http: add http.savecookies option to write out HTTP cookies

HTTP servers may send Set-Cookie headers in a response and expect them
to be set on subsequent requests. By default, libcurl behavior is to
store such cookies in memory and reuse them across requests within a
single session. However, it may also make sense, depending on the
server and the cookies, to store them across sessions. Provide users
an option to enable this behavior, writing cookies out to the same
file specified in http.cookiefile.

Signed-off-by: Dave Borowitz <dborowitz@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -1456,7 +1456,11 @@ http.cookiefile::
 	of the file to read cookies from should be plain HTTP headers or
 	the Netscape/Mozilla cookie file format (see linkgit:curl[1]).
 	NOTE that the file specified with http.cookiefile is only used as
-	input. No cookies will be stored in the file.
+	input unless http.saveCookies is set.
+
+http.savecookies::
+	If set, store cookies received during requests to the file specified by
+	http.cookiefile. Has no effect if http.cookiefile is unset.
 
 http.sslVerify::
 	Whether to verify the SSL certificate when fetching or pushing

http.c

@@ -45,6 +45,7 @@ static long curl_low_speed_time = -1;
 static int curl_ftp_no_epsv;
 static const char *curl_http_proxy;
 static const char *curl_cookie_file;
+static int curl_save_cookies;
 static struct credential http_auth = CREDENTIAL_INIT;
 static int http_proactive_auth;
 static const char *user_agent;
@@ -200,6 +201,10 @@ static int http_options(const char *var, const char *value, void *cb)
 
 	if (!strcmp("http.cookiefile", var))
 		return git_config_string(&curl_cookie_file, var, value);
+	if (!strcmp("http.savecookies", var)) {
+		curl_save_cookies = git_config_bool(var, value);
+		return 0;
+	}
 
 	if (!strcmp("http.postbuffer", var)) {
 		http_post_buffer = git_config_int(var, value);
@@ -513,6 +518,8 @@ struct active_request_slot *get_active_slot(void)
 	slot->callback_data = NULL;
 	slot->callback_func = NULL;
 	curl_easy_setopt(slot->curl, CURLOPT_COOKIEFILE, curl_cookie_file);
+	if (curl_save_cookies)
+		curl_easy_setopt(slot->curl, CURLOPT_COOKIEJAR, curl_cookie_file);
 	curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, pragma_header);
 	curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, curl_errorstr);
 	curl_easy_setopt(slot->curl, CURLOPT_CUSTOMREQUEST, NULL);

t/lib-httpd/apache.conf

@@ -22,6 +22,9 @@ ErrorLog error.log
 <IfModule !mod_version.c>
 	LoadModule version_module modules/mod_version.so
 </IfModule>
+<IfModule !mod_headers.c>
+	LoadModule headers_module modules/mod_headers.so
+</IfModule>
 
 <IfVersion < 2.4>
 LockFile accept.lock
@@ -87,6 +90,11 @@ Alias /auth/dumb/ www/auth/dumb/
 	SetEnv GIT_HTTP_EXPORT_ALL
 	SetEnv GIT_NAMESPACE ns
 </LocationMatch>
+<LocationMatch /smart_cookies/>
+	SetEnv GIT_EXEC_PATH ${GIT_EXEC_PATH}
+	SetEnv GIT_HTTP_EXPORT_ALL
+	Header set Set-Cookie name=value
+</LocationMatch>
 ScriptAliasMatch /smart_*[^/]*/(.*) ${GIT_EXEC_PATH}/git-http-backend/$1
 ScriptAlias /broken_smart/ broken-smart-http.sh/
 <Directory ${GIT_EXEC_PATH}>

t/t5551-http-fetch.sh

@@ -187,6 +187,24 @@ test_expect_success 'dumb clone via http-backend respects namespace' '
 	test_cmp expect actual
 '
 
+cat >cookies.txt <<EOF
+127.0.0.1	FALSE	/smart_cookies/	FALSE	0	othername	othervalue
+EOF
+cat >expect_cookies.txt <<EOF
+# Netscape HTTP Cookie File
+# http://curl.haxx.se/docs/http-cookies.html
+# This file was generated by libcurl! Edit at your own risk.
+
+127.0.0.1	FALSE	/smart_cookies/	FALSE	0	othername	othervalue
+127.0.0.1	FALSE	/smart_cookies/repo.git/info/	FALSE	0	name	value
+EOF
+test_expect_success 'cookies stored in http.cookiefile when http.savecookies set' '
+	git config http.cookiefile cookies.txt &&
+	git config http.savecookies true &&
+	git ls-remote $HTTPD_URL/smart_cookies/repo.git master &&
+	test_cmp expect_cookies.txt cookies.txt
+'
+
 test -n "$GIT_TEST_LONG" && test_set_prereq EXPENSIVE
 
 test_expect_success EXPENSIVE 'create 50,000 tags in the repo' '