[Python] How to have a GDB/Python script use pipes for input and output of debugging target

I want to run GDB with a Python script that also drives the debug target's input, say through a pipe. I cannot seem to get the ordering of the target execution and pipe setup lined up to avoid blocking or an error. I've tried solutions with both blocking and non-blocking opens of the named pipes; a non-blocking example is shared below.

What doesn't help is that GDB doesn't seem to allow for background execution combined with input/output redirection, I try to circumvent that using starti and continue&.

import os

# create input/output pipes

in_pipe = "in"
out_pipe = "out"

try:
os.unlink(in_pipe)
except FileNotFoundError:
pass

try:
os.unlink(out_pipe)
except FileNotFoundError:
pass

os.mkfifo(in_pipe)
os.system(f"sleep infinity > {in_pipe} &")

print("in pipe:", in_pipe)

os.mkfifo(out_pipe)
os.system(f"sleep infinity > {out_pipe} &")

print("out pipe:", out_pipe)

# open in/out pipes to prevent starti command from blocking
# open a tmp read-only FD for the input pipe to prevent it's write-only open from blocking
out_fd = os.open(out_pipe, os.O_RDONLY | os.O_NONBLOCK)
tmp_fd = os.open(in_pipe, os.O_RDONLY | os.O_NONBLOCK) # prevent blocking
in_fd = os.open(in_pipe, os.O_WRONLY | os.O_NONBLOCK)

gdb.execute(f"set target-async on")

gdb.execute(f"starti < {in_pipe} > {out_pipe}")
gdb.execute(f"c&")

print(os.read(out_fd, 8)) # causes BlockingIOError for some reason, even if I ensure enough time for the target to print

print("--- DONE ---")


Is there a way to make this work?

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