[PATCH] windows-nat.c: Don't install a deprecated_xfer_memory method.

[Pierre Muller]

Hi Pedro,

  I think that your patch can be further enhanced by this change:
  ReadProcessMemory and WriteProcessMemory 
function both fail and report ERROR_PARTIAL_COPY
in GetLastError
if only a part of the requested memory was read/written.

  Adding partial memory read/writes to windows native
allows for instance to get the true location at which a 
memory chuck is not available anymore instead of the
start position of the read/write attempt if
it crosses over to region not readable or not writable.


Pierre



@@ -2315,20 +2364,23 @@ windows_stop (ptid_t ptid)
   registers_changed ();                /* refresh register state */
 }

-static int
-windows_xfer_memory (CORE_ADDR memaddr, gdb_byte *our, int len,
-                  int write, struct mem_attrib *mem,
-                  struct target_ops *target)
+static LONGEST
+windows_xfer_memory (gdb_byte *readbuf, const gdb_byte *writebuf,
+                    ULONGEST memaddr, LONGEST len)
 {
   SIZE_T done = 0;
-  if (write)
+  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)));
-      if (!WriteProcessMemory (current_process_handle,
-                              (LPVOID) (uintptr_t) memaddr, our,
-                              len, &done))
-       done = 0;
+      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);
     }
@@ -2336,12 +2388,17 @@ windows_xfer_memory (CORE_ADDR memaddr,
     {
       DEBUG_MEM (("gdb: read target memory, %d bytes at %s\n",
                  len, core_addr_to_string (memaddr)));
-      if (!ReadProcessMemory (current_process_handle,
-                             (LPCVOID) (uintptr_t) memaddr, our,
-                             len, &done))
-       done = 0;
+      success = ReadProcessMemory (current_process_handle,
+                                  (LPCVOID) (uintptr_t) memaddr, readbuf,
+                                  len, &done);
+      if (!success)
+       lasterror = GetLastError ();
     }
-  return done;
+  if (!success && lasterror == ERROR_PARTIAL_COPY && done > 0)
+    return done;
+  else
+    return success ? done : TARGET_XFER_E_IO;
+
 }

 static void

> -----Message d'origine-----
> De : gdb-patches-owner@sourceware.org [mailto:gdb-patches-
> owner@sourceware.org] De la part de Pedro Alves
> Envoyé : vendredi 23 août 2013 20:13
> À : gdb-patches@sourceware.org
> Objet : [PATCH] windows-nat.c: Don't install a deprecated_xfer_memory
> method.
> 
> This stops another target from installing a
> target_ops->deprecated_xfer_memory method.
> 
> I'm not setup for proper Cygwin/Windows testing, but I managed to
> cross build gdb from GNU/Linux, and copy the resulting binary to a
> Windows box.  Running that gdb on itself worked well enough to run to
> main, so I can't imagine any regression from this.  Does anyone want
> (and is willing) to run this through the testsuite?
> 
> gdb/
> 2013-08-23  Pedro Alves  <palves@redhat.com>
> 
> 	* windows-nat.c (windows_xfer_memory): Adjust prototype to follow
> 	xfer_partial's interface.  Return TARGET_XFER_E_IO on error.
> 	(windows_xfer_partial): Defer TARGET_OBJECT_MEMORY handling to
> 	windows_xfer_memory directly.
> 	(init_windows_ops): Don't install a deprecated_xfer_memory method.
> ---
>  gdb/windows-nat.c |   36 ++++++++++++++----------------------
>  1 file changed, 14 insertions(+), 22 deletions(-)
> 
> diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
> index 9a0241b..a4e7107 100644
> --- a/gdb/windows-nat.c
> +++ b/gdb/windows-nat.c
> @@ -2315,20 +2315,20 @@ windows_stop (ptid_t ptid)
>    registers_changed ();		/* refresh register state */
>  }
> 
> -static int
> -windows_xfer_memory (CORE_ADDR memaddr, gdb_byte *our, int len,
> -		   int write, struct mem_attrib *mem,
> -		   struct target_ops *target)
> +static LONGEST
> +windows_xfer_memory (gdb_byte *readbuf, const gdb_byte *writebuf,
> +		     ULONGEST memaddr, LONGEST len)
>  {
>    SIZE_T done = 0;
> -  if (write)
> +  BOOL success;
> +
> +  if (writebuf != NULL)
>      {
>        DEBUG_MEM (("gdb: write target memory, %d bytes at %s\n",
>  		  len, core_addr_to_string (memaddr)));
> -      if (!WriteProcessMemory (current_process_handle,
> -			       (LPVOID) (uintptr_t) memaddr, our,
> -			       len, &done))
> -	done = 0;
> +      success = WriteProcessMemory (current_process_handle,
> +				    (LPVOID) (uintptr_t) memaddr, writebuf,
> +				    len, &done);
>        FlushInstructionCache (current_process_handle,
>  			     (LPCVOID) (uintptr_t) memaddr, len);
>      }
> @@ -2336,12 +2336,11 @@ windows_xfer_memory (CORE_ADDR memaddr, gdb_byte
> *our, int len,
>      {
>        DEBUG_MEM (("gdb: read target memory, %d bytes at %s\n",
>  		  len, core_addr_to_string (memaddr)));
> -      if (!ReadProcessMemory (current_process_handle,
> -			      (LPCVOID) (uintptr_t) memaddr, our,
> -			      len, &done))
> -	done = 0;
> +      success = ReadProcessMemory (current_process_handle,
> +				   (LPCVOID) (uintptr_t) memaddr, readbuf,
> +				   len, &done);
>      }
> -  return done;
> +  return success ? done : TARGET_XFER_E_IO;
>  }
> 
>  static void
> @@ -2442,13 +2441,7 @@ windows_xfer_partial (struct target_ops *ops, enum
> target_object object,
>    switch (object)
>      {
>      case TARGET_OBJECT_MEMORY:
> -      if (readbuf)
> -	return (*ops->deprecated_xfer_memory) (offset, readbuf,
> -					       len, 0/*read*/, NULL, ops);
> -      if (writebuf)
> -	return (*ops->deprecated_xfer_memory) (offset, (gdb_byte *) writebuf,
> -					       len, 1/*write*/, NULL, ops);
> -      return -1;
> +      return windows_xfer_memory (readbuf, writebuf, offset, len);
> 
>      case TARGET_OBJECT_LIBRARIES:
>        return windows_xfer_shared_libraries (ops, object, annex, readbuf,
> @@ -2502,7 +2495,6 @@ init_windows_ops (void)
>    windows_ops.to_fetch_registers = windows_fetch_inferior_registers;
>    windows_ops.to_store_registers = windows_store_inferior_registers;
>    windows_ops.to_prepare_to_store = windows_prepare_to_store;
> -  windows_ops.deprecated_xfer_memory = windows_xfer_memory;
>    windows_ops.to_xfer_partial = windows_xfer_partial;
>    windows_ops.to_files_info = windows_files_info;
>    windows_ops.to_insert_breakpoint = memory_insert_breakpoint;