Get entrypoints from elf files

resolveentry.sh

#!/bin/bash

# Get program entry points with the help of objdump and hexdump
# Copyleft dipswitch@ownage4u.nl 2011

if [[ -z $1 ]]; then
    echo "Usage: $0 <elf>" 1>&2;
    exit 1;
fi;

if [[ ! -e "$1" ]]; then
    echo "No file named '$1' found me mate!" 1>&2;
    exit 2;
fi;

if ! file $1 | grep ELF 2>&1 > /dev/null; then
    echo "Arrgggg this no even looks like an ELF to me, me mate!" 1>&2;
    exit 3;
fi;

CTOR_START="0xffffffff";
CTOR_END="0x00000000";
ADDR_FORMAT='"0x%08x "';
BYTE_COUNT=32;

if file $1 | grep 'ELF 64' 2>&1 > /dev/null; then
    CTOR_START="${CTOR_START}ffffffff";
    CTOR_END="${CTOR_END}00000000";
    ADDR_FORMAT='"0x%08x%08x "';
    BYTE_COUNT=64;
fi;

for addr in $(hexdump -e "$ADDR_FORMAT" -n $BYTE_COUNT -s 0x`objdump -x "$1" | grep .ctors | sed -e 's/  */ /g' | cut -d' ' -f 7 | line` "$1"); do
    if [[ $addr == $CTOR_START ]]; then
	continue;
    elif [[ $addr == $CTOR_END ]]; then
	if [[ -n $FIRST ]]; then
	    echo -ne "\n"
	fi;

	break;
    else
	if [[ -z $FIRST ]]; then
	    echo ".ctors:";
	    FIRST=1;
	fi;

	if [[ $BYTE_COUNT -eq 64 ]]; then
	    echo $addr | sed -e 's/\(0x\)\([0-9a-f]\{8\}\)\([0-9a-f]\{8\}\)/\1\3\2/g'
	else
	    echo $addr;
	fi;
    fi;
done;

tmp=`mktemp /tmp/input.XXXX`;
echo "entrypoints:";
if objdump -x "$1" | grep 'start address' | grep -o '0x[0-9a-f]*' > $tmp; then
    echo ".text:   "`cat ${tmp}`;
fi;

if objdump -j .text -M intel -D "$1" | grep '<_start>:' | grep -o '[0-9a-f]* ' > $tmp; then
    echo "_start:  0x"`cat ${tmp}`;
fi;

if objdump -j .text -M intel -D "$1" | grep '<main>:' | grep -o '[0-9a-f]* ' > $tmp; then
    echo "main:    0x"`cat ${tmp}`;
fi;

if objdump -j .text -M intel -D "$1" | grep '<.text>:' -A20 | grep '__libc_start_main' -B1 | line | grep -o '0x[0-9a-z]*' > $tmp; then
    echo "Stripped main:  "`cat ${tmp}`;
elif objdump -j .text -M intel -D "$1" | grep '<.text>:' -A20 | grep 'hlt' -B2 | line | grep -o '0x[0-9a-z]*' > $tmp; then
    echo "Static stripped main: "`cat ${tmp}`;
fi;

unset FIRST

for addr in $(hexdump -e "$ADDR_FORMAT" -n $BYTE_COUNT -s 0x`objdump -x "$1" | grep .dtors | sed -e 's/  */ /g' | cut -d' ' -f 7 | line` "$1"); do
    if [[ $addr == $CTOR_START ]]; then
	continue;
    elif [[ $addr == $CTOR_END ]]; then
	break;
    else
	if [[ -z $FIRST ]]; then
	    echo -e "\n.dtors:";
	    FIRST=1;
	fi;

	if [[ $BYTE_COUNT -eq 64 ]]; then
	    echo $addr | sed -e 's/\(0x\)\([0-9a-f]\{8\}\)\([0-9a-f]\{8\}\)/\1\3\2/g'
	else
	    echo $addr;
	fi;
    fi;
done;

rm $tmp 2> /dev/null