Implement Linux-variant of MSG_TRUNC input flag used in recv(), recvfrom() and recvmsg().
Posix defines MSG_TRUNC as an output flag, indicating packet/datagram truncation.
Linux extended it a while (~15+ years) ago to act as input flag,
resulting in returning the full packet size regarless of the input
buffer size.
It's a (relatively) popular pattern to do recvmsg( MSG_PEEK | MSG_TRUNC) to get the
packet size, allocate the buffer and issue another call to fetch the packet.
In particular, it's popular in userland netlink code, which is the primary driving factor of this change.
This commit implements the MSG_TRUNC support for SOCK_DGRAM sockets (udp, unix and all soreceive_generic() users).
PR: kern/176322
Reviewed by: pauamma(doc)
Differential Revision: https://reviews.freebsd.org/D35909
MFC after: 1 month
Instead of returning EMSGSIZE pass the error code from fdallocn() directly
to userland. That would be EMFILE, which makes much more sense. This
error code is not listed in the specification[1], but the specification
doesn't cover such edge case at all. Meanwhile the specification lists
EMSGSIZE as the error code for invalid value of msg_iovlen, and FreeBSD
follows that, see sys_recmsg(). Differentiating these two cases will make
a developer/admin life much easier when debugging.
[1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/recvmsg.html
Reviewed by: markj
Differential revision: https://reviews.freebsd.org/D35640
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.
Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96
Document AF_UNIX control messages in unix(4) only, not split between unix(4)
and recv(2).
Also, warn about LOCAL_CREDS effective uid/gid fields, since the write could
be from a setuid or setgid program (with the explicit SCM_CREDS and
LOCAL_PEERCRED, the credentials are read at such a time that it can be
assumed that the process intends for them to be used in this context).
Reviewed by: wblock
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D9298
wraps sendmsg(2) and recvmsg(2) into batch send and receive operation.
The goal of this implementation is only to provide API compatibility
with Linux.
The cancellation behaviour of the functions is not quite right, but
due to relative rare use of cancellation it is considered acceptable
comparing with the complexity of the correct implementation. If
functions are reimplemented as syscalls, the fix would come almost
trivial. The direct use of the syscall trampolines instead of libc
wrappers for sendmsg(2) and recvmsg(2) is to avoid data loss on
cancellation.
Submitted by: Boris Astardzhiev <boris.astardzhiev@gmail.com>
Discussed with: jilles (cancellation behaviour)
MFC after: 1 month
This change allows creating file descriptors with close-on-exec set in some
situations. SOCK_CLOEXEC and SOCK_NONBLOCK can be OR'ed in socket() and
socketpair()'s type parameter, and MSG_CMSG_CLOEXEC to recvmsg() makes file
descriptors (SCM_RIGHTS) atomically close-on-exec.
The numerical values for SOCK_CLOEXEC and SOCK_NONBLOCK are as in NetBSD.
MSG_CMSG_CLOEXEC is the first free bit for MSG_*.
The SOCK_* flags are not passed to MAC because this may cause incorrect
failures and can be done later via fcntl() anyway. On the other hand, audit
is expected to cope with the new flags.
For MSG_CMSG_CLOEXEC, unp_externalize() is extended to take a flags
argument.
Reviewed by: kib
a "null pointer".''
Making good use of the excellent explanations sent to me by Ruslan
Ermilov, Garrett Wollman and Bruce Evans, correct the descriptions of
null pointers. They are just "null pointers", not nil, not NULL or
".Dv NULL".
Suggested by: ru, wollman, bde
Reviewed by: ru, wollman
Pointy hat: keramida
Stop calling system calls "function calls".
Use "The .Fn system call" a-la "The .Nm utility".
When referring to a non-BSD implementation in
the HISTORY section, call syscall a function,
to be safe.
with NetBSD and the Single Unix Specification v2.
This updates some structures with other, almost equivalent types and
effort is under way to get the whole more consistent.
Also removes a double definition of INET6 and some other clean-ups.
Reviewed by: green, bde, phk
Some part obtained from: NetBSD, SUSv2 specification
track.
The $Id$ line is normally at the bottom of the main comment block in the
man page, separated from the rest of the manpage by an empty comment,
like so;
.\" $Id$
.\"
If the immediately preceding comment is a @(#) format ID marker than the
the $Id$ will line up underneath it with no intervening blank lines.
Otherwise, an additional blank line is inserted.
Approved by: bde
