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Bug 4935

Summary: [REGRESSION] Loading XCF files is broken on 32-bit as of 2.0.5
Product: SDL_image Reporter: Austin Hurst <mynameisaustinhurst>
Component: miscAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 CC: miniupnp, sezeroz
Version: 2.0.5   
Hardware: x86   
OS: Windows 7   
Attachments: patch for SDL2
Patch for SDL1.2

Description Austin Hurst 2020-01-11 02:44:38 UTC 
I'm one of the maintainers of the pysdl2 project, and have spent a good chunk of the past week updating the test/CI suite to support the current set of SDL2 libraries. In the process, I think I've found a regression in SDL2_image from 2.0.4 to 2.0.5: loading XCF images (well, our test XCF image) no longer works with the official 32-bit Windows runtime DLLs (returns a null pointer instead of a surface).

Here's the Appveyor output for a commit before I disabled XCF tests on 32bit: https://ci.appveyor.com/project/a-hurst/py-sdl2/builds/29985808

You can see that the tests for IMG_LoadXCF_RW (and other image-loading functions with the .xcf test image) fail with the 32-bit SDL2_image 2.0.5, but pass with the 64-bit SDL2_image 2.0.5 and with the 32-bit SDL2_image 2.0.4 & 2.0.2.

While trying to figure out if it was a pysdl2 or SDL2_image problem, I dug into the source history and found this commit between 2.0.4 and 2.0.5 that looks like a likely culprit, a commit that adds support for 64-bit offsets in XCF files: https://hg.libsdl.org/SDL_image/rev/6536f264b1eb

Not sure how common XCF loading in SDL2 actually is, but I figured you'd want the heads-up!
Comment 1 Ozkan Sezer 2020-10-26 16:22:28 UTC 
Reopened and dropped a note about this at 
https://bugzilla.libsdl.org/show_bug.cgi?id=4413
Comment 2 miniupnp@free.fr 2020-10-26 22:19:23 UTC 
OK, I think I understand what's going on.
XCF files normally have the version in their header, just like 
00000000  67 69 6d 70 20 78 63 66  20 76 30 31 31 00 00 00  |gimp xcf v011...|

but this one has 
00000000  67 69 6d 70 20 78 63 66  20 66 69 6c 65 00 00 00  |gimp xcf file...|

I think it should be interpreted as version 0
Comment 3 miniupnp@free.fr 2020-10-26 22:33:59 UTC 
Created attachment 4486 [details]
patch for SDL2
Comment 4 miniupnp@free.fr 2020-10-26 22:34:32 UTC 
Created attachment 4487 [details]
Patch for SDL1.2
Comment 5 Ozkan Sezer 2020-10-26 23:05:40 UTC 
Thanks, patches applied.

SDL-1.2 branch: https://hg.libsdl.org/SDL_image/rev/bbbffe655cc8

Default branch: https://hg.libsdl.org/SDL_image/rev/80a5e1347ee6

Tested the default branch and seen that showimage does load XCFs.
@Austin Hurst: Is it working for you?  Shall I close this?
Comment 6 Ozkan Sezer 2020-10-31 17:24:13 UTC 
Closing as fixed.