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author | Jeff King <peff@peff.net> | 2018-08-02 14:58:21 -0400 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2018-08-02 12:52:19 -0700 |
commit | 2ec4150713eabc725ba1c43fbe032adb43d5d4cf (patch) | |
tree | 8da54e37098aa507793666245963e79b9ab8bc90 | |
parent | Git 2.16.4 (diff) | |
download | tgif-2ec4150713eabc725ba1c43fbe032adb43d5d4cf.tar.xz |
score_trees(): fix iteration over trees with missing entries
In score_trees(), we walk over two sorted trees to find
which entries are missing or have different content between
the two. So if we have two trees with these entries:
one two
--- ---
a a
b c
c d
we'd expect the loop to:
- compare "a" to "a"
- compare "b" to "c"; because these are sorted lists, we
know that the second tree does not have "b"
- compare "c" to "c"
- compare "d" to end-of-list; we know that the first tree
does not have "d"
And prior to d8febde370 (match-trees: simplify score_trees()
using tree_entry(), 2013-03-24) that worked. But after that
commit, we mistakenly increment the tree pointers for every
loop iteration, even when we've processed the entry for only
one side. As a result, we end up doing this:
- compare "a" to "a"
- compare "b" to "c"; we know that we do not have "b", but
we still increment both tree pointers; at this point
we're out of sync and all further comparisons are wrong
- compare "c" to "d" and mistakenly claim that the second
tree does not have "c"
- exit the loop, mistakenly not realizing that the first
tree does not have "d"
So contrary to the claim in d8febde370, we really do need to
manually use update_tree_entry(), because advancing the tree
pointer depends on the entry comparison.
That means we must stop using tree_entry() to access each
entry, since it auto-advances the pointer. Instead:
- we'll use tree_desc.size directly to know if there's
anything left to look at (which is what tree_entry() was
doing under the hood)
- rather than do an extra struct assignment to "e1" and
"e2", we can just access the "entry" field of tree_desc
directly
That makes us a little more intimate with the tree_desc
code, but that's not uncommon for its callers.
The included test shows off the bug by adding a new entry
"bar.t", which sorts early in the tree and de-syncs the
comparison for "foo.t", which comes after.
Reported-by: George Shammas <georgyo@gmail.com>
Helped-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r-- | match-trees.c | 43 | ||||
-rwxr-xr-x | t/t6029-merge-subtree.sh | 28 |
2 files changed, 54 insertions, 17 deletions
diff --git a/match-trees.c b/match-trees.c index 396b7338df..ad9e5e9744 100644 --- a/match-trees.c +++ b/match-trees.c @@ -82,34 +82,43 @@ static int score_trees(const struct object_id *hash1, const struct object_id *ha int score = 0; for (;;) { - struct name_entry e1, e2; - int got_entry_from_one = tree_entry(&one, &e1); - int got_entry_from_two = tree_entry(&two, &e2); int cmp; - if (got_entry_from_one && got_entry_from_two) - cmp = base_name_entries_compare(&e1, &e2); - else if (got_entry_from_one) + if (one.size && two.size) + cmp = base_name_entries_compare(&one.entry, &two.entry); + else if (one.size) /* two lacks this entry */ cmp = -1; - else if (got_entry_from_two) + else if (two.size) /* two has more entries */ cmp = 1; else break; - if (cmp < 0) + if (cmp < 0) { /* path1 does not appear in two */ - score += score_missing(e1.mode, e1.path); - else if (cmp > 0) + score += score_missing(one.entry.mode, one.entry.path); + update_tree_entry(&one); + } else if (cmp > 0) { /* path2 does not appear in one */ - score += score_missing(e2.mode, e2.path); - else if (oidcmp(e1.oid, e2.oid)) - /* they are different */ - score += score_differs(e1.mode, e2.mode, e1.path); - else - /* same subtree or blob */ - score += score_matches(e1.mode, e2.mode, e1.path); + score += score_missing(two.entry.mode, two.entry.path); + update_tree_entry(&two); + } else { + /* path appears in both */ + if (oidcmp(one.entry.oid, two.entry.oid)) { + /* they are different */ + score += score_differs(one.entry.mode, + two.entry.mode, + one.entry.path); + } else { + /* same subtree or blob */ + score += score_matches(one.entry.mode, + two.entry.mode, + one.entry.path); + } + update_tree_entry(&one); + update_tree_entry(&two); + } } free(one_buf); free(two_buf); diff --git a/t/t6029-merge-subtree.sh b/t/t6029-merge-subtree.sh index 3e692454a7..474a850de6 100755 --- a/t/t6029-merge-subtree.sh +++ b/t/t6029-merge-subtree.sh @@ -29,6 +29,34 @@ test_expect_success 'subtree available and works like recursive' ' ' +test_expect_success 'setup branch sub' ' + git checkout --orphan sub && + git rm -rf . && + test_commit foo +' + +test_expect_success 'setup branch main' ' + git checkout -b main master && + git merge -s ours --no-commit --allow-unrelated-histories sub && + git read-tree --prefix=dir/ -u sub && + git commit -m "initial merge of sub into main" && + test_path_is_file dir/foo.t && + test_path_is_file hello +' + +test_expect_success 'update branch sub' ' + git checkout sub && + test_commit bar +' + +test_expect_success 'update branch main' ' + git checkout main && + git merge -s subtree sub -m "second merge of sub into main" && + test_path_is_file dir/bar.t && + test_path_is_file dir/foo.t && + test_path_is_file hello +' + test_expect_success 'setup' ' mkdir git-gui && cd git-gui && |