So I'm trying to connect to a (Lua) debugger embedded in a program by redirecting the I/O. Currently I create a pair of FIFOs for the read and write streams and connect to them using
cat /tmp/dbg_write & cat > /tmp/dbg_read. This is workable and pretty straightforward, but if you don't exit everything just right you have to go back and kill the background cat command. I figured it was time for a learning experience since there seems like there must be a better way. I'm totally stumped though.
Internally I'm just overriding the debugger's I/O functions to use FIFOs, since stdio is a no-go in this case. As far as I know, there is no way to do bidirectional I/O with the standard Lua APIs like sockets, and pulling in native libs is a no-go since it's embedded.
local dbg = require("debugger") local READ_PIPE, WRITE_PIPE = "/tmp/dbg_read", "/tmp/dbg_write" os.execute(string.format("mkfifo %s %s", READ_PIPE, WRITE_PIPE)) local input, output = io.open(READ_PIPE, "r"), io.open(WRITE_PIPE, "w") function dbg.read(prompt) dbg.write(prompt) return input:read() end function dbg.write(str) output:write(str) output:flush() end
I also tried:
popen("netcat -lU")to create a Unix domain socket, but pipes are unidirectional. Derp.
- Using an existing pty. Seems promising except I don't know how to create one separate from a shell that wants to read from it.
- Using screen to... somehow create a tty session I can interact with. (no idea...)
- Finding an existing utility that can copy from a file/pipe to stdout while also copying from stdin to another.
Anything obvious that I'm missing?