Unlike Linux where fseek/tell will be either 32 or 64 bit depending on the target platform, it will always be 32 bit on windows. We had some macro magic in BLI_winstuff.h that substituted them for 64 bit versions, but that is upsetting the system headers if they get included after BLI_winstuff.h which is problematic for D6811. This diff adds proper functions in blenlib and updates all calls that were using the BLI_winstuff.h header to gain 64 bit file IO. note: Anything that was using the 32 bit versions (ie not including BLI_winstuff.h) will still be using the 32 bit versions, which is perhaps a good code quality Friday project. Differential Revision: https://developer.blender.org/D7160 Reviewers: brecht dfelinto