Xref: utzoo comp.unix.xenix:1270 comp.sys.att:1969
Newsgroups: comp.unix.xenix,comp.sys.att
Path: utzoo!lsuc!dave
From: dave@lsuc.uucp (David Sherman)
Subject: Re: mailx and big files
Reply-To: dave@lsuc.UUCP (David Sherman)
Date: Mon, 4-Jan-88 14:06:20 EST
Summary: >32767 can be negative
Message-ID: <1988Jan4.140623.19127@lsuc.uucp>
References: <2433@dasys1.UUCP>
Organization: Law Society of Upper Canada, Toronto

In article <2433@dasys1.UUCP> samperi@dasys1.UUCP (Dominick Samperi) writes:
>When I use mailx to send a large text file (about 50K or more) via
>'mailx user < file', I get error messages of the form "can't append
>to /usr/mail/user" and "can't write to dead.letter", yet it turns out
>that the contents of the file WAS appended to /usr/mail/user, and
>the contents were also written to dead.letter! Furthermore, there was
>no corruption in either file (/usr/mail/user or dead.letter). I'm using
>an AT compatible, running System V/AT. Any ideas out there?

Sure.  You're using a 16-bit machine, and the value for the number
of bytes written is stored in a regular (short) "int" variable.  Once this
tops 32767, it goes negative.  The code which tests for success of
the write assumes that "n<0" means failure (normally -1 is returned
on failure of a system call), so it tells you the write failed when
in fact it worked fine.

Solution, if you have source, is of course to ensure that the
variable used to store the number of bytes written is a long int.

David Sherman
The Law Society of Upper Canada
Toronto
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