[PATCH 5/7] target: consider byte size when reading/writing memory

[Simon Marchi <simon.marchi@ericsson.com>]

If we are reading/writing from a memory object, the length represents
the number of "addresses" to read/write, so the byte size needs to be
taken into account when allocating memory on gdb's side.

gdb/ChangeLog:

	* target.c (target_read): Consider byte size when reading from a
	memory object.
	(read_memory_robust): Same.
	(read_whatever_is_readable): Same.
	(target_write_with_progress): Consider byte size when
	writing to a memory object.
	* target.h (target_read): Update documentation.
	(target_write): Add documentation.
---
 gdb/target.c | 35 ++++++++++++++++++++++++++++-------
 gdb/target.h | 26 ++++++++++++++++++++++----
 2 files changed, 50 insertions(+), 11 deletions(-)

diff --git a/gdb/target.c b/gdb/target.c
index bd9a0eb..d3ada16 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -1589,6 +1589,15 @@ target_read (struct target_ops *ops,
 	     ULONGEST offset, LONGEST len)
 {
   LONGEST xfered_total = 0;
+  int byte_size = 1;
+
+  /* If we are reading a memory object, find the length of a byte for that
+     architecture.  */
+  if (object == TARGET_OBJECT_MEMORY
+      || object == TARGET_OBJECT_STACK_MEMORY
+      || object == TARGET_OBJECT_CODE_MEMORY
+      || object == TARGET_OBJECT_RAW_MEMORY)
+    byte_size = gdbarch_memory_byte_size (target_gdbarch());
 
   while (xfered_total < len)
     {
@@ -1596,7 +1605,7 @@ target_read (struct target_ops *ops,
       enum target_xfer_status status;
 
       status = target_read_partial (ops, object, annex,
-				    buf + xfered_total,
+				    buf + xfered_total * byte_size,
 				    offset + xfered_total, len - xfered_total,
 				    &xfered_partial);
 
@@ -1639,6 +1648,7 @@ target_read (struct target_ops *ops,
 static void
 read_whatever_is_readable (struct target_ops *ops,
 			   const ULONGEST begin, const ULONGEST end,
+			   int byte_size,
 			   VEC(memory_read_result_s) **result)
 {
   gdb_byte *buf = xmalloc (end - begin);
@@ -1705,7 +1715,7 @@ read_whatever_is_readable (struct target_ops *ops,
 	}
 
       xfer = target_read (ops, TARGET_OBJECT_MEMORY, NULL,
-			  buf + (first_half_begin - begin),
+			  buf + (first_half_begin - begin) * byte_size,
 			  first_half_begin,
 			  first_half_end - first_half_begin);
 
@@ -1741,8 +1751,9 @@ read_whatever_is_readable (struct target_ops *ops,
       /* The [current_end, end) range has been read.  */
       LONGEST region_len = end - current_end;
 
-      r.data = xmalloc (region_len);
-      memcpy (r.data, buf + current_end - begin, region_len);
+      r.data = xmalloc (region_len * byte_size);
+      memcpy (r.data, buf + (current_end - begin) * byte_size,
+	      region_len * byte_size);
       r.begin = current_end;
       r.end = end;
       xfree (buf);
@@ -1769,6 +1780,7 @@ read_memory_robust (struct target_ops *ops,
 		    const ULONGEST offset, const LONGEST len)
 {
   VEC(memory_read_result_s) *result = 0;
+  int byte_size = gdbarch_memory_byte_size (target_gdbarch ());
 
   LONGEST xfered_total = 0;
   while (xfered_total < len)
@@ -1794,7 +1806,7 @@ read_memory_robust (struct target_ops *ops,
       else
 	{
 	  LONGEST to_read = min (len - xfered_total, region_len);
-	  gdb_byte *buffer = (gdb_byte *)xmalloc (to_read);
+	  gdb_byte *buffer = (gdb_byte *) xmalloc (to_read * byte_size);
 
