Add config level support in the config API

Added `struct git_config_entry`: a git_config_entry contains the key, the value, and the config file level from which a config element was found.
Added `git_config_open_level`: build a single-level focused config object from a multi-level one.

We are now storing `git_config_entry`s in the khash of the config_file

6 files changed, 292 insertions, 63 deletions

diff --git a/tests-clar/config/configlevel.c b/tests-clar/config/configlevel.c
new file mode 100644
index 000000000..d947856fa
--- /dev/null
+++ b/tests-clar/config/configlevel.c
@@ -0,0 +1,59 @@
+#include "clar_libgit2.h"
+
+void test_config_configlevel__adding_the_same_level_twice_returns_EEXISTS(void)
+{
+	int error;
+	git_config *cfg;
+
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config9"),
+		GIT_CONFIG_LEVEL_LOCAL, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config15"),
+		GIT_CONFIG_LEVEL_GLOBAL, 0));
+	error = git_config_add_file_ondisk(cfg, cl_fixture("config/config16"),
+		GIT_CONFIG_LEVEL_GLOBAL, 0);
+
+	cl_git_fail(error);
+	cl_assert_equal_i(GIT_EEXISTS, error);
+
+	git_config_free(cfg);
+}
+
+void test_config_configlevel__can_replace_a_config_file_at_an_existing_level(void)
+{
+	git_config *cfg;
+	const char *s;
+
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config18"),
+		GIT_CONFIG_LEVEL_LOCAL, 1));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config19"),
+		GIT_CONFIG_LEVEL_LOCAL, 1));
+
+	cl_git_pass(git_config_get_string(&s, cfg, "core.stringglobal"));
+	cl_assert_equal_s("don't find me!", s);
+
+	git_config_free(cfg);
+}
+
+void test_config_configlevel__can_read_from_a_single_level_focused_file_after_parent_config_has_been_freed(void)
+{
+	git_config *cfg;
+	git_config *single_level_cfg;
+	const char *s;
+
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config18"),
+		GIT_CONFIG_LEVEL_GLOBAL, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config19"),
+		GIT_CONFIG_LEVEL_LOCAL, 0));
+
+	cl_git_pass(git_config_open_level(&single_level_cfg, cfg, GIT_CONFIG_LEVEL_LOCAL));
+
+	git_config_free(cfg);
+
+	cl_git_pass(git_config_get_string(&s, single_level_cfg, "core.stringglobal"));
+	cl_assert_equal_s("don't find me!", s);
+
+	git_config_free(single_level_cfg);
+}
diff --git a/tests-clar/config/multivar.c b/tests-clar/config/multivar.c
index 3b40cd09a..26537e20a 100644
--- a/tests-clar/config/multivar.c
+++ b/tests-clar/config/multivar.c
@@ -12,13 +12,11 @@ void test_config_multivar__cleanup(void)
 	cl_fixture_cleanup("config");
 }
 
-static int mv_read_cb(const char *name, const char *value, void *data)
+static int mv_read_cb(const git_config_entry *entry, void *data)
 {
 	int *n = (int *) data;
 
-	GIT_UNUSED(value);
-
-	if (!strcmp(name, _name))
+	if (!strcmp(entry->name, _name))
 		(*n)++;
 
 	return 0;
@@ -37,11 +35,11 @@ void test_config_multivar__foreach(void)
 	git_config_free(cfg);
 }
 
-static int cb(const char *val, void *data)
+static int cb(const git_config_entry *entry, void *data)
 {
 	int *n = (int *) data;
 
-	GIT_UNUSED(val);
+	GIT_UNUSED(entry);
 
 	(*n)++;
 
diff --git a/tests-clar/config/new.c b/tests-clar/config/new.c
index fae3ce941..6bd719fba 100644
--- a/tests-clar/config/new.c
+++ b/tests-clar/config/new.c
@@ -9,21 +9,16 @@
 void test_config_new__write_new_config(void)
 {
 	const char *out;
-	struct git_config_file *file;
 	git_config *config;
 
