Add index API to remove all files in a directory

This adds the git_index_remove_directory API plus tests.

include/git2/index.h

@@ -313,6 +313,17 @@ GIT_EXTERN(const git_index_entry *) git_index_get_bypath(
 GIT_EXTERN(int) git_index_remove(git_index *index, const char *path, int stage);
 
 /**
+ * Remove all entries from the index under a given directory
+ *
+ * @param index an existing index object
+ * @param dir container directory path
+ * @param stage stage to search
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_index_remove_directory(
+	git_index *index, const char *dir, int stage);
+
+/**
  * Add or update an index entry from an in-memory struct
  *
  * If a previous index entry exists that has the same path and stage

src/index.c

@@ -794,6 +794,44 @@ int git_index_remove(git_index *index, const char *path, int stage)
 	return error;
 }
 
+int git_index_remove_directory(git_index *index, const char *dir, int stage)
+{
+	git_buf pfx = GIT_BUF_INIT;
+	int error = 0;
+	size_t pos;
+	git_index_entry *entry;
+
+	if (git_buf_sets(&pfx, dir) < 0 || git_path_to_dir(&pfx) < 0)
+		return -1;
+
+	git_vector_sort(&index->entries);
+
+	pos = git_index__prefix_position(index, pfx.ptr);
+
+	while (1) {
+		entry = git_vector_get(&index->entries, pos);
+		if (!entry || git__prefixcmp(entry->path, pfx.ptr) != 0)
+			break;
+
+		if (index_entry_stage(entry) != stage) {
+			++pos;
+			continue;
+		}
+
+		git_tree_cache_invalidate_path(index->tree, entry->path);
+
+		if ((error = git_vector_remove(&index->entries, pos)) < 0)
+			break;
+		index_entry_free(entry);
+
+		/* removed entry at 'pos' so we don't need to increment it */
+	}
+
+	git_buf_free(&pfx);
+
+	return error;
+}
+
 static int index_find(git_index *index, const char *path, int stage)
 {
 	struct entry_srch_key srch_key;

tests-clar/index/tests.c

@@ -290,3 +290,86 @@ void test_index_tests__write_invalid_filename(void)
 
 	cl_fixture_cleanup("read_tree");
 }
+
+void test_index_tests__remove_entry(void)
+{
+	git_repository *repo;
+	git_index *index;
+
+	p_mkdir("index_test", 0770);
+
+	cl_git_pass(git_repository_init(&repo, "index_test", 0));
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_assert(git_index_entrycount(index) == 0);
+
+	cl_git_mkfile("index_test/hello", NULL);
+	cl_git_pass(git_index_add_from_workdir(index, "hello"));
+	cl_git_pass(git_index_write(index));
+
+	cl_git_pass(git_index_read(index)); /* reload */
+	cl_assert(git_index_entrycount(index) == 1);
+	cl_assert(git_index_get_bypath(index, "hello", 0) != NULL);
+
+	cl_git_pass(git_index_remove(index, "hello", 0));
+	cl_git_pass(git_index_write(index));
+
+	cl_git_pass(git_index_read(index)); /* reload */
+	cl_assert(git_index_entrycount(index) == 0);
+	cl_assert(git_index_get_bypath(index, "hello", 0) == NULL);
+
+	git_index_free(index);
+	git_repository_free(repo);
+	cl_fixture_cleanup("index_test");
+}
+
+void test_index_tests__remove_directory(void)
+{
+	git_repository *repo;
+	git_index *index;
+
+	p_mkdir("index_test", 0770);
+
+	cl_git_pass(git_repository_init(&repo, "index_test", 0));
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_assert_equal_i(0, (int)git_index_entrycount(index));
+
+	p_mkdir("index_test/a", 0770);
+	cl_git_mkfile("index_test/a/1.txt", NULL);
+	cl_git_mkfile("index_test/a/2.txt", NULL);
+	cl_git_mkfile("index_test/a/3.txt", NULL);
+	cl_git_mkfile("index_test/b.txt", NULL);
+
+	cl_git_pass(git_index_add_from_workdir(index, "a/1.txt"));
+	cl_git_pass(git_index_add_from_workdir(index, "a/2.txt"));
+	cl_git_pass(git_index_add_from_workdir(index, "a/3.txt"));
+	cl_git_pass(git_index_add_from_workdir(index, "b.txt"));
+	cl_git_pass(git_index_write(index));
+
+	cl_git_pass(git_index_read(index)); /* reload */
+	cl_assert_equal_i(4, (int)git_index_entrycount(index));
+	cl_assert(git_index_get_bypath(index, "a/1.txt", 0) != NULL);
+	cl_assert(git_index_get_bypath(index, "a/2.txt", 0) != NULL);
+	cl_assert(git_index_get_bypath(index, "b.txt", 0) != NULL);
+
+	cl_git_pass(git_index_remove(index, "a/1.txt", 0));
+	cl_git_pass(git_index_write(index));
+
+	cl_git_pass(git_index_read(index)); /* reload */
+	cl_assert_equal_i(3, (int)git_index_entrycount(index));
+	cl_assert(git_index_get_bypath(index, "a/1.txt", 0) == NULL);
+	cl_assert(git_index_get_bypath(index, "a/2.txt", 0) != NULL);
+	cl_assert(git_index_get_bypath(index, "b.txt", 0) != NULL);
+
+	cl_git_pass(git_index_remove_directory(index, "a", 0));
+	cl_git_pass(git_index_write(index));
+
+	cl_git_pass(git_index_read(index)); /* reload */
+	cl_assert_equal_i(1, (int)git_index_entrycount(index));
+	cl_assert(git_index_get_bypath(index, "a/1.txt", 0) == NULL);
+	cl_assert(git_index_get_bypath(index, "a/2.txt", 0) == NULL);
+	cl_assert(git_index_get_bypath(index, "b.txt", 0) != NULL);
+
+	git_index_free(index);
+	git_repository_free(repo);
+	cl_fixture_cleanup("index_test");
+}