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fit-findfs.sh
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fit-findfs.sh
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#! /bin/sh
# vim: set tabstop=4 syntax=sh :
# SPDX-License-Identifier: GPL-2.0-or-later
#######################################################################################################
# #
# search the 'filesystem' entry with the largest data size in a FIT image #
# #
###################################################################################################VER#
# #
# fit-findfs.sh, version 0.2 #
# #
# This script is a part of the YourFritz project from https://github.com/PeterPawn/YourFritz. #
# #
###################################################################################################CPY#
# #
# Copyright (C) 2022 P.Haemmerlein (peterpawn@yourfritz.de) #
# #
###################################################################################################LIC#
# #
# This project is free software, you can redistribute it and/or modify it under the terms of the GNU #
# General Public License as published by the Free Software Foundation; either version 2 of the #
# License, or (at your option) any later version. #
# #
# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without #
# even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU #
# General Public License under http://www.gnu.org/licenses/gpl-2.0.html for more details. #
# #
#######################################################################################################
# #
# This script reads a FIT image in AVM's own format and searches for the root filesystem of the #
# frontend OS by AVM. #
# #
# It uses the same techniques to find a root filesystem, as were implemented in the 'fitdump.sh' #
# script from project above. #
# #
#######################################################################################################
# #
# the whole logic as a sealed sub-function #
# #
#######################################################################################################
find_rootfs_in_fit_image()
(
sbo() (
sbo_ro()
{
v1=0; v2=0; v3=0; v4=0
while read -r p _ rt; do
[ "$p" -gt 5 ] && exit 1
[ "$p" -eq 5 ] && [ "$rt" -ne 0377 ] && exit 1
if [ "$p" -eq 5 ]; then
for i in $v4 $v3 $v2 $v1; do
printf -- "%b" "\0$(printf -- "%o" "$i")"
done
exit 0
fi
eval "v$p"=$(( 0$rt ))
done
exit 1
}
( cat; printf -- "%b" "\377" ) | cmp -l -- "$zeros" - 2>"$null" | sbo_ro
)
b2d() (
b2d_ro()
{
i=1; v=0; ff=0
while read -r p _ rt; do
if [ "$ff" -eq 1 ]; then
v=$(( v * 256 ))
ff=255
v=$(( v + ff ))
i=$(( i + 1 ))
ff=0
fi
while [ "$i" -lt "$p" ]; do
v=$(( v * 256 ))
i=$(( i + 1 ))
done
if [ "$rt" = 377 ] && [ $ff -eq 0 ]; then
ff=1
continue
fi
v=$(( v * 256 ))
rt=$(( 0$rt ))
v=$(( v + rt ))
i=$(( p + 1 ))
done
printf -- "%d" $v
}
( cat; printf -- "%b" "\377" ) | cmp -l -- "$zeros" - 2>"$null" | b2d_ro
return 0
)
get_data() ( dd if="$1" bs="$3" count=$(( ( $2 / $3 ) + 1 )) skip=1 2>"$null" | dd bs=1 count="$2" 2>"$null"; )
str() (
strlen()
{
s=1
while read -r p l _; do
[ "$p" -ne "$s" ] && printf -- "%u\n" "$(( s - 1 ))" && return
s=$(( s + 1 ))
done
printf -- "%u\n" "$(( s - 1 ))"
}
l="$(get_data "$1" 256 "$2" | cmp -l -- - "$zeros" 2>"$null" | strlen)"
[ -n "$l" ] && get_data "$1" "$l" "$2"
)
fdt32_align() { [ $(( $1 % 4 )) -gt 0 ] && printf -- "%u\n" $(( ( $1 + fdt32_size ) & ~3 )) || printf -- "%u\n" "$1"; }
get_fdt32_be() ( get_data "$1" 4 "$2" | b2d; )
get_fdt32_le() ( get_data "$1" 4 "$2" | sbo | b2d; )
get_string() {
n="$(printf -- "__fdt_string_%u" "$2")"
f="$(set | sed -n -e "s|^\($n=\).*|\1|p")"
if [ -z "$f" ]; then
v="$(str "$1" "$2")"
printf -- "%s=\"%s\"\n%s=\"\$%s\"\n" "$n" "$v" "$3" "$n"
else
printf -- "%s=\"\$%s\"\n" "$3" "$n"
fi
}
is_printable_string() (
ro() {
i=0
while read -r p l _; do
i=$(( i + 1 ))
[ "$p" -gt "$i" ] && [ "$i" -eq 1 ] && return 1
[ "$l" -lt 040 ] && return 1
[ "$l" -gt 0176 ] && return 1
done
[ "$i" -eq 0 ] && [ "$1" -eq 1 ] && return 1;
[ "$i" -lt $(( $1 - 1 )) ] && return 1
return 0
}
get_data "$1" "$3" "$2" | cmp -l -- - "$zeros" 2>"$null" | ro "$3"
return $?
