Avoid using shell commands

Instead of using shell commands via io.popen() and os.execute(), we now
just open a handle to the standard output TTY, and write to it directly.

Author: kdkasad

plugin/bg.lua

@@ -1,29 +1,27 @@
-local handle = io.popen("tty")
-local tty = handle:read("*a")
-handle:close()
-
-if tty:find("not a tty") then
+local tty = vim.uv.new_tty(1, false)
+if tty == nil then
+	-- Standard out is not a terminal
 	return
 end
 
 local update_count = 0
 
 local reset = function()
 	if os.getenv("TMUX") then
-		os.execute('printf "\\ePtmux;\\e\\033]111\\007\\e\\\\"')
+		tty:write("\x1bPtmux;\x1b\x1b]111\x07\x1b\\")
 	elseif os.getenv("TERM") == "xterm-kitty" then
-		for i=1, update_count do
-			os.execute('printf "\\033]30101\\007" > ' .. tty)
+		for _ = 1, update_count do
+			tty:write("\x1b]30101\x07")
 		end
 	else
-		os.execute('printf "\\033]111\\007" > ' .. tty)
+		tty:write("\x1b]111\x07")
 	end
 end
 
 local update = function()
-	local normal = vim.api.nvim_get_hl_by_name("Normal", true)
-	local bg = normal["background"]
-	local fg = normal["foreground"]
+	local normal = vim.api.nvim_get_hl(0, { name = "Normal", link = false, create = false })
+	local bg = normal.bg
+	local fg = normal.fg
 	if bg == nil then
 		return reset()
 	end
@@ -32,15 +30,15 @@ local update = function()
 	local fghex = string.format("#%06x", fg)
 
 	if os.getenv("TERM") == "xterm-kitty" then
-		os.execute('printf "\\033]30001\\007" > ' .. tty)
+		tty:write("\x1b]30001\x07")
 	end
 
 	if os.getenv("TMUX") then
-		os.execute('printf "\\ePtmux;\\e\\033]11;' .. bghex .. '\\007\\e\\\\"')
-		os.execute('printf "\\ePtmux;\\e\\033]12;' .. fghex .. '\\007\\e\\\\"')
+		tty:write("\x1bPtmux;\x1b\x1b]11;" .. bghex .. "\x07\x1b\\")
+		tty:write("\x1bPtmux;\x1b\x1b]12;" .. fghex .. "\x07\x1b\\")
 	else
-		os.execute('printf "\\033]11;' .. bghex .. '\\007" > ' .. tty)
-		os.execute('printf "\\033]12;' .. fghex .. '\\007" > ' .. tty)
+		tty:write("\x1b]11;" .. bghex .. "\x07")
+		tty:write("\x1b]12;" .. fghex .. "\x07")
 	end
 
 	update_count = update_count + 1