[python] add argument to Value.string

[Tom Tromey <tromey at redhat dot com>]

This adds an "errors" argument to Value.string, to let callers control
the python string decoder, just as they would with string.decode.

Tom

2008-12-02  Tom Tromey  <tromey@redhat.com>

	* python/python-value.c (valpy_string): Add "errors" argument.

2008-12-02  Tom Tromey  <tromey@redhat.com>

	* gdb.texinfo (Values From Inferior): Document new string
	argument.

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index dfc19aa..1e7a22d 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -18247,7 +18247,7 @@ The result @code{bar} will be a @code{gdb.Value} object holding the
 value pointed to by @code{foo}.
 @end defmethod
 
-@defmethod Value string @r{[}encoding@r{]}
+@defmethod Value string @r{[}encoding @r{[}errors@r{]}@r{]}
 If this @code{gdb.Value} represents a string, then this method
 converts the contents to a Python string.  Otherwise, this method will
 throw an exception.
@@ -18263,8 +18263,13 @@ by a zero of the appropriate width.
 If the optional @var{encoding} argument is given, it must be a string
 naming the encoding of the string in the @code{gdb.Value}.  The Python
 codec machinery will be used to convert the string.  If @var{encoding}
-is not given, then the @code{target-charset} (@pxref{Character Sets})
-will be used.
+is not given, or if @var{encoding} is the empty string, then either
+the @code{target-charset} (@pxref{Character Sets}) will be used, or a
+language-specific encoding will be used, if the current language is
+able to supply one.
+
+The optional @var{errors} argument is the same as the corresponding
+argument to Python's @code{string.decode} method.
 @end defmethod
 
 @defmethod Value type
diff --git a/gdb/python/python-value.c b/gdb/python/python-value.c
index 5a7fae0..342cf28 100644
--- a/gdb/python/python-value.c
+++ b/gdb/python/python-value.c
@@ -165,10 +165,11 @@ valpy_string (PyObject *self, PyObject *args)
   volatile struct gdb_exception except;
   PyObject *unicode;
   const char *encoding = NULL;
+  const char *errors = NULL;
   const char *user_encoding = NULL;
   const char *la_encoding = NULL;
 
-  if (!PyArg_ParseTuple (args, "|s", &user_encoding))
+  if (!PyArg_ParseTuple (args, "|ss", &user_encoding, &errors))
     return NULL;
 
   TRY_CATCH (except, RETURN_MASK_ALL)
@@ -187,8 +188,8 @@ valpy_string (PyObject *self, PyObject *args)
       return NULL;
     }
 
-  encoding = user_encoding? user_encoding : la_encoding;
-  unicode = PyUnicode_Decode (buffer, length, encoding, NULL);
+  encoding = (user_encoding && *user_encoding) ? user_encoding : la_encoding;
+  unicode = PyUnicode_Decode (buffer, length, encoding, errors);
   xfree (buffer);
 
   return unicode;