When compiling with IBMs XL C compiler, structure packing was done incorrectly in the BLAKE2 implementation. Packed structs must be enclosed by #pragma pack(1) and #pragma pack(pop) to push and pop the packing settings to/from the compiler's stack.
So #pragma pack() will actually push to the stack instead of pop. As a result, when compiling for 64 bit, my own structs defined in a header were interpreted as packed with 4 byte alignment when used in a module that included my own header and sodium.h. In another module that did not include sodium.h, the struct was correctly interpreted as unpacked (i.e. 8 byte alignment). Passing my struct between both modules did not go well.
When compiling with IBMs XL C compiler, structure packing was done incorrectly in the BLAKE2 implementation. Packed structs must be enclosed by
#pragma pack(1)and#pragma pack(pop)to push and pop the packing settings to/from the compiler's stack.On AIX,
#pragma pack()is equivalent to#pragma pack(pop)according to the docs: https://www.ibm.com/docs/en/xl-c-aix/13.1.2?topic=descriptions-pragma-packOn z/OS, however,
#pragma pack()is equivalent to#pragma pack(4)for C code: https://www.ibm.com/docs/en/zos/2.1.0?topic=descriptions-pragma-packSo
#pragma pack()will actually push to the stack instead of pop. As a result, when compiling for 64 bit, my own structs defined in a header were interpreted as packed with 4 byte alignment when used in a module that included my own header and sodium.h. In another module that did not include sodium.h, the struct was correctly interpreted as unpacked (i.e. 8 byte alignment). Passing my struct between both modules did not go well.This is also why
#pragma pack()is deprecated.