Introduce ui_file_as_string

ui_file_as_string is a variant of ui_file_xstrdup that returns a
std::string instead of a xmalloc'ed char *.  The idea is using the new
function to eliminate "make_cleanup (xfree, ...)"  cleanups
throughout.

Following patches will make use of this.

gdb/ChangeLog:
2016-11-08  Pedro Alves  <palves@redhat.com>

	* ui-file.c (do_ui_file_as_string, ui_file_as_string): New
	functions.
	* ui-file.h: Include <string>.
	(ui_file_as_string): New declaration.

1 files changed, 22 insertions, 0 deletions

diff --git a/gdb/ui-file.c b/gdb/ui-file.c
index a977f89..31228a3 100644
--- a/gdb/ui-file.c
+++ b/gdb/ui-file.c
@@ -356,6 +356,28 @@ ui_file_xstrdup (struct ui_file *file, long *length)
   return acc.buffer;
 }
 
+/* ui_file utility function for converting a ``struct ui_file'' into a
+   std:string.  */
+
+static void
+do_ui_file_as_string (void *context, const char *buffer, long length)
+{
+  std::string *str = (std::string *) context;
+
+  *str = std::string (buffer, length);
+}
+
+/* See ui-file.h.  */
+
+std::string
+ui_file_as_string (struct ui_file *file)
+{
+  std::string str;
+
+  ui_file_put (file, do_ui_file_as_string, &str);
+  return str;
+}
+
 static void
 do_ui_file_obsavestring (void *context, const char *buffer, long length)
 {