add (system repl server)

* module/system/repl/server.scm: New module, listens on a socket for
  connections, then serves repls to those sockets.

* module/Makefile.am: Add repl server.

module/Makefile.am

@@ -324,7 +324,8 @@ SYSTEM_SOURCES =				\
   system/repl/error-handling.scm		\
   system/repl/common.scm			\
   system/repl/command.scm			\
-  system/repl/repl.scm
+  system/repl/repl.scm				\
+  system/repl/server.scm
 
 LIB_SOURCES =					\
   statprof.scm					\

module/system/repl/server.scm

@@ -0,0 +1,131 @@
+;;; Repl server
+
+;; Copyright (C)  2003, 2010 Free Software Foundation, Inc.
+
+;; This library is free software; you can redistribute it and/or
+;; modify it under the terms of the GNU Lesser General Public
+;; License as published by the Free Software Foundation; either
+;; version 3 of the License, or (at your option) any later version.
+;;
+;; This library is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;; Lesser General Public License for more details.
+;;
+;; You should have received a copy of the GNU Lesser General Public
+;; License along with this library; if not, write to the Free Software
+;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+;; 02110-1301 USA
+
+;;; Code:
+
+(define-module (system repl server)
+  #:use-module (system repl repl)
+  #:use-module (ice-9 threads)
+  #:export (make-tcp-server-socket
+            make-unix-domain-server-socket
+            run-server
+            spawn-server
+            stop-server-and-clients!))
+
+(define *open-sockets* '())
+
+(define sockets-lock (make-mutex))
+
+(define (close-socket! s)
+  (with-mutex sockets-lock
+    (set! *open-sockets* (delq! s *open-sockets*)))
+  ;; Close-port could block or raise an exception flushing buffered
+  ;; output.  Hmm.
+  (close-port s))
+
+(define (add-open-socket! s)
+  (with-mutex sockets-lock
+    (set! *open-sockets* (cons s *open-sockets*))))
+
+(define (stop-server-and-clients!)
+  (cond
+   ((with-mutex sockets-lock
+      (and (pair? *open-sockets*)
+           (car *open-sockets*)))
+    => (lambda (s)
+         (close-socket! s)
+         (stop-server-and-clients!)))))
+
+(define* (make-tcp-server-socket #:key
+                          (host #f)
+                          (addr (if host (inet-aton host) INADDR_LOOPBACK))
+                          (port 37146))
+  (let ((sock (socket PF_INET SOCK_STREAM 0)))
+    (setsockopt sock SOL_SOCKET SO_REUSEADDR 1)
+    (bind sock AF_INET addr port)
+    sock))
+
+(define* (make-unix-domain-server-socket #:key (path "/tmp/guile-socket"))
+  (let ((sock (socket PF_UNIX SOCK_STREAM 0)))
+    (setsockopt sock SOL_SOCKET SO_REUSEADDR 1)
+    (bind sock AF_UNIX path)
+    sock))
+
+(define call-with-sigint
+  (if (not (provided? 'posix))
+      (lambda (thunk) (thunk))
+      (lambda (thunk)
+        (let ((handler #f))
+          (dynamic-wind
+            (lambda ()
+              (set! handler
+                    (sigaction SIGINT (lambda (sig) (throw 'interrupt)))))
+            thunk
+            (lambda ()
+              (if handler
+                  ;; restore Scheme handler, SIG_IGN or SIG_DFL.
+                  (sigaction SIGINT (car handler) (cdr handler))
+                  ;; restore original C handler.
+                  (sigaction SIGINT #f))))))))
+
+(define* (run-server #:optional (server-socket (make-tcp-server-socket)))
+  (define (accept-new-client)
+    (catch #t
+      (lambda () (call-with-sigint (lambda () (accept server-socket))))
+      (lambda (k . args)
+        (cond
+         ((port-closed? server-socket)
+          ;; Shutting down.
+          #f)
+         ((eq? k 'interrupt)
+          ;; Interrupt.
+          (close-socket! server-socket)
+          #f)
+         (else
+          (warn "Error accepting client" k args)
+          ;; Retry after a timeout.
+          (sleep 1)
+          (accept-new-client))))))
+  
+  (add-open-socket! server-socket)
+  (listen server-socket 5)
+  (let lp ((client (accept-new-client)))
+    ;; If client is false, we are shutting down.
+    (if client
+        (let ((client-socket (car client))
+              (client-addr (cdr client)))
+          (add-open-socket! client-socket)
+          (make-thread serve-client client-socket client-addr)
+          (lp (accept-new-client))))))
+
+(define* (spawn-server #:optional (server-socket (make-tcp-server-socket)))
+  (make-thread run-server server-socket))
+
+(define (serve-client client addr)
+  (with-continuation-barrier
+   (lambda ()
+     (with-input-from-port client
+       (lambda ()
+         (with-output-to-port client
+           (lambda ()
+             (with-error-to-port client
+               (lambda ()
+                 (with-fluids ((*repl-stack* '()))
+                   (start-repl))))))))))
+  (close-socket! client))