Uploading binary files problem

Question

I have a HTTP server (newLISP running on a Linux box), which runs my CGI scripts. It runs on my Linux box.

I have a strange problem with uploading files using the POST method. My CGI script is simple: it reads everything from stdin, and saves it in a file. I wrote the script for debugging purposes: I wanted to know, what exactly is read.

When I upload a text file, everything is fine. I mean I get something like that:

-----------------------------18218802734725416881815749595
Content-Disposition: form-data; name="uploaded_data"; filename="post.gif"
Content-Type: image/gif

(and here's the content of the text file)

-----------------------------18218802734725416881815749595
Content-Disposition: form-data; name="text_field_name"

text field value
-----------------------------18218802734725416881815749595
Content-Disposition: form-data; name="submit"

Upload
-----------------------------18218802734725416881815749595--

And that's exactly what I should get, according to the RFC 1867 (Form-based File Upload in HTML). (Yes, I renamed this text file to "post.gif".)

The problem is, I get something really strange, when I try to upload any binary file. For example, when I upload a gif image, I get this:

-----------------------------208529943213031756281593958364

Content-Disposition: form-data; name="uploaded_data"; filename="polsl.gif"
Content-Type: image/gif

GIF89a_

What can be the cause of this strange behaviour?

verisimilidude verisimilidude · Accepted Answer · 2010-11-09T13:07:16

It looks like the binary string is being written and the writer is not writing out the non-printing characters. Or it is writing them out and whatever editor you are looking at the file with is filtering them. Try Base-64 encoding the data you receive before you write it to the file and see if that changes things. All GIFs by the way start with the string GIF89a.

Uploading binary files problem

1 Answers