[PATCH 1/7] fsck_tree(): fix shadowed variable

[Jeff King <peff@peff.net>]

Commit b2f2039c2b (fsck: accept an oid instead of a "struct tree" for
fsck_tree(), 2019-10-18) introduced a new "oid" parameter to
fsck_tree(), and we pass it to the report() function when we find
problems. However, that is shadowed within the tree-walking loop by the
existing "oid" variable which we use to store the oid of each tree
entry. As a result, we may report the wrong oid for some problems we
detect within the loop (the entry oid, instead of the tree oid).

Our tests didn't catch this because they checked only that we found the
expected fsck problem, not that it was attached to the correct object.

Let's rename both variables in the function to avoid confusion. This
makes the diff a little noisy (e.g., all of the report() calls outside
the loop wee already correct but need touched), but makes sure we catch
all cases and will avoid similar confusion in the future.

Signed-off-by: Jeff King <peff@peff.net>
---
 fsck.c                     | 40 +++++++++++++++++++-------------------
 t/t7415-submodule-names.sh |  5 +++--
 2 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/fsck.c b/fsck.c
index f82e2fe9e3..46a108839f 100644
--- a/fsck.c
+++ b/fsck.c
@@ -633,7 +633,7 @@ static int verify_ordered(unsigned mode1, const char *name1,
 	return c1 < c2 ? 0 : TREE_UNORDERED;
 }
 
-static int fsck_tree(const struct object_id *oid,
+static int fsck_tree(const struct object_id *tree_oid,
 		     const char *buffer, unsigned long size,
 		     struct fsck_options *options)
 {
@@ -654,7 +654,7 @@ static int fsck_tree(const struct object_id *oid,
 	struct name_stack df_dup_candidates = { NULL };
 
 	if (init_tree_desc_gently(&desc, buffer, size)) {
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_BAD_TREE, "cannot be parsed as a tree");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_BAD_TREE, "cannot be parsed as a tree");
 		return retval;
 	}
 
@@ -664,11 +664,11 @@ static int fsck_tree(const struct object_id *oid,
 	while (desc.size) {
 		unsigned short mode;
 		const char *name, *backslash;
-		const struct object_id *oid;
+		const struct object_id *entry_oid;
 
-		oid = tree_entry_extract(&desc, &name, &mode);
+		entry_oid = tree_entry_extract(&desc, &name, &mode);
 
-		has_null_sha1 |= is_null_oid(oid);
+		has_null_sha1 |= is_null_oid(entry_oid);
 		has_full_path |= !!strchr(name, '/');
 		has_empty_name |= !*name;
 		has_dot |= !strcmp(name, ".");
@@ -678,10 +678,10 @@ static int fsck_tree(const struct object_id *oid,
 
 		if (is_hfs_dotgitmodules(name) || is_ntfs_dotgitmodules(name)) {
 			if (!S_ISLNK(mode))
-				oidset_insert(&gitmodules_found, oid);
+				oidset_insert(&gitmodules_found, entry_oid);
 			else
 				retval += report(options,
-						 oid, OBJ_TREE,
+						 tree_oid, OBJ_TREE,
 						 FSCK_MSG_GITMODULES_SYMLINK,
 						 ".gitmodules is a symbolic link");
 		}
@@ -692,9 +692,9 @@ static int fsck_tree(const struct object_id *oid,
 				has_dotgit |= is_ntfs_dotgit(backslash);
 				if (is_ntfs_dotgitmodules(backslash)) {
 					if (!S_ISLNK(mode))
-						oidset_insert(&gitmodules_found, oid);
+						oidset_insert(&gitmodules_found, entry_oid);
 					else
-						retval += report(options, oid, OBJ_TREE,
+						retval += report(options, tree_oid, OBJ_TREE,
 								 FSCK_MSG_GITMODULES_SYMLINK,
 								 ".gitmodules is a symbolic link");
 				}
@@ -703,7 +703,7 @@ static int fsck_tree(const struct object_id *oid,
 		}
 
 		if (update_tree_entry_gently(&desc)) {
-			retval += report(options, oid, OBJ_TREE, FSCK_MSG_BAD_TREE, "cannot be parsed as a tree");
+			retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_BAD_TREE, "cannot be parsed as a tree");
 			break;
 		}
 
@@ -751,25 +751,25 @@ static int fsck_tree(const struct object_id *oid,
 	name_stack_clear(&df_dup_candidates);
 
 	if (has_null_sha1)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_NULL_SHA1, "contains entries pointing to null sha1");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_NULL_SHA1, "contains entries pointing to null sha1");
 	if (has_full_path)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_FULL_PATHNAME, "contains full pathnames");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_FULL_PATHNAME, "contains full pathnames");
 	if (has_empty_name)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_EMPTY_NAME, "contains empty pathname");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_EMPTY_NAME, "contains empty pathname");
 	if (has_dot)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_HAS_DOT, "contains '.'");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_HAS_DOT, "contains '.'");
 	if (has_dotdot)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_HAS_DOTDOT, "contains '..'");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_HAS_DOTDOT, "contains '..'");
 	if (has_dotgit)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_HAS_DOTGIT, "contains '.git'");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_HAS_DOTGIT, "contains '.git'");
 	if (has_zero_pad)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_ZERO_PADDED_FILEMODE, "contains zero-padded file modes");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_ZERO_PADDED_FILEMODE, "contains zero-padded file modes");
 	if (has_bad_modes)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_BAD_FILEMODE, "contains bad file modes");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_BAD_FILEMODE, "contains bad file modes");
 	if (has_dup_entries)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_DUPLICATE_ENTRIES, "contains duplicate file entries");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_DUPLICATE_ENTRIES, "contains duplicate file entries");
 	if (not_properly_sorted)
-		retval += report(options, oid, OBJ_TREE, FSCK_MSG_TREE_NOT_SORTED, "not properly sorted");
+		retval += report(options, tree_oid, OBJ_TREE, FSCK_MSG_TREE_NOT_SORTED, "not properly sorted");
 	return retval;
 }
 
diff --git a/t/t7415-submodule-names.sh b/t/t7415-submodule-names.sh
index f70368bc2e..5c95247180 100755
--- a/t/t7415-submodule-names.sh
+++ b/t/t7415-submodule-names.sh
@@ -148,13 +148,14 @@ test_expect_success 'fsck detects symlinked .gitmodules file' '
 		{
 			printf "100644 blob $content\t$tricky\n" &&
 			printf "120000 blob $target\t.gitmodules\n"
-		} | git mktree &&
+		} >bad-tree &&
+		tree=$(git mktree <bad-tree) &&
 
 		# Check not only that we fail, but that it is due to the
 		# symlink detector; this grep string comes from the config
 		# variable name and will not be translated.
 		test_must_fail git fsck 2>output &&
-		test_i18ngrep gitmodulesSymlink output
+		test_i18ngrep "tree $tree: gitmodulesSymlink" output
 	)
 '
 
-- 
2.28.0.1295.g4824feede7