Add keyring credential helper for git

bin/git-credential-keyring

@@ -0,0 +1,34 @@
+#!/usr/bin/env lua
+
+-- usage: secret-tool store --label='label' attribute value ...
+--        secret-tool lookup attribute value ...
+--        secret-tool clear attribute value ...
+--        secret-tool search [--all] [--unlock] attribute value ...
+
+local action = ...
+
+local options = {}
+for line in io.stdin:lines() do
+	local key, value = line:match("^(.*)=(.*)$")
+	options[key]=value
+end
+
+if action == "get" then
+	local command = string.format('secret-tool lookup application git username %s host %s', options.username, options.host, options.username, options.host)
+	local file = io.popen(command, "r")
+	local password = file:read("all")
+	if password~="" then
+		print("password="..password)
+	else
+		os.exit(1, true)
+	end
+	file:close()
+elseif action == "store" then
+	local command = string.format('secret-tool store --label="git %s@%s" application git username %s host %s', options.username, options.host, options.username, options.host)
+	local file = io.popen(command, "w")
+	file:write(options.password)
+	file:close()
+elseif action == "erase" then
+	local command = string.format('secret-tool clear application git username %s host %s', options.username, options.host, options.username, options.host)
+	os.execute(command)
+end