reentrant port table stuff

[Chris Cramer]

I'm using the stable CVS branch of Guile. This program eventually
segfaults, because open-output-file and close-port (and open-file, etc)
are not reentrant:

(use-modules (ice-9 threads))

(define (child port)
    (display "Hello" port)
    (newline port))

(define (create-child)
    (begin-thread
        (let ((port (open-output-file "/dev/null")))
        (child port)
        (close-port port))))

(define (test-threads . ignored)
        (let loop ((i 0))
            (create-child)
            (display i) (newline)
            (loop (+ i 1))))

This patch fixes it, by deferring interrupts in scm_add_to_port_table
and scm_remove_from_port_table:

Index: libguile/ports.c
===================================================================
RCS file: /cvsroot/guile/guile/guile-core/libguile/ports.c,v
retrieving revision 1.153.2.1
diff -u -r1.153.2.1 ports.c
--- libguile/ports.c    2001/07/09 07:31:04     1.153.2.1
+++ libguile/ports.c    2001/07/26 19:41:05
@@ -438,6 +438,7 @@
 {
   scm_t_port *entry;
 
+  SCM_DEFER_INTS;
   if (scm_t_portable_size == scm_t_portable_room)
     {
       /* initial malloc is in gc.c.  this doesn't use scm_must_malloc etc.,
@@ -466,6 +467,7 @@
 
   scm_t_portable[scm_t_portable_size] = entry;
   scm_t_portable_size++;
+  SCM_ALLOW_INTS;
 
   return entry;
 }
@@ -482,6 +484,7 @@
 
   if (i >= scm_t_portable_size)
     SCM_MISC_ERROR ("Port not in table: ~S", scm_list_1 (port));
+  SCM_DEFER_INTS;
   if (p->putback_buf)
     scm_must_free (p->putback_buf);
   scm_must_free (p);
@@ -494,6 +497,7 @@
     }
   SCM_SETPTAB_ENTRY (port, 0);
   scm_t_portable_size--;
+  SCM_ALLOW_INTS;
 }
 #undef FUNC_NAME
 
-- 
C. Ray C. aka Christopher Cramer
address@hidden
http://www.pyro.net/~crayc/