The parent rewriting code of 'git log -L' was too aggressive in
freeing memory: assign_range_to_parent() will free the commit->parents
field when it sees that a parent cannot pass off any blame (is a root
commit in rewritten history).
Its caller assign_parents_range() however will, upon finding the first
parent that takes *full* blame for all ranges, rewind and reinstate
all previous parents' line ranges and parent lists. This resurrects
pointers to ranges that were freed in assign_range_to_parent() under
some circumstances.
Furthermore, we must not empty the parent lists either: the same
rewind/reinstate code relies on them.
Do both only if the commit was an ordinary (not merge or root) commit,
in which case the merge code-path discussed here is never taken.
Reported-by: Jonathan Nieder <jrnieder@xxxxxxxxx>
Signed-off-by: Thomas Rast <trast@xxxxxxxxxxxxxxx>
---
[sorry for the double post, forgot to cc the list]
After staring at it for some time, I think this is the problem.
Sadly I cannot come up with an independent test that reproduces it (or
at least generates a valgrind warning). Based on my analysis I tried
diff --git a/t/t4302-log-line-merge-history.sh b/t/t4302-log-line-merge-history.sh
index 8634116..7c86903 100755
--- a/t/t4302-log-line-merge-history.sh
+++ b/t/t4302-log-line-merge-history.sh
@@ -171,4 +171,17 @@ test_expect_success 'validate the graph output.' '
test_cmp current-graph expected-graph
'
+test_expect_success 'set up trivial side merge' '
+ git checkout -b trivial-side &&
+ echo new_line >> path0 &&
+ git add path0 &&
+ git commit -m new_line &&
+ git checkout master &&
+ git merge --no-ff trivial-side
+'
+
+test_expect_success 'log -L on the trivial-merged file' '
+ git log -L /new_line/,+1 path0
+'
+
test_done
but that does not fail. I am hesitant to add your original test
because it strays into the directory where git was built, to test with
git's own history. It just feels wrong.
line.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/line.c b/line.c
index 63dd19a..b0deafb 100644
--- a/line.c
+++ b/line.c
@@ -961,8 +961,10 @@ static int assign_range_to_parent(struct rev_info *rev, struct commit *c,
* If there is no new ranges assigned to the parent,
* we should mark it as a 'root' commit.
*/
- free(c->parents);
- c->parents = NULL;
+ if (c->parents && !c->parents->next) {
+ free(c->parents);
+ c->parents = NULL;
+ }
}
/* and the ranges of current commit c is updated */
--
1.7.3.rc1.333.gf62981
--
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