Merge branch 'jk/fsck-tree-mode-bits-fix' into maint

"git fsck" reads mode from tree objects but canonicalizes the mode
before passing it to the logic to check object sanity, which has
hid broken tree objects from the checking logic.  This has been
corrected, but to help exiting projects with broken tree objects
that they cannot fix retroactively, the severity of anomalies this
code detects has been demoted to "info" for now.
source: <YvQcNpizy9uOZiAz@coredump.intra.peff.net>

* jk/fsck-tree-mode-bits-fix:
  fsck: downgrade tree badFilemode to "info"
  fsck: actually detect bad file modes in trees
  tree-walk: add a mechanism for getting non-canonicalized modes

7 files changed, 51 insertions, 10 deletions

diff --git a/fsck.c b/fsck.c
index dd4822ba1b..b3da1d68c0 100644
--- a/fsck.c
+++ b/fsck.c
@@ -308,7 +308,7 @@ static int fsck_walk_tree(struct tree *tree, void *data, struct fsck_options *op
 		return -1;
 
 	name = fsck_get_object_name(options, &tree->object.oid);
-	if (init_tree_desc_gently(&desc, tree->buffer, tree->size))
+	if (init_tree_desc_gently(&desc, tree->buffer, tree->size, 0))
 		return -1;
 	while (tree_entry_gently(&desc, &entry)) {
 		struct object *obj;
@@ -578,7 +578,7 @@ static int fsck_tree(const struct object_id *tree_oid,
 	const char *o_name;
 	struct name_stack df_dup_candidates = { NULL };
 
-	if (init_tree_desc_gently(&desc, buffer, size)) {
+	if (init_tree_desc_gently(&desc, buffer, size, TREE_DESC_RAW_MODES)) {
 		retval += report(options, tree_oid, OBJ_TREE,
 				 FSCK_MSG_BAD_TREE,
 				 "cannot be parsed as a tree");
diff --git a/fsck.h b/fsck.h
index d07f7a2459..6f801e53b1 100644
--- a/fsck.h
+++ b/fsck.h
@@ -56,7 +56,6 @@ enum fsck_msg_type {
 	FUNC(GITMODULES_PATH, ERROR) \
 	FUNC(GITMODULES_UPDATE, ERROR) \
 	/* warnings */ \
-	FUNC(BAD_FILEMODE, WARN) \
 	FUNC(EMPTY_NAME, WARN) \
 	FUNC(FULL_PATHNAME, WARN) \
 	FUNC(HAS_DOT, WARN) \
@@ -66,6 +65,7 @@ enum fsck_msg_type {
 	FUNC(ZERO_PADDED_FILEMODE, WARN) \
 	FUNC(NUL_IN_COMMIT, WARN) \
 	/* infos (reported as warnings, but ignored by default) */ \
+	FUNC(BAD_FILEMODE, INFO) \
 	FUNC(GITMODULES_PARSE, INFO) \
 	FUNC(GITIGNORE_SYMLINK, INFO) \
 	FUNC(GITATTRIBUTES_SYMLINK, INFO) \
diff --git a/packfile.c b/packfile.c
index 8e812a84a3..e5b1d0ed76 100644
--- a/packfile.c
+++ b/packfile.c
@@ -2243,7 +2243,7 @@ static int add_promisor_object(const struct object_id *oid,
 		struct tree *tree = (struct tree *)obj;
 		struct tree_desc desc;
 		struct name_entry entry;
-		if (init_tree_desc_gently(&desc, tree->buffer, tree->size))
+		if (init_tree_desc_gently(&desc, tree->buffer, tree->size, 0))
 			/*
 			 * Error messages are given when packs are
 			 * verified, so do not print any here.
diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh
index ab7f31f1dc..53c2aa10b7 100755
--- a/t/t1450-fsck.sh
+++ b/t/t1450-fsck.sh
@@ -364,6 +364,20 @@ test_expect_success 'tree entry with type mismatch' '
 	test_i18ngrep ! "dangling blob" out
 '
 