-	cl_git_pass(git_config_file__ondisk(&file, TEST_CONFIG));
-	cl_git_pass(git_config_new(&config));
-	cl_git_pass(git_config_add_file(config, file, 0));
+	cl_git_pass(git_config_open_ondisk(&config, TEST_CONFIG));
 
 	cl_git_pass(git_config_set_string(config, "color.ui", "auto"));
 	cl_git_pass(git_config_set_string(config, "core.editor", "ed"));
 
 	git_config_free(config);
 
-	cl_git_pass(git_config_file__ondisk(&file, TEST_CONFIG));
-	cl_git_pass(git_config_new(&config));
-	cl_git_pass(git_config_add_file(config, file, 0));
+	cl_git_pass(git_config_open_ondisk(&config, TEST_CONFIG));
 
 	cl_git_pass(git_config_get_string(&out, config, "color.ui"));
 	cl_assert_equal_s(out, "auto");
diff --git a/tests-clar/config/read.c b/tests-clar/config/read.c
index fcd22463d..cf781e6bf 100644
--- a/tests-clar/config/read.c
+++ b/tests-clar/config/read.c
@@ -191,22 +191,24 @@ void test_config_read__escaping_quotes(void)
 	git_config_free(cfg);
 }
 
-static int count_cfg_entries(
-	const char *var_name, const char *value, void *payload)
+static int count_cfg_entries_and_compare_levels(
+	const git_config_entry *entry, void *payload)
 {
 	int *count = payload;
-	GIT_UNUSED(var_name);
-	GIT_UNUSED(value);
+
+	if (!strcmp(entry->value, "7") || !strcmp(entry->value, "17"))
+		cl_assert(entry->level == GIT_CONFIG_LEVEL_GLOBAL);
+	else
+		cl_assert(entry->level == GIT_CONFIG_LEVEL_SYSTEM);
+
 	(*count)++;
 	return 0;
 }
 
-static int cfg_callback_countdown(
-	const char *var_name, const char *value, void *payload)
+static int cfg_callback_countdown(const git_config_entry *entry, void *payload)
 {
 	int *count = payload;
-	GIT_UNUSED(var_name);
-	GIT_UNUSED(value);
+	GIT_UNUSED(entry);
 	(*count)--;
 	if (*count == 0)
 		return -100;
@@ -218,11 +220,15 @@ void test_config_read__foreach(void)
 	git_config *cfg;
 	int count, ret;
 
-	cl_git_pass(git_config_open_ondisk(&cfg, cl_fixture("config/config9")));
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config9"),
+		GIT_CONFIG_LEVEL_SYSTEM, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config15"),
+		GIT_CONFIG_LEVEL_GLOBAL, 0));
 
 	count = 0;
-	cl_git_pass(git_config_foreach(cfg, count_cfg_entries, &count));
-	cl_assert_equal_i(5, count);
+	cl_git_pass(git_config_foreach(cfg, count_cfg_entries_and_compare_levels, &count));
+	cl_assert_equal_i(7, count);
 
 	count = 3;
 	cl_git_fail(ret = git_config_foreach(cfg, cfg_callback_countdown, &count));
@@ -231,6 +237,14 @@ void test_config_read__foreach(void)
 	git_config_free(cfg);
 }
 
+static int count_cfg_entries(const git_config_entry *entry, void *payload)
+{
+	int *count = payload;
+	GIT_UNUSED(entry);
+	(*count)++;
+	return 0;
+}
+
 void test_config_read__foreach_match(void)
 {
 	git_config *cfg;
@@ -282,31 +296,129 @@ void test_config_read__whitespace_not_required_around_assignment(void)
 	git_config_free(cfg);
 }
 
-#if 0
+void test_config_read__read_git_config_entry(void)
+{
+	git_config *cfg;
+	const git_config_entry *entry;
 
