bsdinstall: improve pkgbase target retry prompts

These now use bsddialog rather than prompting the user for input on the
console.

Reviewed by:	emaste
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D50270

usr.sbin/bsdinstall/scripts/pkgbase.in

@@ -23,18 +23,6 @@ local function capture(command)
 	return output:match("(.-)\n$") or output
 end
 
-local function prompt_yn(question)
-	while true do
-		io.write(question .. " (y/n) ")
-		local input = io.read()
-		if input == "y" or input == "Y" then
-			return true
-		elseif input == "n" or input == "N" then
-			return false
-		end
-	end
-end
-
 local function append_list(list, other)
 	for _, item in ipairs(other) do
 		table.insert(list, item)
@@ -73,6 +61,18 @@ local function bsddialog(args)
 	return exit_code, output
 end
 
+-- Prompts the user for a yes/no answer to the given question using bsddialog
+-- Returns true if the user answers yes and false if the user answers no.
+local function prompt_yn(question)
+	local exit_code = bsddialog({
+		"--yesno",
+		"--disable-esc",
+		question,
+		0, 0, -- autosize
+	})
+	return exit_code == 0
+end
+
 -- Creates a dialog for component selection mirroring the
 -- traditional tarball component selection dialog.
 local function select_components(components, options)
@@ -254,7 +254,6 @@ local function pkgbase()
 
 	while not os.execute(pkg .. "update") do
 		if not prompt_yn("Updating repositories failed, try again?") then
-			print("Canceled")
 			os.exit(1)
 		end
 	end
@@ -263,7 +262,6 @@ local function pkgbase()
 
 	while not os.execute(pkg .. "install -U -F -y -r FreeBSD-base " .. packages) do
 		if not prompt_yn("Fetching packages failed, try again?") then
-			print("Canceled")
 			os.exit(1)
 		end
 	end