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

     1  #include <sys/socket.h>
     2  #include <limits.h>
     3  #include <time.h>
     4  #include <sys/time.h>
     5  #include <string.h>
     6  #include "syscall.h"
     7  
     8  hidden void __convert_scm_timestamps(struct msghdr *, socklen_t);
     9  
    10  void __convert_scm_timestamps(struct msghdr *msg, socklen_t csize)
    11  {
    12  	if (SCM_TIMESTAMP == SCM_TIMESTAMP_OLD) return;
    13  	if (!msg->msg_control || !msg->msg_controllen) return;
    14  
    15  	struct cmsghdr *cmsg, *last=0;
    16  	long tmp;
    17  	long long tvts[2];
    18  	int type = 0;
    19  
    20  	for (cmsg=CMSG_FIRSTHDR(msg); cmsg; cmsg=CMSG_NXTHDR(msg, cmsg)) {
    21  		if (cmsg->cmsg_level==SOL_SOCKET) switch (cmsg->cmsg_type) {
    22  		case SCM_TIMESTAMP_OLD:
    23  			if (type) break;
    24  			type = SCM_TIMESTAMP;
    25  			goto common;
    26  		case SCM_TIMESTAMPNS_OLD:
    27  			type = SCM_TIMESTAMPNS;
    28  		common:
    29  			memcpy(&tmp, CMSG_DATA(cmsg), sizeof tmp);
    30  			tvts[0] = tmp;
    31  			memcpy(&tmp, CMSG_DATA(cmsg) + sizeof tmp, sizeof tmp);
    32  			tvts[1] = tmp;
    33  			break;
    34  		}
    35  		last = cmsg;
    36  	}
    37  	if (!last || !type) return;
    38  	if (CMSG_SPACE(sizeof tvts) > csize-msg->msg_controllen) {
    39  		msg->msg_flags |= MSG_CTRUNC;
    40  		return;
    41  	}
    42  	msg->msg_controllen += CMSG_SPACE(sizeof tvts);
    43  	cmsg = CMSG_NXTHDR(msg, last);
    44  	cmsg->cmsg_level = SOL_SOCKET;
    45  	cmsg->cmsg_type = type;
    46  	cmsg->cmsg_len = CMSG_LEN(sizeof tvts);
    47  	memcpy(CMSG_DATA(cmsg), &tvts, sizeof tvts);
    48  }
    49  
    50  ssize_t recvmsg(int fd, struct msghdr *msg, int flags)
    51  {
    52  	ssize_t r;
    53  	socklen_t orig_controllen = msg->msg_controllen;
    54  #if LONG_MAX > INT_MAX
    55  	struct msghdr h, *orig = msg;
    56  	if (msg) {
    57  		h = *msg;
    58  		h.__pad1 = h.__pad2 = 0;
    59  		msg = &h;
    60  	}
    61  #endif
    62  	r = socketcall_cp(recvmsg, fd, msg, flags, 0, 0, 0);
    63  	if (r >= 0) __convert_scm_timestamps(msg, orig_controllen);
    64  #if LONG_MAX > INT_MAX
    65  	if (orig) *orig = h;
    66  #endif
    67  	return r;
    68  }