config: "git config --get-urlmatch" parses section.<url>.key

Using the same urlmatch_config_entry() infrastructure, add a new
mode "--get-urlmatch" to the "git config" command, to learn values
for the "virtual" two-level variables customized for the specific
URL.

    git config [--<type>] --get-urlmatch <section>[.<key>] <url>

With <section>.<key> fully specified, the configuration data for
<section>.<urlpattern>.<key> for <urlpattern> that best matches the
given <url> is sought (and if not found, <section>.<key> is used)
and reported.  For example, with this configuration:

    [http]
        sslVerify
    [http "https://weak.example.com"]
        cookieFile = /tmp/cookie.txt
        sslVerify = false

You would get

    $ git config --bool --get-urlmatch http.sslVerify https://good.example.com
    true
    $ git config --bool --get-urlmatch http.sslVerify https://weak.example.com
    false

With only <section> specified, you can get a list of all variables
in the section with their values that apply to the given URL.  E.g

    $ git config --get-urlmatch http https://weak.example.com
    http.cookiefile /tmp/cookie.txt
    http.sslverify false

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 152 insertions, 0 deletions

diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
index d88a6fcb29..b48e2ecc1c 100644
--- a/Documentation/git-config.txt
+++ b/Documentation/git-config.txt
@@ -15,6 +15,7 @@ SYNOPSIS
 'git config' [<file-option>] [type] [-z|--null] --get name [value_regex]
 'git config' [<file-option>] [type] [-z|--null] --get-all name [value_regex]
 'git config' [<file-option>] [type] [-z|--null] --get-regexp name_regex [value_regex]
+'git config' [<file-option>] [type] [-z|--null] --get-urlmatch name URL
 'git config' [<file-option>] --unset name [value_regex]
 'git config' [<file-option>] --unset-all name [value_regex]
 'git config' [<file-option>] --rename-section old_name new_name
@@ -95,6 +96,14 @@ OPTIONS
 	in which section and variable names are lowercased, but subsection
 	names are not.
 
+--get-urlmatch name URL::
+	When given a two-part name section.key, the value for
+	section.<url>.key whose <url> part matches the best to the
+	given URL is returned (if no such key exists, the value for
+	section.key is used as a fallback).  When given just the
+	section as name, do so for all the keys in the section and
+	list them.
+
 --global::
 	For writing options: write to global ~/.gitconfig file rather than
 	the repository .git/config, write to $XDG_CONFIG_HOME/git/config file
@@ -273,6 +282,13 @@ Given a .git/config like this:
 		gitproxy=proxy-command for kernel.org
 		gitproxy=default-proxy ; for all the rest
 
+	; HTTP
+	[http]
+		sslVerify
+	[http "https://weak.example.com"]
+		sslVerify = false
+		cookieFile = /tmp/cookie.txt
+
 you can set the filemode to true with
 
 ------------
@@ -358,6 +374,19 @@ RESET=$(git config --get-color "" "reset")
 echo "${WS}your whitespace color or blue reverse${RESET}"
 ------------
 
+For URLs in `https://weak.example.com`, `http.sslVerify` is set to
+false, while it is set to `true` for all others:
+
+------------
+% git config --bool --get-urlmatch http.sslverify https://good.example.com
+true
+% git config --bool --get-urlmatch http.sslverify https://weak.example.com
+false
+% git config --get-urlmatch http https://weak.example.com
+http.cookiefile /tmp/cookie.txt
+http.sslverify false
+------------
+
 include::config.txt[]
 
 GIT
diff --git a/builtin/config.c b/builtin/config.c
index 12c50734c3..c046f54829 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -2,6 +2,7 @@
 #include "cache.h"
 #include "color.h"
 #include "parse-options.h"
+#include "urlmatch.h"
 
 static const char *const builtin_config_usage[] = {
 	N_("git config [options]"),
@@ -41,6 +42,7 @@ static int respect_includes = -1;
 #define ACTION_SET_ALL (1<<12)
 #define ACTION_GET_COLOR (1<<13)
 #define ACTION_GET_COLORBOOL (1<<14)
+#define ACTION_GET_URLMATCH (1<<15)
 
 #define TYPE_BOOL (1<<0)
 #define TYPE_INT (1<<1)
@@ -57,6 +59,7 @@ static struct option builtin_config_options[] = {
 	OPT_BIT(0, "get", &actions, N_("get value: name [value-regex]"), ACTION_GET),
 	OPT_BIT(0, "get-all", &actions, N_("get all values: key [value-regex]"), ACTION_GET_ALL),
 	OPT_BIT(0, "get-regexp", &actions, N_("get values for regexp: name-regex [value-regex]"), ACTION_GET_REGEXP),
+	OPT_BIT(0, "get-urlmatch", &actions, N_("get value specific for the URL: section[.var] URL"), ACTION_GET_URLMATCH),
 	OPT_BIT(0, "replace-all", &actions, N_("replace all matching variables: name value [value_regex]"), ACTION_REPLACE_ALL),
 	OPT_BIT(0, "add", &actions, N_("add a new variable: name value"), ACTION_ADD),
 	OPT_BIT(0, "unset", &actions, N_("remove a variable: name [value-regex]"), ACTION_UNSET),
@@ -348,6 +351,97 @@ static int get_colorbool(int print)
 		return get_colorbool_found ? 0 : 1;
 }
 
