From 8269ba5b2c48b49ad3418214b7f2af1d84930b3c Mon Sep 17 00:00:00 2001
From: Andy Wingo <wingo@pobox.com>
Date: Thu, 10 Feb 2011 22:28:19 +0100
Subject: [PATCH] ports.c safely accesses the port weak hash table

* libguile/ports.h (scm_i_remove_port): Remove declaration, as it was
  SCM_INTERNAL.
* libguile/ports.c (scm_add_to_port_table): Issue a deprecation
  warning if this function is called.  Remove needless SCM_API
  declaration, it was already declared as such in ports.h.  Safely
  access the port table.
  (scm_i_remove_port): Remove bogus comment about lack of need for
  threadsafety.  Take the port table mutex.
  (scm_close_port): No need to take port table mutex around calling
  scm_i_remove_port.
---
 libguile/ports.c | 29 +++++++++++++++++++----------
 libguile/ports.h |  1 -
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/libguile/ports.c b/libguile/ports.c
index 587998a01..b65650e95 100644
--- a/libguile/ports.c
+++ b/libguile/ports.c
@@ -40,6 +40,7 @@
 
 #include "libguile/_scm.h"
 #include "libguile/async.h"
+#include "libguile/deprecation.h"
 #include "libguile/eval.h"
 #include "libguile/fports.h"  /* direct access for seek and truncate */
 #include "libguile/goops.h"
@@ -624,16 +625,23 @@ scm_new_port_table_entry (scm_t_bits tag)
 #undef FUNC_NAME
 
 #if SCM_ENABLE_DEPRECATED==1
-SCM_API scm_t_port *
+scm_t_port *
 scm_add_to_port_table (SCM port)
 {
-  SCM z = scm_new_port_table_entry (scm_tc7_port);
-  scm_t_port * pt = SCM_PTAB_ENTRY(z);
+  SCM z;
+  scm_t_port * pt;
 
+  scm_c_issue_deprecation_warning ("scm_add_to_port_table is deprecated.");
+
+  scm_i_pthread_mutex_lock (&scm_i_port_table_mutex);
+  z = scm_new_port_table_entry (scm_tc7_port);
+  pt = SCM_PTAB_ENTRY(z);
   pt->port = port;
   SCM_SETCAR (z, SCM_EOL);
   SCM_SETCDR (z, SCM_EOL);
   SCM_SETPTAB_ENTRY (port, pt);
+  scm_i_pthread_mutex_unlock (&scm_i_port_table_mutex);
+
   return pt;
 }
 #endif
@@ -641,20 +649,23 @@ scm_add_to_port_table (SCM port)
 
 /* Remove a port from the table and destroy it.  */
 
-/* This function is not and should not be thread safe. */
-void
+static void
 scm_i_remove_port (SCM port)
 #define FUNC_NAME "scm_remove_port"
 {
-  scm_t_port *p = SCM_PTAB_ENTRY (port);
+  scm_t_port *p;
 
+  scm_i_scm_pthread_mutex_lock (&scm_i_port_table_mutex);
+
+  p = SCM_PTAB_ENTRY (port);
   scm_port_non_buffer (p);
-
   p->putback_buf = NULL;
   p->putback_buf_size = 0;
-
   SCM_SETPTAB_ENTRY (port, 0);
+
   scm_hashq_remove_x (scm_i_port_weak_hash, port);
+
+  scm_i_pthread_mutex_unlock (&scm_i_port_table_mutex);
 }
 #undef FUNC_NAME
 
@@ -827,9 +838,7 @@ SCM_DEFINE (scm_close_port, "close-port", 1, 0, 0,
     rv = (scm_ptobs[i].close) (port);
   else
     rv = 0;
-  scm_i_scm_pthread_mutex_lock (&scm_i_port_table_mutex);
   scm_i_remove_port (port);
-  scm_i_pthread_mutex_unlock (&scm_i_port_table_mutex);
   SCM_CLR_PORT_OPEN_FLAG (port);
   return scm_from_bool (rv >= 0);
 }
diff --git a/libguile/ports.h b/libguile/ports.h
index 09720b5ef..6a669b660 100644
--- a/libguile/ports.h
+++ b/libguile/ports.h
@@ -255,7 +255,6 @@ SCM_API void scm_dynwind_current_input_port (SCM port);
 SCM_API void scm_dynwind_current_output_port (SCM port);
 SCM_API void scm_dynwind_current_error_port (SCM port);
 SCM_API SCM scm_new_port_table_entry (scm_t_bits tag);
-SCM_INTERNAL void scm_i_remove_port (SCM port);
 SCM_API void scm_grow_port_cbuf (SCM port, size_t requested);
 SCM_API SCM scm_pt_size (void);
 SCM_API SCM scm_pt_member (SCM member);