Porting to OS/2: Case #20 CMSG_ALIGN, CMSG_SPACE and CMSG_LEN macros
OS/2 kLIBC has been missing some control message such as CMSG_ALIGN , CMSG_SPACE and CMSG_LEN macros until 0.6.6. They should be like this, Colored By Color Scripter ™ 1 2 3 4 #define CMSG_ALIGN( len ) _ALIGN( len ) #define CMSG_SPACE( len ) ( CMSG_ALIGN( sizeof ( struct cmsghdr )) + \ CMSG_ALIGN( len )) #define CMSG_LEN( len ) ( CMSG_ALIGN( sizeof ( struct cmsghdr )) + ( len )) Here, struct msghdr is in sys/socket.h . See the following link for a detail. https://github.com/komh/os2compat/blob/master/network/cmsg.h