From beea6302e06e7e41b1b835b2327febc97177010e Mon Sep 17 00:00:00 2001
From: Andy Wingo <wingo@pobox.com>
Date: Tue, 21 Jun 2016 09:32:30 +0200
Subject: [PATCH] Fix fixnum-range changes in R6RS fixnum bitops

* module/rnrs/arithmetic/fixnums.scm (fxcopy-bit, fxbit-field)
  (fxcopy-bit-field, fxarithmetic-shift)
  (fxarithmetic-shift-left, fx-arithmetic-shift-right)
  (fxrotate-bit-field, fxreverse-bit-field): Enforce range on amount by
  which to shift.  Fixes #14917.
* test-suite/tests/r6rs-arithmetic-fixnums.test ("fxarithmetic-shift-left"):
  Update test to not shift left by a negative amount.
---
 module/rnrs/arithmetic/fixnums.scm            | 28 +++++++++++++++++--
 test-suite/tests/r6rs-arithmetic-fixnums.test |  2 +-
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/module/rnrs/arithmetic/fixnums.scm b/module/rnrs/arithmetic/fixnums.scm
index 7a5a6215e..4ec1cae0c 100644
--- a/module/rnrs/arithmetic/fixnums.scm
+++ b/module/rnrs/arithmetic/fixnums.scm
@@ -242,28 +242,50 @@
 
   (define (fxcopy-bit fx1 fx2 fx3) 
     (assert-fixnum fx1 fx2 fx3) 
+    (unless (and (<= 0 fx2) (< fx2 (fixnum-width)))
+      (raise (make-assertion-violation)))
     (bitwise-copy-bit fx1 fx2 fx3))
 
   (define (fxbit-field fx1 fx2 fx3)
     (assert-fixnum fx1 fx2 fx3)
+    (unless (and (<= 0 fx2 fx3) (< fx3 (fixnum-width)))
+      (raise (make-assertion-violation)))
     (bitwise-bit-field fx1 fx2 fx3))
 
   (define (fxcopy-bit-field fx1 fx2 fx3 fx4)
     (assert-fixnum fx1 fx2 fx3 fx4)
+    (unless (and (<= 0 fx2 fx3) (< fx3 (fixnum-width)))
+      (raise (make-assertion-violation)))
     (bitwise-copy-bit-field fx1 fx2 fx3 fx4))
 
-  (define (fxarithmetic-shift fx1 fx2) (assert-fixnum fx1 fx2) (ash fx1 fx2))
-  (define fxarithmetic-shift-left fxarithmetic-shift)
+  (define (fxarithmetic-shift fx1 fx2)
+    (assert-fixnum fx1 fx2)
+    (unless (< (abs fx2) (fixnum-width))
+      (raise (make-assertion-violation)))
+    (ash fx1 fx2))
+
+  (define (fxarithmetic-shift-left fx1 fx2)
+    (assert-fixnum fx1 fx2)
+    (unless (and (<= 0 fx2) (< fx2 (fixnum-width)))
+      (raise (make-assertion-violation)))
+    (ash fx1 fx2))
 
   (define (fxarithmetic-shift-right fx1 fx2)
-    (assert-fixnum fx1 fx2) (ash fx1 (- fx2)))
+    (assert-fixnum fx1 fx2)
+    (unless (and (<= 0 fx2) (< fx2 (fixnum-width)))
+      (raise (make-assertion-violation)))
+    (ash fx1 (- fx2)))
 
   (define (fxrotate-bit-field fx1 fx2 fx3 fx4)
     (assert-fixnum fx1 fx2 fx3 fx4)
+    (unless (and (<= 0 fx2 fx3) (< fx3 (fixnum-width)) (< fx4 (- fx3 fx2)))
+      (raise (make-assertion-violation)))
     (bitwise-rotate-bit-field fx1 fx2 fx3 fx4))
   
   (define (fxreverse-bit-field fx1 fx2 fx3)
     (assert-fixnum fx1 fx2 fx3)
+    (unless (and (<= 0 fx2 fx3) (< fx3 (fixnum-width)))
+      (raise (make-assertion-violation)))
     (bitwise-reverse-bit-field fx1 fx2 fx3))
 
 )
diff --git a/test-suite/tests/r6rs-arithmetic-fixnums.test b/test-suite/tests/r6rs-arithmetic-fixnums.test
index 2d9b177f7..9f244722f 100644
--- a/test-suite/tests/r6rs-arithmetic-fixnums.test
+++ b/test-suite/tests/r6rs-arithmetic-fixnums.test
@@ -202,7 +202,7 @@
 	 (fx=? (fxarithmetic-shift -1 -1) -1))))
 
 (with-test-prefix "fxarithmetic-shift-left"
-  (pass-if "simple" (fx=? (fxarithmetic-shift-left -6 -1) -3)))
+  (pass-if "simple" (fx=? (fxarithmetic-shift-left -6 1) -12)))
 
 (with-test-prefix "fxarithmetic-shift-right"
   (pass-if "simple" (fx=? (fxarithmetic-shift-right -6 1) -3)))