my $contents = do { local $/; <DATA> };

while ($contents =~
   /
      \s* ([^=\s]+) \s* = \s*
      (
         (?:
            (?! \s*
               (?:
                  [^=\s]+ \s* =
               |
                  $
               )
            )
            .
         )*
      )
   /xmsg
) {
   print("[$1 => $2]\n");
}

__DATA__
name1=value1
             name2 = value2
name3 = value3
   but wait, there is
 more
name4=
  value4