recv.2 (2010 09)

recv(2) recv(2)

[ENOSR] Buffers could not be allocated for the message that was to be created due to

insufﬁcient STREAMS memory resources.

[ENOTCONN] Receive on a SOCK_STREAM socket that is not yet connected.

[ENOTSOCK] The argument s is a valid ﬁle descriptor, but it is not a socket.

[EOPNOTSUPP] The

MSG_OOB ﬂag was set for a UDP SOCK_DGRAM message-based socket,

MSG_OOB or MSG_PEEK was set for any AF_UNIX socket. The

MSG_OOB

ﬂag is supported only for stream-based TCP SOCK_STREAM sockets. Neither

MSG_PEEK nor MSG_OOB is supported for AF_UNIX sockets.

AF_CCITT only:

recv() was issued on a listen()

socket.

[ETIMEDOUT] The connection timed out during connection establishment, or due to a

transmission timeout on active connection.

[EWOULDBLOCK] Non-blocking I/O is enabled using

ioctl() FIOSNBIO request, and the

requested operation would block.

OBSOLESCENCE

Currently, the

socklen_t and size_t types are the same size. This is compatible with the UNIX 95

and UNIX 03 proﬁles. However, in a future release,

socklen_t might be a different size. In that case,

passing a

size_t pointer will evoke compile-time warnings, which must be corrected in order for the

application to behave correctly. Also, the size of the msghdr and cmsghdr structures and the relative

position of their members will be different, which might affect application behavior. Applications that use

socklen_t now, where appropriate, will avoid such migration problems. On the other hand, applica-

tions that need to be portable to the UNIX 95 proﬁle should follow the X/Open speciﬁcation (see

xopen_networking(7)).

WARNINGS

Linking binary objects compiled to X/Open Sockets speciﬁcation and binary objects compiled to HP-UX

BSD Sockets speciﬁcation to the same executable may result in unexpected behavior, including applica-

tion abnormal termination and unexpected socket errors. See xopen_networking(7) for details and

remedy.

FUTURE DIRECTION

Currently, the default behavior is the HP-UX BSD Sockets; however, it might be changed to X/Open

Sockets in a future release. At that time, any HP-UX BSD Sockets behavior that is incompatible with

X/Open Sockets might be obsoleted. Applications that conform to the X/Open speciﬁcation now will

avoid migration problems (see xopen_networking(7)).

AUTHOR

recv(), recvmsg(), and recvfrom() were developed by HP and the University of California,

Berkeley.