small adjustments to udp-set-receive-buffer-size!

Minor adjustments to a commenably complete addition.

pkgs/racket-doc/scribblings/reference/networking.scrbl

@@ -498,14 +498,13 @@ exception is raised, but not both.}
                                        [size exact-positive-integer?])
                                        void]{
 
-On Unix systems, set the receive buffer size (@tt{SO_RCVBUF}) for
-@racket[udp-socket].
+Set the receive buffer size (@tt{SO_RCVBUF}) for @racket[udp-socket].
+Using a larger buffer can minimize packet loss that can occur due to
+slow polling of a connection, including during a major garbage
+collection.
 
 If @racket[size] is greater than the maximum allowed by the system,
-the @exnraise[exn:fail].
-
-Using a larger buffer can minimize packet loss that can occur during a
-major garbage collection.
+the @exnraise[exn:fail:network].
 
 @history[#:added "7.1.0.11"]}
 

pkgs/racket-test-core/tests/racket/udp.rktl

@@ -57,12 +57,14 @@
 
 (err/rt-test (udp-set-receive-buffer-size! udp1 -1))
 (err/rt-test (udp-set-receive-buffer-size! udp1 0))
+(err/rt-test (udp-set-receive-buffer-size! udp1 (expt 2 300))
+             exn:fail:network?)
 ;; Something a user program might do to find the max allowed size
 (test-values
  '(ok)
  (λ ()
    (let loop ([n 4096])
-     (with-handlers ([exn:fail?
+     (with-handlers ([exn:fail:network?
                       (λ _
                         (let ([n (/ n 2)])
                           (udp-set-receive-buffer-size! udp1 n)

racket/src/io/network/udp-receive.rkt

@@ -164,6 +164,9 @@
   (check who exact-nonnegative-integer? size)
   (atomically
    (check-udp-closed who u)
+   (unless (fixnum? size)
+     (end-atomic)
+     (raise-non-fixnum who size))
    (define r (rktio_udp_set_receive_buffer_size rktio (udp-s u) size))
    (when (rktio-error? r)
      (raise-option-error who "set" r))))
@@ -171,3 +174,11 @@
 (define (raise-option-error who mode v)
   (end-atomic)
   (raise-network-error who v (string-append mode "sockopt failed")))
+
+(define (raise-non-fixnum who size)
+  (raise (exn:fail:network
+          (format (string-append "~a: given size is too large\n"
+                                 "  given size: ~e")
+                  who
+                  size)
+          (current-continuation-marks))))

racket/src/racket/src/network.c

@@ -2704,7 +2704,13 @@ static Scheme_Object *udp_set_receive_buffer_size(int argc, Scheme_Object *argv[
     scheme_wrong_contract("udp-set-receive-buffer-size!", "udp?", 0, argc, argv);
 
   if (!SCHEME_INTP(argv[1]) || (SCHEME_INT_VAL(argv[1]) <= 0)) {
-    scheme_wrong_contract("udp-set-receive-buffer-size!", "exact-positive-integer?", 1, argc, argv);
+    if (SCHEME_BIGNUMP(argv[1]) && SCHEME_BIGPOS(argv[1]))
+      scheme_raise_exn(MZEXN_FAIL_NETWORK,
+                       "udp-set-receive-buffer-size!: given size is too large\n"
+                       "  given size: %V",
+                       argv[1]);
+    else
+      scheme_wrong_contract("udp-set-receive-buffer-size!", "exact-positive-integer?", 1, argc, argv);
     return NULL;
   }