FileUpload without Tempfile

Rails
1

I am looking for a way to upload a file to Rails 3 app, but without
generating a temp file. Googling the issue gave me some insight in how
the file upload works. As I understand Rails creates a temp file when
the file size is larger than 20kb. Is there a way to change this limit
and avoid the temp file generation?

Another solution I was looking in was creating a Rack App and so avoid
the file generation, however, didn’t work either. Same with a Sinatra
app.

Btw. yes it is mandatory that the file is not saved and only kept in
memory for security reasons.

Thanks

2

Thanks for pointing out that it is in Rack. Brings me one step closer
to a solution.

On Apr 8, 2:00pm, Chris M. [email protected] wrote:

app.

What you’ve discovered is that it’s not really Rails or Sinatra that’s
creating the Tempfile – it’s Rack:

rack/lib/rack/utils.rb at main · rack/rack · GitHub

I think you’ll need to dig down to that web server - app interface
level if you want to amend this.

I am not sure what you mean with ‘to that web server’

3

On 8 April 2011 12:38, Helmut J. [email protected] wrote:

I am looking for a way to upload a file to Rails 3 app, but without
generating a temp file. Googling the issue gave me some insight in how
the file upload works. As I understand Rails creates a temp file when
the file size is larger than 20kb. Is there a way to change this limit
and avoid the temp file generation?

Another solution I was looking in was creating a Rack App and so avoid
the file generation, however, didn’t work either. Same with a Sinatra
app.

What you’ve discovered is that it’s not really Rails or Sinatra that’s
creating the Tempfile – it’s Rack:

I think you’ll need to dig down to that web server - app interface
level if you want to amend this.

Chris

4

On 8 Apr 2011, at 13:13, Helmut J. [email protected] wrote:

and avoid the temp file generation?
I think you’ll need to dig down to that web server - app interface
level if you want to amend this.

I am not sure what you mean with ‘to that web server’

Sorry, badly worded. I meant that it’s happening at the interface
between the web server and your app; in this case that’s where Rack
lives.

Chris

5

On Apr 8, 2:22pm, Frederick C. [email protected]
wrote:

Fred

Thanks Fred for pointin to tmpfs, however, using tmpfs would also
allow that the file can be read by anyone with access

6

On Apr 8, 12:38pm, Helmut J. [email protected] wrote:

Another solution I was looking in was creating a Rack App and so avoid
the file generation, however, didn’t work either. Same with a Sinatra
app.

Btw. yes it is mandatory that the file is not saved and only kept in
memory for security reasons.

Is it enough for /tmp to be something like tmpfs (ie non persistent) ?

Fred

7

Btw. yes it is mandatory that the file is not saved and only kept in
memory for security reasons.

You could unlink the Tempfile right after creation, as mentioned here:
http://www.ruby-doc.org/stdlib/libdoc/tempfile/rdoc/classes/Tempfile.html

That will prevent any other process to get hands on that file.

Mike

8

I tried to hack into Rack, however, so far I was not able to avoid
creating a tempfile.