Make modelfunctions.run_executable poll so it doesn't block on full pipe. Also add flag to add stderr to output.

Polling with posix.sleep is definitely not the most efficient way to do this, but it works for now.
We can try to add better C library support in the future.

1 files changed, 21 insertions, 5 deletions

diff --git a/lib/modelfunctions.lua b/lib/modelfunctions.lua
index 8981bdd..4f99780 100644
--- a/lib/modelfunctions.lua
+++ b/lib/modelfunctions.lua
@@ -239,24 +239,40 @@ end
 -- args should be an array where args[1] is the executable
 -- output will never be nil
 -- errtxt will be nil for success and non-nil for failure
-run_executable = function(args)
+-- if include_err, then stderr will be prepended to stdout (if executable doesn't fail)
+run_executable = function(args, include_err)
 	local output = ""
 	local errtxt
        	local res, err = pcall(function()
 		-- For security, set the path
 		posix.setenv("PATH", "/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin")
 
+		args.stdin = "/dev/null"
 		args.stdout = subprocess.PIPE
 		args.stderr = subprocess.PIPE
 		local proc, errmsg, errno = subprocess.popen(args)
 		if proc then
+			local out = {}
+			local err = {}
+			function readpipes()
+				local o = proc.stdout:read("*a")
+				if o ~= "" then out[#out+1] = o end
+				local e = proc.stderr:read("*a")
+				if e ~= "" then err[#err+1] = e end
+			end
+			while nil == proc:poll() do
+				readpipes()
+				posix.sleep(0)
+			end
+			readpipes()
 			proc:wait()
-			output = (proc.stdout:read("*a")) or ""
 			proc.stdout:close()
-			errtxt = (proc.stderr:read("*a"))
 			proc.stderr:close()
-			if proc.exitcode == 0 and string.find(errtxt, "^%s*$") then
-				errtxt = nil
+			output = table.concat(out, "") or ""
+			if proc.exitcode == 0 and include_err and #err > 0 then
+				output = table.concat(err, "")..output
+			elseif proc.exitcode ~= 0 then
+				errtxt = table.concat(err, "") or "Unknown error"
 			end
 		else
 			errtxt = errmsg or "Unknown failure"