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  • #!/bin/bash
    
    # objdiff - a small script for validating that a commit or series of commits
    # didn't change object code.
    #
    # Copyright 2014, Jason Cooper <jason@lakedaemon.net>
    #
    # Licensed under the terms of the GNU GPL version 2
    
    # usage example:
    #
    # $ git checkout COMMIT_A
    # $ <your fancy build command here>
    # $ ./scripts/objdiff record path/to/*.o
    #
    # $ git checkout COMMIT_B
    # $ <your fancy build command here>
    # $ ./scripts/objdiff record path/to/*.o
    #
    # $ ./scripts/objdiff diff COMMIT_A COMMIT_B
    # $
    
    # And to clean up (everything is in .tmp_objdiff/*)
    # $ ./scripts/objdiff clean all
    #
    # Note: 'make mrproper' will also remove .tmp_objdiff
    
    GIT_DIR="`git rev-parse --git-dir`"
    
    if [ -d "$GIT_DIR" ]; then
    	TMPD="${GIT_DIR%git}tmp_objdiff"
    
    	[ -d "$TMPD" ] || mkdir "$TMPD"
    else
    	echo "ERROR: git directory not found."
    	exit 1
    fi
    
    usage() {
    	echo "Usage: $0 <command> <args>"
    	echo "  record    <list of object files>"
    	echo "  diff      <commitA> <commitB>"
    	echo "  clean     all | <commit>"
    	exit 1
    }
    
    dorecord() {
    	[ $# -eq 0 ] && usage
    
    	FILES="$*"
    
    	CMT="`git rev-parse --short HEAD`"
    
    	OBJDUMP="${CROSS_COMPILE}objdump"
    	OBJDIFFD="$TMPD/$CMT"
    
    	[ ! -d "$OBJDIFFD" ] && mkdir -p "$OBJDIFFD"
    
    	for f in $FILES; do
    		dn="${f%/*}"
    		bn="${f##*/}"
    
    		[ ! -d "$OBJDIFFD/$dn" ] && mkdir -p "$OBJDIFFD/$dn"
    
    		# remove addresses for a more clear diff
    		# http://dummdida.tumblr.com/post/60924060451/binary-diff-between-libc-from-scientificlinux-and
    		$OBJDUMP -D "$f" | sed "s/^[[:space:]]\+[0-9a-f]\+//" \
    			>"$OBJDIFFD/$dn/$bn"
    	done
    }
    
    dodiff() {
    	[ $# -ne 2 ] && [ $# -ne 0 ] && usage
    
    	if [ $# -eq 0 ]; then
    		SRC="`git rev-parse --short HEAD^`"
    		DST="`git rev-parse --short HEAD`"
    	else
    		SRC="`git rev-parse --short $1`"
    		DST="`git rev-parse --short $2`"
    	fi
    
    	DIFF="`which colordiff`"
    
    	if [ ${#DIFF} -eq 0 ] || [ ! -x "$DIFF" ]; then
    		DIFF="`which diff`"
    	fi
    
    	SRCD="$TMPD/$SRC"
    	DSTD="$TMPD/$DST"
    
    	if [ ! -d "$SRCD" ]; then
    		echo "ERROR: $SRCD doesn't exist"
    		exit 1
    	fi
    
    	if [ ! -d "$DSTD" ]; then
    		echo "ERROR: $DSTD doesn't exist"
    		exit 1
    	fi
    
    	$DIFF -Nurd $SRCD $DSTD
    }
    
    doclean() {
    	[ $# -eq 0 ] && usage
    	[ $# -gt 1 ] && usage
    
    	if [ "x$1" = "xall" ]; then
    		rm -rf $TMPD/*
    	else
    		CMT="`git rev-parse --short $1`"
    
    		if [ -d "$TMPD/$CMT" ]; then
    			rm -rf $TMPD/$CMT
    		else
    			echo "$CMT not found"
    		fi
    	fi
    }
    
    [ $# -eq 0 ] &&	usage
    
    case "$1" in
    	record)
    		shift
    		dorecord $*
    		;;
    	diff)
    		shift
    		dodiff $*
    		;;
    	clean)
    		shift
    		doclean $*
    		;;
    	*)
    		echo "Unrecognized command '$1'"
    		exit 1
    		;;
    esac