size_t 定义

size_t 在/usr/include/linux/types.h    typedef _kernel_size_t size_t;

 32位机器： /usr/include/asm/posix_types.h  

           typedef unsigned int    __kernel_size_t;    4字节

 64位机器：/usr/include/asm-x86_64/posix_types.h  

          typedef unsigned long   __kernel_size_t;   8字节