-BEGIN_TEST(config10, "a repo's config overrides the global config")
-	git_repository *repo;
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config9"),
+		GIT_CONFIG_LEVEL_SYSTEM, 0));
+
+	cl_git_pass(git_config_get_config_entry(&entry, cfg, "core.dummy2"));
+	cl_assert_equal_s("core.dummy2", entry->name);
+	cl_assert_equal_s("42", entry->value);
+	cl_assert_equal_i(GIT_CONFIG_LEVEL_SYSTEM, entry->level);
+
+	git_config_free(cfg);
+}
+
+/*
+ * At the beginning of the test:
+ *  - config9 has: core.dummy2=42
+ *  - config15 has: core.dummy2=7
+ *  - config16 has: core.dummy2=28
+ */
+void test_config_read__local_config_overrides_global_config_overrides_system_config(void)
+{
 	git_config *cfg;
-	int32_t version;
+	int32_t i;
+
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config9"),
+		GIT_CONFIG_LEVEL_SYSTEM, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config15"),
+		GIT_CONFIG_LEVEL_GLOBAL, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config16"),
+		GIT_CONFIG_LEVEL_LOCAL, 0));
+
+	cl_git_pass(git_config_get_int32(&i, cfg, "core.dummy2"));
+	cl_assert_equal_i(28, i);
+
+	git_config_free(cfg);
+
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config9"),
+		GIT_CONFIG_LEVEL_SYSTEM, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config15"),
+		GIT_CONFIG_LEVEL_GLOBAL, 0));
+
+	cl_git_pass(git_config_get_int32(&i, cfg, "core.dummy2"));
+	cl_assert_equal_i(7, i);
 
-	cl_git_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
-	cl_git_pass(git_repository_config(&cfg, repo, GLOBAL_CONFIG, NULL));
-	cl_git_pass(git_config_get_int32(cfg, "core.repositoryformatversion", &version));
-	cl_assert(version == 0);
 	git_config_free(cfg);
-	git_repository_free(repo);
-END_TEST
+}
 
-BEGIN_TEST(config11, "fall back to the global config")
-	git_repository *repo;
+/*
+ * At the beginning of the test:
+ *  - config9 has: core.global does not exist
+ *  - config15 has: core.global=17
+ *  - config16 has: core.global=29
+ *
+ * And also:
+ *  - config9 has: core.system does not exist
+ *  - config15 has: core.system does not exist
+ *  - config16 has: core.system=11
+ */
+void test_config_read__fallback_from_local_to_global_and_from_global_to_system(void)
+{
 	git_config *cfg;
-	int32_t num;
+	int32_t i;
 
-	cl_git_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
-	cl_git_pass(git_repository_config(&cfg, repo, GLOBAL_CONFIG, NULL));
-	cl_git_pass(git_config_get_int32(cfg, "core.something", &num));
-	cl_assert(num == 2);
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config9"),
+		GIT_CONFIG_LEVEL_SYSTEM, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config15"),
+		GIT_CONFIG_LEVEL_GLOBAL, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config16"),
+		GIT_CONFIG_LEVEL_LOCAL, 0));
+
+	cl_git_pass(git_config_get_int32(&i, cfg, "core.global"));
+	cl_assert_equal_i(17, i);
+	cl_git_pass(git_config_get_int32(&i, cfg, "core.system"));
+	cl_assert_equal_i(11, i);
+
+	git_config_free(cfg);
+}
+
+/*
+ * At the beginning of the test, config18 has:
+ *	int32global = 28
+ *	int64global = 9223372036854775803
+ *	boolglobal = true
+ *	stringglobal = I'm a global config value!
+ *
+ * And config19 has:
+ *	int32global = -1
+ *	int64global = -2
+ *	boolglobal = false
+ *	stringglobal = don't find me!
+ *
+ */
+void test_config_read__simple_read_from_specific_level(void)
+{
+	git_config *cfg, *cfg_specific;
+	int i;
+	int64_t l, expected = +9223372036854775803;
+	const char *s;
+
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config18"),
+		GIT_CONFIG_LEVEL_GLOBAL, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config19"),
+		GIT_CONFIG_LEVEL_SYSTEM, 0));
+
+	cl_git_pass(git_config_open_level(&cfg_specific, cfg, GIT_CONFIG_LEVEL_GLOBAL));
+
+	cl_git_pass(git_config_get_int32(&i, cfg_specific, "core.int32global"));
+	cl_assert_equal_i(28, i);
+	cl_git_pass(git_config_get_int64(&l, cfg_specific, "core.int64global"));
+	cl_assert(l == expected);
+	cl_git_pass(git_config_get_bool(&i, cfg_specific, "core.boolglobal"));
+	cl_assert_equal_b(true, i);
+	cl_git_pass(git_config_get_string(&s, cfg_specific, "core.stringglobal"));
+	cl_assert_equal_s("I'm a global config value!", s);
+
+	git_config_free(cfg_specific);
 	git_config_free(cfg);
-	git_repository_free(repo);
-END_TEST
-#endif
+}
diff --git a/tests-clar/config/stress.c b/tests-clar/config/stress.c
index 6e7db6e8f..317e877f7 100644
--- a/tests-clar/config/stress.c
+++ b/tests-clar/config/stress.c
@@ -4,11 +4,13 @@
 #include "fileops.h"
 #include "posix.h"
 
