diff --git a/collects/mzlib/string.ss b/collects/mzlib/string.ss
index 5738fb1..0154fa6 100644
--- a/collects/mzlib/string.ss
+++ b/collects/mzlib/string.ss
@@ -10,6 +10,7 @@
 	   regexp-replace-quote
 	   regexp-match*
 	   regexp-match-positions*
+	   regexp-match-peek-positions*
 	   regexp-split
 	   regexp-match-exact?
            regexp-match/fail-without-reading)
@@ -127,17 +128,13 @@
   (define (regexp-replace-quote s)
     (unless (string? s)
       (raise-type-error 'regexp-replace-quote "string" s))
-    (regexp-replace* "\\\\" s "\\\\\\\\"))
+    (regexp-replace* "&" (regexp-replace* "\\\\" s "\\\\\\\\") "\\\\&"))
 
   (define regexp-match/fail-without-reading
-    (opt-lambda (pattern input-port [start-k 0] [end-k #f] [output-port #f])
+    (opt-lambda (pattern input-port [start-k 0] [end-k #f])
       (unless (input-port? input-port)
         (raise-type-error 'regexp-match/fail-without-reading "input port" input-port))
-      (let ([m (apply regexp-match-peek-positions
-                      pattern input-port start-k end-k
-                      (if output-port
-                          (list output-port)
-                          null))])
+      (let ([m (regexp-match-peek-positions pattern input-port start-k end-k)])
         (and m
              ;; What happens if someone swipes our chars before we can get them?
              (begin
@@ -150,76 +147,193 @@
                             (cdr m)))))))))
 
   ;; Helper function for the regexp functions below.
-  (define (regexp-fn name success failure)
-    (opt-lambda (pattern string [start 0] [end (and (string? string)
-						    (string-length string))])
+  (define (regexp-fn name success-k port-success-k failure-k port-failure-k 
+		     need-leftover? peek?)
+    (lambda (pattern string start end)
 
       (unless (or (string? pattern) (regexp? pattern))
 	(raise-type-error name "regexp or string" pattern))
-      (unless (string? string)
-	(raise-type-error name "string" string))
+      (if peek?
+	  (unless (input-port? string)
+	    (raise-type-error name "input-port" string))
+	  (unless (or (string? string) (input-port? string))
+	    (raise-type-error name "string or input-port" string)))
       (unless (and (number? start) (exact? start) (integer? start) (start . >= . 0))
 	(raise-type-error name "non-negative exact integer" start))
-      (unless (and (number? end) (exact? end) (integer? end) (end . >= . 0))
-	(raise-type-error name "non-negative exact integer" end))
-      (unless (start . <= . (string-length string))
+      (unless (or (not end) 
+		  (and (number? end) (exact? end) (integer? end) (end . >= . 0)))
+	(raise-type-error name "non-negative exact integer or false" end))
+      (unless (or (input-port? string)
+		  (start . <= . (string-length string)))
 	(raise-mismatch-error
 	 name
-	 (format "starting offset index ~a out of range [0,~a] for string: " 
-		 start
+	 (format "starting offset index out of range [0,~a]: " 
 		 (string-length string))
-	 string))
-      (unless (<= start end (string-length string))
+	 start))
+      (unless (or (not end)
+		  (and (start . <= . end)
+		       (or (input-port? string)
+			   (end . <= . (string-length string)))))
 	(raise-mismatch-error
 	 name
-	 (format "ending offset index ~a out of range [~a,~a] for string: " 
+	 (format "ending offset index out of range [~a,~a]: " 
 		 end
-		 start
 		 (string-length string))
-	 string))
+	 start))
 
