# Slurp file in one - assuming there's room:-)
open FILE, "<fname" or die "open() - $!";
local undef $/;
@files = <FILE>
close FILE;

while (@files) {
  #
  # do something with file $_
  #
  shift @files;
}

END {
  # Save any state
  @files && do {
    open FILE, ">fname" or die "Cannot save state - $!";
    printf FILE "@files";
    close FILE;
  };
}