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[PATCH 5/6] config: add a notion of "scope"

From
Jeff King <peff@peff.net>
Date
May 18, 2016, 22:44 UTC
Message-ID
<20160518224423.GE22443@sigill.intra.peff.net>
In-Reply-To
<20160518223712.GA18317@sigill.intra.peff.net>

A config callback passed to git_config() doesn't know very much about the context in which it sees a variable. It can ask whether the variable comes from a file, and get the file name. But without analyzing the filename (which is hard to do accurately), it cannot tell whether it is in system-level config, user-level config, or repo-specific config.

Generally this doesn't matter; the point of not passing this to the callback is that it should treat the config the same no matter where it comes from. But some programs, like upload-pack, are a special case: we should be able to run them in an untrusted repository, which means we cannot use any "dangerous" config from the repository config file (but it is OK to use it from system or user config).

This patch teaches the config code to record the "scope" of each variable, and make it available inside config callbacks, similar to how we give access to the filename. The scope is the starting source for a particular parsing operation, and remains the same even if we include other files (so a .git/config which includes another file will remain CONFIG_SCOPE_REPO, as it would be similarly untrusted).

Signed-off-by: Jeff King <peff@peff.net>
---
 cache.h                | 11 +++++++++++
 config.c               | 23 +++++++++++++++++++++++
 t/helper/test-config.c | 16 ++++++++++++++++
 t/t1308-config-set.sh  |  3 +++
 4 files changed, 53 insertions(+)
diff --git a/cache.h b/cache.h
index 29c579b..81bd96a 100644
--- a/cache.h
+++ b/cache.h
@@ -1601,6 +1601,16 @@ extern const char *get_log_output_encoding(void);
 extern const char *get_commit_output_encoding(void);
 
 extern int git_config_parse_parameter(const char *, config_fn_t fn, void *data);
+
+enum config_scope {
+	CONFIG_SCOPE_UNKNOWN = 0,
+	CONFIG_SCOPE_SYSTEM,
+	CONFIG_SCOPE_GLOBAL,
+	CONFIG_SCOPE_REPO,
+	CONFIG_SCOPE_CMDLINE,
+};
+
+extern enum config_scope current_config_scope(void);
 extern const char *current_config_origin_type(void);
 extern const char *current_config_name(void);
 
@@ -1694,6 +1704,7 @@ struct key_value_info {
 	const char *filename;
 	int linenr;
 	const char *origin_type;
+	enum config_scope scope;
 };
 
 extern NORETURN void git_die_config(const char *key, const char *err, ...) __attribute__((format(printf, 2, 3)));
diff --git a/config.c b/config.c
index 75afdd7..995e886 100644
--- a/config.c
+++ b/config.c
@@ -57,6 +57,15 @@ struct config_source {
 static struct config_source *cf;
 static struct key_value_info *current_config_kvi;
 
+/*
+ * Similar to the variables above, this gives access to the "scope" of the
+ * current value (repo, global, etc). For cached values, it can be found via
+ * the current_config_kvi as above. During parsing, the current value can be
+ * found in this variable. It's not part of "cf" because it transcends a single
+ * file (i.e., a file included from .git/config is still in "repo" scope).
+ */
+static enum config_scope current_parsing_scope;
+
 static int zlib_compression_seen;
 
 /*
@@ -1233,22 +1242,27 @@ static int do_git_config_sequence(config_fn_t fn, void *data)
 	char *user_config = expand_user_path("~/.gitconfig");
 	char *repo_config = git_pathdup("config");
 
+	current_parsing_scope = CONFIG_SCOPE_SYSTEM;
 	if (git_config_system() && !access_or_die(git_etc_gitconfig(), R_OK, 0))
 		ret += git_config_from_file(fn, git_etc_gitconfig(),
 					    data);
 
+	current_parsing_scope = CONFIG_SCOPE_GLOBAL;
 	if (xdg_config && !access_or_die(xdg_config, R_OK, ACCESS_EACCES_OK))
 		ret += git_config_from_file(fn, xdg_config, data);
 
 	if (user_config && !access_or_die(user_config, R_OK, ACCESS_EACCES_OK))
 		ret += git_config_from_file(fn, user_config, data);
 
+	current_parsing_scope = CONFIG_SCOPE_REPO;
 	if (repo_config && !access_or_die(repo_config, R_OK, 0))
 		ret += git_config_from_file(fn, repo_config, data);
 
