thodg/libgit2

diff --git a/include/git2/tree.h b/include/git2/tree.h
index 2d3534f..b3c22e7 100644
--- a/include/git2/tree.h
+++ b/include/git2/tree.h
@@ -81,6 +81,14 @@ GIT_INLINE(void) git_tree_free(git_tree *tree)
 GIT_EXTERN(const git_oid *) git_tree_id(const git_tree *tree);
 
 /**
+ * Get the repository that contains the tree.
+ *
+ * @param tree A previously loaded tree.
+ * @return Repository that contains this tree.
+ */
+GIT_EXTERN(git_repository *) git_tree_owner(const git_tree *tree);
+
+/**
  * Get the number of entries listed in a tree
  *
  * @param tree a previously loaded tree.
diff --git a/src/checkout.c b/src/checkout.c
index 33de7ad..d9f0f8f 100644
--- a/src/checkout.c
+++ b/src/checkout.c
@@ -448,8 +448,7 @@ static int checkout_get_actions(
 		!(error == GIT_ENOTFOUND || error == GIT_EORPHANEDHEAD))
 			return -1;
 
-	if ((error = git_iterator_for_tree_range(
-			 &hiter, data->repo, head, pfx, pfx)) < 0)
+	if ((error = git_iterator_for_tree_range(&hiter, head, pfx, pfx)) < 0)
 		goto fail;
 
 	if ((diff->opts.flags & GIT_DIFF_DELTAS_ARE_ICASE) != 0 &&
diff --git a/src/diff.c b/src/diff.c
index c4bfc36..822ae5b 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -570,7 +570,7 @@ static int diff_list_init_from_iterators(
 	return 0;
 }
 
-static int diff_from_iterators(
+int git_diff__from_iterators(
 	git_diff_list **diff_ptr,
 	git_repository *repo,
 	git_iterator *old_iter,
@@ -610,9 +610,10 @@ static int diff_from_iterators(
 
 	/* run iterators building diffs */
 	while (oitem || nitem) {
+		int cmp = oitem ? (nitem ? diff->entrycomp(oitem, nitem) : -1) : 1;
 
 		/* create DELETED records for old items not matched in new */
-		if (oitem && (!nitem || diff->entrycomp(oitem, nitem) < 0)) {
+		if (cmp < 0) {
 			if (diff_delta__from_one(diff, GIT_DELTA_DELETED, oitem) < 0)
 				goto fail;
 
@@ -637,7 +638,7 @@ static int diff_from_iterators(
 		/* create ADDED, TRACKED, or IGNORED records for new items not
 		 * matched in old (and/or descend into directories as needed)
 		 */
-		else if (nitem && (!oitem || diff->entrycomp(oitem, nitem) > 0)) {
+		else if (cmp > 0) {
 			git_delta_t delta_type = GIT_DELTA_UNTRACKED;
 
 			/* check if contained in ignored parent directory */
@@ -733,7 +734,7 @@ static int diff_from_iterators(
 		 * (or ADDED and DELETED pair if type changed)
 		 */
 		else {
-			assert(oitem && nitem && diff->entrycomp(oitem, nitem) == 0);
+			assert(oitem && nitem && cmp == 0);
 
 			if (maybe_modified(old_iter, oitem, new_iter, nitem, diff) < 0 ||
 				git_iterator_advance(old_iter, &oitem) < 0 ||
@@ -759,8 +760,8 @@ fail:
 	git_iterator *a = NULL, *b = NULL; \
 	char *pfx = opts ? git_pathspec_prefix(&opts->pathspec) : NULL; \
 	GITERR_CHECK_VERSION(opts, GIT_DIFF_OPTIONS_VERSION, "git_diff_options"); \
-	if (!(error = MAKE_FIRST) && !(error = MAKE_SECOND)) \
-		error = diff_from_iterators(diff, repo, a, b, opts); \
+    if (!(error = MAKE_FIRST) && !(error = MAKE_SECOND)) \
+		error = git_diff__from_iterators(diff, repo, a, b, opts); \
 	git__free(pfx); git_iterator_free(a); git_iterator_free(b); \
 } while (0)
 
@@ -776,8 +777,8 @@ int git_diff_tree_to_tree(
 	assert(diff && repo);
 
 	DIFF_FROM_ITERATORS(
-		git_iterator_for_tree_range(&a, repo, old_tree, pfx, pfx),
-		git_iterator_for_tree_range(&b, repo, new_tree, pfx, pfx)
+		git_iterator_for_tree_range(&a, old_tree, pfx, pfx),
+		git_iterator_for_tree_range(&b, new_tree, pfx, pfx)
 	);
 
 	return error;
@@ -798,7 +799,7 @@ int git_diff_index_to_tree(
 		return error;
 
 	DIFF_FROM_ITERATORS(
-		git_iterator_for_tree_range(&a, repo, old_tree, pfx, pfx),
+		git_iterator_for_tree_range(&a, old_tree, pfx, pfx),
 	    git_iterator_for_index_range(&b, index, pfx, pfx)
 	);
 
@@ -838,7 +839,7 @@ int git_diff_workdir_to_tree(
 	assert(diff && repo);
 
