Use unique_xmalloc_ptr for read_string

This changes read_string's "buffer" out-parameter to be a
unique_xmalloc_ptr, then updates the users.  This allows for the
removal of some cleanups.

I chose unique_xmalloc_ptr rather than byte_vector here due to the way
Guile unwinding seems to work.

Tested by the buildbot.

gdb/ChangeLog
2018-06-18  Tom Tromey  <tom@tromey.com>

	* valprint.h (read_string): Update.
	* valprint.c (read_string): Change type of "buffer".
	(val_print_string): Update.
	* python/py-value.c (valpy_string): Update.
	* language.h (struct language_defn) <la_get_string>: Change
	type of "buffer".
	(default_get_string, c_get_string): Update.
	* language.c (default_get_string): Change type of "buffer".
	* guile/scm-value.c (gdbscm_value_to_string): Update.
	* c-lang.c (c_get_string): Change type of "buffer".

1 files changed, 4 insertions, 8 deletions

diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c
index 30a0082da85..1b880fa1917 100644
--- a/gdb/python/py-value.c
+++ b/gdb/python/py-value.c
@@ -517,9 +517,8 @@ static PyObject *
 valpy_string (PyObject *self, PyObject *args, PyObject *kw)
 {
   int length = -1;
-  gdb_byte *buffer;
+  gdb::unique_xmalloc_ptr<gdb_byte> buffer;
   struct value *value = ((value_object *) self)->value;
-  PyObject *unicode;
   const char *encoding = NULL;
   const char *errors = NULL;
   const char *user_encoding = NULL;
@@ -542,12 +541,9 @@ valpy_string (PyObject *self, PyObject *args, PyObject *kw)
   END_CATCH
 
   encoding = (user_encoding && *user_encoding) ? user_encoding : la_encoding;
-  unicode = PyUnicode_Decode ((const char *) buffer,
-			      length * TYPE_LENGTH (char_type),
-			      encoding, errors);
-  xfree (buffer);
-
-  return unicode;
+  return PyUnicode_Decode ((const char *) buffer.get (),
+			   length * TYPE_LENGTH (char_type),
+			   encoding, errors);
 }
 
 /* A helper function that implements the various cast operators.  */