[RFA] windows-nat.c: Handle ERROR_PARTIAL_COPY in windows_xfer_memory function

["Pierre Muller" <pierre.muller@ics-cnrs.unistra.fr>]

This is the patch that Pedro suggested I send
after his commit to remove deprecated_xfer_memory
in windows-nat.c.

  Pedro suggested that I submit this patch separately
(which I do here)... and with a gdbserver counterpart,
which I don't...

  I tried, but finally realized that given the
read_memory / write_memory functions type defined
in target.h target_ops structure,
there is no way of passing information of partial 
copy and of the length of this partial copy.
Indeed, the comments state that the return value is either 0 for success
or errno...

This is not compatible with returning information that only part of the
request length
was read/written.
  Changing this semantics is too much work with high risks of breaking
things elsewhere...

  

Pierre Muller
GDB pascal language maintainer

PS: the use of plongest function is because I got an warning about %d
used for 'long long integer' type.


2013-09-01  Pierre Muller  <muller@sourceware.org>

	* windows-nat.c (windows_xfer_memory): Fix compilation failure
	by use of plongest function.
	Handle ERROR_PARTIAL_COPY error code.


Index: src/gdb/windows-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/windows-nat.c,v
retrieving revision 1.258
diff -u -p -r1.258 windows-nat.c
--- src/gdb/windows-nat.c	27 Aug 2013 11:36:09 -0000	1.258
+++ src/gdb/windows-nat.c	1 Sep 2013 21:20:51 -0000
@@ -2324,26 +2324,34 @@ windows_xfer_memory (gdb_byte *readbuf, 
 {
   SIZE_T done = 0;
   BOOL success;
+  DWORD lasterror = 0;
 
   if (writebuf != NULL)
     {
-      DEBUG_MEM (("gdb: write target memory, %d bytes at %s\n",
-		  len, core_addr_to_string (memaddr)));
+      DEBUG_MEM (("gdb: write target memory, %s bytes at %s\n",
+		  plongest (len), core_addr_to_string (memaddr)));
       success = WriteProcessMemory (current_process_handle,
 				    (LPVOID) (uintptr_t) memaddr, writebuf,
 				    len, &done);
+      if (!success)
+       lasterror = GetLastError ();
       FlushInstructionCache (current_process_handle,
 			     (LPCVOID) (uintptr_t) memaddr, len);
     }
   else
     {
-      DEBUG_MEM (("gdb: read target memory, %d bytes at %s\n",
-		  len, core_addr_to_string (memaddr)));
+      DEBUG_MEM (("gdb: read target memory, %s bytes at %s\n",
+		  plongest (len), core_addr_to_string (memaddr)));
       success = ReadProcessMemory (current_process_handle,
 				   (LPCVOID) (uintptr_t) memaddr, readbuf,
 				   len, &done);
+      if (!success)
+       lasterror = GetLastError ();
     }
-  return success ? done : TARGET_XFER_E_IO;
+  if (!success && lasterror == ERROR_PARTIAL_COPY && done > 0)
+    return done;
+  else
+    return success ? done : TARGET_XFER_E_IO;
 }
 
 static void