 	DIFF_FROM_ITERATORS(
-		git_iterator_for_tree_range(&a, repo, old_tree, pfx, pfx),
+		git_iterator_for_tree_range(&a, old_tree, pfx, pfx),
 	    git_iterator_for_workdir_range(&b, repo, pfx, pfx)
 	);
 
diff --git a/src/diff.h b/src/diff.h
index f93bab1..8f5ea34 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -61,6 +61,12 @@ extern bool git_diff_delta__should_skip(
 extern int git_diff__oid_for_file(
 	git_repository *, const char *, uint16_t, git_off_t, git_oid *);
 
+extern int git_diff__from_iterators(
+	git_diff_list **diff_ptr,
+	git_repository *repo,
+	git_iterator *old_iter,
+	git_iterator *new_iter,
+	const git_diff_options *opts);
 
 #endif
 
diff --git a/src/index.c b/src/index.c
index f3ced9e..1e5b280 100644
--- a/src/index.c
+++ b/src/index.c
@@ -1641,8 +1641,7 @@ int git_index_read_tree_match(
 
 	pfx = git_pathspec_prefix(strspec);
 
-	if ((error = git_iterator_for_tree_range(
-			 &iter, INDEX_OWNER(index), tree, pfx, pfx)) < 0 ||
+	if ((error = git_iterator_for_tree_range(&iter, tree, pfx, pfx)) < 0 ||
 		(error = git_iterator_current(iter, &entry)) < 0)
 		goto cleanup;
 
diff --git a/src/iterator.c b/src/iterator.c
index 0fdf0c6..7061067 100644
--- a/src/iterator.c
+++ b/src/iterator.c
@@ -18,7 +18,7 @@
 	(P)->base.type    = GIT_ITERATOR_ ## NAME_UC; \
 	(P)->base.start   = start ? git__strdup(start) : NULL; \
 	(P)->base.end     = end ? git__strdup(end) : NULL; \
-	(P)->base.ignore_case = 0; \
+	(P)->base.ignore_case = false; \
 	(P)->base.current = NAME_LC ## _iterator__current; \
 	(P)->base.at_end  = NAME_LC ## _iterator__at_end; \
 	(P)->base.advance = NAME_LC ## _iterator__advance; \
@@ -29,6 +29,25 @@
 		return -1; \
 	} while (0)
 
+static int iterator__reset_range(
+	git_iterator *iter, const char *start, const char *end)
+{
+	if (start) {
+		if (iter->start)
+			git__free(iter->start);
+		iter->start = git__strdup(start);
+		GITERR_CHECK_ALLOC(iter->start);
+	}
+
+	if (end) {
+		if (iter->end)
+			git__free(iter->end);
+		iter->end = git__strdup(end);
+		GITERR_CHECK_ALLOC(iter->end);
+	}
+
+	return 0;
+}
 
 static int empty_iterator__no_item(
 	git_iterator *iter, const git_index_entry **entry)
@@ -44,16 +63,16 @@ static int empty_iterator__at_end(git_iterator *iter)
 	return 1;
 }
 
-static int empty_iterator__noop(git_iterator *iter)
+static int empty_iterator__reset(
+	git_iterator *iter, const char *start, const char *end)
 {
-	GIT_UNUSED(iter);
+	GIT_UNUSED(iter); GIT_UNUSED(start); GIT_UNUSED(end);
 	return 0;
 }
 
 static int empty_iterator__seek(git_iterator *iter, const char *prefix)
 {
-	GIT_UNUSED(iter);
-	GIT_UNUSED(prefix);
+	GIT_UNUSED(iter); GIT_UNUSED(prefix);
 	return -1;
 }
 
@@ -72,7 +91,7 @@ int git_iterator_for_nothing(git_iterator **iter)
 	i->at_end  = empty_iterator__at_end;
 	i->advance = empty_iterator__no_item;
 	i->seek    = empty_iterator__seek;
-	i->reset   = empty_iterator__noop;
+	i->reset   = empty_iterator__reset;
 	i->free    = empty_iterator__free;
 
 	*iter = i;
@@ -91,17 +110,15 @@ struct tree_iterator_frame {
 
 typedef struct {
 	git_iterator base;
-	git_repository *repo;
 	tree_iterator_frame *stack, *tail;
 	git_index_entry entry;
 	git_buf path;
 	bool path_has_filename;
 } tree_iterator;
 
-static const git_tree_entry *tree_iterator__tree_entry(tree_iterator *ti)
+GIT_INLINE(const git_tree_entry *)tree_iterator__tree_entry(tree_iterator *ti)
 {
-	return (ti->stack == NULL) ? NULL :
-		git_tree_entry_byindex(ti->stack->tree, ti->stack->index);
+	return git_tree_entry_byindex(ti->stack->tree, ti->stack->index);
 }
 
 static char *tree_iterator__current_filename(
@@ -116,25 +133,34 @@ static char *tree_iterator__current_filename(
 	return ti->path.ptr;
 }
 
-static void tree_iterator__pop_frame(tree_iterator *ti)
+static void tree_iterator__free_frame(tree_iterator_frame *tf)
 {
-	tree_iterator_frame *tf = ti->stack;
-	ti->stack = tf->next;
-	if (ti->stack != NULL) {
-		git_tree_free(tf->tree); /* don't free the initial tree */
-		ti->stack->prev = NULL;  /* disconnect prev */
-	}
+	if (!tf)
+		return;
+	git_tree_free(tf->tree);
 	git__free(tf);
 }
 
