MFC r359680: mail/gprof/tip: tap with the ugly stick

The ugly stick here is this bit in the respective headers:

#ifndef EXTERN
#define EXTERN extern
#endif

with a follow-up #define EXTERN in a single .c file to push all of their
definitions into one spot. A pass should be made over these three later to
push these definitions into the correct files instead, but this will suffice
for now and at a more leisurely pace.

MFC r357269:

Merge r357267 from the clang1000-import branch:

Fix the following -Werror warning from clang 10.0.0 in tip:

usr.bin/tip/tip/tip.c:428:4: error: misleading indentation; statement is not part of the previous 'if' [-Werror,-Wmisleading-indentation]
if (gch == EOF)
^
usr.bin/tip/tip/tip.c:426:5: note: previous statement is here
} else if (!cumode && gch == character(value(FORCE)))
^

The intent was to have the EOF check grouped with the getchar() call
just above it. This was accidentally introduced in r354624.

MFC r354624

tip/cu: check for EOF on input on the local side

If cu reads an EOF on the input side, it goes into a tight loop
sending a garbage byte to the remote. With this change, it exits
gracefully, along with its child.

Sponsored by: Dell EMC Isilon

Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Make tip exit if the device disappears, for instance when unplugging
or resetting USB serial devices.

Somebody[tm] should rewrite tip(1) to use two thread instead of two
processes or maybe even use that new-fangled "select(2)" or positively
futuristic "poll(2)" system call.

Relinquish exclusive TTY access when tip(1) or cu(1) exit.
Previously they would have left TIOCEXCL enabled, requiring
either a reboot or use of tip/cu as the root user.

Observed when running QEMU with character devices redirected to pty instances.

MFC after: 2 weeks

Fix compilation warnings (up to level 3).

Resolve merge conflicts.

make prototpyes match functions, and declare things static as needed

Fix merge conflicts, and because this still has a zillion warnings,
protect the build with a WARNS=2.

Fix the build.

If the user exists abruptly, tip's "tipout" child can hang around
forever. Since the lock file doesn't get cleaned up, this prevents
other users from accessing the target device.

(phk adds: Man, this has been bugging me for YEARS!)

PR: 12528
Submitted by: Craig Leres leres@ee.lbl.gov
MFC after: 1 week

#include <errno.h> where needed. Kill extern int errno;.

Minor warnings in tip corrected.

Fix warning: return type of `main' is not `int'

$Id$ -> $FreeBSD$

Rename a function to avoid conflict with the new syscall 'pwrite'.

sizeof(foo - 1) isn't the same as sizeof(foo) - 1.

Pointed out by: Theo De Raadt.

o Use snprintf rather than sprintf.
o Revert gid to caller before a shell so we can run setgid.
o minor style nits to make bruce happy :-)
o use strncpy correctly.

Many places in the code NULL is used in integer context, where
plain 0 should be used. This happens to work because we #define
NULL to 0, but is stylistically wrong and can cause problems
for people trying to port bits of code to other environments.

PR: 2752
Submitted by: Arne Henrik Juul <arnej@imf.unit.no>

Removed a buffer overflow in args().

While I'm here, fix a bug with 'register' in conjunction with setjmp(),
staticize and do some -Wall cleaning.

Change from using sys/param.h and MAXPATHLEN to using limits.h and PATH_MAX
to avoid the NOFILE problem. Back out NOFILE kludge. Fix unexploitable
buffer overflow in tipout.c.
Reviewed by: millert@openbsd.org (tipout.c)
Submitted by: millert@openbsd.org (rest of idea)

Fix buffer overflow. prompt didn't get a size for its buffer,
so it could overflow it. Also made some filenames MAXPATHLEN long rather
than 80 long.

Add prototypes, usage(). Use err(3).

Make tip recognize EOF in more cases.

Tom Gray's new tip changes to support a modem capabilities database and
fixes to many assorted bugs and misfeatures.
Submitted by: Tom Gray - DCA <dcasba@rain.org>