I can't tell if you mean "write the server-side code to handle
the uploaded file" or "write the client-side code to simulate
what a browser does to upload a file".
If the former, use CGI.pm:
CREATING A FILE UPLOAD FIELD
print $query->filefield(-name=>'uploaded_file',
-default=>'starting value',
-size=>50,
-maxlength=>80);
-or-
print $query->filefield('uploaded_file','starting value',50
+,80);
filefield() will return a file upload field for Netscape
2.0 browsers. In order to take full advantage of this you
must use the new multipart encoding scheme for the form.
You can do this either by calling start_form() with an
encoding type of &CGI::MULTIPART, or by calling the new
method start_multipart_form() instead of vanilla
start_form().
Parameters
1. The first parameter is the required name for the field
(-name).
2. The optional second parameter is the starting value
for the field contents to be used as the default file
name (-default).
For security reasons, browsers don't pay any attention
to this field, and so the starting value will always
be blank. Worse, the field loses its "sticky" behav-
ior and forgets its previous contents. The starting
value field is called for in the HTML specification,
however, and possibly some browser will eventually
provide support for it.
3. The optional third parameter is the size of the field
in characters (-size).
4. The optional fourth parameter is the maximum number of
characters the field will accept (-maxlength).
When the form is processed, you can retrieve the entered
filename by calling param():
$filename = $query->param('uploaded_file');
Different browsers will return slightly different things
for the name. Some browsers return the filename only.
Others return the full path to the file, using the path
conventions of the user's machine. Regardless, the name
returned is always the name of the file on the user's
machine, and is unrelated to the name of the temporary
file that CGI.pm creates during upload spooling (see
below).
The filename returned is also a file handle. You can read
the contents of the file using standard Perl file reading
calls:
# Read a text file and print it out
while (<$filename>) {
print;
}
# Copy a binary file to somewhere safe
open (OUTFILE,">>/usr/local/web/users/feedback");
while ($bytesread=read($filename,$buffer,1024)) {
print OUTFILE $buffer;
}
If the latter, use HTTP::Request::Common:
The POST method also supports the `multi-
part/form-data' content used for Form-based File
Upload as specified in RFC 1867. You trigger this
content format by specifying a content type of
`'form-data'' as one of the request headers. If one
of the values in the $form_ref is an array reference,
then it is treated as a file part specification with
the following interpretation:
[ $file, $filename, Header => Value... ]
The first value in the array ($file) is the name of a
file to open. This file will be read and its content
placed in the request. The routine will croak if the
file can't be opened. Use an `undef' as $file value
if you want to specify the content directly. The
$filename is the filename to report in the request.
If this value is undefined, then the basename of the
$file will be used. You can specify an empty string
as $filename if you don't want any filename in the
request.