Re: logic error

On Fri, Aug 19, 2011 at 09:04:10AM -0500, Bob Friesenhahn wrote:
> On Fri, 19 Aug 2011, [email protected] wrote:
>>
>> The code that performs this begins at line ~5408 in
>> magick/display.c. Unfortunately, it appears the renaming of the file
>> is carried out in a separate function, in a clone of the ImageInfo,
>> and this work will never get back to the scope that emits the error msg.
>>
>> Without a larger overhaul, do you think skipping the politeness of
>> returning the (potentially incorrect) filename could be skipped from
>> the error msg?
>
> I will take a look at what can be done.  Obviously any error message  
> should reflect the path which was (attempted to be) written to and the  
> reason for the falure, rather than the source source image name.  As you 
> say, it make take some exploring to find the best way to retrieve the 
> correct error.  It seems likely that the ExceptionInfo struct accessed 
> like (*image)->exception_info contains the best information.

Ah... My first thought was with (*image)->image_info... (which
isn't "obviously easy" to make work, given the scoping I described
previously). I think we both realize it's got to be something other than
just (*image)->filename, though. I'll take a look at your suggestion
too and see if some solution presents itself.

> Running the software with the MAGICK_DEBUG variable set to 'exception'  
> will reveal the actual underlying exceptions which are thrown:

Good tip. You've mentioned this in other contexts, and it's not yet
baked into my habbits; that'll come ;)

> % MAGICK_DEBUG=exception gm display seaworld.jpg&
> [1] 26085
> freddy:~% 08:53:35 0:27 0.210u 26085 blob.c/OpenBlob/3485/FileOpen:
>   Unable to open file (/blah/seaworld.jpg)
> 08:53:35 0:27 0.210u 26085 jpeg.c/WriteJPEGImage/1738/FileOpen:
>   Unable to open file (/blah/seaworld.jpg)
>
> % MAGICK_DEBUG=exception gm display seaworld.pbm&
> [1] 26092
> % 08:55:13 0:26 0.180u 26092 blob.c/OpenBlob/3485/FileOpen:
>   Unable to open file (/blah/seaworld.pbm)
> 08:55:13 0:26 0.180u 26092 pnm.c/WritePNMImage/1293/FileOpen:
>   Unable to open file (/blah/seaworld.pbm)
>
> Would you be happier if the notification window said "Unable to open  
> file (/blah/seaworld.pbm)" rather than the file name?

My scenario was this:
kamloops$ pwd
/home/bch/nowrite
kamloops$ ls -ld . 
dr-xr-xr-x  2 root  wheel  512 Aug 19 09:08 .
kamloops$ ls -ld * 
-rw-r--r--  1 root  users  56716 Aug 19 09:08 bird.jpg
kamloops$ env MAGICK_DEBUG=exception gm display bird.jpg 
09:10:05 0:17 0.030u 557 jpeg.c/WriteJPEGImage/1737/FileOpen:
  Unable to open file (bird2.jpg)


The above was generated by trying to save the "bird.jpg" image as
"bird2.jpg". I guess an error of "Unable to open file (bird2.jpg)"
would be better error, yes.

> Bob
> -- 
> Bob Friesenhahn
> [email protected], http://www.simplesystems.org/users/bfriesen/
> GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

-- 
Brad Harder
Method Logic Digital Consulting
http://methodlogic.net/
http://twitter.com/bcharder


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