File nethack-escapes-revamp.patch of Package nethack

From 612755bfb5c412079795c68ba392df5d93874ed8 Mon Sep 17 00:00:00 2001
From: "nethack.rankin" <nethack.rankin>
Date: Thu, 4 Aug 2011 02:41:44 +0000
Subject: [PATCH] escapes() revamp

     Partial rewrite of escapes(), mostly changing its if-then-else
logic so that end-of-string can be checked once instead for each case.
The previous version had a bug if the input string ended with backslash
and one decimal digit (due to being lumped together with the handling
for trailing \X or \O).
---
 src/options.c | 82 ++++++++++++++++++++++++++++++---------------------
 1 file changed, 48 insertions(+), 34 deletions(-)

Index: src/options.c
===================================================================
--- src/options.c.orig
+++ src/options.c
@@ -633,32 +633,45 @@ escapes(cp, tp)
 const char	*cp;
 char *tp;
 {
+    static NEARDATA const char
+	oct[] = "01234567", dec[] = "0123456789",
+	hex[] = "00112233445566778899aAbBcCdDeEfF";
+    const char *dp;
+    int cval, meta, dcount;
+
     while (*cp)
     {
-	int	cval = 0, meta = 0;
-
-	if (*cp == '\\' && index("mM", cp[1])) {
-		meta = 1;
-		cp += 2;
-	}
-	if (*cp == '\\' && index("0123456789xXoO", cp[1]))
-	{
-	    const char *dp, *hex = "00112233445566778899aAbBcCdDeEfF";
-	    int dcount = 0;
+	/* \M has to be followed by something to do meta conversion,
+	   otherwise it will just be \M which ultimately yields 'M' */
+	meta = (*cp == '\\' && (cp[1] == 'm' || cp[1] == 'M') && cp[2]);
+	if (meta) cp += 2;
 
-	    cp++;
-	    if (*cp == 'x' || *cp == 'X')
-		for (++cp; (dp = index(hex, *cp)) && (dcount++ < 2); cp++)
-		    cval = (cval * 16) + (dp - hex) / 2;
-	    else if (*cp == 'o' || *cp == 'O')
-		for (++cp; (index("01234567",*cp)) && (dcount++ < 3); cp++)
-		    cval = (cval * 8) + (*cp - '0');
-	    else
-		for (; (index("0123456789",*cp)) && (dcount++ < 3); cp++)
-		    cval = (cval * 10) + (*cp - '0');
-	}
-	else if (*cp == '\\')		/* C-style character escapes */
-	{
+	cval = dcount = 0; /* for decimal, octal, hexadecimal cases */
+	if ((*cp != '\\' && *cp != '^') || !cp[1]) {
+	    /* simple character, or nothing left for \ or ^ to escape */
+	    cval = *cp++;
+	} else if (*cp == '^') {	/* expand control-character syntax */
+	    cval = (*++cp & 0x1f);
+	    ++cp;
+	/* remaining cases are all for backslash and we know cp[1] is not \0 */
+	} else if (index(dec, cp[1])) {
+	    ++cp;	/* move past backslash to first digit */
+	    do {
+		cval = (cval * 10) + (*cp - '0');
+	    } while (*++cp && index(dec, *cp) && ++dcount < 3);
+	} else if ((cp[1] == 'o' || cp[1] == 'O') &&
+		cp[2] && index(oct, cp[2])) {
+	    cp += 2;	/* move past backslash and 'O' */
+	    do {
+		cval = (cval * 8) + (*cp - '0');
+	    } while (*++cp && index(oct, *cp) && ++dcount < 3);
+	} else if ((cp[1] == 'x' || cp[1] == 'X') &&
+		cp[2] && (dp = index(hex, cp[2])) != 0) {
+	    cp += 2;	/* move past backslash and 'X' */
+	    do {
+		cval = (cval * 16) + ((int)(dp - hex) / 2);
+	    } while (*++cp && (dp = index(hex, *cp)) != 0 && ++dcount < 2);
+	} else {			/* C-style character escapes */
 	    switch (*++cp)
 	    {
 	    case '\\': cval = '\\'; break;
@@ -668,18 +681,12 @@ char *tp;
 	    case 'r': cval = '\r'; break;
 	    default: cval = *cp;
 	    }
-	    cp++;
-	}
-	else if (*cp == '^')		/* expand control-character syntax */
-	{
-	    cval = (*++cp & 0x1f);
-	    cp++;
+	    ++cp;
 	}
-	else
-	    cval = *cp++;
+
 	if (meta)
 	    cval |= 0x80;
-	*tp++ = cval;
+	*tp++ = (char)cval;
     }
     *tp = '\0';
 }