+struct urlmatch_current_candidate_value {
+	char value_is_null;
+	struct strbuf value;
+};
+
+static int urlmatch_collect_fn(const char *var, const char *value, void *cb)
+{
+	struct string_list *values = cb;
+	struct string_list_item *item = string_list_insert(values, var);
+	struct urlmatch_current_candidate_value *matched = item->util;
+
+	if (!matched) {
+		matched = xmalloc(sizeof(*matched));
+		strbuf_init(&matched->value, 0);
+		item->util = matched;
+	} else {
+		strbuf_reset(&matched->value);
+	}
+
+	if (value) {
+		strbuf_addstr(&matched->value, value);
+		matched->value_is_null = 0;
+	} else {
+		matched->value_is_null = 1;
+	}
+	return 0;
+}
+
+static char *dup_downcase(const char *string)
+{
+	char *result;
+	size_t len, i;
+
+	len = strlen(string);
+	result = xmalloc(len + 1);
+	for (i = 0; i < len; i++)
+		result[i] = tolower(string[i]);
+	result[i] = '\0';
+	return result;
+}
+
+static int get_urlmatch(const char *var, const char *url)
+{
+	char *section_tail;
+	struct string_list_item *item;
+	struct urlmatch_config config = { STRING_LIST_INIT_DUP };
+	struct string_list values = STRING_LIST_INIT_DUP;
+
+	config.collect_fn = urlmatch_collect_fn;
+	config.cascade_fn = NULL;
+	config.cb = &values;
+
+	if (!url_normalize(url, &config.url))
+		die(config.url.err);
+
+	config.section = dup_downcase(var);
+	section_tail = strchr(config.section, '.');
+	if (section_tail) {
+		*section_tail = '\0';
+		config.key = section_tail + 1;
+		show_keys = 0;
+	} else {
+		config.key = NULL;
+		show_keys = 1;
+	}
+
+	git_config_with_options(urlmatch_config_entry, &config,
+				given_config_file, respect_includes);
+
+	for_each_string_list_item(item, &values) {
+		struct urlmatch_current_candidate_value *matched = item->util;
+		struct strbuf key = STRBUF_INIT;
+		struct strbuf buf = STRBUF_INIT;
+
+		strbuf_addstr(&key, item->string);
+		format_config(&buf, key.buf,
+			      matched->value_is_null ? NULL : matched->value.buf);
+		fwrite(buf.buf, 1, buf.len, stdout);
+		strbuf_release(&key);
+		strbuf_release(&buf);
+
+		strbuf_release(&matched->value);
+	}
+	string_list_clear(&config.vars, 1);
+	string_list_clear(&values, 1);
+	free(config.url.url);
+
+	free((void *)config.section);
+	return 0;
+}
+
 int cmd_config(int argc, const char **argv, const char *prefix)
 {
 	int nongit = !startup_info->have_repository;
@@ -499,6 +593,10 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 		check_argc(argc, 1, 2);
 		return get_value(argv[0], argv[1]);
 	}
+	else if (actions == ACTION_GET_URLMATCH) {
+		check_argc(argc, 2, 2);
+		return get_urlmatch(argv[0], argv[1]);
+	}
 	else if (actions == ACTION_UNSET) {
 		check_argc(argc, 1, 2);
 		if (argc == 2)
diff --git a/t/t1300-repo-config.sh b/t/t1300-repo-config.sh
index c4a7d84f46..c23f4781e1 100755
--- a/t/t1300-repo-config.sh
+++ b/t/t1300-repo-config.sh
@@ -1087,6 +1087,31 @@ test_expect_success 'barf on incomplete string' '
 	grep " line 3 " error
 '
 
+test_expect_success 'urlmatch' '
+	cat >.git/config <<-\EOF &&
+	[http]
+		sslVerify
+	[http "https://weak.example.com"]
+		sslVerify = false
+		cookieFile = /tmp/cookie.txt
+	EOF
+
+	echo true >expect &&
+	git config --bool --get-urlmatch http.SSLverify https://good.example.com >actual &&
+	test_cmp expect actual &&
+
+	echo false >expect &&
+	git config --bool --get-urlmatch http.sslverify https://weak.example.com >actual &&
+	test_cmp expect actual &&
+
+	{
+		echo http.cookiefile /tmp/cookie.txt &&
+		echo http.sslverify false
+	} >expect &&
+	git config --get-urlmatch HTTP https://weak.example.com >actual &&
+	test_cmp expect actual
+'
+
 # good section hygiene
 test_expect_failure 'unsetting the last key in a section removes header' '
 	cat >.git/config <<-\EOF &&