bug#46881: 28.0.50; pdumper dumping causes way too many syscalls

[Eli Zaretskii]

> From: Pip Cet <pipcet@gmail.com>
> Date: Fri, 5 Mar 2021 02:30:13 +0000
> Cc: Eli Zaretskii <eliz@gnu.org>, Paul Eggert <eggert@cs.ucla.edu>, 
> 46881@debbugs.gnu.org
> 
> > It looks fine, but wouldn't dumping to a FILE* (with internal buffering)
> > do the same basic thing in a simpler way?
> 
> I initially set out to do that, but decided against it. We don't just
> write sequentially (when FILE I/O helps, a little), we also have the
> seek-and-fixup phase, and it didn't seem any simpler at that point..

I'm not sure I understand: what's wrong with fseek?