1272 SYSCALL_DEFINE3(socket, int, family, int, type, int, protocol)
1273 {
1274     int retval;
1275     struct socket *sock;
1276     int flags;
1277
1278     /* Check the SOCK_* constants for consistency. */
1279     BUILD_BUG_ON(SOCK_CLOEXEC != O_CLOEXEC);
1280     BUILD_BUG_ON((SOCK_MAX | SOCK_TYPE_MASK) != SOCK_TYPE_MASK);
1281     BUILD_BUG_ON(SOCK_CLOEXEC & SOCK_TYPE_MASK);
1282     BUILD_BUG_ON(SOCK_NONBLOCK & SOCK_TYPE_MASK);
1283
1284     flags = type & ~SOCK_TYPE_MASK;
1285     if (flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
1286         return -EINVAL;
1287     type &= SOCK_TYPE_MASK;
1288
1289     if (SOCK_NONBLOCK != O_NONBLOCK && (flags & SOCK_NONBLOCK))
1290         flags = (flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
1291
1292     retval = sock_create(family, type, protocol, &sock);
1293     if (retval 0)
1294         goto out;
1295
1296     retval = sock_map_fd(sock, flags & (O_CLOEXEC | O_NONBLOCK));
1297     if (retval 0)
1298         goto out_release;
1299
1300 out:
1301     /* It may be already another descriptor 8) Not kernel problem. */
1302     return retval;
1303
1304 out_release:
1305     sock_release(sock);
1306     return retval;
1307 }


enum sock_type {
    SOCK_STREAM    = 1,
    SOCK_DGRAM    = 2,
    SOCK_RAW    = 3,
    SOCK_RDM    = 4,
    SOCK_SEQPACKET    = 5,
    SOCK_DCCP    = 6,
    SOCK_PACKET    = 10,
};

#define SOCK_CLOEXEC    O_CLOEXEC
#ifndef SOCK_NONBLOCK
#define SOCK_NONBLOCK    O_NONBLOCK
#endif