concurrent write(2) calls write bad data to file

[Jan Edler]

Our version of UNIX has locked the file table entry on every write
for several years now.  The only time it doesn't is when writing
to a "slow" device, like a terminal (and such devices don't usually
maintain the notion of "file position" anyway).  Nulls do not appear
in the output file when running the posted test program.

I don't see any really good reason for not handling this case correctly;
there is some overhead in getting the extra lock, but that doesn't
seem like a good enough reason to me.

Jan Edler
New York University, Ultracomputer Project
edler at nyu
cmcl2!edler