Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

MFC r259054:
Performance and debugging enhancements:
+ Remove UNAME_P=$(...) from startup/misc -- already supplied by common.subr
+ Use f_getvar instead of $(eval echo \$$var) -- f_getvar is sub-shell free
+ Add `-e' and `-k var' options to f_eval_catch -- increasing use-cases
+ Use f_eval_catch to display errors on failure -- reducing duplicated code
+ Use f_eval_catch when we need output from a command -- improving debugging
+ Optimize f_isinter of strings.subr for performance -- now sub-shell free
+ Improve error checking on pidfiles -- using f_eval_catch and f_isinteger
+ Use $var_to_set arg of f_ifconfig_{inet,netmask} -- eliminate sub-shells
+ Use f_sprintf instead of $(printf ...) -- consolidate sub-shells
+ Use $var_to_set arg of f_route_get_default -- eliminate sub-shells
+ Add f_count to replace $(set -- ...;echo $#) -- eliminate sub-shells
+ Add f_count_ifs to replace $(IFS=x;set -- ...;echo $#) -- no sub-shells
+ Replace var="$var${var:+ }..." in loops with var="$var ..." with a follow-
up var="${var# }" to trim leading whitespace -- optimize loops
+ Use $var_to_set arg of f_resolv_conf_nameservers -- eliminate sub-shells
+ Comments for the f_eval_catch function
+ Remove a duplicate `local ... desc ...' in f_device_get_all of device.subr
+ Use $var_to_set arg of f_device_capacity -- eliminate sub-shells
+ Whitespace fixes in f_dialog_init of dialog.subr
+ Optimize f_inet_atoi of media/tcpip.subr for performance -- sub-shell free
+ In several cases, send stderr to /dev/null -- clean up runtime execution
+ Change f_err of common.subr to go to program stderr not terminal stderr,
allowing redirection of output from functions that use f_err
+ Disable debugging when using f_getvar to get variable argument to
f_startup_rcconf_map_expand of startup/rcconf.subr
+ Use f_replace_all instead of $(echo ... | tr | sed) -- performance
+ Add a $var_to_set option to f_index_{file,menusel_{command,keyword}} of
common.subr -- centralize sub-shells

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Introduce centralized [X]dialog(1) exit codes to `dialog.subr' and make-use
throughout the bsdconfig(8) code. While we're here, add an explicit argument
to lvalue-seeking invocations of "return" that previously had no argument.
Also, consolidate a single instance of double-newline and remove some
comments that are no longer required (given increased readability with new
exit codes).

Approved by: re (glebius)

Fix typos in the BSD License.

Be consistent with other usr.sbin programs w/respect to the copyright
wording ("All rights reserved."); I had the casing wrong on many instances.

Don't prevent the user from hanging their system by changing network
settings while NFS mounts are active; but DO warn them and make the
default action to do nothing. (thanks julian)

More whitespace.

Alphabetize library includes.

Use a case-statement instead of multiple (separate even) if-statements.

Improvements to whitespace and comments.

Similar to r251236, improve the portion of dialog(1) API in dialog.subr
responsible for retrieving stored input (for the --inputbox and --password
widgets).

When we (Ron McDowell and I) developed the first version of bsdconfig, it
used temporary files to store responses from dialog(1). That hasn't been
true for a very long time, so the need to always execute some clean-up
function is long-deprecated. The function that used to perform these clean-
up routines for these widgets was f_dialog_inputstr().

We really don't need f_dialog_inputstr() for its originally designed purpose
as all dialog invocations no longer require temporary files.

