builtin/config: introduce "set" subcommand

Introduce a new "set" subcommand to git-config(1). Please refer to
preceding commits regarding the motivation behind this change.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

Documentation/git-config.txt

@@ -11,9 +11,7 @@ SYNOPSIS
 [verse]
 'git config list' [<file-option>] [<display-option>] [--includes]
 'git config get' [<file-option>] [<display-option>] [--includes] [--all] [--regexp=<regexp>] [--value=<value>] [--fixed-value] [--default=<default>] <name>
-'git config' [<file-option>] [--type=<type>] [--comment=<message>] [--fixed-value] [--show-origin] [--show-scope] [-z|--null] <name> [<value> [<value-pattern>]]
-'git config' [<file-option>] [--type=<type>] [--comment=<message>] --add <name> <value>
-'git config' [<file-option>] [--type=<type>] [--comment=<message>] [--fixed-value] --replace-all <name> <value> [<value-pattern>]
+'git config set' [<file-option>] [--type=<type>] [--comment=<message>] [--all] [--value=<value>] [--fixed-value] <name> <value>
 'git config' [<file-option>] [--fixed-value] --unset <name> [<value-pattern>]
 'git config' [<file-option>] [--fixed-value] --unset-all <name> [<value-pattern>]
 'git config' [<file-option>] --rename-section <old-name> <new-name>
@@ -27,7 +25,7 @@ You can query/set/replace/unset options with this command. The name is
 actually the section and the key separated by a dot, and the value will be
 escaped.
 
-Multiple lines can be added to an option by using the `--add` option.
+Multiple lines can be added to an option by using the `--append` option.
 If you want to update or unset an option which can occur on multiple
 lines, a `value-pattern` (which is an extended regular expression,
 unless the `--fixed-value` option is given) needs to be given.  Only the
@@ -82,6 +80,13 @@ get::
 	emits all values associated with key. Returns error code 1 if key is
 	not present.
 
+set::
+	Set value for one or more config options. By default, this command
+	refuses to write multi-valued config options. Passing `--all` will
+	replace all multi-valued config options with the new value, whereas
+	`--value=` will replace all config options whose values match the given
+	pattern.
+
 [[OPTIONS]]
 OPTIONS
 -------
@@ -90,10 +95,9 @@ OPTIONS
 	Default behavior is to replace at most one line. This replaces
 	all lines matching the key (and optionally the `value-pattern`).
 
---add::
+--append::
 	Adds a new line to the option without altering any existing
-	values.  This is the same as providing '^$' as the `value-pattern`
-	in `--replace-all`.
+	values. This is the same as providing '--value=^$' in `set`.
 
 --comment <message>::
 	Append a comment at the end of new or modified lines.
@@ -296,6 +300,9 @@ recommended to migrate to the new syntax.
 'git config <name>'::
 	Replaced by `git config get <name>`.
 
+'git config <name> <value> [<value-pattern>]'::
+	Replaced by `git config set [--value=<pattern>] <name> <value>`.
+
 -l::
 --list::
 	Replaced by `git config list`.
@@ -315,6 +322,9 @@ recommended to migrate to the new syntax.
 --get-color <name> [<default>]::
 	Replaced by `git config get --type=color [--default=<default>] <name>`.
 
+--add <name> <value>::
+	Replaced by `git config set --append <name> <value>`.
+
 CONFIGURATION
 -------------
 `pager.config` is only respected when listing configuration, i.e., when
@@ -361,7 +371,7 @@ precedence over values read earlier.  When multiple values are taken then all
 values of a key from all files will be used.
 
 By default, options are only written to the repository specific
-configuration file. Note that this also affects options like `--replace-all`
+configuration file. Note that this also affects options like `set`
 and `--unset`. *'git config' will only ever change one file at a time*.
 
 You can limit which configuration sources are read from or written to by
@@ -497,15 +507,15 @@ Given a .git/config like this:
 you can set the filemode to true with
 
 ------------
-% git config core.filemode true
+% git config set core.filemode true
 ------------
 
 The hypothetical proxy command entries actually have a postfix to discern
 what URL they apply to. Here is how to change the entry for kernel.org
 to "ssh".
 
