https://github.com/falk-werner/sd-image
Extract and update partitions of a filesystem image file
https://github.com/falk-werner/sd-image
Last synced: 2 months ago
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Extract and update partitions of a filesystem image file
- Host: GitHub
- URL: https://github.com/falk-werner/sd-image
- Owner: falk-werner
- License: mit
- Created: 2022-10-05T17:19:07.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2022-10-05T17:56:02.000Z (over 2 years ago)
- Last Synced: 2025-02-01T20:17:27.526Z (4 months ago)
- Size: 3.91 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# sd-image
Extract and update partitions of a filesystem image file.
## Use case
Sometimes one might need to modify an sd card image, e.g. exchange a file in
the root file system. This might be achieved in two steps
1. determine the position of the desired partition within the image
_(`fdisk -l sd.img` might be used for this)_
2. mounting the image as loopback device
_(typically something like `mount -o loop,offset=$((49152*512)) sd.img /mnt`)_
This works pretty fine as long as one has the privileges to use the `mount`
command. Unfortunately, this is not always the case. While it is a good idea
to restrict access to `mount` command, there is no security problem with the
use case to change the contents of a file one has already access to.
Tools like [e2tools](https://github.com/e2tools/e2tools) allow to modify
`ext2/3/4` file system images. The only thing missing is a tool to extract
partitions from an image and updates them.
This is were `sd-image.py` comes in handy. To add a local file to an existing
image, the following sequence can be used:
````
sd-image.py extract -i sd.img -p 1 -f rootfs.ext4
e2cp some.file rootfs.ext4:/path/to/some.file
sd-image.py update -i sd.img -p 1 -f rootfs.ext4
````
## Usage
### List paritions
````
sd-image.py list -i sd.img
NR STATUS TYPE START SIZE
----------------------------------------------
0 active FAT32 8388608 16777216
1 inactive Linux 25165824 262144000
````
| Argument | Description |
| -------- | ----------- |
| -i image | file name of the sd card image |
### Extract partition form image
````
sd-image.py extract -i sd.img -p 1 -f rootfs.ext4
````
| Argument | Description |
| --------- | ----------- |
| -i image | file name of the sd card image |
| -p number | number of the partition to extract (zero-based) |
| -f file | file name of the parition to extract |
### Update partition of image
````
sd-image.py update -i sd.img -p 1 -f rootfs.ext4
````
| Argument | Description |
| --------- | ----------- |
| -i image | file name of the sd card image |
| -p number | number of the partition to extract (zero-based) |
| -f file | file name of the parition to extract |
## Further information
- [Master boot record](https://en.wikipedia.org/wiki/Master_boot_record)
- [e2tools](https://github.com/e2tools/e2tools)