github.com/afumu/libc@v0.0.6/musl/src/network/recvmmsg.c (about)

     1  #define _GNU_SOURCE
     2  #include <sys/socket.h>
     3  #include <limits.h>
     4  #include <errno.h>
     5  #include <time.h>
     6  #include "syscall.h"
     7  
     8  #define IS32BIT(x) !((x)+0x80000000ULL>>32)
     9  #define CLAMP(x) (int)(IS32BIT(x) ? (x) : 0x7fffffffU+((0ULL+(x))>>63))
    10  
    11  hidden void __convert_scm_timestamps(struct msghdr *, socklen_t);
    12  
    13  int recvmmsg(int fd, struct mmsghdr *msgvec, unsigned int vlen, unsigned int flags, struct timespec *timeout)
    14  {
    15  #if LONG_MAX > INT_MAX
    16  	struct mmsghdr *mh = msgvec;
    17  	unsigned int i;
    18  	for (i = vlen; i; i--, mh++)
    19  		mh->msg_hdr.__pad1 = mh->msg_hdr.__pad2 = 0;
    20  #endif
    21  #ifdef SYS_recvmmsg_time64
    22  	time_t s = timeout ? timeout->tv_sec : 0;
    23  	long ns = timeout ? timeout->tv_nsec : 0;
    24  	int r = __syscall_cp(SYS_recvmmsg_time64, fd, msgvec, vlen, flags,
    25  			timeout ? ((long long[]){s, ns}) : 0);
    26  	if (SYS_recvmmsg == SYS_recvmmsg_time64 || r!=-ENOSYS)
    27  		return __syscall_ret(r);
    28  	if (vlen > IOV_MAX) vlen = IOV_MAX;
    29  	socklen_t csize[vlen];
    30  	for (int i=0; i<vlen; i++) csize[i] = msgvec[i].msg_hdr.msg_controllen;
    31  	r = __syscall_cp(SYS_recvmmsg, fd, msgvec, vlen, flags,
    32  		timeout ? ((long[]){CLAMP(s), ns}) : 0);
    33  	for (int i=0; i<r; i++)
    34  		__convert_scm_timestamps(&msgvec[i].msg_hdr, csize[i]);
    35  	return __syscall_ret(r);
    36  #else
    37  	return syscall_cp(SYS_recvmmsg, fd, msgvec, vlen, flags, timeout);
    38  #endif
    39  }