-      (let* ((expr (if (regexp? pattern) 
-		       pattern 
-		       (regexp pattern)))
-	     (match (regexp-match-positions expr string start end)))
-	(if match
-	    (let ((match-start (caar match))
-		  (match-end (cdar match)))
-	      (when (= match-start match-end)
-		(error name "pattern matched a zero-length substring"))
-	      (success expr string start end match-start match-end))
-	    (failure expr string start end)))))
+      (when (and (positive? start)
+		 (input-port? string)
+		 need-leftover?)
+	;; Skip start chars:
+	(let ([s (make-string 4096)])
+	  (let loop ([n 0])
+	    (unless (= n start)
+	      (let ([m (read-string-avail! s string 0 (min (- start n) 4096))])
+		(unless (eof-object? m)
+		  (loop (+ n m))))))))
+
+      (let ((expr (if (regexp? pattern) 
+		      pattern 
+		      (regexp pattern))))
+	(if (and (input-port? string)
+		 port-success-k)
+	    ;; Input port match, get string
+	    (let ([discarded 0]
+		  [leftover-port (and need-leftover?
+				      (open-output-string))])
+	      (let ([match (regexp-match expr string 
+					 (if need-leftover? 0 start) 
+					 (and end (if need-leftover? (- end start) end))
+					 (if need-leftover?
+					     leftover-port
+					     (make-custom-output-port
+					      #f
+					      (lambda (s start end flush?)
+						(let ([c (- end start)])
+						  (set! discarded (+ c discarded))
+						  c))
+					      void
+					      void)))]
+		    [leftovers (and need-leftover?
+				    (get-output-string leftover-port))])
+		(if match
+		    (port-success-k expr string (car match) 
+				    (and end (- end 
+						(if need-leftover?
+						    (+ (string-length leftovers) start)
+						    discarded)
+						(string-length (car match))))
+				    leftovers)
+		    (port-failure-k leftovers))))
+	    ;; String/port match, get positions
+	    (let ([match ((if peek?
+			      regexp-match-peek-positions
+			      regexp-match-positions) 
+			  expr string start end)])
+	      (if match
+		  (let ((match-start (caar match))
+			(match-end (cdar match)))
+		    (when (= match-start match-end)
+		      (error name "pattern matched a zero-length substring"))
+		    (success-k expr string start end match-start match-end))
+		  (failure-k expr string start end)))))))
+
+  (define-syntax wrap
+    (syntax-rules ()
+      [(_ out orig)
+       (define out 
+	 (opt-lambda (pattern string [start 0] [end #f])
+	   (orig pattern string start end)))]))
 
   ;; Returns all the positions at which the pattern matched.
-  (define regexp-match-positions*
+  (define -regexp-match-positions*
     (regexp-fn 'regexp-match-positions*
+	       ;; success-k:
 	       (lambda (expr string start end match-start match-end)
 		 (cons (cons match-start match-end)
-		       (regexp-match-positions* expr string match-end end)))
+		       (if (string? string)
+			   (regexp-match-positions* expr string match-end end)
+			   ;; Need to shift index of rest as reading:
+			   (map (lambda (p)
+				  (cons (+ match-end (car p))
+					(+ match-end (cdr p))))
+				(regexp-match-positions* expr string 0 (and end (- end match-end)))))))
+	       ;; port-success-k --- use string case
+	       #f
+	       ;; fail-k:
 	       (lambda (expr string start end)
-		 null)))
+		 null)
+	       ;; port-fail-k --- use string case
+	       #f
+	       #f
+	       #f))
+  (wrap regexp-match-positions* -regexp-match-positions*)
+
+  ;; Returns all the positions at which the pattern matched.
+  (define -regexp-match-peek-positions*
+    (regexp-fn 'regexp-match-peek-positions*
+	       ;; success-k:
+	       (lambda (expr string start end match-start match-end)
+		 (cons (cons match-start match-end)
+		       (regexp-match-peek-positions* expr string match-end end)))
+	       ;; port-success-k --- use string case
+	       #f
+	       ;; fail-k:
+	       (lambda (expr string start end)
+		 null)
+	       ;; port-fail-k --- use string case
+	       #f
+	       #f
+	       #t))
+  (wrap regexp-match-peek-positions* -regexp-match-peek-positions*)
 
   ;; Splits a string into a list by removing any piece which matches
   ;; the pattern.
-  (define regexp-split
+  (define -regexp-split
     (regexp-fn 'regexp-split
+	       ;; success-k
 	       (lambda (expr string start end match-start match-end)
 		 (cons
 		  (substring string start match-start)
 		  (regexp-split expr string match-end end)))
+	       ;; port-success-k:
+	       (lambda (expr string match-string new-end leftovers)
+		 (cons 
+		  leftovers
+		  (regexp-split expr string 0 new-end)))
+	       ;; failure-k:
 	       (lambda (expr string start end)
 		 (list
-		  (substring string start end)))))
+		  (substring string start (or end (string-length string)))))
+	       ;; port-fail-k
+	       (lambda (leftover)
+		 (list leftover))
+	       #t
+	       #f))
+  (wrap regexp-split -regexp-split)
 
   ;; Returns all the matches for the pattern in the string.
-  (define regexp-match*
+  (define -regexp-match*
     (regexp-fn 'regexp-match*
+	       ;; success-k:
 	       (lambda (expr string start end match-start match-end)
 		 (cons
 		  (substring string match-start match-end)
 		  (regexp-match* expr string match-end end)))
-	       (lambda args
-		 (list))))
+	       ;; port-success-k:
+	       (lambda (expr string match-string new-end leftovers)
+		 (cons
+		  match-string
+		  (regexp-match* expr string 0 new-end)))
+	       ;; fail-k:
+	       (lambda (expr string start end)
+		 null)
+	       ;; port-fail-k:
+	       (lambda (leftover)
+		 null)
+	       #f
+	       #f))
+  (wrap regexp-match* -regexp-match*)
 
   (define regexp-match-exact?
     (lambda (p s)