64315 - Wrong image displayed when a broken PNG/GIF is loaded

Status: RESOLVED WORKSFORME

(Core :: Graphics: ImageLib, defect)

Description

[Guy Rixon]

From Bugzilla Helper:
User-Agent: Mozilla/4.76 [en] (X11; U; SunOS 5.8 sun4u)
BuildID:    2000123121

I was testing a CGI script that feeds GIF and PNG images direct to the browser:
Content-type: image/png and all that, with no HTML or XML involved in the
layout.  I found that if the script gave a broken image, then mozilla displayed
the last image that it had loaded correctly before the breakage.

Reproducible: Always
Steps to Reproduce:
1.Make a trivial CGI to send a PNG, plus an HTML page to invoke it.
2.Invoke the CGI, get the image.
3.Break the CGI s.t. it now sends an invalid response.
4.Re-run the CGI.

Actual Results:  The same image is displayed for the first and second
invocations. 

Expected Results:  The second invocation should display something different. The
"torn" icon that NS 4.x uses to indicate a broken image would be ideal.

If I get time tomorrow, I may set up example CGIs for you to see this problem.

Comment 1

[Keyser Sose]

Could you put up a test cgi script it would help us a lot :) Thanks.

Comment 2

[Guy Rixon]

I can't reproduce the behaviour that I saw yesterday under controlled
conditions, so I think we're going to have to treat this report as a spurion. Sorry.

What I have shown, is that if the server sends a Content-type: image/gif header
and then sends data for a PNG, mozilla ignores the header and draws the image
correctly. (Try http://archive.ast.cam.ac.uk/~gtr/moz-png-test.html - the OK
button streams a PNG, and the NBG button streams a different PNG having first
sent a header announcing a GIF.) But I guess this behaviour is an anti-bug :-)

Comment 3

[Keyser Sose]

Thanks for the update and good bug report. Marking WORKSFORME if it happens
again reopen it.