 	  LONGEST xfered_partial =
 	      target_read (ops, TARGET_OBJECT_MEMORY, NULL,
@@ -1806,7 +1818,7 @@ read_memory_robust (struct target_ops *ops,
 	      /* Got an error reading full chunk.  See if maybe we can read
 		 some subrange.  */
 	      xfree (buffer);
-	      read_whatever_is_readable (ops, offset + xfered_total,
+	      read_whatever_is_readable (ops, offset + xfered_total, byte_size,
 					 offset + xfered_total + to_read, &result);
 	      xfered_total += to_read;
 	    }
@@ -1836,6 +1848,15 @@ target_write_with_progress (struct target_ops *ops,
 			    void (*progress) (ULONGEST, void *), void *baton)
 {
   LONGEST xfered_total = 0;
+  int byte_size = 1;
+
+  /* If we are writing to a memory object, find the length of a byte for that
+     architecture.  */
+  if (object == TARGET_OBJECT_MEMORY
+      || object == TARGET_OBJECT_STACK_MEMORY
+      || object == TARGET_OBJECT_CODE_MEMORY
+      || object == TARGET_OBJECT_RAW_MEMORY)
+    byte_size = gdbarch_memory_byte_size (target_gdbarch ());
 
   /* Give the progress callback a chance to set up.  */
   if (progress)
@@ -1847,7 +1868,7 @@ target_write_with_progress (struct target_ops *ops,
       enum target_xfer_status status;
 
       status = target_write_partial (ops, object, annex,
-				     (gdb_byte *) buf + xfered_total,
+				     buf + xfered_total * byte_size,
 				     offset + xfered_total, len - xfered_total,
 				     &xfered_partial);
 
diff --git a/gdb/target.h b/gdb/target.h
index ad50f07..c72f8b4 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -259,12 +259,15 @@ typedef enum target_xfer_status
 			     ULONGEST len,
 			     ULONGEST *xfered_len);
 
-/* Request that OPS transfer up to LEN 8-bit bytes of the target's
-   OBJECT.  The OFFSET, for a seekable object, specifies the
-   starting point.  The ANNEX can be used to provide additional
+/* Request that OPS transfer up to LEN bytes of the target's OBJECT.  When
+   reading from a memory object, the byte size is architecture dependent and
+   can be found using gdbarch_memory_byte_size.  Otherwise, a byte is 1 octet
+   long.  BUF should point to a buffer large enough to hold the read data,
+   taking into account the byte size.  The OFFSET, for a seekable object,
+   specifies the starting point.  The ANNEX can be used to provide additional
    data-specific information to the target.
 
-   Return the number of bytes actually transfered, or a negative error
+   Return the number of bytes actually transferred, or a negative error
    code (an 'enum target_xfer_error' value) if the transfer is not
    supported or otherwise fails.  Return of a positive value less than
    LEN indicates that no further transfer is possible.  Unlike the raw
@@ -294,6 +297,21 @@ extern VEC(memory_read_result_s)* read_memory_robust (struct target_ops *ops,
 						      const ULONGEST offset,
 						      const LONGEST len);
 
+/* Request that OPS transfer up to LEN bytes from BUF to the target's
+   OBJECT.  When writing to a memory object, the byte size is
+   architecture dependent and can be found using
+   gdbarch_memory_byte_size.  Otherwise, a byte is 1 octet long. The
+   OFFSET, for a seekable object, specifies the starting point.  The
+   ANNEX can be used to provide additional data-specific information to
+   the target.
+
+   Return the number of bytes actually transferred, or a negative error
+   code (an 'enum target_xfer_status' value) if the transfer is not
+   supported or otherwise fails.  Return of a positive value less than
+   LEN indicates that no further transfer is possible.  Unlike the raw
+   to_xfer_partial interface, callers of these functions do not need to
+   retry partial transfers.  */
+
 extern LONGEST target_write (struct target_ops *ops,
 			     enum target_object object,
 			     const char *annex, const gdb_byte *buf,
-- 
2.1.4