Convert strsearch() arguments to const char *

Also clean up the implementation a little.

include/ircaux.h

@@ -132,7 +132,7 @@ char *	base64_encode	(const void *data, size_t size);
 /* From words.c */
 #define SOS -32767
 #define EOS 32767
-char	*BX_strsearch			(register char *, char *, char *, int);
+char *BX_strsearch(const char *, const char *, const char *, int);
 char *BX_move_to_word(const char *, int);
 char *BX_move_word_rel(const char *, char **, int);
 char *BX_extract(char *, int, int);

include/modval.h

@@ -199,7 +199,7 @@ extern Function_ptr *global;
 
 
 /* words.c reg.c */
-#define strsearch (*(char *(*)(char *, char *, char *, int ))global[STRSEARCH])
+#define strsearch (*(char *(*)(const char *, const char *, const char *, int ))global[STRSEARCH])
 #define move_to_word (*(char *(*)(const char *, int))global[MOVE_TO_WORD])
 #define move_word_rel (*(char *(*)(const char *, char **, int ))global[MOVE_WORD_REL])
 #define extract (*(char *(*)(char *, int , int ))global[EXTRACT])

source/words.c

@@ -15,36 +15,45 @@ CVS_REVISION(words_c)
 #include "ircaux.h"
 #include "modval.h"
 
-/*
- * search() looks for a character forward or backward from mark 
+/* strsearch()
+ *
+ * If how > 0, returns a pointer to the how'th matching character forwards
+ * from mark, in the string starting at start.
+ * If how < 0, returns a pointer to the -how'th matching character backwards
+ * from mark, in the string starting at start.
+ * If how == 0, returns NULL.
+ *
+ * NULL mark begins the search at start.
+ *
+ * A matching character is any character in chars, unless chars starts with ^, 
+ * in which case a matching character is any character NOT in chars.
+ *
+ * If there are insufficient matching characters, NULL is returned.
  */
-extern char	*BX_strsearch(register char *start, char *mark, char *chars, int how)
+extern char	*BX_strsearch(const char *start, const char *mark, const char *chars, int how)
 {
+	const char *ptr = NULL;
+
 	if (!mark)
 		mark = start;
 
 	if (how > 0)   /* forward search */
 	{
-		mark = sindex(mark, chars);
-		how--;
-		for (; how > 0 && mark && *mark; how--)
-			mark = sindex(mark + 1, chars);
-	}
-
-	else if (how == 0)
-		return NULL;
-
-	else  /* how < 0 */
+		for (; how > 0 && mark; how--)
 		{
-		mark = rsindex(mark, start, chars, -how);
-#if 0
-		how++;
-		for (;(how < 0) && *mark && **mark;how++)
-			*mark = rsindex(*mark-1, start, chars);
-#endif
+			ptr = sindex(mark, chars);
+			if (ptr)
+				mark = ptr + 1;
+			else
+				mark = NULL;
+		}
+	}
+	else if (how < 0)
+	{
+		ptr = rsindex(mark, start, chars, -how);
 	}
 
-	return mark;
+	return (char *)ptr;
 }
 
 /* move_to_word()