)
__yf_ansi_sgr() { printf -- '\033[%sm' "$1"; }
__yf_ansi_bold__="$(__yf_ansi_sgr 1)"
__yf_ansi_yellow__="$(__yf_ansi_sgr 33)"
__yf_ansi_bright_red__="$(__yf_ansi_sgr 91)"
__yf_ansi_bright_green__="$(__yf_ansi_sgr 92)"
__yf_ansi_reset__="$(__yf_ansi_sgr 0)"
__yf_get_script_lines() {
sed -n -e "/^#*${1}#\$/,/^#\{20\}.*#\$/p" -- "$0" | \
sed -e '1d;$d' | \
sed -e 's|# \(.*\) *#$|\1|' | \
sed -e 's|^#*#$|--|p' | \
sed -e '$d' | \
sed -e 's| *$||'
}
__yf_show_script_name() {
[ -n "$1" ] && printf -- '%s' "$1"
printf -- '%s' "${0#*/}"
[ -n "$1" ] && printf -- "%s" "${__yf_ansi_reset__}"
}
__yf_show_license() { __yf_get_script_lines 'LIC'; }
__yf_show_version() {
printf -- "\n%s%s%s, " "${__yf_ansi_bold__}" "$(__yf_get_script_lines 'VER' | sed -n -e "2s|^\([^,]*\),.*|\1|p")" "${__yf_ansi_reset__}"
v_display="$(__yf_get_script_lines 'VER' | sed -n -e "2s|^[^,]*, \(.*\)|\1|p")"
printf -- "%s\n" "$v_display"
}
__yf_show_copyright() { __yf_get_script_lines 'CPY'; }
usage() {
exec 1>&2
__yf_show_version
__yf_show_copyright
__yf_show_license
printf -- "\n"
printf -- "%sfit-findfs.sh%s - locate a filesystem BLOB in a FIT image\n\n" "${__yf_ansi_bold__}" "${__yf_ansi_reset__}"
printf -- "Usage: %s [ options ] <fit-image>\n\n" "$0"
printf -- "Options:\n\n"
printf -- "-f or --force-copy - always create and use a copy on temporary storage,\n"
printf -- " even if input is a regular file\n"
printf -- "\n"
}
entry() (
img="$1"
offset="$2"
parent="$3"
level="$4"
filesystem_found=0
ramdisk_found=0
data=$(get_fdt32_be "$img" "$offset")
# shellcheck disable=SC2050
while [ 1 -eq 1 ]; do
case "$data" in
("$fdt_begin_node")
name_off="$(( offset + fdt32_size ))"
eval "$(get_string "$img" $name_off "name")"
[ -z "$name" ] && name="/"
offset=$(fdt32_align $(( offset + fdt32_size + ${#name} + 1 )) )
eval "$(entry "$img" "$offset" "$name" "$(( level + 1 ))" 5>&1)"
offset="$next_offset"
;;
("$fdt_end_node")
offset=$(( offset + fdt32_size ))
{
[ -n "$fs_node_name" ] && printf -- "fs_node_name=\"%s\" fs_offset=%u fs_size=%u " "$fs_node_name" "$fs_offset" "$fs_size"
# shellcheck disable=SC2154
[ -n "$rd_node_name" ] && printf -- "rd_node_name=\"%s\" rd_offset=%u rd_size=%u " "$rd_node_name" "$rd_offset" "$rd_size"
printf -- "next_offset=%u" "$offset"
} 1>&5
if [ "$filesystem_found" = "1" ] && [ "$type_found" = "$filesystem_type" ] && [ -n "$data_found" ]; then
printf -- " fs_size=%u fs_offset=%u fs_node_name=\"%s\"" "$fs_size" "$fs_offset" "$parent" 1>&5
fi
if [ "$ramdisk_found" = "1" ]; then
if [ "$fs_size" -eq 0 ] && [ "$rd_size" -lt "$new_rd_size" ]; then
printf -- " rd_size=%u rd_offset=%u rd_node_name=\"%s\"" "$new_rd_size" "$new_rd_offset" "$parent" 1>&5
