#! /bin/bash

# print_function_binary functionName binaryName
# Author: Samuel Ellicott 2022-11-16
# Outputs the disassembled and hex form of a C function to the command line 

function_name=$1
binary_name=$2

# Get the function memory offset and length
function_entry=`objdump -t $binary_name | grep -P "$function_name([^@]|$)" | grep '.text'`
output=$(echo $function_entry | sed -En -e 's/^(\w*)(\s*[.[:alnum:]]*){3}\s*(\w*).*$/0x\1 0x\3/p')
read begin length <<<$output
end=$(( begin + length ))

# get the function file offset
code_offset=$(readelf -l $binary_name | grep LOAD | head -n 1 | sed -En -e 's/^\s*LOAD\s*\w*\s*(\w*).*$/\1/p')

file_begin=$(( begin - code_offset ))

echo "Dissembled Output"
objdump -d --start-address=$begin --stop-address=$end $binary_name | tail -n +7
echo ""

echo "C Output"
xxd -i -s $file_begin -l $length $binary_name