Man pages for O_CLOFORK implementation

These are Ricardo Branco's man page updates for affected functions
using O_CLOFORK (and associated variants) for NetBSD (with
a few minor changes and additions by me).

branches: 1.66.2;
Document the error code when O_REGULAR is specified and the last
path component is not a regular file.

branches: 1.65.6;
Remove superfluous article.

Clarify use of open flags in open(2).

(Avoid using values of three that are equal to four.)

Note that open(O_ASYNC) does not work as advertised.

This matches Linux, which also advertises the same semantics and
fails to implement it, according to:

https://man7.org/linux/man-pages/man2/fcntl.2.html

(At what point should we collectively stop advertising the semantics
that doesn't work and call the bug a feature?)

Sort errors.

Document O_EXEC, and add some extra explanation for O_CREAT from FreeBSD.

Open was present in v1
https://www.bell-labs.com/usr/dmr/www/man22.pdf

branches: 1.59.4; 1.59.6;
Remove Tn.

Add O_REGULAR to enforce opening of only regular files
(like we have O_DIRECTORY for directories).
This is better than open(, O_NONBLOCK), fstat()+S_ISREG() because opening
devices can have side effects.

branches: 1.57.2;
file system police.

branches: 1.56.16;
Add openat(2) specific errors.

Revert defective O_SEARCH implementation committed by manu@ along with
the *at system calls on November 18th of last year. Reasons to revert
it include:
- it is incorrect in a whole variety of ways (but fortunately, one
of them is that the missing and improper permission checks have
no net effect);
- it was committed without review or discussion;
- core ruled that all the new O_* flags pertaining to the *at calls
needed to wait until their semantics could be clarified.

manu was asked to revert it on these grounds but has ignored the request.

I have left O_SEARCH defined and visible and made open() explicitly
ignore it. This way, most code that tries to use it will continue to
build and run. I've also arranged lib/libc/c063/t_o_search.c so that
the tests that make use of the O_SEARCH semantics will disappear until
O_SEARCH comes back, and fixed some mistakes and/or incorrect hacks
that were causing some of these to succeed despite the broken O_SEARCH
implementation.

Bump date. New sentence, new line. Wording/articles.
Sort errors while here.

Remove trailing whitespace.

Add most system calls for POSIX extended API set, part 2, with test cases:
faccessat(2), fchmodat(2), fchownat(2), fstatat(2), mkdirat(2), mkfifoat(2),
mknodat(2), linkat(2), readlinkat(2), symlinkat(2), renameat(2), unlinkat(2),
utimensat(2), openat(2).

Also implement O_SEARCH for openat(2)

Still missing:
- some flags for openat(2)
- fexecve(2) implementation

branches: 1.51.6;
As discussed in tech-kern, provide the means to prevent delivery of SIGPIPE
on EPIPE for all file descriptor types:

- provide O_NOSIGPIPE for open,kqueue1,pipe2,dup3,fcntl(F_{G,S}ETFL) [NetBSD]
- provide SOCK_NOSIGPIPE for socket,socketpair [NetBSD]
- provide SO_NOSIGPIPE for {g,s}seckopt [NetBSD/FreeBSD/MacOSX]
- provide F_{G,S}ETNOSIGPIPE for fcntl [MacOSX]

branches: 1.50.4;
sync with reality (prototype of open is varyadic)

exec is on a higher plane of existence.

Document O_CLOEXEC.

Bump date for O_DIRECTORY, more markup, merge two error sections.

implement O_DIRECTORY as standardized in POSIX-2008,
for both native and linux emulations.
this fixes the rest of PR 43695.

O_NOFOLLOW is not a non-standard extension any longer (2, 6 years? who counts).

Note a difference to IEEE Std 2003.1-2008. Bump date.

Explain how O_NOFOLLOW may cause EFTYPE. From joerg.
While here, sort errors. Bump date.

Consistently use `.Brq Dv XXX' across syscalls man pages, for NAME_MAX
and PATH_MAX.

Sort ERRORS section.

Mention the history of stat(2) and fix the history of open(2).

Bump date for previous.

open(2) can fail with EPERM.

Bump date for previous.
New sentence, new line.

add support for O_DIRECT (I/O directly to application memory,
bypassing any kernel caching for file data).

Add article. Remove superfluous braces.

lib/26532: Manual page for open(2) bit difficult to understand:
apply patch with small improvement - s/conditions/methods/

document the flags O_ALT_IO and O_NOCTTY

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22280, verified by myself.

O_NOFOLLOW is another non-standard extension

Use
.In header.h
instead of
.Fd #include \*[Lt]header.h\*[Gt]
Much easier to read and write, and supported by groff for ages.
Okayed by ross.

Use "its" instead of "it's" where appropriate.
From Soren Jacobsen in PR 20730.

Merge the nathanw_sa branch.

Provide O_NOFOLLOW with compatibility with the joneses.

-1 -> \-1.

- move return values info into RETURN VALUES section.
- note that O_SHLOCK and O_EXLOCK are not portable.
from OpenBSD.

Remove the cross reference of fileno(3). It is more appropriate to
cross reference this from fopen(3). After discussion with John Heasley
in PR/17224.

Add Xr to fileno(3), as request in lib/17224.

Generate <>& symbolically. I'm avoiding .../dist/... directories for now.

Sort sections, sort SEE ALSO, punctuation and miscellanous fixes.

Boring whitespace fixes.

branches: 1.19.4;
Merge duplicate mentions of EPERM, EACCESS, ... into one entry
(where applicable).

branches: 1.18.2;
Add a LIBRARY section to system call manual pages. While it's clear that the
libraries contain stubs only (with minor exceptions a la pipe(2)), the purpose
of this section is to provide linkage information.

Add ENXIO error for FIFOs.

branches: 1.16.4;
Last of the .Os cleanups. .Os is defined in the tmac.doc-common file,
so we shouldn't override it with versions in the manpages. Wheee!

first pass at fixing up capitalization of function names and
arguments; ensure that each is correct with respect to the
implementation, rather than being correct as per english.

Per IEEE Std 1003.1b-1993, Synchronous I/O Option, add O_DSYNC (synchronized
I/O data integrity completion) and O_RSYNC (complete read operations at the
same level of integrity requested for write operations).

fix mdoc references

Document the O_SYNC flag, and where its semantics are defined (XPG4.2).
Be more clear about how file access modes are specified, and do a bit
of general cleanup.

Nuke trailing comma in SEE ALSO section.

branches: 1.10.2;
xref getdtablesize(3) not getdtablesize(2)

Add/update 1003.1 conformance notice.

merge with lite, keeping most local changes. clean up Ids

Use symbolic names {NAME_MAX} & {PATH_MAX} instead of 255 and 1023 in
description of ENAMETOOLONG error.

bleh

Tell user to #include <fcntl.h>, not <sys/fcntl.h> or <sys/file.h>.

Manpage formatting tweaks.

Clean up manpages:
Use .Fn rather than .Nm macro in HISTORY and STANDARDS sections.
Use .At and .St macros instead of spelling out "Version 6 UNIX",
"IEEE 1003.1-1988 (POSIX)", etc.

Add RCS indentifiers.

branches: 1.1.1;
Initial revision