1#!/bin/bash
  2
  3# objdiff - a small script for validating that a commit or series of commits
  4# didn't change object code.
  5#
  6# Copyright 2014, Jason Cooper <jason@lakedaemon.net>
  7#
  8# Licensed under the terms of the GNU GPL version 2
  9
 10# usage example:
 11#
 12# $ git checkout COMMIT_A
 13# $ <your fancy build command here>
 14# $ ./scripts/objdiff record path/to/*.o
 15#
 16# $ git checkout COMMIT_B
 17# $ <your fancy build command here>
 18# $ ./scripts/objdiff record path/to/*.o
 19#
 20# $ ./scripts/objdiff diff COMMIT_A COMMIT_B
 21# $
 22
 23# And to clean up (everything is in .tmp_objdiff/*)
 24# $ ./scripts/objdiff clean all
 25#
 26# Note: 'make mrproper' will also remove .tmp_objdiff
 27
 28SRCTREE=$(cd $(git rev-parse --show-toplevel 2>/dev/null); pwd)
 29
 30if [ -z "$SRCTREE" ]; then
 31	echo >&2 "ERROR: Not a git repository."
 32	exit 1
 33fi
 34
 35TMPD=$SRCTREE/.tmp_objdiff
 36
 37usage() {
 38	echo >&2 "Usage: $0 <command> <args>"
 39	echo >&2 "  record    <list of object files or directories>"
 40	echo >&2 "  diff      <commitA> <commitB>"
 41	echo >&2 "  clean     all | <commit>"
 42	exit 1
 43}
 44
 45get_output_dir() {
 46	dir=${1%/*}
 47
 48	if [ "$dir" = "$1" ]; then
 49		dir=.
 50	fi
 51
 52	dir=$(cd $dir; pwd)
 53
 54	echo $TMPD/$CMT${dir#$SRCTREE}
 55}
 56
 57do_objdump() {
 58	dir=$(get_output_dir $1)
 59	base=${1##*/}
 60	dis=$dir/${base%.o}.dis
 61
 62	[ ! -d "$dir" ] && mkdir -p $dir
 63
 64	# remove addresses for a cleaner diff
 65	# http://dummdida.tumblr.com/post/60924060451/binary-diff-between-libc-from-scientificlinux-and
 66	$OBJDUMP -D $1 | sed "s/^[[:space:]]\+[0-9a-f]\+//" > $dis
 67}
 68
 69dorecord() {
 70	[ $# -eq 0 ] && usage
 71
 72	FILES="$*"
 73
 74	CMT="`git rev-parse --short HEAD`"
 75
 76	OBJDUMP="${CROSS_COMPILE}objdump"
 77
 78	for d in $FILES; do
 79		if [ -d "$d" ]; then
 80			for f in $(find $d -name '*.o')
 81			do
 82				do_objdump $f
 83			done
 84		else
 85			do_objdump $d
 86		fi
 87	done
 88}
 89
 90dodiff() {
 91	[ $# -ne 2 ] && [ $# -ne 0 ] && usage
 92
 93	if [ $# -eq 0 ]; then
 94		SRC="`git rev-parse --short HEAD^`"
 95		DST="`git rev-parse --short HEAD`"
 96	else
 97		SRC="`git rev-parse --short $1`"
 98		DST="`git rev-parse --short $2`"
 99	fi
100
101	DIFF="`which colordiff`"
102
103	if [ ${#DIFF} -eq 0 ] || [ ! -x "$DIFF" ]; then
104		DIFF="`which diff`"
105	fi
106
107	SRCD="$TMPD/$SRC"
108	DSTD="$TMPD/$DST"
109
110	if [ ! -d "$SRCD" ]; then
111		echo >&2 "ERROR: $SRCD doesn't exist"
112		exit 1
113	fi
114
115	if [ ! -d "$DSTD" ]; then
116		echo >&2 "ERROR: $DSTD doesn't exist"
117		exit 1
118	fi
119
120	$DIFF -Nurd $SRCD $DSTD
121}
122
123doclean() {
124	[ $# -eq 0 ] && usage
125	[ $# -gt 1 ] && usage
126
127	if [ "x$1" = "xall" ]; then
128		rm -rf $TMPD/*
129	else
130		CMT="`git rev-parse --short $1`"
131
132		if [ -d "$TMPD/$CMT" ]; then
133			rm -rf $TMPD/$CMT
134		else
135			echo >&2 "$CMT not found"
136		fi
137	fi
138}
139
140[ $# -eq 0 ] &&	usage
141
142case "$1" in
143	record)
144		shift
145		dorecord $*
146		;;
147	diff)
148		shift
149		dodiff $*
150		;;
151	clean)
152		shift
153		doclean $*
154		;;
155	*)
156		echo >&2 "Unrecognized command '$1'"
157		exit 1
158		;;
159esac