local $/;
my $file = (<>);

my $spdx_regex = '/\*[ \t]*SPDX-License-Identifier:[ \t]*';
my $spdx_actual = '/* SPDX-License-Identifier: ';

# any // use converted to /* ... */
$file =~ s@^//[ \t]*SPDX-License-Identifier:[ \t]*(.*)\n@/* SPDX-License-Identifier: $1 */\n@;

# first line use with /* without trailing */ gets */ added and 2nd line updated
$file =~ m@^\s*${spdx_regex}([^\n]+)\n@;
if (defined $1 && $1 !~ m@\*/$@) {
    $file =~ s@^[ \t]*${spdx_regex}([^\n]+)\n@${spdx_actual}$1 */\n/* @;
    $file =~ s@^[ \t]*${spdx_regex}([^\n]+)\n[ \t]*/\*[ \t]+\*@${spdx_actual}$1\n/* @;
    $file =~ s@^\s*${spdx_regex}([^\n]+)\n/\* \n@${spdx_actual}$1\n/*\n@;
}

print $file;