For diff family commands, we can tell them to exclude changes outside
of some directories if --relative is requested.
In diff_unmerge(), NULL will be returned if the requested path is
outside of the interesting directories, thus we'll run into NULL
pointer dereference in run_diff_files when trying to dereference
its return value.
Checking for return value of diff_unmerge before dereferencing
is not sufficient, though. Since, diff engine will try to work on such
pathspec later.
Let's not run diff on those unintesting entries, instead.
As a side effect, by skipping like that, we can save some CPU cycles.
Reported-by: Thomas De Zeeuw <thomas@xxxxxxxxxx>
Tested-by: Carlo Arenas <carenas@xxxxxxxxx>
Signed-off-by: Đoàn Trần Công Danh <congdanhqx@xxxxxxxxx>
---
Range-diff against v1:
1: 57a9edc3af ! 1: 0d73c71819 diff-lib: ignore all outsider if --relative asked
@@ Commit message
pointer dereference in run_diff_files when trying to dereference
its return value.
- We can simply check for NULL there before dereferencing said
- return value. However, we can do better by not running diff
- on those unintesting entries. Let's do that instead.
+ Checking for return value of diff_unmerge before dereferencing
+ is not sufficient, though. Since, diff engine will try to work on such
+ pathspec later.
+
+ Let's not run diff on those unintesting entries, instead.
+ As a side effect, by skipping like that, we can save some CPU cycles.
Reported-by: Thomas De Zeeuw <thomas@xxxxxxxxxx>
+ Tested-by: Carlo Arenas <carenas@xxxxxxxxx>
Signed-off-by: Đoàn Trần Công Danh <congdanhqx@xxxxxxxxx>
-
- ## Notes ##
- Check for return value of diff_unmerge is not enough.
-
- Yes, it works with --name-only, however, with only --relative,
- git-diff shows unmerged entries outside of subdir, too.
-
- Furthermore, the filename in "diff --cc" ignores the relative prefix.
- Fixing this requires touching all over places, at least from my study.
- Let's fix the crash, first.
-
- We have two choices here:
-
- * Check pair, aka return value of diff_unmerge, like my original
- suggestion, and the unmerged entries from outside will be shown, too.
- Some inconsistent will be observed, --name-only won't list files
- outside of subdir, while the patch shows them. At least, it doesn't
- create false impression of no change outside of subdir.
-
- * Skip all outsiders, like this patch.
-
- While I prefer this approach, I don't know all ramifications of this change,
- let's say an entry moved to outside of subdir in one side, and modified in
- other side.
-
- Because, I pick the different approach, Junio's ack isn't included here.
-
- Cc: Junio C Hamano <gitster@xxxxxxxxx>
-
## diff-lib.c ##
@@ diff-lib.c: int run_diff_files(struct rev_info *revs, unsigned int option)
if (!ce_path_match(istate, ce, &revs->prune_data, NULL))
diff-lib.c | 4 +++
t/t4045-diff-relative.sh | 53 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 57 insertions(+)
diff --git a/diff-lib.c b/diff-lib.c
index f9eadc4fc1..ca085a03ef 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -117,6 +117,10 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
if (!ce_path_match(istate, ce, &revs->prune_data, NULL))
continue;
+ if (revs->diffopt.prefix &&
+ strncmp(ce->name, revs->diffopt.prefix, revs->diffopt.prefix_length))
+ continue;
+
if (ce_stage(ce)) {
struct combine_diff_path *dpath;
struct diff_filepair *pair;
diff --git a/t/t4045-diff-relative.sh b/t/t4045-diff-relative.sh
index 61ba5f707f..8cbbe53262 100755
--- a/t/t4045-diff-relative.sh
+++ b/t/t4045-diff-relative.sh
@@ -162,4 +162,57 @@ check_diff_relative_option subdir file2 true --no-relative --relative
check_diff_relative_option . file2 false --no-relative --relative=subdir
check_diff_relative_option . file2 true --no-relative --relative=subdir
+test_expect_success 'setup diff --relative unmerged' '
+ test_commit zero file0 &&
+ test_commit base subdir/file0 &&
+ git switch -c br1 &&
+ test_commit one file0 &&
+ test_commit sub1 subdir/file0 &&
+ git switch -c br2 base &&
+ test_commit two file0 &&
+ git switch -c br3 &&
+ test_commit sub3 subdir/file0
+'
+
+test_expect_success 'diff --relative without change in subdir' '
+ git switch br2 &&
+ test_when_finished "git merge --abort" &&
+ test_must_fail git merge one &&
+ git -C subdir diff --relative >out &&
+ test_must_be_empty out &&
+ git -C subdir diff --relative --name-only >out &&
+ test_must_be_empty out
+'
+
+test_expect_success 'diff --relative --name-only with change in subdir' '
+ git switch br3 &&
+ test_when_finished "git merge --abort" &&
+ test_must_fail git merge sub1 &&
+ test_write_lines file0 file0 >expected &&
+ git -C subdir diff --relative --name-only >out &&
+ test_cmp expected out
+'
+
+test_expect_failure 'diff --relative with change in subdir' '
+ git switch br3 &&
+ br1_blob=$(git rev-parse --short --verify br1:subdir/file0) &&
+ br3_blob=$(git rev-parse --short --verify br3:subdir/file0) &&
+ test_when_finished "git merge --abort" &&
+ test_must_fail git merge br1 &&
+ cat >expected <<-EOF &&
+ diff --cc file0
+ index $br3_blob,$br1_blob..0000000
+ --- a/file0
+ +++ b/file0
+ @@@ -1,1 -1,1 +1,5 @@@
+ ++<<<<<<< HEAD
+ +sub3
+ ++=======
+ + sub1
+ ++>>>>>>> sub1
+ EOF
+ git -C subdir diff --relative >out &&
+ test_cmp expected out
+'
+
test_done
--
2.33.0.254.g68ee769121
