bug#16133: 24.3; copy-file fails on chmod when copying to FAT filesystem

[Eli Zaretskii]

> Date: Sat, 21 Dec 2013 20:01:24 -0800
> From: Paul Eggert <eggert@cs.ucla.edu>
> CC: 16133@debbugs.gnu.org, ran@lasgalen.net
> 
> Eli Zaretskii wrote:
> > Emacs throws an error, and stops the copy operation,
> > even if there are more files to copy.
> 
> copy-file copies just one file, so there can't be any more
> files to copy.  When GNU 'cp' is acting like copy-file and
> is copying just one file, it doesn't do anything more to the
> file after fchmod fails -- it simply exits with nonzero status,
> which corresponds to Emacs throwing an error.

I was referring to the use case described here:

  http://debbugs.gnu.org/cgi/bugreport.cgi?bug=16133#14

The 'cp' equivalent of that is when it is invoked to copy more than
one file, or copy a directory.  In that case, it does not exit on the
first fchown error (at least the version  I have here doesn't), but
instead reports the error and continues.

Signaling an error from copy-file makes it inconvenient to write
functions that copy many files or entire directories.