-static int tree_iterator__to_end(tree_iterator *ti)
+static bool tree_iterator__pop_frame(tree_iterator *ti)
 {
-	while (ti->stack && ti->stack->next)
-		tree_iterator__pop_frame(ti);
+	tree_iterator_frame *tf = ti->stack;
 
-	if (ti->stack)
-		ti->stack->index = git_tree_entrycount(ti->stack->tree);
+	/* don't free the initial tree/frame */
+	if (!tf->next)
+		return false;
+
+	ti->stack = tf->next;
+	ti->stack->prev = NULL;
+
+	tree_iterator__free_frame(tf);
+
+	return true;
+}
 
+static int tree_iterator__to_end(tree_iterator *ti)
+{
+	while (tree_iterator__pop_frame(ti)) /* pop all */;
+	ti->stack->index = git_tree_entrycount(ti->stack->tree);
 	return 0;
 }
 
@@ -205,7 +231,7 @@ static int tree_iterator__expand_tree(tree_iterator *ti)
 			git__prefixcmp(ti->path.ptr, ti->base.end) > 0)
 			return tree_iterator__to_end(ti);
 
-		if ((error = git_tree_lookup(&subtree, ti->repo, &te->oid)) < 0)
+		if ((error = git_tree_lookup(&subtree, ti->base.repo, &te->oid)) < 0)
 			return error;
 
 		relpath = NULL;
@@ -247,12 +273,13 @@ static int tree_iterator__advance(
 		ti->path_has_filename = false;
 	}
 
-	while (ti->stack != NULL) {
+	while (1) {
 		te = git_tree_entry_byindex(ti->stack->tree, ++ti->stack->index);
 		if (te != NULL)
 			break;
 
-		tree_iterator__pop_frame(ti);
+		if (!tree_iterator__pop_frame(ti))
+			break; /* no frames left to pop */
 
 		git_buf_rtruncate_at_char(&ti->path, '/');
 	}
@@ -279,30 +306,36 @@ static int tree_iterator__seek(git_iterator *self, const char *prefix)
 static void tree_iterator__free(git_iterator *self)
 {
 	tree_iterator *ti = (tree_iterator *)self;
-	while (ti->stack != NULL)
-		tree_iterator__pop_frame(ti);
+
+	while (tree_iterator__pop_frame(ti)) /* pop all */;
+
+	tree_iterator__free_frame(ti->stack);
+	ti->stack = ti->tail = NULL;
+
 	git_buf_free(&ti->path);
 }
 
-static int tree_iterator__reset(git_iterator *self)
+static int tree_iterator__reset(
+	git_iterator *self, const char *start, const char *end)
 {
 	tree_iterator *ti = (tree_iterator *)self;
 
-	while (ti->stack && ti->stack->next)
-		tree_iterator__pop_frame(ti);
+	while (tree_iterator__pop_frame(ti)) /* pop all */;
 
-	if (ti->stack)
-		ti->stack->index =
-			git_tree__prefix_position(ti->stack->tree, ti->base.start);
+	if (iterator__reset_range(self, start, end) < 0)
+		return -1;
+
+	ti->stack->index =
+		git_tree__prefix_position(ti->stack->tree, ti->base.start);
 
 	git_buf_clear(&ti->path);
+	ti->path_has_filename = false;
 
 	return tree_iterator__expand_tree(ti);
 }
 
 int git_iterator_for_tree_range(
 	git_iterator **iter,
-	git_repository *repo,
 	git_tree *tree,
 	const char *start,
 	const char *end)
@@ -313,9 +346,12 @@ int git_iterator_for_tree_range(
 	if (tree == NULL)
 		return git_iterator_for_nothing(iter);
 
+	if ((error = git_tree__dup(&tree, tree)) < 0)
+		return error;
+
 	ITERATOR_BASE_INIT(ti, tree, TREE);
 
-	ti->repo  = repo;
+	ti->base.repo = git_tree_owner(tree);
 	ti->stack = ti->tail = tree_iterator__alloc_frame(tree, ti->base.start);
 
 	if ((error = tree_iterator__expand_tree(ti)) < 0)
@@ -396,9 +432,12 @@ static int index_iterator__seek(git_iterator *self, const char *prefix)
 	return -1;
 }
 
-static int index_iterator__reset(git_iterator *self)
+static int index_iterator__reset(
+	git_iterator *self, const char *start, const char *end)
 {
 	index_iterator *ii = (index_iterator *)self;
+	if (iterator__reset_range(self, start, end) < 0)
+		return -1;
 	ii->current = ii->base.start ?
 		git_index__prefix_position(ii->index, ii->base.start) : 0;
 	index_iterator__skip_conflicts(ii);
@@ -424,9 +463,10 @@ int git_iterator_for_index_range(
 	ITERATOR_BASE_INIT(ii, index, INDEX);
 
 	ii->index = index;
+	ii->base.repo = git_index_owner(index);
 	ii->base.ignore_case = ii->index->ignore_case;
 
-	index_iterator__reset((git_iterator *)ii);
+	index_iterator__reset((git_iterator *)ii, NULL, NULL);
 
 	*iter = (git_iterator *)ii;
 
