Re: Long file names in VFAT broken with iocharset=utf8

[Roland Kuhn]

Hi Andrey!

On 7 May 2007, at 19:51, Andrey Borzenkov wrote:

This was posted in one of Russian forums. It was not possible to archive (under Linux, using tar) vfat directory where files had long Russian names (really long - over 150 - 170 characters) - tar returned stat failure. When

looking with plain ls, file names appeared truncated.




fat_search_long allocates fixed 256 bytes buffer for UTF-8 name.

Am I off track here?

Now looking at current (2.6.21) fat driver, __fat_readdir allocates large enough buffer (PAGE_SIZE-522) for UTF-8 name; but for iocharset=utf8 it calls uni16_to_x8() which artificially limits length of UTF-8 name to 256 ... which is obviously not enough for long UTF-8 Russian string (2 bytes per character) not to mention the - theoretical - general case of 6 bytes UTF-8 characters. Similar problem has apparently vfat_lookup()->...->fat_search_long () call chain. Except this appears to be broken even in case of "utf8", because

PATH_MAX specifically counts _bytes_ not characters, so UTF-8 does not matter. ISTR that PATH_MAX was 256 at some point, but I just quickly grepped /usr/include and found various mention of 4096, so where's the central repository for this configuration item? A hard- coded value of 256 somewhere inside the kernel smells like a bug.

Ciao,
                    Roland

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