filesize

Indicates the number of bytes occupied by this segment on disk. For segments that require more memory at runtime than they do at build time, vmsize can be larger than filesize. For example, the __PAGEZERO segment generated by the linker for MH_EXECUTABLE files has a vmsize of 0x1000 but a filesize of 0. Because __PAGEZERO contains no data, there is no need for it to occupy any space until runtime. Also, the static linker often allocates uninitialized data at the end of the __DATA segment; in this case, the vmsize is larger than the filesize. The loader guarantees that any memory of this sort is initialized with zeros.

uint64_t filesize;