Fix crash and memory leak in $aliasctl(COMMAND MATCH)

glob_commands() would run off the end of the irc_command array if given a match that matched
the last command.  It also leaked memory because it used m_s3cat() to construct the string,
then passed that to m_strdup().

This fixes these problems by reworking glob_commands(), and at the same time removes the use
of alloca() and wild_match() by using strncmp() instead to match the start of a string.  Move
glob_commands() to alias.c and make it static since it's only used for aliasctl().

Change the 'name' argument of find_command() and find_dll_command() to const char * at the same
time, so that glob_commands()'s prefix argument can be const char * too.

source/alias.c

@@ -2227,14 +2227,36 @@ char *lookup_member(char *varname, char *var_args, char *ptr, char *args)
 
 /****************************** ALIASCTL ************************************/
 #define EMPTY empty_string
-#define RETURN_EMPTY return m_strdup(EMPTY)
+#define EMPTY_STRING m_strdup(EMPTY)
+#define RETURN_EMPTY return EMPTY_STRING 
 #define RETURN_IF_EMPTY(x) if (empty( x )) RETURN_EMPTY
 #define GET_INT_ARG(x, y) {RETURN_IF_EMPTY(y); x = my_atol(safe_new_next_arg(y, &y));}
 #define GET_FLOAT_ARG(x, y) {RETURN_IF_EMPTY(y); x = atof(safe_new_next_arg(y, &y));}
 #define GET_STR_ARG(x, y) {RETURN_IF_EMPTY(y); x = new_next_arg(y, &y);RETURN_IF_EMPTY(x);}
 #define RETURN_STR(x) return m_strdup(x ? x : EMPTY)
+#define RETURN_MSTR(x) return ((x) ? (x) : EMPTY_STRING)
 #define RETURN_INT(x) return m_strdup(ltoa(x));
 
+/* glob_commands()
+ * Returns a space-separated list of commands beginning with 'prefix'.
+ */
+static char *glob_commands(const char *prefix, int *cnt)
+{
+	IrcCommand *var;
+	char *mylist = NULL;
+	const size_t prefix_len = strlen(prefix);
+
+	*cnt = 0;
+	/* let's do a command completion here */
+	for (var = find_command(prefix, cnt);
+		var && var->name && !strncmp(prefix, var->name, prefix_len);
+		var++)
+	{
+		m_s3cat(&mylist, space, var->name);
+	}
+	RETURN_MSTR(mylist);
+}
+
 /* Used by function_aliasctl */
 /* MUST BE FIXED */
 BUILT_IN_FUNCTION(aliasctl)
@@ -2321,7 +2343,7 @@ BUILT_IN_FUNCTION(aliasctl)
 			else if (list == VAR_ALIAS)
 				mlist = glob_assign_alias(listc, &num);
 			else if (list == -1)
-				return glob_commands(listc, &num, 0);
+				return glob_commands(listc, &num);
 
 			for (ctr = 0; ctr < num; ctr++)
 			{
@@ -2345,7 +2367,7 @@ BUILT_IN_FUNCTION(aliasctl)
 			else if (list == VAR_ALIAS)
 				mlist = pmatch_assign_alias(listc, &num);
 			else if (list == -1)
-				return glob_commands(listc, &num, 1);
+				return glob_commands(listc, &num);
 
 			for (ctr = 0; ctr < num; ctr++)
 			{

source/commands.c

@@ -153,7 +153,7 @@ char	lame_wait_nick[] = "***LW***";
 char	wait_nick[] = "***W***";
 
 #ifdef WANT_DLL
-	IrcCommandDll *find_dll_command (char *, int *);
+	IrcCommandDll *find_dll_command (const char *, int *);
 	IrcCommandDll *dll_commands = NULL;
 #endif
 
@@ -904,25 +904,6 @@ BUILT_IN_COMMAND(init_ftp)
 }
 #endif
 
-char *glob_commands(char *name, int *cnt, int pmatch)
-{
-IrcCommand *var = NULL;
-char *loc_match;
-char *mylist = NULL;
-	*cnt = 0;
-	/* let's do a command completion here */
-	if (!(var = find_command(name, cnt)))
-		return m_strdup(empty_string);
-	loc_match = alloca(strlen(name)+2);
-	sprintf(loc_match, "%s*", (name && *name) ? name : empty_string);
-	while (wild_match(loc_match, var->name))
-	{
-		m_s3cat(&mylist, space, var->name);
-		var++;
-	}
-	return m_strdup(mylist ? mylist : empty_string);
-}
-
 /*
  * find_command: looks for the given name in the command list, returning a
  * pointer to the first match and the number of matches in cnt.  If no
@@ -932,7 +913,7 @@ char *mylist = NULL;
  * returned and cnt is set to the number of matches * -1.  Thus is 4 commands
  * matched, but the first was as exact match, cnt is -4.
  */
-IrcCommand *BX_find_command(char *com, int *cnt)
+IrcCommand *BX_find_command(const char *com, int *cnt)
 {
 	IrcCommand *retval;
 	int loc;
@@ -951,7 +932,7 @@ IrcCommand *BX_find_command(char *com, int *cnt)
 }
 
 #ifdef WANT_DLL
-IrcCommandDll * find_dll_command(char *com, int *cnt)
+IrcCommandDll *find_dll_command(const char *com, int *cnt)
 {
 	int len = 0;