Initial revision

1 files changed, 101 insertions, 0 deletions

diff --git a/libpager/pager-memcpy.c b/libpager/pager-memcpy.c
new file mode 100644
index 00000000..86f1e397
--- /dev/null
+++ b/libpager/pager-memcpy.c
@@ -0,0 +1,101 @@
+/* Fault-safe copy into or out of pager-backed memory.
+   Copyright (C) 1996 Free Software Foundation, Inc.
+   Written by Roland McGrath.
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   This program 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
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+#include "pager.h"
+#include <hurd/sigpreempt.h>
+#include <assert.h>
+
+/* Try to copy *SIZE bytes between the region OTHER points to
+   and the region at OFFSET in the pager indicated by PAGER and MEMOBJ.
+   If PROT is VM_PROT_READ, copying is from the pager to OTHER;
+   if PROT contains VM_PROT_WRITE, copying is from OTHER into the pager.
+   *SIZE is always filled in the actual number of bytes successfully copied.
+   Returns an error code if the pager-backed memory faults;
+   if there is no fault, returns 0 and *SIZE will be unchanged.  */
+
+error_t
+pager_memcpy (struct pager *pager, memory_object_t memobj,
+	      vm_offset_t offset, void *other, size_t *size,
+	      vm_prot_t prot)
+{
+  vm_address_t window = 0;
+  vm_size_t windowsize = 8 * vm_page_size;
+  size_t to_copy = *size;
+  error_t err;
+
+  error_t copy (struct hurd_signal_preempter *preempter)
+    {
+      while (to_copy > 0)
+	{
+	  size_t pageoff = offset & (vm_page_size - 1);
+
+	  if (window)
+	    /* Deallocate the old window.  */
+	    vm_deallocate (mach_task_self (), window, windowsize);
+
+	  /* Map in and copy a standard-sized window, unless that is
+	     more than the total left to be copied.  */
+
+	  if (windowsize > pageoff + to_copy)
+	    windowsize = pageoff + to_copy;
+
+	  window = 0;
+	  err = vm_map (mach_task_self (), &window, windowsize, 0, 1,
+			memobj, offset - pageoff, 0,
+			prot, prot, VM_INHERIT_NONE);
+	  if (err)
+	    return;
+
+	  /* Realign the fault preempter for the new mapping window.  */
+	  preempter->first = window;
+	  preempter->last = window + windowsize;
+
+	  if (prot == VM_PROT_READ)
+	    memcpy (other, (const void *) window + pageoff,
+		    windowsize - pageoff);
+	  else
+	    memcpy ((void *) window + pageoff, other, windowsize - pageoff);
+
+	  offset += windowsize - pageoff;
+	  other += windowsize - pageoff;
+	  to_copy -= windowsize - pageoff;
+	}
+      return 0;
+    }
+
+  jmp_buf buf;
+  void fault (int signo, long int sigcode, struct sigcontext *scp)
+    {
+      assert (scp->sc_error == EKERN_MEMORY_ERROR);
+      err = pager_get_error (pager, sigcode - window + offset);
+      to_copy -= sigcode - window;
+      longjmp (buf, 1);
+    }
+
+  if (setjmp (buf) == 0)
+    hurd_catch_signal (sigmask (SIGSEGV) | sigmask (SIGBUS),
+		       window, window + windowsize,
+		       &copy, (sighandler_t) &fault);
+
+  if (window)
+    vm_deallocate (mach_task_self (), window, windowsize);
+
+  *size -= to_copy;
+
+  return err;
+}