Mount single logical partition from image of entire disk (device)

Question

The method below works to mount a primary partition from the disk image, but fails trying to mount a logical partition under an extended partition. Is there a way around this? I have 3 logical partitions under the extended partition and none of these will mount using the steps below.

Get the partition layout of the image

$ sudo fdisk -lu sda.img
...
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
...
  Device Boot      Start         End      Blocks   Id  System
sda.img1   *          56     6400000     3199972+   c  W95 FAT32 (LBA)

Calculate the offset from the start of the image to the partition start

Sector size * Start = (in the case) 56 * 512 = 28672

Mount it on /dev/loop0 using the offset

sudo losetup -o 28672 /dev/loop0 sda.img

Now the partition resides on /dev/loop0. You can fsck it, mount it etc

sudo fsck -fv /dev/loop0
sudo mount /dev/loop0 /mnt

Unmount

sudo umount /mnt
sudo losetup -d /dev/loop0

What do you mean? It works just fine for logical partitions. Instead of mucking with offsets, you can also just run sudo partx -a /dev/loop0 to get all of the partitions to show up normally. — psusi, Jul 17 '14 at 01:44
See the answers in this question: https://askubuntu.com/questions/69363/mount-single-partition-from-image-of-entire-disk-device — erik, May 05 '20 at 22:31

score 0 · Answer 1 · answered Jul 17 '14 at 17:15

Here's a script I use to mount partitions from image files. See the comments at the start of the script for usage information.

#!/bin/bash

# mount_image, a program that mounts a specific partition from a RAW
# disk image file, such as a full-disk dd copy or a file used by QEMU.
# Note that compressed and other space-saving formats (qcaw2, etc.)
# will NOT work!

# Use:
# mount_image image_file partition_number mount_point
#
# For instance,
#
# mount_image image.raw 2 /mnt/shared
#
# mounts partition 2 from image.raw at /mnt/shared.

# This program relies on my GPT fdisk (gdisk) program to help identify
# partitions. I could have used regular fdisk, but this would have
# limited the program to working with MBR-formatted disks. With gdisk,
# both MBR- and GPT-formatted disks will work.

gdisk -l $1 > /tmp/mount_image.tmp
let StartSector=`egrep "^   $2|^  $2" /tmp/mount_image.tmp | fmt -u -s | sed -e 's/^[ \t]*//' | head -1 | cut -d " " -f 2`

let StartByte=($StartSector*512)

echo "Mounting partition $2, which begins at sector $StartSector"

mount -o loop,offset=$StartByte $1 $3

rm /tmp/mount_image.tmp

Mount single logical partition from image of entire disk (device)

1 Answers1