Modifying the cramfs image

1. Mount the cramfs file system image as a loop device. This will be read-only image.

2. Create a new directory (e.g $HOME/initrd-new) which will be used for modifying the image (RW mode)

3. Go to the mounted cramfs image directory and get the list of files using the following command

find / > /tmp/filelist.txt

4. Use cpio to copy the contents from the mounted directory to the new directory

cat /tmp/filelist.txt | cpio -pdm /$HOME/initrd-new

5. modify the contents in the new directory as required.

6. Once the changes are done, use mkcramfs to create the cramfs image again.

mkcramfs /tmp/new-initrd new-initrd

Useful References – Android Internals

http://honeypod.blogspot.com/2007/12/initialize-libc-for-android.html

http://honeypod.blogspot.com/2007/12/shared-library-hello-world-for-android.html

http://honeypod.blogspot.com/2007/12/dynamically-linked-hello-world-for.html

http://honeypod.blogspot.com/2007/12/compile-android-kernel-from-source.html

http://benno.id.au/blog/2007/11/29/android-update-systemimg

http://benno.id.au/blog/2007/11/29/android-qemu

http://benno.id.au/blog/2007/11/26/what-is-android

http://benno.id.au/blog/2007/11/21/android-neo1973

http://benno.id.au/blog/2007/11/18/android-runtime-strace

http://benno.id.au/blog/2007/11/18/android-framework-startup

http://benno.id.au/blog/2007/11/13/android-under-the-hood

http://benno.id.au/blog/2007/11/14/android-busybox

http://www.billrocks.org/ideas/index.php?/archives/20-Debugging-Android-Native-C-Applications-with-gdb.html

http://euedge.com/blog/2007/12/06/google-android-runs-on-sharp-zaurus-sl-c760

http://davanum.wordpress.com/2007/12/09/android-invoke-jni-based-methods-bridging-cc-and-java

http://nemustech.blogspot.com/2007/12/android-porting-to-real-target-hw.html

http://nemustech.blogspot.com/2007/12/android-porting-notes.html

Useful References – Linux ELF format

http://www.linuxforums.org/misc/understanding_elf_using_readelf_and_objdump_2.html

http://www.airs.com/blog/archives/category/programming/page/5/

http://www.securityfocus.com/infocus/1872

http://plan99.net/~mike/blog/2006/08/25/elf-and-program-loading/

http://plan99.net/~mike/blog/page/2/

http://em386.blogspot.com/2006/10/resolving-elf-relocation-name-symbols.html

http://packetstormsecurity.org/papers/bypass/GOT_Hijack.txt

http://www.greyhat.ch/lab/downloads/pic.html

http://www.linux-foundation.org/spec/book/ELF-IA32/ELF-IA32.html#STD.IA32.ABI.4

http://neuronicimpulses.blogspot.com/2005_12_01_archive.html

Linux: Dynamic Library interposition in *nix Operating system

Articles on Dynamic library interposition using LD_PRELOAD path which can be used for tuning performance, collecting runtime statistics, or debugging applications etc. Check it out @

http://developers.sun.com/solaris/articles/lib_interposers.html for Solaris

http://www.linuxjournal.com/article/7795 for Linux