gdb: make extract_integer take an array_view

I think it would make sense for extract_integer, extract_signed_integer
and extract_unsigned_integer to take an array_view.  This way, when we
extract an integer, we can validate that we don't overflow the buffer
passed by the caller (e.g. ask to extract a 4-byte integer but pass a
2-byte buffer).

 - Change extract_integer to take an array_view
 - Add overloads of extract_signed_integer and extract_unsigned_integer
   that take array_views.  Keep the existing versions so we don't
   need to change all callers, but make them call the array_view
   versions.

This shortens some places like:

  result = extract_unsigned_integer (value_contents (result_val).data (),
				     TYPE_LENGTH (value_type (result_val)),
				     byte_order);

into

  result = extract_unsigned_integer (value_contents (result_val), byte_order);

value_contents returns an array view that is of length
`TYPE_LENGTH (value_type (result_val))` already, so the length is
implicitly communicated through the array view.

Change-Id: Ic1c1f98c88d5c17a8486393af316f982604d6c95

1 files changed, 20 insertions, 3 deletions

diff --git a/gdb/defs.h b/gdb/defs.h
index f7e09ec..3b6a0e6 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -63,6 +63,7 @@
 
 #include "gdbsupport/host-defs.h"
 #include "gdbsupport/enum-flags.h"
+#include "gdbsupport/array-view.h"
 
 /* Scope types enumerator.  List the types of scopes the compiler will
    accept.  */
@@ -500,20 +501,36 @@ enum symbol_needs_kind
 /* In findvar.c.  */
 
 template<typename T, typename = RequireLongest<T>>
-T extract_integer (const gdb_byte *addr, int len, enum bfd_endian byte_order);
+T extract_integer (gdb::array_view<const gdb_byte>, enum bfd_endian byte_order);
+
+static inline LONGEST
+extract_signed_integer (gdb::array_view<const gdb_byte> buf,
+			enum bfd_endian byte_order)
+{
+  return extract_integer<LONGEST> (buf, byte_order);
+}
 
 static inline LONGEST
 extract_signed_integer (const gdb_byte *addr, int len,
 			enum bfd_endian byte_order)
 {
-  return extract_integer<LONGEST> (addr, len, byte_order);
+  return extract_signed_integer (gdb::array_view<const gdb_byte> (addr, len),
+				 byte_order);
+}
+
+static inline ULONGEST
+extract_unsigned_integer (gdb::array_view<const gdb_byte> buf,
+			  enum bfd_endian byte_order)
+{
+  return extract_integer<ULONGEST> (buf, byte_order);
 }
 
 static inline ULONGEST
 extract_unsigned_integer (const gdb_byte *addr, int len,
 			  enum bfd_endian byte_order)
 {
-  return extract_integer<ULONGEST> (addr, len, byte_order);
+  return extract_unsigned_integer (gdb::array_view<const gdb_byte> (addr, len),
+				   byte_order);
 }
 
 extern int extract_long_unsigned_integer (const gdb_byte *, int,