* exceptions.cc (_cygtls::handle_exceptions): Call new

mmap_is_attached_or_noreserve_page function in case of access violation
	and allow application to retry access on noreserve pages.
	* mmap.cc (mmap_is_attached_or_noreserve_page): Changed from
	mmap_is_attached_page.  Handle also noreserve pages now.  Change
	comment accordingly.
	* winsup.h (mmap_is_attached_or_noreserve_page): Declare instead of
	mmap_is_attached_page.

winsup/cygwin/ChangeLog

@@ -1,3 +1,14 @@
+2006-07-13  Corinna Vinschen  <corinna@vinschen.de>
+
+	* exceptions.cc (_cygtls::handle_exceptions): Call new
+	mmap_is_attached_or_noreserve_page function in case of access violation
+	and allow application to retry access on noreserve pages.
+	* mmap.cc (mmap_is_attached_or_noreserve_page): Changed from
+	mmap_is_attached_page.  Handle also noreserve pages now.  Change
+	comment accordingly.
+	* winsup.h (mmap_is_attached_or_noreserve_page): Declare instead of
+	mmap_is_attached_page.
+
 2006-07-12  Corinna Vinschen  <corinna@vinschen.de>
 
 	* mmap.cc (mmap_record::alloc_page_map): Don't call VirtualProtect

winsup/cygwin/exceptions.cc

@@ -526,17 +526,21 @@ _cygtls::handle_exceptions (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT
       break;
 
     case STATUS_ACCESS_VIOLATION:
-      if (mmap_is_attached_page (e->ExceptionInformation[1]))
-	{
+      switch (mmap_is_attached_or_noreserve_page (e->ExceptionInformation[1]))
+        {
+	case 2:		/* MAP_NORESERVE page, now commited. */
+	  return 0;
+	case 1:		/* MAP_NORESERVE page, commit failed, or
+			   access to mmap page beyond EOF. */
 	  si.si_signo = SIGBUS;
 	  si.si_code = BUS_OBJERR;
-	}
-      else
-	{
+	  break;
+	default:
 	  MEMORY_BASIC_INFORMATION m;
 	  VirtualQuery ((PVOID) e->ExceptionInformation[1], &m, sizeof m);
 	  si.si_signo = SIGSEGV;
 	  si.si_code = m.State == MEM_FREE ? SEGV_MAPERR : SEGV_ACCERR;
+	  break;
 	}
       break;
 

winsup/cygwin/mmap.cc

@@ -900,13 +900,25 @@ map::del_list (unsigned i)
 }
 
 /* This function is called from exception_handler when a segmentation
-   violation has happened.  The function should return true, if the
-   faulting address (the parameter) is within attached pages.  In this
-   case the exception_handler raises SIGBUS, as demanded by the memory
-   protection extension described in SUSv3 (see the mmap man page).
-   If false is returned, a normal SIGSEGV is raised. */
-bool
-mmap_is_attached_page (ULONG_PTR addr)
+   violation has happened.  We have two cases to check here.
+   
+   First, is it an address within "attached" mmap pages (indicated by
+   the __PROT_ATTACH protection, see there)?  In this case the function
+   returns 1 and the exception_handler raises SIGBUS, as demanded by the
+   memory protection extension described in SUSv3 (see the mmap man
+   page).
+   
+   Second, check if the address is within "noreserve" mmap pages
+   (indicated by MAP_NORESERVE flag).  If so, the function calls
+   VirtualAlloc to commit the page and returns 2.  The exception handler
+   then just returns with 0 and the affected application retries the
+   failing memory access.  If VirtualAlloc fails, the function returns
+   1, so that the exception handler raises a SIGBUS, as described in the
+   MAP_NORESERVE man pages for Linux and Solaris.
+   
+   In any other case 0 is returned and a normal SIGSEGV is raised. */
+int
+mmap_is_attached_or_noreserve_page (ULONG_PTR addr)
 {
   list *map_list;
   long record_idx;
@@ -916,13 +928,16 @@ mmap_is_attached_page (ULONG_PTR addr)
 
   addr = rounddown (addr, pagesize);
   if (!(map_list = mmapped_areas.get_list_by_fd (-1)))
-    return false;
+    return 0;
   if ((record_idx = map_list->search_record ((caddr_t)addr, pagesize,
 					     u_addr, u_len, -1)) < 0)
-    return false;
-  if (!map_list->get_record (record_idx)->attached ())
-    return false;
-  return true;
+    return 0;
+  if (map_list->get_record (record_idx)->attached ())
+    return 1;
+  if (!map_list->get_record (record_idx)->noreserve ())
+    return 0;
+  DWORD new_prot = map_list->get_record (record_idx)->gen_protect ();
+  return VirtualAlloc ((void *)addr, pagesize, MEM_COMMIT, new_prot) ? 2 : 1;
 }
 
 static caddr_t

winsup/cygwin/winsup.h

@@ -299,7 +299,7 @@ size_t getsystempagesize ();
 
 /* mmap functions. */
 void mmap_init ();
-bool mmap_is_attached_page (ULONG_PTR);
+int mmap_is_attached_or_noreserve_page (ULONG_PTR addr);
 
 int winprio_to_nice (DWORD) __attribute__ ((regparm (1)));
 DWORD nice_to_winprio (int &) __attribute__ ((regparm (1)));