1 #define _GNU_SOURCE
2 #include <sys/socket.h>
3 #include <limits.h>
4 #include <errno.h>
5 #include "syscall.h"
6 7 int 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 }
25 error:
26 return i ? i : -1;
27 #else
28 return syscall_cp(SYS_sendmmsg, fd, msgvec, vlen, flags);
29 #endif
30 }
31