comments on proposed uthread_write.c changes
wollman at khavrinen.lcs.mit.edu
Tue Sep 9 17:34:37 PDT 2003
<<On Tue, 9 Sep 2003 19:46:12 -0400 (EDT), Daniel Eischen <eischen at vigrid.com> said:
> Libc_r's write treats a return of 0 from __sys_write() as a
> partial write and continues looping.
This is a bug. The Standard is quite clear that a write of zero bytes
is not possible unless the supplied buffer length is zero. In the
specific case of non-blocking files, if data might be written but
doing so would cause the calling thread to block, write() must return
-1 with errno set to [EAGAIN]; it may not return zero. Therefore, a
zero return from write() always indicates a permanent condition.
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