+#define TEST_CONFIG "git-test-config"
+
 void test_config_stress__initialize(void)
 {
 	git_filebuf file = GIT_FILEBUF_INIT;
 
-	cl_git_pass(git_filebuf_open(&file, "git-test-config", 0));
+	cl_git_pass(git_filebuf_open(&file, TEST_CONFIG, 0));
 
 	git_filebuf_printf(&file, "[color]\n\tui = auto\n");
 	git_filebuf_printf(&file, "[core]\n\teditor = \n");
@@ -18,19 +20,16 @@ void test_config_stress__initialize(void)
 
 void test_config_stress__cleanup(void)
 {
-	p_unlink("git-test-config");
+	p_unlink(TEST_CONFIG);
 }
 
 void test_config_stress__dont_break_on_invalid_input(void)
 {
 	const char *editor, *color;
-	struct git_config_file *file;
 	git_config *config;
 
-	cl_assert(git_path_exists("git-test-config"));
-	cl_git_pass(git_config_file__ondisk(&file, "git-test-config"));
-	cl_git_pass(git_config_new(&config));
-	cl_git_pass(git_config_add_file(config, file, 0));
+	cl_assert(git_path_exists(TEST_CONFIG));
+	cl_git_pass(git_config_open_ondisk(&config, TEST_CONFIG));
 
 	cl_git_pass(git_config_get_string(&color, config, "color.ui"));
 	cl_git_pass(git_config_get_string(&editor, config, "core.editor"));
@@ -40,13 +39,10 @@ void test_config_stress__dont_break_on_invalid_input(void)
 
 void test_config_stress__comments(void)
 {
-	struct git_config_file *file;
 	git_config *config;
 	const char *str;
 
-	cl_git_pass(git_config_file__ondisk(&file, cl_fixture("config/config12")));
-	cl_git_pass(git_config_new(&config));
-	cl_git_pass(git_config_add_file(config, file, 0));
+	cl_git_pass(git_config_open_ondisk(&config, cl_fixture("config/config12")));
 
 	cl_git_pass(git_config_get_string(&str, config, "some.section.other"));
 	cl_assert(!strcmp(str, "hello! \" ; ; ; "));
@@ -62,21 +58,16 @@ void test_config_stress__comments(void)
 
 void test_config_stress__escape_subsection_names(void)
 {
-	struct git_config_file *file;
 	git_config *config;
 	const char *str;
 
 	cl_assert(git_path_exists("git-test-config"));
-	cl_git_pass(git_config_file__ondisk(&file, "git-test-config"));
-	cl_git_pass(git_config_new(&config));
-	cl_git_pass(git_config_add_file(config, file, 0));
+	cl_git_pass(git_config_open_ondisk(&config, TEST_CONFIG));
 
 	cl_git_pass(git_config_set_string(config, "some.sec\\tion.other", "foo"));
 	git_config_free(config);
 
-	cl_git_pass(git_config_file__ondisk(&file, "git-test-config"));
-	cl_git_pass(git_config_new(&config));
-	cl_git_pass(git_config_add_file(config, file, 0));
+	cl_git_pass(git_config_open_ondisk(&config, TEST_CONFIG));
 
 	cl_git_pass(git_config_get_string(&str, config, "some.sec\\tion.other"));
 	cl_assert(!strcmp("foo", str));
diff --git a/tests-clar/config/write.c b/tests-clar/config/write.c
index eeda4d66a..d98d1dd53 100644
--- a/tests-clar/config/write.c
+++ b/tests-clar/config/write.c
@@ -3,12 +3,14 @@
 void test_config_write__initialize(void)
 {
 	cl_fixture_sandbox("config/config9");
+	cl_fixture_sandbox("config/config15");
 	cl_fixture_sandbox("config/config17");
 }
 
 void test_config_write__cleanup(void)
 {
 	cl_fixture_cleanup("config9");
+	cl_fixture_cleanup("config15");
 	cl_fixture_cleanup("config17");
 }
 
