In article <FB30E6123B22D211B52800A0C9CFBB19010C0E9F@LONES2>, "BAZLEY, Sebastian"
<[EMAIL PROTECTED]> writes:
> On VMS, syswrite() returns undef if one tries to write more than 65535 bytes
> on a socket.
Probably to more devices than just a socket; my bet is that any
non-file-structured device would have the problem.
As should be obvious, this is the (in)famous "length as an unsigned short"
in QIO calls. Perl calls the CRTL `write' function which does the QIO.
> This can cause problems for other modules, so how about forcing the call to
> write a maximum of 65535 bytes? [The caller should always be prepared to
> handle a shorter write, so this should not break any code.]
Should, but watch out; I've seen plenty of unix code with:
if (write(fd, buf, n) != n) {die_horribly}
> It seems to me that undef should be reserved for more "serious" errors.
>
> Anyone agree/disagree/other solutions?
>
> [This problem showed up on VMS 7.2-1 with UCX 5.0A. I have not tried any
> other combinations.]
Watch out though, if you just break at a random place it's possible you'll
have problems with carriage control bytes.
For example in Perl if you do a print to a mailbox:
print MBX "blah blah\n";
The "\n" is stripped (by the CRTL) before writing to the mailbox. If
you read from a mailbox, a "\n" is tacked on the end of the record by
the CRTL before Perl gets the data.
My *bet* is that you want to break at \n bytes, but you'll have to try
it and see.
--
Drexel University \V --Chuck Lane
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