Don't pass "-" to non-pipe LESSOPEN unless it starts with a dash.

NEWS.VER

@@ -12,7 +12,13 @@
 
 ======================================================================
 
-	Major changes between "less" versions 424 and @@VERSION@@
+	Major changes between "less" versions 429 and @@VERSION@@
+
+* Don't pass "-" to non-pipe LESSOPEN unless it starts with "-".
+
+======================================================================
+
+	Major changes between "less" versions 424 and 429
 
 * LESSOPEN pipe will now be used on standard input, if the LESSOPEN
   environment variable begins with "|-".

filename.c

@@ -843,17 +843,17 @@ open_altfile(filename, pf, pfd)
 #else
 		lessopen++;
 		returnfd = 1;
-		if (*lessopen == '-') {
-			/*
-			 * Lessopen preprocessor will accept "-" as a filename.
-			 */
-			lessopen++;
-		} else {
-			if (strcmp(filename, "-") == 0)
-				return (NULL);
-		}
 #endif
 	}
+	if (*lessopen == '-') {
+		/*
+		 * Lessopen preprocessor will accept "-" as a filename.
+		 */
+		lessopen++;
+	} else {
+		if (strcmp(filename, "-") == 0)
+			return (NULL);
+	}
 
 	len = strlen(lessopen) + strlen(filename) + 2;
 	cmd = (char *) ecalloc(len, sizeof(char));

less.nro.VER

@@ -1149,11 +1149,19 @@ postprocessor is "\-".
 .PP
 For compatibility with previous versions of
 .I less,
-the input pipe is not used if
+the input preprocessor or pipe is not used if
 .I less
 is viewing standard input.  
-However, if the character after the vertical bar is a dash (\-),
-the input pipe is used on standard input as well as other files.
+However, if the first character of LESSOPEN is a dash (\-),
+the input preprocessor is used on standard input as well as other files.
+In this case, the dash is not considered to be part of 
+the preprocessor command.
+If standard input is being viewed, the input preprocessor is passed
+a file name consisting of a single dash.
+Similarly, if the first two characters of LESSOPEN are vertical bar and dash
+(|\-), the input pipe is used on standard input as well as other files.
+Again, in this case the dash is not considered to be part of 
+the input pipe command.
 
 .SH "NATIONAL CHARACTER SETS"
 There are three types of characters in the input file:

version.c

@@ -720,6 +720,8 @@ v426  10/27/08  Fix ignaw terminal handling (thanks to Per Hedeland);
 v427  3/16/09   A few Win32 fixes (thanks to Jason Hood).
 v428  3/30/09   Add "|-" syntax to LESSOPEN.
 v429  4/10/09   Fix search highlighting bug with underlined text.
+-----------------------------------------------------------------
+v430  4/22/09   Don't pass "-" to non-pipe LESSOPEN unless it starts with "-".
 */
 
-char version[] = "429";
+char version[] = "430";