@@ -69,6 +71,40 @@ void test_config_write__delete_value(void)
 	git_config_free(cfg);
 }
 
+/*
+ * At the beginning of the test:
+ *  - config9 has: core.dummy2=42
+ *  - config15 has: core.dummy2=7
+ */
+void test_config_write__delete_value_at_specific_level(void)
+{
+	git_config *cfg, *cfg_specific;
+	int32_t i;
+
+	cl_git_pass(git_config_open_ondisk(&cfg, "config15"));
+	cl_git_pass(git_config_get_int32(&i, cfg, "core.dummy2"));
+	cl_assert(i == 7);
+	git_config_free(cfg);
+
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, "config9",
+		GIT_CONFIG_LEVEL_LOCAL, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, "config15",
+		GIT_CONFIG_LEVEL_GLOBAL, 0));
+
+	cl_git_pass(git_config_open_level(&cfg_specific, cfg, GIT_CONFIG_LEVEL_GLOBAL));
+
+	cl_git_pass(git_config_delete(cfg_specific, "core.dummy2"));
+	git_config_free(cfg);
+
+	cl_git_pass(git_config_open_ondisk(&cfg, "config15"));
+	cl_assert(git_config_get_int32(&i, cfg, "core.dummy2") == GIT_ENOTFOUND);
+	cl_git_pass(git_config_set_int32(cfg, "core.dummy2", 7));
+
+	git_config_free(cfg_specific);
+	git_config_free(cfg);
+}
+
 void test_config_write__write_subsection(void)
 {
 	git_config *cfg;
@@ -139,7 +175,45 @@ void test_config_write__escape_value(void)
 	git_config_free(cfg);
 }
 
-void test_config_write__add_value_in_file_with_no_clrf_at_the_end(void)
+void test_config_write__add_value_at_specific_level(void)
+{
+	git_config *cfg, *cfg_specific;
+	int i;
+	int64_t l, expected = +9223372036854775803;
+	const char *s;
+
+	// open config15 as global level config file
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, "config9",
+		GIT_CONFIG_LEVEL_LOCAL, 0));
+	cl_git_pass(git_config_add_file_ondisk(cfg, "config15",
+		GIT_CONFIG_LEVEL_GLOBAL, 0));
+
+	cl_git_pass(git_config_open_level(&cfg_specific, cfg, GIT_CONFIG_LEVEL_GLOBAL));
+
+	cl_git_pass(git_config_set_int32(cfg_specific, "core.int32global", 28));
+	cl_git_pass(git_config_set_int64(cfg_specific, "core.int64global", expected));
+	cl_git_pass(git_config_set_bool(cfg_specific, "core.boolglobal", true));
+	cl_git_pass(git_config_set_string(cfg_specific, "core.stringglobal", "I'm a global config value!"));
+	git_config_free(cfg_specific);
+	git_config_free(cfg);
+
+	// open config15 as local level config file
+	cl_git_pass(git_config_open_ondisk(&cfg, "config15"));
+
+	cl_git_pass(git_config_get_int32(&i, cfg, "core.int32global"));
+	cl_assert_equal_i(28, i);
+	cl_git_pass(git_config_get_int64(&l, cfg, "core.int64global"));
+	cl_assert(l == expected);
+	cl_git_pass(git_config_get_bool(&i, cfg, "core.boolglobal"));
+	cl_assert_equal_b(true, i);
+	cl_git_pass(git_config_get_string(&s, cfg, "core.stringglobal"));
+	cl_assert_equal_s("I'm a global config value!", s);
+
+	git_config_free(cfg);
+}
+
+void test_config_write__add_value_at_file_with_no_clrf_at_the_end(void)
 {
 	git_config *cfg;
 	int i;