problem with CGI, multipart forms, images and MSIE Mac OS X

Francis Hwang · Sep 10, 2004

I suppose it's possible that I'm the only Ruby programmer ever to run
into this problem, but I'm having an obscure problem with the CGI
library. Maybe it's a bug or maybe I'm just missing something.

I'm using a multipart form with images for buttons and trying to
detect which image was used to submit. With a form like this:

<form action="/test/upload.rb" method="post"
enctype="multipart/form-data">
<input name="text" />
<br />Small: <input type="file" name="small" />
<br /><input type="image" src="/baseims/submit_button.gif"
name="button" />
</form>

I should get values for either "button" or "button.x" and "button.y",
or both. Depending on the browser. Here's what my /test/upload.rb
looks like:

puts "Content-type: text/html\n\n"
cgi = CGI.new
puts "<br />text: #{ cgi['text'].readlines.join( "\n" ) }"
puts "<br />button.x: #{ cgi['button.x'].readlines.join( "\n" ) }"
puts "<br />button.y: #{ cgi['button.y'].readlines.join( "\n" ) }"
puts "<br />button: #{ cgi['button'].readlines.join( "\n" ) }"

When I do this in Safari, it's fine. But when I do this in MSIE OS X,
I get nothing for any of the button values.

At first I thought this might be a MSIE problem, but I did the exact
same thing with PHP and it works fine in both Safari and MSIE. So
maybe I'm doing something really wrong, or maybe I've hit an obscure
bug? Advice would be much appreciated.

Francis

Brian Candler · Sep 11, 2004

At first I thought this might be a MSIE problem, but I did the exact
same thing with PHP and it works fine in both Safari and MSIE. So
maybe I'm doing something really wrong, or maybe I've hit an obscure
bug? Advice would be much appreciated.

My suggestion: write a test program which does something like

data = $stdin.read
puts "Content-type: text/html\r\n\r\n<html>#{CGI.escapeHTML(data)}</html>"

instead of using the CGI library. And do the same in PHP. Then you can tell
whether the data *is* getting posted to you by the browser (and hence a bug
in CGI which you can replicate), or is not.

Also: try printing #{ cgi.params['button'].inspect } - see if you get an
empty array, or an array containing one element (an empty string), which is
different of course.

And you could also try setting <input ..... name="button" value="foo">

Brian.

Francis Hwang · Sep 13, 2004

So I tried this. This is what it looks like through Safari:

------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="text"

------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="small";
filename=""

------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="button.x"

46
------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="button.y"

9
------------0xKhTmLbOuNdArY--

Here's what it looks like through MSIE Mac OS X:

-----------------------------141511461516657
Content-Disposition: form-data; name="text"

-----------------------------141511461516657
Content-Disposition: form-data; name="small";
filename=""

-----------------------------141511461516657
Content-Disposition: form-data; name="button.x"

14
-----------------------------141511461516657
Content-Disposition: form-data; name="button.y"

7
-----------------------------141511461516657--

So, the data is being posted through both browser, but I can't seem to
retrieve it through the standard CGI library. The main difference is
that the boundary lines are different. Not sure if that would have any
impact.

Does this look like a bug?

Francis

Brian Candler said:
At first I thought this might be a MSIE problem, but I did the exact
same thing with PHP and it works fine in both Safari and MSIE. So
maybe I'm doing something really wrong, or maybe I've hit an obscure
bug? Advice would be much appreciated.

Click to expand...

My suggestion: write a test program which does something like

data = $stdin.read
puts "Content-type: text/html\r\n\r\n<html>#{CGI.escapeHTML(data)}</html>"

instead of using the CGI library. And do the same in PHP. Then you can tell
whether the data *is* getting posted to you by the browser (and hence a bug
in CGI which you can replicate), or is not.

Also: try printing #{ cgi.params['button'].inspect } - see if you get an
empty array, or an array containing one element (an empty string), which is
different of course.

And you could also try setting <input ..... name="button" value="foo">

Brian.

Patrick May · Sep 14, 2004

Hello,

So I tried this. This is what it looks like through Safari:

------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="text"

------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="small";
filename=""

------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="button.x"

46
------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="button.y"

9
------------0xKhTmLbOuNdArY--

Here's what it looks like through MSIE Mac OS X:

-----------------------------141511461516657
Content-Disposition: form-data; name="text"

-----------------------------141511461516657
Content-Disposition: form-data; name="small";
filename=""

-----------------------------141511461516657
Content-Disposition: form-data; name="button.x"

14
-----------------------------141511461516657
Content-Disposition: form-data; name="button.y"

7
-----------------------------141511461516657--

So, the data is being posted through both browser, but I can't seem to
retrieve it through the standard CGI library. The main difference is
that the boundary lines are different. Not sure if that would have any
impact.

Does this look like a bug?

The boundry doesn't matter, it just has to be unique. It may be a bug.
Narf inherits this code, I'll test it tomorrow.

~ pat

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problem with CGI, multipart forms, images and MSIE Mac OS X

Francis Hwang

Brian Candler

Francis Hwang

Patrick May

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