# The executable "brprintconf_mfcj6510dw" binary is looking for "/opt/brother/Printers/%s/inf/br%sfunc" and "/opt/brother/Printers/%s/inf/br%src".
# Whereby, %s is printf(3) string substitution for stdin's arg0 (the command's own filename) from the 10th char forwards, as a runtime dependency.
# e.g. Say the filename is "0123456789ABCDE", the runtime will be looking for /opt/brother/Printers/ABCDE/inf/brABCDEfunc.
# Presumably, the binary was designed to be deployed under the filename "printconf_mfcj6510dw", whereby it will search for "/opt/brother/Printers/mfcj6510dw/inf/brmfcj6510dwfunc".
# For NixOS, we want to change the string to the store path of brmfcj6510dwfunc and brmfcj6510dwrc but we're faced with two complications:
# 1. Too little room to specify the nix store path. We can't even take advantage of %s by renaming the file to the store path hash since the variable is too short and can't contain the whole hash.
# 2. The binary needs the directory it's running from to be r/w.
# What:
# As such, we strip the path and substitution altogether, leaving only "brmfcj6510dwfunc" and "brmfcj6510dwrc", while filling the leftovers with nulls.
# Fully null terminating the cstrings is necessary to keep the array the same size and preventing overflows.
# We then use a shell script to link and execute the binary, func and rc files in a temporary directory.
# How:
# In the package, we dump the raw binary as a string of search-able hex values using hexdump. We execute the substitution with sed. We then convert the hex values back to binary form using xxd.
# We also write a shell script that invoked "mktemp -d" to produce a r/w temporary directory and link what we need in the temporary directory.
# Result:
# The user can run brprintconf_mfcj6510dw in the shell.
