I am using CGI.pm and am allowing a user to upload a file. I would like to detect different scenarios and display an appropriate error message when invalid inputs are specified by the user. For example if the user selects a directory to be uploaded I would like to detect this and say 'Sorry, you've chosen a directory. This is an invalid file.'. If the user chooses a zero byte file then I'd like to say, 'Sorry, you have selected an empty file for upload.' My problem is I don't know how to tell the difference between a directory, a zero byte file and a non-existant file. I read somewhere that you should be able to use the -d operator with a file handle if you want. So, I tried this but it didn't work! I typed c:\oracle in my file browse box (the name of a directory on my computer) and submitted to my CGI Perl script.

my $err="";
my $inputFileHandle = $cgi->param("FILE");

if ( -d <$inputFileHandle> )
{
   $err.="This is a directory.<br/>";
}

if ( !-f <$inputFileHandle> )
{
   $err.="This is not a plain file.<br/>";
}

if ( -z <$inputFileHandle> )
{
   $err.="This is a zero byte file.<br/>";
}

if ( !-e <$inputFileHandle> )
{
   $err.="This is a non-existing file.<br/>";
}

[download]
These flag operators didn't work as I expected. !-e and !-f actually got entered every time and the -d and -z blocks were never entered regardless of whether the file was valid, empty, non-existing or a directory.

Is there another way I can detect more information about what a CGI upload file handle points to with Perl?

Thanks,
  Will

In reply to Error detection on CGI file upload attempts by willjones

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