+	current_parsing_scope = CONFIG_SCOPE_CMDLINE;
 	if (git_config_from_parameters(fn, data) < 0)
 		die(_("unable to parse command-line config"));
 
+	current_parsing_scope = CONFIG_SCOPE_UNKNOWN;
 	free(xdg_config);
 	free(user_config);
 	free(repo_config);
@@ -1387,6 +1401,7 @@ static int configset_add_value(struct config_set *cs, const char *key, const cha
 		kv_info->linenr = -1;
 		kv_info->origin_type = NULL;
 	}
+	kv_info->scope = current_parsing_scope;
 	si->util = kv_info;
 
 	return 0;
@@ -2486,3 +2501,11 @@ const char *current_config_name(void)
 		die("BUG: current_config_name called outside config callback");
 	return name ? name : "";
 }
+
+enum config_scope current_config_scope(void)
+{
+	if (current_config_kvi)
+		return current_config_kvi->scope;
+	else
+		return current_parsing_scope;
+}
diff --git a/t/helper/test-config.c b/t/helper/test-config.c
index 3605ef8..509aeef 100644
--- a/t/helper/test-config.c
+++ b/t/helper/test-config.c
@@ -35,6 +35,21 @@
  *
  */
 
+static const char *scope_name(enum config_scope scope)
+{
+	switch (scope) {
+	case CONFIG_SCOPE_SYSTEM:
+		return "system";
+	case CONFIG_SCOPE_GLOBAL:
+		return "global";
+	case CONFIG_SCOPE_REPO:
+		return "repo";
+	case CONFIG_SCOPE_CMDLINE:
+		return "cmdline";
+	default:
+		return "unknown";
+	}
+}
 static int iterate_cb(const char *var, const char *value, void *data)
 {
 	static int nr;
@@ -46,6 +61,7 @@ static int iterate_cb(const char *var, const char *value, void *data)
 	printf("value=%s\n", value ? value : "(null)");
 	printf("origin=%s\n", current_config_origin_type());
 	printf("name=%s\n", current_config_name());
+	printf("scope=%s\n", scope_name(current_config_scope()));
 
 	return 0;
 }
diff --git a/t/t1308-config-set.sh b/t/t1308-config-set.sh
index b241338..486b41c 100755
--- a/t/t1308-config-set.sh
+++ b/t/t1308-config-set.sh
@@ -237,16 +237,19 @@ test_expect_success 'iteration shows correct origins' '
 	value=!test-config
 	origin=file
 	name=$(pwd)/.gitconfig
+	scope=global
 
 	key=foo.bar
 	value=from-repo
 	origin=file
 	name=.git/config
+	scope=repo
 
 	key=foo.bar
 	value=from-cmdline
 	origin=command line
 	name=
+	scope=cmdline
 	EOF
 	git -c foo.bar=from-cmdline test-config iterate >actual &&
 	test_cmp expect actual

-- 
2.8.2.888.gecb1fe3
Previous: Jeff KingNext: Jeff King
Message 14 of 23 in “pack-objects hook for upload-pack”
  1. 0/6 pack-objects hook for upload-packJeff King, May 18, 2016
  2. 1/6 git_config_with_options: drop "found" countingJeff King, May 18, 2016
  3. 2/6 git_config_parse_parameter: refactor cleanup codeJeff King, May 18, 2016
  4. 3/6 config: set up config_source for command-line configJeff King, May 18, 2016
  5. 4/6 config: return configset value for current_config_ functionsJeff King, May 18, 2016
  6. Jeff KingMay 19, 2016
  7. Duy NguyenMay 26, 2016
  8. Junio C HamanoMay 26, 2016
  9. Jeff KingMay 26, 2016
  10. Junio C HamanoMay 26, 2016
  11. Jeff KingMay 27, 2016
  12. Junio C HamanoMay 27, 2016
  13. Jeff KingMay 27, 2016
  14. 5/6 config: add a notion of "scope"Jeff King, May 18, 2016
  15. 6/6 upload-pack: provide a hook for running pack-objectsJeff King, May 18, 2016
  16. Jeff KingMay 19, 2016
  17. Ævar Arnfjörð BjarmasonMay 19, 2016
  18. Jeff KingMay 19, 2016
  19. Ævar Arnfjörð BjarmasonMay 19, 2016
  20. Jeff KingMay 26, 2016
  21. Junio C HamanoMay 25, 2016
  22. Jeff KingMay 26, 2016
  23. Junio C HamanoMay 26, 2016

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