@@ -456,36 +496,19 @@ struct workdir_iterator_frame {
 	workdir_iterator_frame *next;
 	git_vector entries;
 	size_t index;
-	char *start;
 };
 
 typedef struct {
 	git_iterator base;
-	git_repository *repo;
-	size_t root_len;
 	workdir_iterator_frame *stack;
+	int (*entrycmp)(const void *pfx, const void *item);
 	git_ignores ignores;
 	git_index_entry entry;
 	git_buf path;
+	size_t root_len;
 	int is_ignored;
 } workdir_iterator;
 
-static int git_path_with_stat_cmp_case(const void *a, const void *b)
-{
-	const git_path_with_stat *path_with_stat_a = a;
-	const git_path_with_stat *path_with_stat_b = b;
-
-	return strcmp(path_with_stat_a->path, path_with_stat_b->path);
-}
-
-static int git_path_with_stat_cmp_icase(const void *a, const void *b)
-{
-	const git_path_with_stat *path_with_stat_a = a;
-	const git_path_with_stat *path_with_stat_b = b;
-
-	return strcasecmp(path_with_stat_a->path, path_with_stat_b->path);
-}
-
 GIT_INLINE(bool) path_is_dotgit(const git_path_with_stat *ps)
 {
 	if (!ps)
@@ -494,26 +517,34 @@ GIT_INLINE(bool) path_is_dotgit(const git_path_with_stat *ps)
 		const char *path = ps->path;
 		size_t len  = ps->path_len;
 
-		return len >= 4 &&
-			tolower(path[len - 1]) == 't' &&
-			tolower(path[len - 2]) == 'i' &&
-			tolower(path[len - 3]) == 'g' &&
-			path[len - 4] == '.' &&
-			(len == 4 || path[len - 5] == '/');
+		if (len < 4)
+			return false;
+		if (path[len - 1] == '/')
+			len--;
+		if (tolower(path[len - 1]) != 't' ||
+			tolower(path[len - 2]) != 'i' ||
+			tolower(path[len - 3]) != 'g' ||
+			tolower(path[len - 4]) != '.')
+			return false;
+		return (len == 4 || path[len - 5] == '/');
 	}
 }
 
-static workdir_iterator_frame *workdir_iterator__alloc_frame(workdir_iterator *wi)
+static workdir_iterator_frame *workdir_iterator__alloc_frame(
+	workdir_iterator *wi)
 {
 	workdir_iterator_frame *wf = git__calloc(1, sizeof(workdir_iterator_frame));
-	git_vector_cmp entry_compare = CASESELECT(wi->base.ignore_case, git_path_with_stat_cmp_icase, git_path_with_stat_cmp_case);
+	git_vector_cmp entry_compare = CASESELECT(wi->base.ignore_case,
+		git_path_with_stat_cmp_icase, git_path_with_stat_cmp);
 
 	if (wf == NULL)
 		return NULL;
+
 	if (git_vector_init(&wf->entries, 0, entry_compare) != 0) {
 		git__free(wf);
 		return NULL;
 	}
+
 	return wf;
 }
 
@@ -530,16 +561,32 @@ static void workdir_iterator__free_frame(workdir_iterator_frame *wf)
 
 static int workdir_iterator__update_entry(workdir_iterator *wi);
 
-static int workdir_iterator__entry_cmp_case(const void *prefix, const void *item)
+static int workdir_iterator__entry_cmp_case(const void *pfx, const void *item)
 {
 	const git_path_with_stat *ps = item;
-	return git__prefixcmp((const char *)prefix, ps->path);
+	return git__prefixcmp((const char *)pfx, ps->path);
 }
 
-static int workdir_iterator__entry_cmp_icase(const void *prefix, const void *item)
+static int workdir_iterator__entry_cmp_icase(const void *pfx, const void *item)
 {
 	const git_path_with_stat *ps = item;
-	return git__prefixcmp_icase((const char *)prefix, ps->path);
+	return git__prefixcmp_icase((const char *)pfx, ps->path);
+}
+
+static void workdir_iterator__seek_frame_start(
+	workdir_iterator *wi, workdir_iterator_frame *wf)
+{
+	if (!wf)
+		return;
+
+	if (wi->base.start)
+		git_vector_bsearch3(
+			&wf->index, &wf->entries, wi->entrycmp, wi->base.start);
+	else
+		wf->index = 0;
+
+	if (path_is_dotgit(git_vector_get(&wf->entries, wf->index)))
+		wf->index++;
 }
 
 static int workdir_iterator__expand_dir(workdir_iterator *wi)
@@ -548,39 +595,26 @@ static int workdir_iterator__expand_dir(workdir_iterator *wi)
 	workdir_iterator_frame *wf = workdir_iterator__alloc_frame(wi);
 	GITERR_CHECK_ALLOC(wf);
 
-	error = git_path_dirload_with_stat(wi->path.ptr, wi->root_len, &wf->entries);
+	error = git_path_dirload_with_stat(
+		wi->path.ptr, wi->root_len, wi->base.ignore_case,
+		wi->base.start, wi->base.end, &wf->entries);
+
 	if (error < 0 || wf->entries.length == 0) {
 		workdir_iterator__free_frame(wf);
 		return GIT_ENOTFOUND;
 	}
 
