[9fans] allowing space (ASCII 0x20) in file names

[G. David Butler gdb@dbSystems.com]

>From: "Russ Cox" <rsc@plan9.bell-labs.com>

>> The problem is that the RFC2060 "International Mailbox Naming
>> Convention" has one more character in its alphabet than Plan9
>> allows in names so there is no place to map the space.
>
>There are more problems than that.  I'm pretty sure RFC2060 doesn't
>specify a name length, and Plan9 limits you to 27 bytes.  So you're
>going to have to keep some sort of translation table between IMAP
>names and Plan9 names anyway.  

I think each component limited to 27 octets is ok.  Now what is fun
is the namespace starting with a '#'!  (not a real problem, just strip
it or use ./#blah.)

>If this limit wasn't there and you were content to keep the mailbox
>names in encoded form (probably a nice choice, since then you never
>have to decode or encode them) you could substitute 0x7F for space
>in the Plan9 names and you'd be all set -- both are one byte in
>UTF-8, and RFC2060 can't have raw 7Fs while Plan9 can't have raw spaces.

Hold on, /sys/src/9/port/chan.c excludes 0x7f even though
/sys/src/fs/port/dentry.c doesn't.  Should we allow 0x7f?

-------------------------------------------------------------------
G. David Butler   | Who I? Zathras, a Plan9er. Nobody uses Zathras'
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