 ------------
-% git config core.gitproxy '"ssh" for kernel.org' 'for kernel.org$'
+% git config set --value='for kernel.org$' core.gitproxy '"ssh" for kernel.org'
 ------------
 
 This makes sure that only the key/value pair for kernel.org is replaced.
@@ -541,26 +551,26 @@ If you like to live dangerously, you can replace *all* core.gitproxy by a
 new one with
 
 ------------
-% git config --replace-all core.gitproxy ssh
+% git config set --all core.gitproxy ssh
 ------------
 
 However, if you really only want to replace the line for the default proxy,
 i.e. the one without a "for ..." postfix, do something like this:
 
 ------------
-% git config core.gitproxy ssh '! for '
+% git config set --value='! for ' core.gitproxy ssh
 ------------
 
 To actually match only values with an exclamation mark, you have to
 
 ------------
-% git config section.key value '[!]'
+% git config set --value='[!]' section.key value
 ------------
 
 To add a new proxy, without altering any of the existing ones, use
 
 ------------
-% git config --add core.gitproxy '"proxy-command" for example.com'
+% git config set --append core.gitproxy '"proxy-command" for example.com'
 ------------
 
 An example to use customized color from the configuration in your

builtin/config.c

@@ -18,6 +18,7 @@
 static const char *const builtin_config_usage[] = {
 	N_("git config list [<file-option>] [<display-option>] [--includes]"),
 	N_("git config get [<file-option>] [<display-option>] [--includes] [--all] [--regexp=<regexp>] [--value=<value>] [--fixed-value] [--default=<default>] <name>"),
+	N_("git config set [<file-option>] [--type=<type>] [--all] [--value=<value>] [--fixed-value] <name> <value>"),
 	NULL
 };
 
@@ -31,6 +32,11 @@ static const char *const builtin_config_get_usage[] = {
 	NULL
 };
 
+static const char *const builtin_config_set_usage[] = {
+	N_("git config set [<file-option>] [--type=<type>] [--comment=<message>] [--all] [--value=<value>] [--fixed-value] <name> <value>"),
+	NULL
+};
+
 static char *key;
 static regex_t *key_regexp;
 static const char *value_pattern;
@@ -849,9 +855,66 @@ static int cmd_config_get(int argc, const char **argv, const char *prefix)
 	return get_value(argv[0], value_pattern, flags);
 }
 
+static int cmd_config_set(int argc, const char **argv, const char *prefix)
+{
+	const char *value_pattern = NULL, *comment_arg = NULL;
+	char *comment = NULL;
+	int flags = 0, append = 0;
+	struct option opts[] = {
+		CONFIG_LOCATION_OPTIONS,
+		CONFIG_TYPE_OPTIONS,
+		OPT_GROUP(N_("Filter")),
+		OPT_BIT(0, "all", &flags, N_("replace multi-valued config option with new value"), CONFIG_FLAGS_MULTI_REPLACE),
+		OPT_STRING(0, "value", &value_pattern, N_("pattern"), N_("show config with values matching the pattern")),
+		OPT_BIT(0, "fixed-value", &flags, N_("use string equality when comparing values to value pattern"), CONFIG_FLAGS_FIXED_VALUE),
+		OPT_GROUP(N_("Other")),
+		OPT_STRING(0, "comment", &comment_arg, N_("value"), N_("human-readable comment string (# will be prepended as needed)")),
+		OPT_BOOL(0, "append", &append, N_("add a new line without altering any existing values")),
+		OPT_END(),
+	};
+	struct key_value_info default_kvi = KVI_INIT;
+	char *value;
+	int ret;
+
+	argc = parse_options(argc, argv, prefix, opts, builtin_config_set_usage,
+			     PARSE_OPT_STOP_AT_NON_OPTION);
+	check_write();
+	check_argc(argc, 2, 2);
+
+	if ((flags & CONFIG_FLAGS_FIXED_VALUE) && !value_pattern)
+		die(_("--fixed-value only applies with --value=<pattern>"));
+	if (append && value_pattern)
+		die(_("--append cannot be used with --value=<pattern>"));
+	if (append)
+		value_pattern = CONFIG_REGEX_NONE;
+
+	comment = git_config_prepare_comment_string(comment_arg);
+
+	handle_config_location(prefix);
+
+	value = normalize_value(argv[0], argv[1], &default_kvi);
+
+	if ((flags & CONFIG_FLAGS_MULTI_REPLACE) || value_pattern) {
+		ret = git_config_set_multivar_in_file_gently(given_config_source.file,
+							     argv[0], value, value_pattern,
+							     comment, flags);
+	} else {
+		ret = git_config_set_in_file_gently(given_config_source.file,
+						    argv[0], comment, value);
+		if (ret == CONFIG_NOTHING_SET)
+			error(_("cannot overwrite multiple values with a single value\n"
+			"       Use a regexp, --add or --replace-all to change %s."), argv[0]);
+	}
+
+	free(comment);
+	free(value);
+	return ret;
+}
+
 static struct option builtin_subcommand_options[] = {
 	OPT_SUBCOMMAND("list", &subcommand, cmd_config_list),
 	OPT_SUBCOMMAND("get", &subcommand, cmd_config_get),
+	OPT_SUBCOMMAND("set", &subcommand, cmd_config_set),
 	OPT_END(),
 };