-	git_vector_sort(&wf->entries);
-
-	if (!wi->stack)
-		wf->start = wi->base.start;
-	else if (wi->stack->start &&
-		ITERATOR_PREFIXCMP(wi->base, wi->stack->start, wi->path.ptr + wi->root_len) == 0)
-		wf->start = wi->stack->start;
-
-	if (wf->start)
-		git_vector_bsearch3(
-			&wf->index,
-			&wf->entries,
-			CASESELECT(wi->base.ignore_case, workdir_iterator__entry_cmp_icase, workdir_iterator__entry_cmp_case),
-			wf->start);
-
-	if (path_is_dotgit(git_vector_get(&wf->entries, wf->index)))
-		wf->index++;
-
-	wf->next  = wi->stack;
-	wi->stack = wf;
+	workdir_iterator__seek_frame_start(wi, wf);
 
 	/* only push new ignores if this is not top level directory */
-	if (wi->stack->next != NULL) {
+	if (wi->stack != NULL) {
 		ssize_t slash_pos = git_buf_rfind_next(&wi->path, '/');
 		(void)git_ignore__push_dir(&wi->ignores, &wi->path.ptr[slash_pos + 1]);
 	}
 
+	wf->next  = wi->stack;
+	wi->stack = wf;
+
 	return workdir_iterator__update_entry(wi);
 }
 
@@ -611,8 +645,10 @@ static int workdir_iterator__advance(
 	if (wi->entry.path == NULL)
 		return 0;
 
-	while ((wf = wi->stack) != NULL) {
+	while (1) {
+		wf   = wi->stack;
 		next = git_vector_get(&wf->entries, ++wf->index);
+
 		if (next != NULL) {
 			/* match git's behavior of ignoring anything named ".git" */
 			if (path_is_dotgit(next))
@@ -621,15 +657,15 @@ static int workdir_iterator__advance(
 			break;
 		}
 
-		/* pop workdir directory stack */
-		wi->stack = wf->next;
-		workdir_iterator__free_frame(wf);
-		git_ignore__pop_dir(&wi->ignores);
-
-		if (wi->stack == NULL) {
+		/* pop stack if anything is left to pop */
+		if (!wf->next) {
 			memset(&wi->entry, 0, sizeof(wi->entry));
 			return 0;
 		}
+
+		wi->stack = wf->next;
+		workdir_iterator__free_frame(wf);
+		git_ignore__pop_dir(&wi->ignores);
 	}
 
 	error = workdir_iterator__update_entry(wi);
@@ -650,18 +686,24 @@ static int workdir_iterator__seek(git_iterator *self, const char *prefix)
 	return 0;
 }
 
-static int workdir_iterator__reset(git_iterator *self)
+static int workdir_iterator__reset(
+	git_iterator *self, const char *start, const char *end)
 {
 	workdir_iterator *wi = (workdir_iterator *)self;
+
 	while (wi->stack != NULL && wi->stack->next != NULL) {
 		workdir_iterator_frame *wf = wi->stack;
 		wi->stack = wf->next;
 		workdir_iterator__free_frame(wf);
 		git_ignore__pop_dir(&wi->ignores);
 	}
-	if (wi->stack)
-		wi->stack->index = 0;
-	return 0;
+
+	if (iterator__reset_range(self, start, end) < 0)
+		return -1;
+
+	workdir_iterator__seek_frame_start(wi, wi->stack);
+
+	return workdir_iterator__update_entry(wi);
 }
 
 static void workdir_iterator__free(git_iterator *self)
@@ -680,7 +722,8 @@ static void workdir_iterator__free(git_iterator *self)
 
 static int workdir_iterator__update_entry(workdir_iterator *wi)
 {
-	git_path_with_stat *ps = git_vector_get(&wi->stack->entries, wi->stack->index);
+	git_path_with_stat *ps =
+		git_vector_get(&wi->stack->entries, wi->stack->index);
 
 	git_buf_truncate(&wi->path, wi->root_len);
 	memset(&wi->entry, 0, sizeof(wi->entry));
@@ -691,8 +734,8 @@ static int workdir_iterator__update_entry(workdir_iterator *wi)
 	if (git_buf_put(&wi->path, ps->path, ps->path_len) < 0)
 		return -1;
 
-	if (wi->base.end &&
-		ITERATOR_PREFIXCMP(wi->base, wi->path.ptr + wi->root_len, wi->base.end) > 0)
+	if (wi->base.end && ITERATOR_PREFIXCMP(
+			wi->base, wi->path.ptr + wi->root_len, wi->base.end) > 0)
 		return 0;
 
 	wi->entry.path = ps->path;
@@ -716,7 +759,7 @@ static int workdir_iterator__update_entry(workdir_iterator *wi)
 
 	/* detect submodules */
 	if (S_ISDIR(wi->entry.mode)) {
-		int res = git_submodule_lookup(NULL, wi->repo, wi->entry.path);
+		int res = git_submodule_lookup(NULL, wi->base.repo, wi->entry.path);
 		bool is_submodule = (res == 0);
 		if (res == GIT_ENOTFOUND)
 			giterr_clear();
@@ -750,10 +793,10 @@ int git_iterator_for_workdir_range(
 		return error;
 
 	ITERATOR_BASE_INIT(wi, workdir, WORKDIR);
-	wi->repo = repo;
+	wi->base.repo = repo;
 
 	if ((error = git_repository_index__weakptr(&index, repo)) < 0) {
-		git__free(wi);
+		git_iterator_free((git_iterator *)wi);
 		return error;
 	}
 
