[REF] Unpacking and repacking stock rom .img files

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As most of you are aware, the stock rom tarball is comprised of several .img files which don't seem to be of any file system format and it is difficult at first to see what is inside these files without flashing via Odin.

Well, thanks to fguy, this thread http://forum.xda-developers.com/show....php?t=1054836 provided me the necessary inspiration to investigate just exactly what are these img made of.

Hopefully, this will allow easy removal of all the Samsung junk, deodexing, rooting etc etc without going through adb.

As it turns out, they are simply sparse ext4 images, and the AOSP source tree already contains the necessary utilities to both unpack and repack these img files via "ext4_utils" in system/extras (http://android.git.kernel.org/?p=pla...ras.git;a=tree)

For your convenience, I have provided a repackage of the source code for ext4_utils with a simple Makefile, for keen developers to make the necessary tools for unpacking and repacking the stock img files. Making these tools requires a linux development environment, which is beyond the scope of this topic.

To make the tools, simple extract the attached source code and type "make".

To unpack the .img file:

./simg2img factoryfs.img output.img

To view the contents of .img file:

mkdir tempdir; mount -o loop output.img tempdir

To repack .img file:

./mkuserimg.sh -s /some/directory/with/files ./factoryfs_custom.img ext4 ./temp 512M

As I do not have Odin at the moment, I am not able to test the repacked files can be reflashed successfully. I will test this shortly.


UPDATE
I have just tested repacking the stock factoryfs.img. It so happens that the original ext4_utils does not properly preserve permissions on the new ext4 image. I have made a slight modification to the source and reuploaded the zip.

You can now successfully unpack, remove and change the stock apps, root and modify the stock image using instructions above!!

I hope this will help people create their own custom roms.

you mean, with these tools anyone with fair knowledge of linux can create custom ROMs ? what all we can do with this trick to an image/stock ROM ? pls explain
keen to know what change it could bring to the present scenario of tweaks...

Yes and you can even provide root privileges to stock rom without having to pass through insecure firmware

As you said anyone with a little knowledge of Linux could do that
It's only unpacking and repackaging new rom

Sent from my GT-I9100 using Tapatalk

very good jazzor

what is so special samsung img file?

There is nothing special about the img file. It is just that I have not seen anyone write a guide to modify these img files yet. They are simple compressed ext4 images as explained in the first post. AOSP already recognises this format and have made available utilities for you to modify and create your own img files which can be flashed via Odin

hope someone can make this tool....i know little linux knowledge....

Hi, I have given make a mistake, it can be?

Thanks.

borou@borou-casa:~/discoduro/BASURILLA/GSII/Varios/ext4_utils$ make
gcc -I. -DANDROID -c make_ext4fs.c
gcc -I. -DANDROID -c make_ext4fs_main.c
gcc -I. -DANDROID -c ext4_utils.c
gcc -I. -DANDROID -c allocate.c
gcc -I. -DANDROID -c backed_block.c
gcc -I. -DANDROID -c output_file.c
output_file.c:25:18: fatal error: zlib.h: No existe el fichero o el directorio
compilation terminated.
make: *** [output_file.o] Error 1

Originally Posted by BoRoU

Hi, I have given make a mistake, it can be?

Thanks.

hi BoRoU, try this:

$ apt-get install zlib1g-dev

Perfect. Gracies.

i get a warning when i try the option make

root@galaxy-1:/home/galaxy/ext4_utils# make
gcc -I. -DANDROID -c make_ext4fs.c
gcc -I. -DANDROID -c make_ext4fs_main.c
gcc -I. -DANDROID -c ext4_utils.c
gcc -I. -DANDROID -c allocate.c
gcc -I. -DANDROID -c backed_block.c
gcc -I. -DANDROID -c output_file.c
gcc -I. -DANDROID -c contents.c
contents.c: In function ‘make_directory’:
contents.c:118:3: warning: format ‘%llu’ expects type ‘long long unsigned int’, but argument 4 has type ‘u32’

how can i fix this?