smb@cs.columbia.edu said:
>  reversed the order of  the second and third arguments to lseek

Oh, yes, feeling sheepish...
So it turns out to be an alpha specific problem, still getting
zel637: {2} ./a.out
a.out: write: Invalid argument

(That test was to track down compilation failures I described
in a mail to current-users and tech-toolchain, subject
"can't compile empty files anymore". That also happens
only on alpha as it looks.)

best regards
Matthias