+test_expect_success 'tree entry with bogus mode' '
+	test_when_finished "remove_object \$blob" &&
+	test_when_finished "remove_object \$tree" &&
+	blob=$(echo blob | git hash-object -w --stdin) &&
+	blob_oct=$(echo $blob | hex2oct) &&
+	tree=$(printf "100000 foo\0${blob_oct}" |
+	       git hash-object -t tree --stdin -w --literally) &&
+	git fsck 2>err &&
+	cat >expect <<-EOF &&
+	warning in tree $tree: badFilemode: contains bad file modes
+	EOF
+	test_cmp expect err
+'
+
 test_expect_success 'tag pointing to nonexistent' '
 	badoid=$(test_oid deadbeef) &&
 	cat >invalid-tag <<-EOF &&
diff --git a/t/t5504-fetch-receive-strict.sh b/t/t5504-fetch-receive-strict.sh
index b0b795aca9..ac4099ca89 100755
--- a/t/t5504-fetch-receive-strict.sh
+++ b/t/t5504-fetch-receive-strict.sh
@@ -352,4 +352,21 @@ test_expect_success \
 	grep "Cannot demote unterminatedheader" act
 '
 
+test_expect_success 'badFilemode is not a strict error' '
+	git init --bare badmode.git &&
+	tree=$(
+		cd badmode.git &&
+		blob=$(echo blob | git hash-object -w --stdin | hex2oct) &&
+		printf "123456 foo\0${blob}" |
+		git hash-object -t tree --stdin -w --literally
+	) &&
+
+	rm -rf dst.git &&
+	git init --bare dst.git &&
+	git -C dst.git config transfer.fsckObjects true &&
+
+	git -C badmode.git push ../dst.git $tree:refs/tags/tree 2>err &&
+	grep "$tree: badFilemode" err
+'
+
 test_done
diff --git a/tree-walk.c b/tree-walk.c
index 506234b4b8..74f4d710e8 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -47,17 +47,20 @@ static int decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned l
 
 	/* Initialize the descriptor entry */
 	desc->entry.path = path;
-	desc->entry.mode = canon_mode(mode);
+	desc->entry.mode = (desc->flags & TREE_DESC_RAW_MODES) ? mode : canon_mode(mode);
 	desc->entry.pathlen = len - 1;
 	oidread(&desc->entry.oid, (const unsigned char *)path + len);
 
 	return 0;
 }
 
-static int init_tree_desc_internal(struct tree_desc *desc, const void *buffer, unsigned long size, struct strbuf *err)
+static int init_tree_desc_internal(struct tree_desc *desc, const void *buffer,
+				   unsigned long size, struct strbuf *err,
+				   enum tree_desc_flags flags)
 {
 	desc->buffer = buffer;
 	desc->size = size;
+	desc->flags = flags;
 	if (size)
 		return decode_tree_entry(desc, buffer, size, err);
 	return 0;
@@ -66,15 +69,16 @@ static int init_tree_desc_internal(struct tree_desc *desc, const void *buffer, u
 void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
 {
 	struct strbuf err = STRBUF_INIT;
-	if (init_tree_desc_internal(desc, buffer, size, &err))
+	if (init_tree_desc_internal(desc, buffer, size, &err, 0))
 		die("%s", err.buf);
 	strbuf_release(&err);
 }
 
-int init_tree_desc_gently(struct tree_desc *desc, const void *buffer, unsigned long size)
+int init_tree_desc_gently(struct tree_desc *desc, const void *buffer, unsigned long size,
+			  enum tree_desc_flags flags)
 {
 	struct strbuf err = STRBUF_INIT;
-	int result = init_tree_desc_internal(desc, buffer, size, &err);
+	int result = init_tree_desc_internal(desc, buffer, size, &err, flags);
 	if (result)
 		error("%s", err.buf);
 	strbuf_release(&err);
diff --git a/tree-walk.h b/tree-walk.h
index a5058469e9..6305d53150 100644
--- a/tree-walk.h
+++ b/tree-walk.h
@@ -34,6 +34,11 @@ struct tree_desc {
 
 	/* counts the number of bytes left in the `buffer`. */
 	unsigned int size;
+
+	/* option flags passed via init_tree_desc_gently() */
+	enum tree_desc_flags {
+		TREE_DESC_RAW_MODES = (1 << 0),
+	} flags;
 };
 
 /**
@@ -79,7 +84,8 @@ int update_tree_entry_gently(struct tree_desc *);
  */
 void init_tree_desc(struct tree_desc *desc, const void *buf, unsigned long size);
 
-int init_tree_desc_gently(struct tree_desc *desc, const void *buf, unsigned long size);
+int init_tree_desc_gently(struct tree_desc *desc, const void *buf, unsigned long size,
+			  enum tree_desc_flags flags);
 
 /*
  * Visit the next entry in a tree. Returns 1 when there are more entries