From: Jo-Philipp Wich <jo@mein.io>
Date: Wed, 17 Jan 2018 20:15:47 +0000 (+0100)
Subject: luci-app-nlbw: fix sporadic premature EOF when rendering JSON data
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=08916f4335e96e4a3c9dcf77262fa151348ed93c;p=oweals%2Fluci.git

luci-app-nlbw: fix sporadic premature EOF when rendering JSON data

Specific timing patterns sometimes caused the LuCI controller to prematurely
stop reading data, resulting in truncated JSON output.

Turn the nonblocking waitpid() call into a blocking call after the IO read
loop to avoid this issue.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>
---

diff --git a/applications/luci-app-nlbwmon/luasrc/controller/nlbw.lua b/applications/luci-app-nlbwmon/luasrc/controller/nlbw.lua
index bb56bc6e6..a8c577929 100644
--- a/applications/luci-app-nlbwmon/luasrc/controller/nlbw.lua
+++ b/applications/luci-app-nlbwmon/luasrc/controller/nlbw.lua
@@ -28,16 +28,17 @@ local function exec(cmd, args, writer)
 
 		while true do
 			local buffer = fdi:read(2048)
-			local wpid, stat, code = nixio.waitpid(pid, "nohang")
 
-			if writer and buffer and #buffer > 0 then
-				writer(buffer)
+			if not buffer or #buffer == 0 then
+				break
 			end
 
-			if wpid and stat == "exited" then
-				break
+			if writer then
+				writer(buffer)
 			end
 		end
+
+		nixio.waitpid(pid)
 	elseif pid == 0 then
 		nixio.dup(fdo, nixio.stdout)
 		fdi:close()