@@ -769,6 +812,8 @@ int git_iterator_for_workdir_range(
 	}
 
 	wi->root_len = wi->path.size;
+	wi->entrycmp = wi->base.ignore_case ?
+		workdir_iterator__entry_cmp_icase : workdir_iterator__entry_cmp_case;
 
 	if ((error = workdir_iterator__expand_dir(wi)) < 0) {
 		if (error == GIT_ENOTFOUND)
@@ -837,10 +882,13 @@ static int spoolandsort_iterator__seek(git_iterator *self, const char *prefix)
 	return -1;
 }
 
-static int spoolandsort_iterator__reset(git_iterator *self)
+static int spoolandsort_iterator__reset(
+	git_iterator *self, const char *start, const char *end)
 {
 	spoolandsort_iterator *si = (spoolandsort_iterator *)self;
 
+	GIT_UNUSED(start); GIT_UNUSED(end);
+
 	si->position = 0;
 
 	return 0;
diff --git a/src/iterator.h b/src/iterator.h
index 77ead76..9fe6844 100644
--- a/src/iterator.h
+++ b/src/iterator.h
@@ -28,32 +28,33 @@ typedef enum {
 
 struct git_iterator {
 	git_iterator_type_t type;
+	git_repository *repo;
 	char *start;
 	char *end;
+	bool ignore_case;
+
 	int (*current)(git_iterator *, const git_index_entry **);
 	int (*at_end)(git_iterator *);
 	int (*advance)(git_iterator *, const git_index_entry **);
 	int (*seek)(git_iterator *, const char *prefix);
-	int (*reset)(git_iterator *);
+	int (*reset)(git_iterator *, const char *start, const char *end);
 	void (*free)(git_iterator *);
-	unsigned int ignore_case:1;
 };
 
 extern int git_iterator_for_nothing(git_iterator **iter);
 
 extern int git_iterator_for_tree_range(
-	git_iterator **iter, git_repository *repo, git_tree *tree,
+	git_iterator **iter, git_tree *tree,
 	const char *start, const char *end);
 
 GIT_INLINE(int) git_iterator_for_tree(
-	git_iterator **iter, git_repository *repo, git_tree *tree)
+	git_iterator **iter, git_tree *tree)
 {
-	return git_iterator_for_tree_range(iter, repo, tree, NULL, NULL);
+	return git_iterator_for_tree_range(iter, tree, NULL, NULL);
 }
 
 extern int git_iterator_for_index_range(
-	git_iterator **iter, git_index *index,
-	const char *start, const char *end);
+	git_iterator **iter, git_index *index, const char *start, const char *end);
 
 GIT_INLINE(int) git_iterator_for_index(
 	git_iterator **iter, git_index *index)
@@ -90,7 +91,8 @@ GIT_INLINE(int) git_iterator_spoolandsort(
 	git_iterator **iter, git_iterator *towrap,
 	git_vector_cmp comparer, bool ignore_case)
 {
-	return git_iterator_spoolandsort_range(iter, towrap, comparer, ignore_case, NULL, NULL);
+	return git_iterator_spoolandsort_range(
+		iter, towrap, comparer, ignore_case, NULL, NULL);
 }
 
 /* Entry is not guaranteed to be fully populated.  For a tree iterator,
@@ -124,9 +126,10 @@ GIT_INLINE(int) git_iterator_seek(
 	return iter->seek(iter, prefix);
 }
 
-GIT_INLINE(int) git_iterator_reset(git_iterator *iter)
+GIT_INLINE(int) git_iterator_reset(
+	git_iterator *iter, const char *start, const char *end)
 {
-	return iter->reset(iter);
+	return iter->reset(iter, start, end);
 }
 
 GIT_INLINE(void) git_iterator_free(git_iterator *iter)
@@ -149,6 +152,11 @@ GIT_INLINE(git_iterator_type_t) git_iterator_type(git_iterator *iter)
 	return iter->type;
 }
 
+GIT_INLINE(git_repository *) git_iterator_owner(git_iterator *iter)
+{
+	return iter->repo;
+}
+
 extern int git_iterator_current_tree_entry(
 	git_iterator *iter, const git_tree_entry **tree_entry);
 
diff --git a/src/notes.c b/src/notes.c
index f96b5b1..8a27bdb 100644
--- a/src/notes.c
+++ b/src/notes.c
@@ -593,7 +593,7 @@ int git_note_foreach(
 
 	if (!(error = retrieve_note_tree_and_commit(
 			&tree, &commit, repo, &notes_ref)) &&
-		!(error = git_iterator_for_tree(&iter, repo, tree)))
+		!(error = git_iterator_for_tree(&iter, tree)))
 		error = git_iterator_current(iter, &item);
 
 	while (!error && item) {
diff --git a/src/path.c b/src/path.c
index 87eded3..569101c 100644
--- a/src/path.c
+++ b/src/path.c
@@ -770,18 +770,30 @@ int git_path_dirload(
 int git_path_with_stat_cmp(const void *a, const void *b)
 {
 	const git_path_with_stat *psa = a, *psb = b;
-	return git__strcmp_cb(psa->path, psb->path);
+	return strcmp(psa->path, psb->path);
+}
+
+int git_path_with_stat_cmp_icase(const void *a, const void *b)
+{
+	const git_path_with_stat *psa = a, *psb = b;
+	return strcasecmp(psa->path, psb->path);
 }
 
