git-blame bug

Hi,

I ran across this git-blame failure the other day: if a directory is deleted and a file is created with the same name in a single commit, then git blame will fail on it with this error:
fatal: internal error in blame::find_origin

Anyway, patch 1/2 shows this failure with a test, and 2/2 is a possible fix. They should apply on maint.

Thanks,
--
Ben

Ben Willard (2):
t8006: Add test to show blame failure
blame: Fix corner case when a directory becomes a file

 builtin-blame.c  |   12 ++++++++----
 t/t8006-blame.sh |   21 +++++++++++++++++++++
 2 files changed, 29 insertions(+), 4 deletions(-)
 create mode 100755 t/t8006-blame.sh

'git blame' fails on a file which was changed from a directory to a file in a single commit. This test shows the failure.

---
 t/t8006-blame.sh |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)
 create mode 100755 t/t8006-blame.sh

new file mode 100755
index 0000000..7c271f0
@@ -0,0 +1,21 @@
+#!/bin/sh
+
+test_description='git blame on file which changed from a directory to a file in the same commit'
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	mkdir dir &&
+	touch dir/file &&
+	git add dir/file &&
+	git commit -m "Add dir/file" &&
+	git rm dir/file &&
+	echo "File contents" > dir &&
+	git add dir &&
+	git commit -m "Add dir as a file"
+'
+
+test_expect_failure 'blame runs on dir' '
+	git blame dir
+'
+
+test_done

1.6.3.1.279.gd4bf4

find_origin() assumes that there will be only one listing in diff_queued_diff, but this is not the case when a directory becomes a file in a single commit. So, don't fail in this case.

---
 builtin-blame.c  |   12 ++++++++----
 t/t8006-blame.sh |    2 +-
 2 files changed, 9 insertions(+), 5 deletions(-)

index cf74a92..3e217af 100644
@@ -363,16 +363,14 @@ static struct origin *find_origin(struct scoreboard *sb,
 	diffcore_std(&diff_opts);
 
 	/* It is either one entry that says "modified", or "created",
-	 * or nothing.
+	 * or nothing, or two entries (a "deleted" and an "add").
 	 */
 	if (!diff_queued_diff.nr) {
 		/* The path is the same as parent */
 		porigin = get_origin(sb, parent, origin->path);
 		hashcpy(porigin->blob_sha1, origin->blob_sha1);
 	}
-	else if (diff_queued_diff.nr != 1)
-		die("internal error in blame::find_origin");
-	else {
+	else if (diff_queued_diff.nr == 1) {
 		struct diff_filepair *p = diff_queued_diff.queue[0];
 		switch (p->status) {
 		default:

@@ -388,6 +386,12 @@ static struct origin *find_origin(struct scoreboard *sb,
 			break;
 		}
 	}
+	else if (diff_queued_diff.nr == 2) {
+		/* Both added and removed, (ie. directory became a file) */
+	}
+	else {
+		die("internal error in blame::find_origin");
+	}
 	diff_flush(&diff_opts);
 	diff_tree_release_paths(&diff_opts);
 	if (porigin) {

index 7c271f0..17f38ff 100755
@@ -14,7 +14,7 @@ test_expect_success 'setup' '
 	git commit -m "Add dir as a file"
 '
 
-test_expect_failure 'blame runs on dir' '
+test_expect_success 'blame runs on dir' '
 	git blame dir
 '
 

1.6.3.1.279.gd4bf4

Thanks.

Your problem analysis is almost correct but the solution is wrong.

By the way, I'd rather not see people waste a whole _new_ test script when there are existing test scripts availble for the command.

-- >8 --
Subject: [PATCH] blame: correctly handle a path that used to be a directory

When trying to see if the same path exists in the parent, we ran "diff-tree" with pathspec set to the path we are interested in with the parent, and expect either to have exactly one resulting filepair (either "changed from the parent", "created when there was none") or nothing (when there is no change from the parent).

If the path used to be a directory, however, we will also see unbounded number of entries that talk about the files that used to exist underneath the directory in question. Correctly pick only the entry that describes the path we are interested in in such a case (namely, the creation of the path as a regular file).

Noticed by Ben Willard.

---
 builtin-blame.c  |   26 ++++++++++++++++++--------
 t/t8003-blame.sh |   15 +++++++++++++++
 2 files changed, 33 insertions(+), 8 deletions(-)

index cf74a92..0afdb16 100644
@@ -362,18 +362,28 @@ static struct origin *find_origin(struct scoreboard *sb,
 			       "", &diff_opts);
 	diffcore_std(&diff_opts);
 
-	/* It is either one entry that says "modified", or "created",
-	 * or nothing.
-	 */
 	if (!diff_queued_diff.nr) {
 		/* The path is the same as parent */
 		porigin = get_origin(sb, parent, origin->path);
 		hashcpy(porigin->blob_sha1, origin->blob_sha1);
-	}
-	else if (diff_queued_diff.nr != 1)
-		die("internal error in blame::find_origin");
-	else {
-		struct diff_filepair *p = diff_queued_diff.queue[0];
+	} else {
+		/*
+		 * Since origin->path is a pathspec, if the parent
+		 * commit had it as a directory, we will see a whole
+		 * bunch of deletion of files in the directory that we
+		 * do not care about.
+		 */
+		int i;
+		struct diff_filepair *p = NULL;
+		for (i = 0; i < diff_queued_diff.nr; i++) {
+			const char *name;
+			p = diff_queued_diff.queue[i];
+			name = p->one->path ? p->one->path : p->two->path;
+			if (!strcmp(name, origin->path))
+				break;
+		}
+		if (!p)
+			die("internal error in blame::find_origin");
 		switch (p->status) {
 		default:
 			die("internal error in blame::find_origin (%c)",

index 966bb0a..13c25f1 100755
@@ -129,4 +129,19 @@ test_expect_success 'blame wholesale copy and more' '
 
 '
 
+test_expect_success 'blame path that used to be a directory' '
+	mkdir path &&
+	echo A A A A A >path/file &&
+	echo B B B B B >path/elif &&
+	git add path &&
+	test_tick &&
+	git commit -m "path was a directory" &&
+	rm -fr path &&
+	echo A A A A A >path &&
+	git add path &&
+	test_tick &&
+	git commit -m "path is a regular file" &&
+	git blame HEAD^.. -- path
+'
+
 test_done

1.6.3.1.263.g85347

Ah, I guess it was more complicated than I thought.

I'll remember that for next time.

I tested this patch and it works.

Thanks Junio,
--
Ben