1#define _GNU_SOURCE 2#include <sys/socket.h> 3#include <limits.h> 4#include <errno.h> 5#include "syscall.h" 6 7int sendmmsg(int fd, struct mmsghdr *msgvec, unsigned int vlen, unsigned int flags) 8{ 9#if LONG_MAX > INT_MAX 10 /* Can't use the syscall directly because the kernel has the wrong 11 * idea for the types of msg_iovlen, msg_controllen, and cmsg_len, 12 * and the cmsg blocks cannot be modified in-place. */ 13 int i; 14 if (vlen > IOV_MAX) vlen = IOV_MAX; /* This matches the kernel. */ 15 if (!vlen) return 0; 16 for (i=0; i<vlen; i++) { 17 /* As an unfortunate inconsistency, the sendmmsg API uses 18 * unsigned int for the resulting msg_len, despite sendmsg 19 * returning ssize_t. However Linux limits the total bytes 20 * sent by sendmsg to INT_MAX, so the assignment is safe. */ 21 ssize_t r = sendmsg(fd, &msgvec[i].msg_hdr, flags); 22 if (r < 0) goto error; 23 msgvec[i].msg_len = r; 24 } 25error: 26 return i ? i : -1; 27#else 28 return syscall_cp(SYS_sendmmsg, fd, msgvec, vlen, flags); 29#endif 30} 31