Ahh, but that's not the case. You cannot just delete the check, since
not all combinations of bytes are valid UTF8. UTF bytes FE & FF never
appear in a byte sequence for instance.
UTF8 is more that two bytes btw, up to 6 bytes are used to represent an
UTF8 character.
The 5 and 6 byte characters are currently not in use tho.
I didn't actually notice the difference in UTF8 width between my
original patch and my last, so attached, updated patch.
Regards,
John Hansen
-----Original Message-----
From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
Sent: Saturday, August 07, 2004 3:07 PM
To: John Hansen
Cc: Hackers; Patches
Subject: Re: [HACKERS] UNICODE characters above 0x10000
"John Hansen" <john@geeknet.com.au> writes:
> My apologies for not reading the code properly.
> Attached patch using pg_utf_mblen() instead of an indexed table.
> It now also do bounds checks.
I think you missed my point. If we don't need this limitation, the
correct patch is simply to delete the whole check (ie, delete lines
827-836 of wchar.c, and for that matter we'd then not need the encoding
local variable). What's really at stake here is whether anything else
breaks if we do that. What else, if anything, assumes that UTF
characters are not more than 2 bytes?
Now it's entirely possible that the underlying support is a few bricks
shy of a load --- for instance I see that pg_utf_mblen thinks there are
no UTF8 codes longer than 3 bytes whereas your code goes to 4. I'm not
an expert on this stuff, so I don't know what the UTF8 spec actually
says. But I do think you are fixing the code at the wrong level.
regards, tom lane