Comment 3 for bug 1599539

I noticed another bug in vvfat disk image generation. Applying the patch I attached earlier made testing easier. I'm less sure what the actual problem is.

Steps to reproduce (you'll need to have cpio, md5sum and GNU GRUB 2.x installed):
0. Apply the patch and build qemu-img.
1. Create a directory, cd into it and unpack the attached cpio file.
2. Run: qemu-img convert fat:. ../xxx.img
3. Run: for fname in $(grub-fstest ../xxx.img ls '(loop0,msdos1)/'); do grub-fstest ../xxx.img cat "(loop0,msdos1)/$fname" | md5sum | sed -e "s,-,$fname,"; done | md5sum -c
4. Observe how almost all checksum tests fail.

Alternatively, the image can be tested inside a virtual machine. You probably get the idea.

(File names and data have been changed for the sake of anonymity and better compressibility)