From d606b2a8fff94afa21bae57bd0045b409136b72d Mon Sep 17 00:00:00 2001
From: PatR <rankin@nethack.org>
Date: Tue, 20 Dec 2016 12:43:35 -0800
Subject: [PATCH] tty's compress_str(), core's dat/keyhelp

Rewrite 3.6.1's compress_str() to avoid peeking past the end of the
input string.  This should eliminate the reported valgrind complaint.
The problem was noticed for post-3.6.0 code introduced [by me...] last
June, but it looks like it was present in the old code too.

Also, fix the wording in the paragraph about NUL in the keyhelp text.

tty_putstr() always passes non-message window text through compress_str(),
clobbering usage of two spaces to separate sentences.  putstr()'s caller
ought to have more control over that (possibly via its hardly ever used
'attribute' arg?).
---
 dat/keyhelp      | 12 ++++++------
 win/tty/wintty.c | 27 +++++++++++++++------------
 2 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/dat/keyhelp b/dat/keyhelp
index 41ab37ef1..d4df8d444 100644
--- a/dat/keyhelp
+++ b/dat/keyhelp
@@ -14,12 +14,12 @@
 	is reporting the wrong character but will be operating correctly if
 	it describes ^J when you type ^M.
 
-	A NUL character, typed as ^<space> on some keyboards, ^@ on others,
-	and maybe not typeable at all on yet others.  It is not used as a
-	command, and will be converted into ESC before reaching 'whatdoes'.
-	Unlike ^M, this transformation is performed by NetHack itself.
-	But like ^M, if you type NUL and get feedback about ESC, the
-	situation is expected.
+	A NUL character, which is typed as ^<space> on some keyboards,
+	^@ on others, and maybe not typeable at all on yet others, is not
+	used as a command, and will be converted into ESC before reaching
+	'whatdoes'.  Unlike ^M, this transformation is performed within
+	NetHack.  But like ^M, if you type NUL and get feedback about ESC,
+	the situation is expected.
 
 	ESC itself is a synonym for ^[, and is another source of oddity.
 	Various function keys, including cursor arrow keys, may transmit
diff --git a/win/tty/wintty.c b/win/tty/wintty.c
index e38e3e7c8..adec33c22 100644
--- a/win/tty/wintty.c
+++ b/win/tty/wintty.c
@@ -2448,19 +2448,22 @@ const char *str;
        topline wrapping converts space at wrap point into newline,
        we reverse that here */
     if ((int) strlen(str) >= CO || index(str, '\n')) {
-        register const char *bp0 = str;
-        char c, nxtc, *bp1 = cbuf, *endbp1 = &cbuf[sizeof cbuf - 1];
+        const char *in_str = str;
+        char c, *outstr = cbuf, *outend = &cbuf[sizeof cbuf - 1];
+        boolean was_space = TRUE; /* True discards all leading spaces;
+                                     False would retain one if present */
 
-        cbuf[0] = cbuf[sizeof cbuf - 1] = '\0'; /* superfluous */
-        nxtc = (*bp0 == '\n') ? ' ' : *bp0;
-        do {
-            c = nxtc;
-            nxtc = bp0[1];
-            if (nxtc == '\n')
-                nxtc = ' ';
-            if (c != ' ' || nxtc != ' ')
-                *bp1++ = c;
-        } while (*bp0++ && bp1 < endbp1);
+        while ((c = *in_str++) != '\0' && outstr < outend) {
+            if (c == '\n')
+                c = ' ';
+            if (was_space && c == ' ')
+                continue;
+            *outstr++ = c;
+            was_space = (c == ' ');
+        }
+        if ((was_space && outstr > cbuf) || outstr == outend)
+            --outstr; /* remove trailing space or make room for terminator */
+        *outstr = '\0';
         str = cbuf;
     }
     return str;