fi
fi
exit 0
;;
("$fdt_prop")
value_size="$(get_fdt32_be "$img" $(( offset + fdt32_size )))"
name_off="$(( fdt_start + fdt_off_dt_strings + $(get_fdt32_be "$img" $(( offset + ( 2 * fdt32_size ) )) ) ))"
eval "$(get_string "$img" $name_off "name")"
data_offset=$(( offset + 3 * fdt32_size ))
if [ "$value_size" -gt 512 ]; then
[ "$name" = "$data_name" ] && file_size="$value_size" && file_offset="$data_offset"
elif is_printable_string "$img" "$data_offset" "$value_size"; then
eval "$(get_string "$img" $(( offset + 3 * fdt32_size )) "str")"
if [ "$name" = "$filesystem_indicator" ]; then
# filesystem entries with 'avm,kernel-args = [...]mtdparts_ext=[...]' are for the frontend
# shellcheck disable=SC2154
if [ -n "$(expr "$str" : ".*\($filesystem_indicator_marker\).*")" ]; then
filesystem_found=1
fs_size="$file_size"
fs_offset="$file_offset"
fs_node_name="$parent"
fi
elif [ "$name" = "$type_name" ]; then
type_found="$str"
if [ "$type_found" = "$ramdisk_type" ]; then
ramdisk_found=1
new_rd_size="$file_size"
new_rd_offset="$file_offset"
fi
fi
fi
offset=$(fdt32_align $(( data_offset + value_size )) )
;;
("$fdt_nop")
offset=$(( offset + fdt32_size ))
;;
("$fdt_end")
offset=$(( offset + fdt32_size ))
break
;;
esac
data=$(get_fdt32_be "$img" "$offset")
done
{
[ -n "$fs_node_name" ] && printf -- "fs_node_name=\"%s\" fs_offset=%u fs_size=%u " "$fs_node_name" "$fs_offset" "$fs_size"
[ -n "$rd_node_name" ] && printf -- "rd_node_name=\"%s\" rd_offset=%u rd_size=%u " "$rd_node_name" "$rd_offset" "$rd_size"
printf -- "next_offset=%u\n" "$offset"
} 1>&5
)
null="/dev/null"
zeros="/dev/zero"
filesystem_indicator="avm,kernel-args"
filesystem_indicator_marker="mtdparts_ext="
data_name="data"
type_name="type"
filesystem_type="filesystem"
ramdisk_type="ramdisk"
force_tmpcopy=0
while [ "$(expr "$1" : "\(.\).*")" = "-" ]; do
[ "$1" = "--" ] && shift && break
if [ "$1" = "-f" ] || [ "$1" = "--force-copy" ]; then
force_tmpcopy=1
shift
elif [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
usage
exit 0
else
printf "Unknown option: %s\a\n" "$1" 1>&2 && exit 1
fi
done
fdt_begin_node=1
fdt_end_node=2
fdt_prop=3
fdt_nop=4
fdt_end=9
fdt32_size=4
img="$1"
magic="$(dd if="$img" bs=4 count=1 2>"$null" | b2d)"
if ! [ "$magic" = "218164734" ]; then
printf "Invalid magic value (0x%08x) found at offset 0x%02x.\a\n" "$magic" "0" 1>&2
exit 1
fi
next_offset=$(( next_offset + fdt32_size ))
payload_size="$(get_fdt32_le "$img" "$next_offset")"
if ! [ -f "$img" ] || [ "$force_tmpcopy" -eq 1 ]; then
tmpdir="${TMP:-$TMPDIR}"
[ -z "$tmpdir" ] && tmpdir="/tmp"
tmpimg="$tmpdir/fit-image-$$"
