#!/usr/bin/sh -efu
fatal() {
echo "$*" >&2
exit 1
}
pkg="$1"
[ -n "$pkg" ] && [ -e "$pkg" ] ||
fatal "No package supplied"
_dd() {
local o="$1"; shift
dd if="$pkg" skip="$o" iflag=skip_bytes status=none $*
}
calcsize() {
case "$(_dd $1 bs=4 count=1 | tr -d '\0')" in
"$(printf '\216\255\350')"*) ;; # '\x8e\xad\xe8'
*) fatal "File doesn't look like rpm: $pkg" ;;
esac
offset=$(($1 + 8))
local i b b0 b1 b2 b3 b4 b5 b6 b7
i=0
while [ $i -lt 8 ]; do
# add . to not loose \n
# strip \0 as it gets dropped with warning otherwise
b="$(_dd $(($offset + $i)) bs=1 count=1 | tr -d '\0' ; echo .)"
b=${b%.} # strip . again
[ -z "$b" ] &&
b="0" ||
b="$(exec printf '%u\n' "'$b")"
eval "b$i=\$b"
i=$(($i + 1))
done
rsize=$((8 + ((($b0 << 24) + ($b1 << 16) + ($b2 << 8) + $b3) << 4) + ($b4 << 24) + ($b5 << 16) + ($b6 << 8) + $b7))
offset=$(($offset + $rsize))
}
case "$(_dd 0 bs=4 count=1 | tr -d '\0')" in
"$(printf '\355\253\356\333')"*) ;; # '\xed\xab\xee\xdb'
*) fatal "File doesn't look like rpm: $pkg" ;;
esac
calcsize 96
sigsize=$rsize
calcsize $(($offset + (8 - ($sigsize % 8)) % 8))
hdrsize=$rsize
case "$(_dd $offset bs=2 count=1 | tr -d '\0')" in
"$(printf '\102\132')") _dd $offset | bunzip2 ;; # '\x42\x5a'
"$(printf '\037\213')") _dd $offset | gunzip ;; # '\x1f\x8b'
"$(printf '\375\067')") _dd $offset | xzcat ;; # '\xfd\x37'
"$(printf '\135')") _dd $offset | unlzma ;; # '\x5d\x00'
"$(printf '\050\265')") _dd $offset | unzstd ;; # '\x28\xb5'
*) fatal "Unrecognized payload compression format in rpm file: $pkg" ;;
esac
