then allocate a new layer, which would also not be seen, and so on. Lookups for the lost layers obviously wouldn't work, but before we even hit any lookup stage, we'd generally run out of memory and die. Our tests didn't notice either of these cases because they didn't have enough marks to trigger the push-down behavior. The new tests in t9304 cover both cases (and fail without this patch). We can solve the problem by having insert_mark() take a pointer-to-pointer of the top-level of the set. Then our push down can assign to it in a way that the caller actually sees. Note the subtle reordering in option_rewrite_submodules(). Our call to read_mark_file() may modify our top-level set pointer, so we have to wait until after it returns to assign its value into the string_list. Reported-by: Sergey Brester <serg.brester@sebres.de> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-15 17:38:49 +02:00
#!/bin/sh
test_description='test exotic situations with marks'
. ./test-lib.sh
test_expect_success 'setup dump of basic history' '
test_commit one &&
git fast-export --export-marks=marks HEAD >dump
'
test_expect_success 'setup large marks file' '
# normally a marks file would have a lot of useful, unique
# marks. But for our purposes, just having a lot of nonsense
# ones is fine. Start at 1024 to avoid clashing with marks
# legitimately used in our tiny dump.
blob=$(git rev-parse HEAD:one.t) &&
for i in $(test_seq 1024 16384)
do
echo ":$i $blob"
done >>marks
'
test_expect_success 'import with large marks file' '
git fast-import --import-marks=marks <dump
'
test_expect_success 'setup dump with submodule' '
git submodule add "$PWD" sub &&
git commit -m "add submodule" &&
git fast-export HEAD >dump
'
test_expect_success 'setup submodule mapping with large id' '
old=$(git rev-parse HEAD:sub) &&
new=$(echo $old | sed s/./a/g) &&
echo ":12345 $old" >from &&
echo ":12345 $new" >to
'
test_expect_success 'import with submodule mapping' '
git init dst &&
git -C dst fast-import \
--rewrite-submodules-from=sub:../from \
--rewrite-submodules-to=sub:../to \
<dump &&
git -C dst rev-parse HEAD:sub >actual &&
echo "$new" >expect &&
test_cmp expect actual
'
test_done