Merge branch 'mg/config-symbolic-constants'

* mg/config-symbolic-constants:
  config: Give error message when not changing a multivar
  config: define and document exit codes

Documentation/git-config.txt

@@ -50,16 +50,18 @@ The default is to assume the config file of the current repository,
 .git/config unless defined otherwise with GIT_DIR and GIT_CONFIG
 (see <<FILES>>).
 
-This command will fail if:
+This command will fail (with exit code ret) if:
 
-. The config file is invalid,
-. Can not write to the config file,
-. no section was provided,
-. the section or key is invalid,
-. you try to unset an option which does not exist,
-. you try to unset/set an option for which multiple lines match, or
-. you use '--global' option without $HOME being properly set.
+. The config file is invalid (ret=3),
+. can not write to the config file (ret=4),
+. no section or name was provided (ret=2),
+. the section or key is invalid (ret=1),
+. you try to unset an option which does not exist (ret=5),
+. you try to unset/set an option for which multiple lines match (ret=5),
+. you try to use an invalid regexp (ret=6), or
+. you use '--global' option without $HOME being properly set (ret=128).
 
+On success, the command returns the exit code 0.
 
 OPTIONS
 -------

builtin/config.c

@@ -436,9 +436,14 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 			      NULL, NULL);
 	}
 	else if (actions == ACTION_SET) {
+		int ret;
 		check_argc(argc, 2, 2);
 		value = normalize_value(argv[0], argv[1]);
-		return git_config_set(argv[0], value);
+		ret = git_config_set(argv[0], value);
+		if (ret == CONFIG_NOTHING_SET)
+			error("cannot overwrite multiple values with a single value\n"
+			"       Use a regexp, --add or --set-all to change %s.", argv[0]);
+		return ret;
 	}
 	else if (actions == ACTION_SET_ALL) {
 		check_argc(argc, 2, 3);

cache.h

@@ -1023,6 +1023,16 @@ extern const char *packed_object_info_detail(struct packed_git *, off_t, unsigne
 /* Dumb servers support */
 extern int update_server_info(int);
 
+/* git_config_parse_key() returns these negated: */
+#define CONFIG_INVALID_KEY 1
+#define CONFIG_NO_SECTION_OR_NAME 2
+/* git_config_set(), git_config_set_multivar() return the above or these: */
+#define CONFIG_NO_LOCK -1
+#define CONFIG_INVALID_FILE 3
+#define CONFIG_NO_WRITE 4
+#define CONFIG_NOTHING_SET 5
+#define CONFIG_INVALID_PATTERN 6
+
 typedef int (*config_fn_t)(const char *, const char *, void *);
 extern int git_default_config(const char *, const char *, void *);
 extern int git_config_from_file(config_fn_t fn, const char *, void *);

config.c

@@ -1123,12 +1123,12 @@ int git_config_parse_key(const char *key, char **store_key, int *baselen_)
 
 	if (last_dot == NULL || last_dot == key) {
 		error("key does not contain a section: %s", key);
-		return -2;
+		return -CONFIG_NO_SECTION_OR_NAME;
 	}
 
 	if (!last_dot[1]) {
 		error("key does not contain variable name: %s", key);
-		return -2;
+		return -CONFIG_NO_SECTION_OR_NAME;
 	}
 
 	baselen = last_dot - key;
@@ -1165,7 +1165,7 @@ int git_config_parse_key(const char *key, char **store_key, int *baselen_)
 
 out_free_ret_1:
 	free(*store_key);
-	return -1;
+	return -CONFIG_INVALID_KEY;
 }
 
 /*
@@ -1221,7 +1221,7 @@ int git_config_set_multivar(const char *key, const char *value,
 	if (fd < 0) {
 		error("could not lock config file %s: %s", config_filename, strerror(errno));
 		free(store.key);
-		ret = -1;
+		ret = CONFIG_NO_LOCK;
 		goto out_free;
 	}
 
@@ -1235,12 +1235,12 @@ int git_config_set_multivar(const char *key, const char *value,
 		if ( ENOENT != errno ) {
 			error("opening %s: %s", config_filename,
 			      strerror(errno));
-			ret = 3; /* same as "invalid config file" */
+			ret = CONFIG_INVALID_FILE; /* same as "invalid config file" */
 			goto out_free;
 		}
 		/* if nothing to unset, error out */
 		if (value == NULL) {
-			ret = 5;
+			ret = CONFIG_NOTHING_SET;
 			goto out_free;
 		}
 
@@ -1268,7 +1268,7 @@ int git_config_set_multivar(const char *key, const char *value,
 					REG_EXTENDED)) {
 				error("invalid pattern: %s", value_regex);
 				free(store.value_regex);
-				ret = 6;
+				ret = CONFIG_INVALID_PATTERN;
 				goto out_free;
 			}
 		}
@@ -1290,7 +1290,7 @@ int git_config_set_multivar(const char *key, const char *value,
 				regfree(store.value_regex);
 				free(store.value_regex);
 			}
-			ret = 3;
+			ret = CONFIG_INVALID_FILE;
 			goto out_free;
 		}
 
@@ -1303,7 +1303,7 @@ int git_config_set_multivar(const char *key, const char *value,
 		/* if nothing to unset, or too many matches, error out */
 		if ((store.seen == 0 && value == NULL) ||
 				(store.seen > 1 && multi_replace == 0)) {
-			ret = 5;
+			ret = CONFIG_NOTHING_SET;
 			goto out_free;
 		}
 
@@ -1364,7 +1364,7 @@ int git_config_set_multivar(const char *key, const char *value,
 
 	if (commit_lock_file(lock) < 0) {
 		error("could not commit config file %s", config_filename);
-		ret = 4;
+		ret = CONFIG_NO_WRITE;
 		goto out_free;
 	}