 int git_path_dirload_with_stat(
 	const char *path,
 	size_t prefix_len,
+	bool ignore_case,
+	const char *start_stat,
+	const char *end_stat,
 	git_vector *contents)
 {
 	int error;
 	unsigned int i;
 	git_path_with_stat *ps;
 	git_buf full = GIT_BUF_INIT;
+	int (*strncomp)(const char *a, const char *b, size_t sz);
+	size_t start_len = start_stat ? strlen(start_stat) : 0;
+	size_t end_len = end_stat ? strlen(end_stat) : 0, cmp_len;
 
 	if (git_buf_set(&full, path, prefix_len) < 0)
 		return -1;
@@ -793,11 +805,23 @@ int git_path_dirload_with_stat(
 		return error;
 	}
 
+	strncomp = ignore_case ? git__strncasecmp : git__strncmp;
+
+	/* stat struct at start of git_path_with_stat, so shift path text */
 	git_vector_foreach(contents, i, ps) {
 		size_t path_len = strlen((char *)ps);
-
 		memmove(ps->path, ps, path_len + 1);
 		ps->path_len = path_len;
+	}
+
+	git_vector_foreach(contents, i, ps) {
+		/* skip if before start_stat or after end_stat */
+		cmp_len = min(start_len, ps->path_len);
+		if (cmp_len && strncomp(ps->path, start_stat, cmp_len) < 0)
+			continue;
+		cmp_len = min(end_len, ps->path_len);
+		if (cmp_len && strncomp(ps->path, end_stat, cmp_len) > 0)
+			continue;
 
 		if ((error = git_buf_joinpath(&full, full.ptr, ps->path)) < 0 ||
 			(error = git_path_lstat(full.ptr, &ps->st)) < 0)
@@ -806,11 +830,14 @@ int git_path_dirload_with_stat(
 		git_buf_truncate(&full, prefix_len);
 
 		if (S_ISDIR(ps->st.st_mode)) {
-			ps->path[path_len] = '/';
-			ps->path[path_len + 1] = '\0';
+			ps->path[ps->path_len++] = '/';
+			ps->path[ps->path_len] = '\0';
 		}
 	}
 
+	/* sort now that directory suffix is added */
+	git_vector_sort(contents);
+
 	git_buf_free(&full);
 
 	return error;
diff --git a/src/path.h b/src/path.h
index b629227..db260d8 100644
--- a/src/path.h
+++ b/src/path.h
@@ -321,18 +321,33 @@ typedef struct {
 } git_path_with_stat;
 
 extern int git_path_with_stat_cmp(const void *a, const void *b);
+extern int git_path_with_stat_cmp_icase(const void *a, const void *b);
 
 /**
  * Load all directory entries along with stat info into a vector.
  *
- * This is just like git_path_dirload except that each entry in the
- * vector is a git_path_with_stat structure that contains both the
- * path and the stat info, plus directories will have a / suffixed
- * to their path name.
+ * This adds four things on top of plain `git_path_dirload`:
+ *
+ * 1. Each entry in the vector is a `git_path_with_stat` struct that
+ *    contains both the path and the stat info
+ * 2. The entries will be sorted alphabetically
+ * 3. Entries that are directories will be suffixed with a '/'
+ * 4. Optionally, you can be a start and end prefix and only elements
+ *    after the start and before the end (inclusively) will be stat'ed.
+ *
+ * @param path The directory to read from
+ * @param prefix_len The trailing part of path to prefix to entry paths
+ * @param ignore_case How to sort and compare paths with start/end limits
+ * @param start_stat As optimization, only stat values after this prefix
+ * @param end_stat As optimization, only stat values before this prefix
+ * @param contents Vector to fill with git_path_with_stat structures
  */
 extern int git_path_dirload_with_stat(
 	const char *path,
 	size_t prefix_len,
+	bool ignore_case,
+	const char *start_stat,
+	const char *end_stat,
 	git_vector *contents);
 
 #endif
diff --git a/src/submodule.c b/src/submodule.c
index 21a1875..3d9950d 100644
--- a/src/submodule.c
+++ b/src/submodule.c
@@ -1156,7 +1156,7 @@ static int load_submodule_config_from_head(
 	if ((error = git_repository_head_tree(&head, repo)) < 0)
 		return error;
 
-	if ((error = git_iterator_for_tree(&i, repo, head)) < 0) {
+	if ((error = git_iterator_for_tree(&i, head)) < 0) {
 		git_tree_free(head);
 		return error;
 	}
diff --git a/src/tree.c b/src/tree.c
index efb991d..7f1b9fe 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -207,9 +207,14 @@ void git_tree__free(git_tree *tree)
 	git__free(tree);
 }
 
-const git_oid *git_tree_id(const git_tree *c)
+const git_oid *git_tree_id(const git_tree *t)
 {
-	return git_object_id((const git_object *)c);
+	return git_object_id((const git_object *)t);
+}
+
+git_repository *git_tree_owner(const git_tree *t)
+{
+	return git_object_owner((const git_object *)t);
 }
 
 git_filemode_t git_tree_entry_filemode(const git_tree_entry *entry)
@@ -296,6 +301,9 @@ int git_tree__prefix_position(git_tree *tree, const char *path)
 	struct tree_key_search ksearch;
 	size_t at_pos;
 
