#!/bin/sh

# Copyright (c) 2010, 2011 George Danchev <danchev@spnet.net>
# Copyright (c) 2010, 2011 Thomas Schmitt <scdbackup@gmx.net>
# Copyright (c) 2010, 2011 Steve McIntyre <steve@einval.com>
# This script is distributed according to the terms of the GNU GPL v2.
# This should be better rewritten in C at some future point. Ref: pwd code.

# Create a list of checksums encoded in hexadecimal format and print to standard output

# Format Description
# A line in the emerging file is to be composed as follows:
#
# The MD5 checksum of the file content must be encoded in 32 hex digits
# [0-9afAF], or
# The SHA256 checksum of the file content must be encoded in 64 hex digits
# [0-9afAF]
#
# Next come two blanks.
#
# The byte size of the file content must be encoded in 12 decimal digits
# or blanks.
#
# Next come two blanks.
#
# The rest of the line up to the newline character is a semi-literal file
# address. Its basename has to be the same as the basename of the data file
# when it is used as one of the input files for the jigdo file generator.

# The semi-literal address and the address mapping define what will be
# listed as file address in the jigdo file.
# The address may bear at its start a literal text that shall be recognized by
# the address mapping (e.g. -jigdo-map) of the jigdo file generator.
# The rest of the address must be usable as file address in both situations:
# When the jigdo file gets generated, and when the jigdo file gets read
# to inflate the template file into the original payload image.
# The address mappings at both occasions can be used to adapt to a change
# of the absolute location of the listed files.
# Between both mappings, the parent directory is represented by a symbolic
# text, like "Debian:".

# A simple strategy to cope with this is to write absolute paths into the
# output checksum file, and to use matching absolute paths in the -jigdo-map
# directives. Keep in mind that mapping is purely literal. Symbolic links
# are neither resolved nor can they confuse the mapping.

set -e

SELF=jigdo-gen-checksum-list
VER=0.2

OPT_ABSOLUTE=1

usage() {
    cat << USAGE
usage: $SELF [option] DIR FILE ...
 -a, --make-absolute    make absolute paths, avoiding any symlinks (default)
 -l, --keep-literal     leave paths untouched, literally as supplied
 -v, --version          print version
 -h, --help             print help
 -e, --examples         print examples
 -c, --checksum-algo	speciify checksum algorithm.
                        Valid options are md5 (default) and sha256
USAGE
}

examples() {
    cat << EXAMPLES
examples:
 $SELF datadir datafile
 $SELF --keep-literal datadir datafile
 find . -type f | xargs $SELF
 find . -exec $SELF '{}' ';'
EXAMPLES
}

md5list_gnu() {
    item="$1"
    if [ $OPT_ABSOLUTE -eq 1 ] ; then
        dn=`dirname "$item"`  # dirname
        fn=`basename "$item"` # filename
        od=`pwd -P`           # old dir
        cd "$dn" || exit 1
        item=`pwd -P`/"$fn"   # absolute physical file path, avoiding all symlinks
        cd "$od" || exit 1
    fi
    MD5=`md5sum "$item" | awk '{print $1}'`
    SIZ=`/usr/bin/stat -c %s "$item"`
    printf '%32s  %12s  %s\n' "$MD5" "$SIZ" "$item"
}

sha256list_gnu() {
    item="$1"
    if [ $OPT_ABSOLUTE -eq 1 ] ; then
        dn=`dirname "$item"`  # dirname
        fn=`basename "$item"` # filename
        od=`pwd -P`           # old dir
        cd "$dn" || exit 1
        item=`pwd -P`/"$fn"   # absolute physical file path, avoiding all symlinks
        cd "$od" || exit 1
    fi
    SHA256=`sha256sum "$item" | awk '{print $1}'`
    SIZ=`/usr/bin/stat -c %s "$item"`
    printf '%64s  %12s  %s\n' "$SHA256" "$SIZ" "$item"
}

md5list_freebsd() {
    item="$1"
    if [ $OPT_ABSOLUTE -eq 1 ] ; then
        dn=`dirname "$item"`  # dirname
        fn=`basename "$item"` # filename
        od=`pwd -P`           # old dir
        cd "$dn" || exit 1
        item=`pwd -P`/"$fn"   # absolute physical file path, avoiding all symlinks
        cd "$od" || exit 1
    fi
    MD5=`md5 -q "$item"`
    SIZ=`/usr/bin/stat -f %z "$item"`
    printf '%32s  %12s  %s\n' "$MD5" "$SIZ" "$item"
}

sha256list_freebsd() {
    item="$1"
    if [ $OPT_ABSOLUTE -eq 1 ] ; then
        dn=`dirname "$item"`  # dirname
        fn=`basename "$item"` # filename
        od=`pwd -P`           # old dir
        cd "$dn" || exit 1
        item=`pwd -P`/"$fn"   # absolute physical file path, avoiding all symlinks
        cd "$od" || exit 1
    fi
    SHA256=`sha256 -q "$item"`
    SIZ=`/usr/bin/stat -f %z "$item"`
    printf '%64s  %12s  %s\n' "$SHA256" "$SIZ" "$item"
}

walkdir() {
    DR="$1"
    for item in `find "$DR" -type f` ; do
        $CHECKSUM_LIST "$item"
    done
}


# main()
if [ "$1" = "" ] ; then
    usage
    exit 1
fi

OPT_ALGO="md5"

case "$1" in
    --make-absolute|-a)
        OPT_ABSOLUTE=1;
        shift;
        ;;
    --keep-literal|-l)
        OPT_ABSOLUTE=0;
        shift;
        ;;
    --checksum-algo|-c)
        OPT_ALGO=$2;
        shift;
        shift;
        ;;
    --version|-v)
        printf '%s %s\n' "$SELF" "$VER"
        exit 0
        ;;
    --help|-h)
        usage
        exit 0
        ;;
    --examples|-e)
        examples
        exit 0
#   *)
#       usage
#       exit 1
#       ;;
esac

if [ "$OPT_ALGO" != "md5" ] && [ "$OPT_ALGO" != "sha256" ] ; then
    echo "Unrecognised checksum algorithm \"$OPT_ALGO\""
    echo "Allowed values are \"md5\" and \"sha256\"";
    exit 1
fi

SYSTEM=`uname -s`
case $SYSTEM in
    Linux|GNU/kFreeBSD)
	case $OPT_ALGO in
	    md5)
		CHECKSUM_LIST=md5list_gnu;;
	    sha256)
		CHECKSUM_LIST=sha256list_gnu;;
	esac;;
    FreeBSD)
	case $OPT_ALGO in
	    md5)
		CHECKSUM_LIST=md5list_freebsd;;
	    sha256)
		CHECKSUM_LIST=sha256list_freebsd;;
	esac;;
    *)
        echo "System type $SYSTEM unsupported"
        echo "Abort."
        exit 1;;
esac

for i in "$@" ; do
    if [ -d "$i" ] ; then
        DR="$i"
        if [ $OPT_ABSOLUTE -eq 1 ] ; then
            od=`pwd -P`           # old dir
            cd "$DR" || exit 1
            DR=`pwd -P`           # absolute physical dir path, avoiding all symlinks
            cd "$od" || exit 1
        fi
        walkdir "$DR"
    elif [ -f "$i" ] ; then
        FL="$i"
        $CHECKSUM_LIST "$FL"
    else
        usage
        exit 1
    fi;

done

exit 0