Re: [Libguestfs] [PATCH nbdkit 2/4] server: Add nbdkit_shutdown() call.

On 3/4/20 9:17 AM, Richard W.M. Jones wrote: >+ return INT64_C (1024*1024); This looks fishy. POSIX says that: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stdint.h.html#t... "The argument in any instance of these macros shall be an unsuffixed integer constant with a value that does not exceed the limits for the corresponding type. ...For example, if uint_least64_t is a name for the type unsigned long long, then UINT64_C(0x123) might expand to the integer constant 0x123ULL." In fact, in glibc's /usr/include/stdint.h, we have: # if __WORDSIZE == 64 # define INT64_C(c) c ## L # else # define INT64_C(c) c ## LL # endif Your code works by sheer luck (expanding to the three tokens '1024', '*', '1024L'), which in turn results in an expression with 64-bit type, but in general, INT64_C should ONLY be used on a single literal value, not an arbitrary expression. But you really don't need to use INT64_C; we can just rely on C's automatic type promotion to turn our 'int' expression 1024*1024 into the proper int64_t return value.