+	if (!path)
+		return 0;
+
 	ksearch.filename = path;
 	ksearch.filename_len = strlen(path);
 
diff --git a/src/tree.h b/src/tree.h
index e0bcd6a..c28523d 100644
--- a/src/tree.h
+++ b/src/tree.h
@@ -29,6 +29,10 @@ struct git_treebuilder {
 	git_vector entries;
 };
 
+GIT_INLINE(int) git_tree__dup(git_tree **dest, git_tree *source)
+{
+	return git_object__dup((git_object **)dest, (git_object *)source);
+}
 
 GIT_INLINE(bool) git_tree_entry__is_tree(const struct git_tree_entry *e)
 {
diff --git a/src/util.c b/src/util.c
index 9813eb6..831b073 100644
--- a/src/util.c
+++ b/src/util.c
@@ -199,9 +199,17 @@ int git__strncmp(const char *a, const char *b, size_t sz)
 
 int git__strncasecmp(const char *a, const char *b, size_t sz)
 {
-	while (sz && *a && *b && tolower(*a) == tolower(*b))
+	int al, bl;
+
+	while (sz && *a && *b) {
+		al = (unsigned char)tolower(*a);
+		bl = (unsigned char)tolower(*b);
+		if (al != bl)
+			break;
 		--sz, ++a, ++b;
-	return !sz ? 0 : (tolower(*a) - tolower(*b));
+	}
+
+	return !sz ? 0 : al - bl;
 }
 
 void git__strntolower(char *str, size_t len)
diff --git a/tests-clar/diff/iterator.c b/tests-clar/diff/iterator.c
index 1d83960..b579063 100644
--- a/tests-clar/diff/iterator.c
+++ b/tests-clar/diff/iterator.c
@@ -31,25 +31,35 @@ static void tree_iterator_test(
 	git_tree *t;
 	git_iterator *i;
 	const git_index_entry *entry;
-	int count = 0;
+	int count = 0, count_post_reset = 0;
 	git_repository *repo = cl_git_sandbox_init(sandbox);
 
 	cl_assert(t = resolve_commit_oid_to_tree(repo, treeish));
-	cl_git_pass(git_iterator_for_tree_range(&i, repo, t, start, end));
-	cl_git_pass(git_iterator_current(i, &entry));
+	cl_git_pass(git_iterator_for_tree_range(&i, t, start, end));
 
+	/* test loop */
+	cl_git_pass(git_iterator_current(i, &entry));
 	while (entry != NULL) {
 		if (expected_values != NULL)
 			cl_assert_equal_s(expected_values[count], entry->path);
-
 		count++;
+		cl_git_pass(git_iterator_advance(i, &entry));
+	}
 
+	/* test reset */
+	cl_git_pass(git_iterator_reset(i, NULL, NULL));
+	cl_git_pass(git_iterator_current(i, &entry));
+	while (entry != NULL) {
+		if (expected_values != NULL)
+			cl_assert_equal_s(expected_values[count_post_reset], entry->path);
+		count_post_reset++;
 		cl_git_pass(git_iterator_advance(i, &entry));
 	}
 
 	git_iterator_free(i);
 
-	cl_assert(expected_count == count);
+	cl_assert_equal_i(expected_count, count);
+	cl_assert_equal_i(count, count_post_reset);
 
 	git_tree_free(t);
 }
@@ -294,7 +304,7 @@ void test_diff_iterator__tree_special_functions(void)
 		repo, "24fa9a9fc4e202313e24b648087495441dab432b");
 	cl_assert(t != NULL);
 
-	cl_git_pass(git_iterator_for_tree_range(&i, repo, t, NULL, NULL));
+	cl_git_pass(git_iterator_for_tree_range(&i, t, NULL, NULL));
 	cl_git_pass(git_iterator_current(i, &entry));
 
 	while (entry != NULL) {
@@ -520,7 +530,7 @@ static void workdir_iterator_test(
 {
 	git_iterator *i;
 	const git_index_entry *entry;
-	int count = 0, count_all = 0;
+	int count = 0, count_all = 0, count_all_post_reset = 0;
 	git_repository *repo = cl_git_sandbox_init(sandbox);
 
 	cl_git_pass(git_iterator_for_workdir_range(&i, repo, start, end));
@@ -547,10 +557,26 @@ static void workdir_iterator_test(
 		cl_git_pass(git_iterator_advance(i, &entry));
 	}
 
+	cl_git_pass(git_iterator_reset(i, NULL, NULL));
+	cl_git_pass(git_iterator_current(i, &entry));
+
+	while (entry != NULL) {
+		if (S_ISDIR(entry->mode)) {
+			cl_git_pass(git_iterator_advance_into_directory(i, &entry));
+			continue;
+		}
+		if (expected_names != NULL)
+			cl_assert_equal_s(
+				expected_names[count_all_post_reset], entry->path);
+		count_all_post_reset++;
+		cl_git_pass(git_iterator_advance(i, &entry));
+	}
+
 	git_iterator_free(i);
 
-	cl_assert_equal_i(expected_count,count);
+	cl_assert_equal_i(expected_count, count);
 	cl_assert_equal_i(expected_count + expected_ignores, count_all);
+	cl_assert_equal_i(count_all, count_all_post_reset);
 }
 
 void test_diff_iterator__workdir_0(void)