From 3bdce55f8992d5a367d3cd69b98fd7dc10c22fc0 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Fri, 18 Jun 2021 10:44:23 +0200
Subject: [dev] dev_find_paritions: Add debug output, better hex2bin support

---
 modules/dev.inc | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 59 insertions(+), 6 deletions(-)

(limited to 'modules/dev.inc')

diff --git a/modules/dev.inc b/modules/dev.inc
index f213fa0..1c804a3 100644
--- a/modules/dev.inc
+++ b/modules/dev.inc
@@ -41,6 +41,7 @@ dev_find_partitions() {
 	local label number mbrid uuid
 	for dev in $(find $target* -type b); do
 		dev_get_type "$dev" || continue
+		echo "$dev is $number - MBR=$mbrid, UUID=$uuid, label=$label" >&2
 		if regex_imatch "$mbrid" "^($want_type)$" || regex_imatch "$uuid" "^($want_uuid)$" \
 				|| regex_match "$label" "^($want_label)$"; then
 			printf "%s\n" "$(blockdev --getsize64 "$dev") $dev"
@@ -74,11 +75,12 @@ dev_get_type() {
 	label="$( grep -Po '(?<=^PARTNAME=).*$' "/sys/block/${devn}/${partn}/uevent" )"
 	number="$( grep -Po '(?<=^PARTN=).*$' "/sys/block/${devn}/${partn}/uevent" )"
 	local gpt=
-	if [ "$( dd if="$dev" bs=1 count=8 skip=512 2> /dev/null )" = "EFI PART" ]; then
+	if [ "$( dd if="$dev" bs=1 count=8 skip=512 2> /dev/null )" = "EFI PART" ] 2> /dev/null; then
 		gpt=512
-	elif [ "$( dd if="$dev" bs=1 count=8 skip=4096 2> /dev/null )" = "EFI PART" ]; then
+	elif [ "$( dd if="$dev" bs=1 count=8 skip=4096 2> /dev/null )" = "EFI PART" ] 2> /dev/null; then
 		gpt=4096
 	fi
+	echo "Checking $partn (on $dev) GPT='$gpt', label='$label'" >&2
 	# Check if mbr signatur is there, no GPT label was in uevent, and no protective MBR
 	local t1="$( __read_mbrid "$dev" 0 1 )"
 	if [ -z "$label" ] && [ "$number" -lt 1000 ]  && [ "$number" -gt 0 ] \
@@ -157,17 +159,24 @@ dev_get_type() {
 		fi
 		# Convert raw hex stream to proper string representation. First 3 groups are little endian.
 		uuid="$( dd if="$dev" bs=1 count=16 skip="$(( current + entry_size * (number - 1) ))" 2> /dev/null \
-			| xxd -p | sed -r 's/^(..)(..)(..)(..)(..)(..)(..)(..)(....)/\4\3\2\1-\6\5-\8\7-\9-/' )"
+			| __bin2hex | sed -r 's/^(..)(..)(..)(..)(..)(..)(..)(..)(....)/\4\3\2\1-\6\5-\8\7-\9-/' )"
 		return 0
 	fi
 	# Unknown
 	return 1
 }
 
+# stdin = binary data, stdout = raw, unformatted hex
+# __hex2bin()
+
+# stdin = binary data, stdout = raw, unformatted hex
+# $1 = number of bytes to read and reverse (1, 2, 4, 8)
+# __hex2bin_le()
+
 # Get MBR type of partition (1 byte) as hex
 # Pass "$device" "$lba_offset" "$partition_number"
 __read_mbrid() {
-	dd if="$1" bs=1 skip=$(( 512 * $2 + 446 + ($3 - 1) * 16 + 4 )) count=1 2> /dev/null | xxd -p
+	dd if="$1" bs=1 skip=$(( 512 * $2 + 446 + ($3 - 1) * 16 + 4 )) count=1 2> /dev/null | __bin2hex
 }
 
 # Get LBA start address of MBR partition
@@ -179,12 +188,56 @@ __read_mbrstart() {
 # Read the MBR signature in the given sector
 # Pass "$device" "$lba_offset"
 __read_mbrsig() {
-	dd if="$1" bs=1 skip=$(( 512 * $2 + 510 )) count=2 2> /dev/null | xxd -p
+	dd if="$1" bs=1 skip=$(( 512 * $2 + 510 )) count=2 2> /dev/null | __bin2hex
 }
 
 # Read a little endian value at given byte offset
 # Pass "$source_path" "$byte_offset" "$size"
 __read_le() {
-	local v="$( dd if="$1" bs=1 count="$3" skip="$2" 2> /dev/null | xxd -e -g "$3" | cut -d' ' -f2 )"
+	local v="$( dd if="$1" bs=1 count="$3" skip="$2" 2> /dev/null | __bin2hex_le "$3" )"
 	echo $(( 0x$v ))
 }
+
+__init() {
+	local t
+	# init __hex2bin
+	t="7a32337465737431323374657374"
+	if [ "$( printf z23test123test | xxd -p )" = "$t" ]; then
+		#echo "Using xxd" >&2
+		__bin2hex() { xxd -p; }
+	elif [ "$( printf z23test123test | od -t x1 -An | tr -d '\n ' )" = "$t" ]; then
+		#echo "Using od" >&2
+		__bin2hex() { od -t x1 -An | tr -d '\n '; }
+	elif [ "$( printf z23test123test | hexdump -ve '/1 "%02x"' )" = "$t" ]; then
+		#echo "Using hexdump" >&2
+		__bin2hex() { hexdump -ve '/1 "%02x"'; }
+	else
+		echo "No suitable tool for converting binary to hex" >&2
+		exit 1
+	fi
+	# init __hex2bin_le
+	t="383736353433327a"
+	if [ "$( printf z2345678 | xxd -e -g 8 | cut -d' ' -f2 )" = "$t" ]; then
+		#echo "Using xxd" >&2
+		__bin2hex_le() { xxd -e -g "$1" | cut -d' ' -f2; }
+	elif [ "$( printf z2345678 | od -t x8 -An | tr -d '\n ' )" = "$t" ]; then
+		#echo "Using od" >&2
+		__bin2hex_le() { od -t "x$1" -An | tr -d '\n '; }
+	elif [ "$( printf z2345678 | hexdump -ve '/4 "%02x"' \
+			| sed 's/\(........\)\(........\)/\2\1/' )" = "$t" ]; then
+		#echo "Using hexdump" >&2
+		__bin2hex_le() {
+			if [ "$1" -lt 8 ]; then
+				hexdump -ve "/$1"' "%02x"'
+			else
+				hexdump -ve '/4 "%02x"' | sed 's/\(........\)\(........\)/\2\1/'
+			fi
+		}
+	else
+		echo "No suitable tool for converting binary data to little endian hex" >&2
+		exit 1
+	fi
+	unset -f __init
+}
+
+__init
-- 
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