Just as in r251236, redesign f_dialog_inputstr() in the following four ways:

1. Rename f_dialog_inputstr() to f_dialog_inputstr_fetch()
2. Introduce the new first-argument of $var_to_set to reduce forking
3. Create a corresponding f_dialog_inputstr_store() to abstract storage
4. Offload the sanitization to a new function, f_dialog_line_sanitize()

It should be noted that f_dialog_line_sanitize() -- unlike its cousin from
SVN r251236, f_dialog_data_sanitize() -- trims leading/trailing whitespace
from the user's input. This helps prevent errors and common mistakes caused
by the fact that the new cdialog implementation allows the right-arrow
cursor key to go beyond the last byte of realtime input (adding whitespace
at the end of the typed value).

While we're centralizing the sanitization, let's rewrite f_dialog_input()
while we're here to likewise reduce forking. The f_dialog_input() function
now expects the first argument of $var_to_set instead of producing results
on standard-out.

These changes greatly improve readability and also improve performance.

Improve portion of the dialog(1) API in dialog.subr responsible for
retrieving stored data (for the --menu, --calendar, --timebox, --checklist,
and --radiolist widgets).

When we (Ron McDowell and I) developed the first version of bsdconfig, it
used temporary files to store responses from dialog(1). That hasn't been
true for some very long time, so the need to always store the return status
of dialog(1) and then call some function to clean-up is long-deprecated. The
function that used to do the clean-up was f_dialog_menutag().

We really don't need f_dialog_menutag() for its originally designed purpose,
as all dialog invocations (even when in a sub-shell) do not use temporary
files anymore.

However, we do need to keep f_dialog_menutag() around because it still fills
the need of being able to abstract the procedure for fetching stored data
provided by functions that display the aforementioned widgets.

In re-designing f_dialog_menutag(), four important changes are made:

1. Rename f_dialog_menutag() to f_dialog_menutag_fetch()
2. Introduce the new first-argument of $var_to_set to reduce number of forks
3. Create a corresponding f_dialog_menutag_store() to abstract the storage
4. Offload the sanitization to a new function, f_dialog_data_sanitize()

NOTE: That last one is important. Not all functions need to store their data
for later fetching, meanwhile every invocation of dialog should be sanitized
(as we learned early-on in the i18n-effort -- underlying libraries will spit
warnings to stderr for bad values of $LANG and since dialog outputs its
responses to stderr, we need to sanitize every response of these warnings).

These changes greatly improve readbaility and also improve performance by
reducing unnecessary forking.

UI improvements. First, implement --default-item whenever and wherever
possible to save keystrokes. Second, overhaul startup/rcdelete for much
improved performance. Last, but not least, kill-off useage of --clear
and implement --keep-tite in harmony to minimize jarring transitions.
Also, fix local variable names where necessary while we're here with
other minor comment-enhancements/typo-corrections.

Add more debugging to help with diagnosis of program-flow when needed.

Use f_show_help() where printf(1) syntax is desired.

Reverse SVN r240770 -- jilles@ made a suggestion that allowed us to redesign
our embedded rescue environment to support /dev/null making r240770 obsolete.

Reviewed by: jilles, adrian (co-mentor)
Approved by: jilles, adrian (co-mentor)

Replace redirections to /dev/null with "close file-descriptor" syntax (>&-).

Reviewed by: adrian (co-mentor)
Approved by: adrian (co-mentor)

Change all invocations of dialog(1) to no-longer require temporary files.
This allows bsdconfig to -- like bsdinstall -- operate from read-only media.

Reviewed by: adrian (co-mentor)
Approved by: adrian (co-mentor)

Move major includes into /usr/share/bsdconfig for easy external access.

Reviewed by: adrian (co-mentor)
Approved by: adrian (co-mentor)

Correct double "the the"

Approved by: cperciva
MFC after: 3 days

Import bsdconfig(8) as a replacement for the post-install abilities of
deprecated sysinstall(8). NOTE: WITH_BSDCONFIG is currently required.

Submitted by: Devin Teske (dteske), Ron McDowell <rcm@fuzzwad.org>
Reviewed by: Ron McDowell <rcm@fuzzwad.org>
Approved by: Ed Maste (emaste)