Added `sandbox-exit-handler' to control the exit handler

svn: r12654

collects/scheme/sandbox.ss

@@ -15,8 +15,9 @@
          sandbox-coverage-enabled
          sandbox-namespace-specs
          sandbox-override-collection-paths
-         sandbox-security-guard
          sandbox-path-permissions
+         sandbox-security-guard
+         sandbox-exit-handler
          sandbox-network-guard
          sandbox-make-inspector
          sandbox-make-logger
@@ -138,6 +139,11 @@
 
 (define sandbox-security-guard (make-parameter default-sandbox-guard))
 
+(define (default-sandbox-exit-handler _)
+  (error 'exit "sandboxed code cannot exit"))
+
+(define sandbox-exit-handler (make-parameter default-sandbox-exit-handler))
+
 (define sandbox-make-inspector (make-parameter make-inspector))
 
 (define sandbox-make-logger (make-parameter current-logger))
@@ -594,7 +600,7 @@
     [current-command-line-arguments '#()]
     ;; restrict the sandbox context from this point
     [current-security-guard (sandbox-security-guard)]
-    [exit-handler (lambda x (error 'exit "user code cannot exit"))]
+    [exit-handler (sandbox-exit-handler)]
     [current-inspector ((sandbox-make-inspector))]
     [current-logger ((sandbox-make-logger))]
     ;; This breaks because we need to load some libraries that are trusted

collects/scribblings/reference/sandbox.scrbl

@@ -448,6 +448,12 @@ collection libraries (including
 @scheme[make-evalautor] for more information.}
 
 
+@defparam[sandbox-exit-handler handler (any/c . -> . any)]{
+
+A parameter that determines the initial @scheme[(exit-handler)] for
+sandboxed evaluations.  The default handler simply throws an error.}
+
+
 @defparam[sandbox-network-guard proc
           (symbol?
            (or/c (and/c string? immutable?) #f)