From ec79563b8fb11d33fcd4917ec58cc515a50370c1 Mon Sep 17 00:00:00 2001
From: Martijn Dekker <martijn@inlv.org>
Date: Sun, 7 Feb 2021 05:37:22 +0000
Subject: [PATCH] libast: optget(): fix emphasis state initialisation

This fixes a bug in libast optget()'s use of emphasis in the
display of --man(uals) via standard error on a terminal.

Symptom:

$ printf --man 2>&1 | more
(ok; emphasis disabled, no escape codes shown)
$ printf --man
(ok; emphasis correctly displayed)
$ printf --man 2>&1 | more
(whoops; emphasis not disabled; escape codes garble 'more' output)

The problem was that the state.emphasis variable was not
initialised and, when set to one, was never reset again
(except through the use of the --api, --html or --nroff option).

The source code also reveals an undocumented feature: if the
environment variable $ERROR_OPTIONS contains 'noemphasi', emphasis
is forced off, else if it contains 'emphasi', it's forced on.
Other characters (such as the final 's' of emphasis) are ignored.
This was also broken (forcing off didn't work) and is now fixed.

src/lib/libast/misc/optget.c:
- Do not assume that enabling emphasis is forever; re-initialise
  the state on every relevant getopts invocation.
- Increase the number of terminals on which emphasis is displayed
  using ANSI escape codes. (This is a hack and we should ask the OS
  for the correct codes, but never mind -- ANSI is now universal.)
---
 src/lib/libast/misc/optget.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/src/lib/libast/misc/optget.c b/src/lib/libast/misc/optget.c
index 6b249737f..ae49831d3 100644
--- a/src/lib/libast/misc/optget.c
+++ b/src/lib/libast/misc/optget.c
@@ -2535,21 +2535,19 @@ opthelp(const char* oopts, const char* what)
 		sfputc(mp, '\f');
 		break;
 	default:
-		if (!state.emphasis)
+		state.emphasis = 0;
+		if (x = getenv("ERROR_OPTIONS"))
 		{
-			if (x = getenv("ERROR_OPTIONS"))
+			if (strmatch(x, "*noemphasi*"))
+				break;
+			if (strmatch(x, "*emphasi*"))
 			{
-				if (strmatch(x, "*noemphasi*"))
-					break;
-				if (strmatch(x, "*emphasi*"))
-				{
-					state.emphasis = 1;
-					break;
-				}
-			}
-			if ((x = getenv("TERM")) && strmatch(x, "(ansi|vt100|xterm)*") && isatty(sffileno(sfstderr)))
 				state.emphasis = 1;
+				break;
+			}
 		}
+		if ((x = getenv("TERM")) && strmatch(x, "(ansi|vt???|xterm|linux|cons|wsvt|sun)*") && isatty(sffileno(sfstderr)))
+			state.emphasis = 1;
 		break;
 	}
 	x = "";