Update: I've found a workaround. If I submit a dummy form field along with the file, it works. Is this a ColdFusion bug, or is there something in the HTTP spec that says forms must contain at least one non-file form field?
Update 2: I'm convinced this is a ColdFusion cfhttp bug. This is based on Leigh's answer and the fact that I used the code below to submit a form with only the file element using javascript, and it works fine:
<form enctype="multipart/form-data" action="<cfoutput>#CGI.PATH_INFO#</cfoutput>" method="POST" name="theForm">
<input name="theFile" type="file" /><br/>
</form>
<a href="#" onclick="document.theForm.submit()">submit</a>
I'm running into a problem uploading files from a ColdFusion server to another webserver. It seems that cfhttpparam type="file" is indiscriminately appending a newline (carriage return and line feed) to the end of the file. This is breaking binary files. This does not happen when I manually upload the file via form field. I have tried with and without mimetype parameter, and I've tried lying about mimetype with various binary formats (exe, zip, jpg), but nothing has worked. Is there some parameter I'm missing, or is this a bug in ColdFusion? (I'm running on CF 8.0.1.195765 on WinXP.)
Below is test code I'm using, it just uploads the file to the same directory. The manual upload works, but the server-based upload ends up appending a CRLF to the file.
<cfset MyDir = "C:\test" />
<cfset MyFile = "test.zip" />
<cfif IsDefined("Form.TheFile")>
<cffile action="upload" fileField="theFile" destination="#MyDir#" nameConflict="MakeUnique" />
<cfelse>
<cfhttp url="http://#CGI.SERVER_NAME##CGI.SCRIPT_NAME#" method="POST" throwOnError="Yes">
<cfhttpparam type="file" name="theFile" file="#MyDir#\#MyFile#" />
</cfhttp>
</cfif>
<html><body>
<h2>Manual upload</h2>
<form enctype="multipart/form-data" action="<cfoutput>#CGI.PATH_INFO#</cfoutput>" method="POST">
<input name="theFile" type="file" /><br/>
<input type="submit" value="Submit" />
</form>
</body></html>