[Linux] Some PNG textures cause segfaults

[Graf Zahl]

grAb is only looked at in the constructor. Once the values are known there is no need to read them again. And for texture creation they are simply not needed.

[Edward-san]

Hmm, before that weird len, in the previous loop, when 'lump' has:

'Length = 2853, StartPos = 351, FilePos = 412',

'len' is 6 and 'id' matches the tRNS chunk, then inside the switch, ColorType is 2, making the condition (ColorType == 3) false, so the code break the switch without doing any seek. Could it be the problem?

[Edward-san]

Aha, if I add 'else lump->Seek (len, SEEK_CUR);' after the if (ColorType == 3) block, the crash doesn't happen anymore.

[Graf Zahl]

Yup. It seems to be random chance that on Windows the values in these variables just happen to be something that doesn't make it throw up.
The entire 'tRNS' case is broken, it has to readjust the file pointer in case it doesn't read anything.

[Edward-san]

Shouldn't the fix be merged in the maint branch together with this commit?

[Graf Zahl]

There's probably more that needs to be merged into maint. But that can wait until a new release is imminent.