Use correct case path in icase tree iterator

If there are case-ambiguities in the path of a case insensitive
tree iterator, it will now rewrite the entire path when it gives
the path name to an entry, so a tree with "A/b/C/d.txt" and
"a/B/c/E.txt" will give the true full paths (instead of case-
folding them both to "A/B/C/d.txt" or "a/b/c/E.txt" or something
like that.

src/iterator.c

@@ -189,11 +189,30 @@ typedef struct {
 	tree_iterator_frame *head, *top;
 	git_index_entry entry;
 	git_buf path;
+	int path_ambiguities;
 	bool path_has_filename;
 	int (*strcomp)(const char *a, const char *b);
 	int (*strncomp)(const char *a, const char *b, size_t sz);
 } tree_iterator;
 
+static const git_tree_entry *tree_iterator__get_tree_entry(
+	tree_iterator_frame *tf, const tree_iterator_entry *entry, size_t i)
+{
+	git_tree *tree;
+
+	if (!entry) {
+		if (i >= tf->n_entries)
+			return NULL;
+		entry = &tf->entries[i];
+	}
+
+	tree = tf->parent->entries[entry->parent_entry_index].tree;
+	if (!tree)
+		return NULL;
+
+	return git_tree_entry_byindex(tree, entry->parent_tree_index);
+}
+
 static char *tree_iterator__current_filename(
 	tree_iterator *ti, const git_tree_entry *te)
 {
@@ -210,39 +229,27 @@ static char *tree_iterator__current_filename(
 	return ti->path.ptr;
 }
 
-static int tree_iterator__create_top_frame(tree_iterator *ti, git_tree *tree)
+static void tree_iterator__rewrite_filename(tree_iterator *ti)
 {
-	size_t sz = sizeof(tree_iterator_frame) + sizeof(tree_iterator_entry);
-	tree_iterator_frame *top = git__calloc(sz, sizeof(char));
-	GITERR_CHECK_ALLOC(top);
+	tree_iterator_frame *scan = ti->head;
+	size_t current = scan->current;
+	ssize_t strpos = ti->path.size;
+	const git_tree_entry *te;
 
-	top->n_entries = 1;
-	top->next = 1;
-	top->start = ti->base.start;
-	top->startlen = top->start ? strlen(top->start) : 0;
-	top->entries[0].tree = tree;
+	while (scan && scan->parent) {
+		tree_iterator_entry *entry = &scan->entries[current];
 
-	ti->head = ti->top = top;
+		te = tree_iterator__get_tree_entry(scan, entry, 0);
+		if (!te)
+			break;
 
-	return 0;
-}
+		strpos -= te->filename_len;
+		memcpy(&ti->path.ptr[strpos], te->filename, te->filename_len);
+		strpos -= 1; /* separator */
 
-static const git_tree_entry *tree_iterator__get_tree_entry(
-	tree_iterator_frame *tf, const tree_iterator_entry *entry, size_t i)
-{
-	git_tree *tree;
-
-	if (!entry) {
-		if (i >= tf->n_entries)
-			return NULL;
-		entry = &tf->entries[i];
+		current = entry->parent_entry_index;
+		scan = scan->parent;
 	}
-
-	tree = tf->parent->entries[entry->parent_entry_index].tree;
-	if (!tree)
-		return NULL;
-
-	return git_tree_entry_byindex(tree, entry->parent_tree_index);
 }
 
 static int tree_iterator__entry_cmp(const void *a, const void *b, void *p)
@@ -290,6 +297,9 @@ static int tree_iterator__set_next(tree_iterator *ti, tree_iterator_frame *tf)
 		last_te = te;
 	}
 
+	if (tf->next > tf->current + 1)
+		ti->path_ambiguities++;
+
 	if (last_te && !tree_iterator__current_filename(ti, last_te))
 		return -1;
 