dd if="$img" of="$tmpimg" bs=$(( 1024 * 1024 )) count=$(( ( payload_size + 64 + 8 ) / ( 1024 * 1024 ) + 1 )) 2>$null || exit 1
trap '[ -f "$tmpimg" ] && rm -f "$tmpimg" 2>/dev/null' EXIT
img="$tmpimg"
fi
next_offset=$(( next_offset + fdt32_size + 64 ))
fdt_magic="$(get_fdt32_be "$img" "$next_offset")"
if { [ "$fdt_magic" -gt 0 ] && [ "$fdt_magic" -ne 3490578157 ]; } || { [ "$fdt_magic" -lt 0 ] && [ "$fdt_magic" -ne -804389139 ]; }; then
printf "Invalid FDT magic found.\a\n" 1>&2 && exit 1
fi
fdt_start=$next_offset
next_offset=$(( next_offset + fdt32_size ))
fdt_totalsize="$(get_fdt32_be "$img" "$next_offset")"
next_offset=$(( next_offset + fdt32_size ))
[ "$fdt_totalsize" -ne "$payload_size" ] && printf "Data size mismatch in image file.\a\n" 1>&2 && exit 1
fdt_off_dt_struct="$(get_fdt32_be "$img" "$next_offset")"
next_offset=$(( next_offset + fdt32_size ))
fdt_off_dt_strings="$(get_fdt32_be "$img" "$next_offset")"
next_offset=$(( next_offset + fdt32_size ))
# fdt_off_mem_rsvmap="$(get_fdt32_be "$img" "$next_offset")"
next_offset=$(( next_offset + fdt32_size ))
fdt_version="$(get_fdt32_be "$img" "$next_offset")"
next_offset=$(( next_offset + fdt32_size ))
# fdt_last_comp_version="$(get_fdt32_be "$img" "$next_offset")"
if [ "$fdt_version" -ge 2 ]; then
next_offset=$(( next_offset + fdt32_size ))
# fdt_boot_cpuid_phys="$(get_fdt32_be "$img" "$next_offset")"
if [ "$fdt_version" -ge 2 ]; then
next_offset=$(( next_offset + fdt32_size ))
# fdt_size_dt_strings="$(get_fdt32_be "$img" "$next_offset")"
if [ "$fdt_version" -ge 17 ]; then
next_offset=$(( next_offset + fdt32_size ))
# fdt_size_dt_struct="$(get_fdt32_be "$img" "$next_offset")"
fi
fi
fi
fs_size=0
fs_offset=0
rd_size=0
fs_offset=0
fs_node_name=""
rd_node_name=""
next_offset=$(( fdt_start + fdt_off_dt_struct ))
eval "$(entry "$img" "$next_offset" "-" 0 5>&1)"
if [ "$fs_size" -gt 0 ]; then
printf "rootfs_type=squashfs rootfs_offset=%u rootfs_size=%u\n" "$fs_offset" "$fs_size"
elif [ "$rd_size" -gt 0 ]; then
printf "rootfs_type=ramdísk rootfs_offset=%u rootfs_size=%u\n" "$rd_offset" "$rd_size"
else
printf "No rootfs candicates found.\a\n" 1>&2 && exit 1
fi
)
#######################################################################################################
# #
# invoke sealed function from above #
# #
#######################################################################################################
find_rootfs_in_fit_image "$@"
#######################################################################################################
# #
# end of script #
# #
#######################################################################################################