Le 28 oct. 08 Γ 12:50, Gerriet M. Denkmann a Γ©crit :
On 28 Oct 2008, at 01:39, Jeremy Pereira wrote:
On 26 Oct 2008, at 09:55, Gerriet M. Denkmann wrote:
On 26 Oct 2008, at 00:30, Postmaster wrote:
On 14 Oct 2008, at 21:00, Gerriet M. Denkmann wrote:
On 14 Oct 2008, at 18:07, Jason Coco wrote:
On Oct 14, 2008, at 11:28 , Gerriet M. Denkmann wrote:
HFS+ stores files in decomposed UTF-8. Checking the system
headers,
"system headers" is kind of vague: which file exactly do you have
in mind?
it can store files with a maximum file name length of 255 bytes.
How do you get 256 bytes of UTF-8 into 255 bytes?
Checking the system header hfs_format.h for HFSUniStr255 one sees
that it can store file names with a maximum length of 255 u_int16_t.
And there is no real problem of putting the 128 shorts of Utf-16
into 255 u_int16_t.
It's actually the VFS layer I was thinking of. The OS X VFS uses
UTF-8 (otherwise there would be no backward compatibility for calls
like open(2) etc). I got the 255 byte limit by looking at struct
dirent defined in /usr/include/sys/dirent.h which is the structure
used in the readdir syscall.
I have just tried getdirentries() which uses the dirent structure
described in /usr/include/sys/dirent.h .
The result was (for me) quite a surprise.
What I did:
1. created a file in Desktop
2. renamed it in Finder to:
"ππππππππππππππππππππππππππππππππππππππππππππππππππππππππππππππππ
".
(128 Utf-16 shorts, but 256 Utf-8 bytes).
3. ran getdirentries() and got:
file
(255
)"ππππππππππππππππππππππππππππππππππππππππππππππππππππππππππππππ
#185D41"
4. used open() and read() with this (seemingly garbled) filename -
and it just works!
But open() and fopen() also work with the real filename.
And: renaming a file in Finder with this (garbled) name does not
work: Finder claims that this name is already in use. Which is not
true: HFS+ has only the real filename stored.
No idea who does the translation between real filename and garbled
version.
Very strange indeed.
Kind regards,
Gerriet.
This kind of transformation was already done when using long file name
on OS 9 (where long mean more than 32 characters).
It was a mechanism used to workaround the limit imposed by the OS that
was more strict that the HFS+ limit.
Look like this feature is always here.
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