@@ -376,8 +386,12 @@ static int tree_iterator__push_frame(tree_iterator *ti)
 	return 0;
 }
 
-static bool tree_iterator__move_to_next(tree_iterator_frame *tf)
+static bool tree_iterator__move_to_next(
+	tree_iterator *ti, tree_iterator_frame *tf)
 {
+	if (tf->next > tf->current + 1)
+		ti->path_ambiguities--;
+
 	while (tf->current < tf->next) {
 		if (tf->parent && tf->entries[tf->current].tree) {
 			git_tree_free(tf->entries[tf->current].tree);
@@ -396,7 +410,7 @@ static bool tree_iterator__pop_frame(tree_iterator *ti)
 	if (!tf->parent)
 		return false;
 
-	tree_iterator__move_to_next(tf);
+	tree_iterator__move_to_next(ti, tf);
 
 	ti->head = tf->parent;
 	ti->head->child = NULL;
@@ -427,6 +441,9 @@ static int tree_iterator__current(
 	if (ti->entry.path == NULL)
 		return -1;
 
+	if (ti->path_ambiguities > 0)
+		tree_iterator__rewrite_filename(ti);
+
 	if (iterator__past_end(ti, ti->entry.path)) {
 		while (tree_iterator__pop_frame(ti)) /* pop to top */;
 		ti->head->current = ti->head->n_entries;
@@ -478,7 +495,7 @@ static int tree_iterator__advance(
 	}
 
 	/* scan forward and up, advancing in frame or popping frame when done */
-	while (!tree_iterator__move_to_next(tf) && tree_iterator__pop_frame(ti))
+	while (!tree_iterator__move_to_next(ti, tf) && tree_iterator__pop_frame(ti))
 		tf = ti->head;
 
 	/* find next and load trees */
@@ -510,6 +527,7 @@ static int tree_iterator__reset(
 	if (iterator__reset_range(self, start, end) < 0)
 		return -1;
 	git_buf_clear(&ti->path);
+	ti->path_ambiguities = 0;
 
 	return tree_iterator__push_frame(ti); /* re-expand top tree */
 }
@@ -537,6 +555,23 @@ static void tree_iterator__free(git_iterator *self)
 	git_buf_free(&ti->path);
 }
 
+static int tree_iterator__create_top_frame(tree_iterator *ti, git_tree *tree)
+{
+	size_t sz = sizeof(tree_iterator_frame) + sizeof(tree_iterator_entry);
+	tree_iterator_frame *top = git__calloc(sz, sizeof(char));
+	GITERR_CHECK_ALLOC(top);
+
+	top->n_entries = 1;
+	top->next = 1;
+	top->start = ti->base.start;
+	top->startlen = top->start ? strlen(top->start) : 0;
+	top->entries[0].tree = tree;
+
+	ti->head = ti->top = top;
+
+	return 0;
+}
+
 int git_iterator_for_tree(
 	git_iterator **iter,
 	git_tree *tree,

tests-clar/repo/iterator.c

@@ -456,7 +456,7 @@ void test_repo_iterator__tree_case_conflicts(void)
 	const char *expect_cs[] = {
 		"A/1.file", "A/3.file", "a/2.file", "a/4.file" };
 	const char *expect_ci[] = {
-		"a/1.file", "a/2.file", "a/3.file", "a/4.file" };
+		"A/1.file", "a/2.file", "A/3.file", "a/4.file" };
 
 	g_repo = cl_git_sandbox_init("icase");
 
@@ -479,7 +479,7 @@ void test_repo_iterator__tree_case_conflicts(void)
 
 	cl_git_pass(git_iterator_for_tree(
 		&i, tree, GIT_ITERATOR_IGNORE_CASE, NULL, NULL));
-	expect_iterator_items(i, 4, expect_ci, -4, expect_ci);
+	expect_iterator_items(i, 4, expect_ci, 4, expect_ci);
 	git_iterator_free(i);
 
 	git_tree_free(tree);