[U-Boot] [PATCH 00/17] fs: fat: extend FAT write operations

[Heinrich Schuchardt]

On 07/20/2018 04:57 AM, AKASHI Takahiro wrote:
> This patch series is an attempt to address FAT write related issues
> in an effort of running UEFI SCT (Self-Certification Test) to verify
> UEFI support on u-boot.
> 
> SCT is a test platform as well as an extentisive collection of test
> cases for UEFI specification. It can run all the tests automatically
> and save test results to dedicated log files.
> 
> AFAIK, what's missing in the current fat file system to safely run
> SCT without errors (I don't mean test case failures) are:
> * write a file located under sub-directories
> * write a file with non-zero offset
> * delete a file
> * create a directory
> 
> Patch#1 to patch#6 are some sort of preparatory ones.
> Patch#7 implements write with sub-directories path.
> Patch#8 to patch#10 implement write with non-zero offset.
> Patch#11 to patch#15 are related to creating a directory.
> Patch#16 provides delete, but it doesn't actually delete a file
> but instead return 0 with purging a file content, which is good
> enough to run SCT for now.
> Finally, patch#17 fixes a minor bug in fs-test.sh.
> 
> I applied this patch set on top of v2018.07 along with a couple of
> yet-to--be-upstreamed UEFI-related patches, and could successfully
> run unmodified SCT[1] on qemu-arm.
> 
> [1] http://uefi.org/testtools

Thanks Takahiro for getting this all implemented.

I have some questions concerning code pages:

The FAT file system contains a short name and a long name. The short 
name is in the 8-bit code page of the system. The long name is 16bit 
Unicode.

Which local code page do you assume? I would suggest to use 437 as we do 
in some other drivers.

With your patch fat_mkdir() and fat_file_write() do not yet support 
UTF-8 as file names and convert this to the 437 local page for the short 
name and to UTF-16 for the long name.

Without this conversoin we will not be able to implement the EFI 
specification.

normalize_longname() simply ignores codes 0x80-0xFF. Please, have a look at

https://www.win.tue.nl/~aeb/linux/fs/fat/fatgen103.pdf
Microsoft Extensible Firmware Initiative FAT32 File System Specification
FAT: General Overview of On-Disk Format
Version 1.03, December 6, 2000

Shouldn't we implement the base-name algorithm as described in the paper?

Best regards

Heinrich