Eliminate make_cleanup_ui_file_delete / make ui_file a class hierarchy

This patch starts from the desire to eliminate
make_cleanup_ui_file_delete, but then goes beyond.  It makes ui_file &
friends a real C++ class hierarchy, and switches temporary
ui_file-like objects to stack-based allocation.

- mem_fileopen -> string_file

mem_fileopen is replaced with a new string_file class that is treated
as a value class created on the stack.  This alone eliminates most
make_cleanup_ui_file_delete calls, and, simplifies code a whole lot
(diffstat shows around 1k loc dropped.)

string_file's internal buffer is a std::string, thus the "string" in
the name.  This simplifies the implementation much, compared to
mem_fileopen, which managed growing its internal buffer manually.

- ui_file_as_string, ui_file_strdup, ui_file_obsavestring all gone

The new string_file class has a string() method that provides direct
writable access to the internal std::string buffer.  This replaced
ui_file_as_string, which forced a copy of the same data the stream had
inside.  With direct access via a writable reference, we can instead
move the string out of the string_stream, avoiding deep string
copying.

Related, ui_file_xstrdup calls are replaced with xstrdup'ping the
stream's string, and ui_file_obsavestring is replaced by
obstack_copy0.

With all those out of the way, getting rid of the weird ui_file_put
mechanism was possible.

- New ui_file::printf, ui_file::puts, etc. methods

These simplify / clarify client code.  I considered splitting
client-code changes, like these, e.g.:

  -  stb = mem_fileopen ();
  -  fprintf_unfiltered (stb, "%s%s%s",
  -		      _("The valid values are:\n"),
  -		      regdesc,
  -		      _("The default is \"std\"."));
  +  string_file stb;
  +  stb.printf ("%s%s%s",
  +	      _("The valid values are:\n"),
  +	      regdesc,
  +	      _("The default is \"std\"."));

In two steps, with the first step leaving fprintf_unfiltered (etc.)
calls in place, and only afterwards do a pass to change all those to
call stb.printf etc..  I didn't do that split, because (when I tried),
it turned out to be pointless make-work: the first pass would have to
touch the fprintf_unfiltered line anyway, to replace "stb" with
"&stb".

- gdb_fopen replaced with stack-based objects

This avoids the need for cleanups or unique_ptr's.  I.e., this:

      struct ui_file *file = gdb_fopen (filename, "w");
      if (filename == NULL)
 	perror_with_name (filename);
      cleanups = make_cleanup_ui_file_delete (file);
      // use file.
      do_cleanups (cleanups);

is replaced with this:

      stdio_file file;
      if (!file.open (filename, "w"))
 	perror_with_name (filename);
      // use file.

- odd contorsions in null_file_write / null_file_fputs around when to
  call to_fputs / to_write eliminated.

- Global null_stream object

A few places that were allocating a ui_file in order to print to
"nowhere" are adjusted to instead refer to a new 'null_stream' global
stream.

- TUI's tui_sfileopen eliminated.  TUI's ui_file much simplified

The TUI's ui_file was serving a dual purpose.  It supported being used
as string buffer, and supported being backed by a stdio FILE.  The
string buffer part is gone, replaced by using of string_file.  The
'FILE *' support is now much simplified, by making the TUI's ui_file
inherit from stdio_file.

gdb/ChangeLog:
2017-02-02  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (type_as_string): Use string_file.
	* ada-valprint.c (ada_print_floating): Use string_file.
	* ada-varobj.c (ada_varobj_scalar_image)
	(ada_varobj_get_value_image): Use string_file.
	* aix-thread.c (aix_thread_extra_thread_info): Use string_file.
	* arm-tdep.c (_initialize_arm_tdep): Use string_printf.
	* breakpoint.c (update_inserted_breakpoint_locations)
	(insert_breakpoint_locations, reattach_breakpoints)
	(print_breakpoint_location, print_one_detail_ranged_breakpoint)
	(print_it_watchpoint): Use string_file.
	(save_breakpoints): Use stdio_file.
	* c-exp.y (oper): Use string_file.
	* cli/cli-logging.c (set_logging_redirect): Use ui_file_up and
	tee_file.
	(pop_output_files): Use delete.
	(handle_redirections): Use stdio_file and tee_file.
	* cli/cli-setshow.c (do_show_command): Use string_file.
	* compile/compile-c-support.c (c_compute_program): Use
	string_file.
	* compile/compile-c-symbols.c (generate_vla_size): Take a
	'string_file &' instead of a 'ui_file *'.
	(generate_c_for_for_one_variable): Take a 'string_file &' instead
	of a 'ui_file *'.  Use string_file.
	(generate_c_for_variable_locations): Take a 'string_file &'
	instead of a 'ui_file *'.
	* compile/compile-internal.h (generate_c_for_for_one_variable):
	Take a 'string_file &' instead of a 'ui_file *'.
	* compile/compile-loc2c.c (push, pushf, unary, binary)
	(print_label, pushf_register_address, pushf_register)
	(do_compile_dwarf_expr_to_c): Take a 'string_file &' instead of a
	'ui_file *'.  Adjust.
	* compile/compile.c (compile_to_object): Use string_file.
	* compile/compile.h (compile_dwarf_expr_to_c)
	(compile_dwarf_bounds_to_c): Take a 'string_file &' instead of a
	'ui_file *'.
	* cp-support.c (inspect_type): Use string_file and obstack_copy0.
	(replace_typedefs_qualified_name): Use string_file and
	obstack_copy0.
	* disasm.c (gdb_pretty_print_insn): Use string_file.
	(gdb_disassembly): Adjust reference the null_stream global.
	(do_ui_file_delete): Delete.
	(gdb_insn_length): Use null_stream.
	* dummy-frame.c (maintenance_print_dummy_frames): Use stdio_file.
	* dwarf2loc.c (dwarf2_compile_property_to_c)
	(locexpr_generate_c_location, loclist_generate_c_location): Take a
	'string_file &' instead of a 'ui_file *'.
	* dwarf2loc.h (dwarf2_compile_property_to_c): Likewise.
	* dwarf2read.c (do_ui_file_peek_last): Delete.
	(dwarf2_compute_name): Use string_file.
	* event-top.c (gdb_setup_readline): Use stdio_file.
	* gdbarch.sh (verify_gdbarch): Use string_file.
	* gdbtypes.c (safe_parse_type): Use null_stream.
	* guile/scm-breakpoint.c (gdbscm_breakpoint_commands): Use
	string_file.
	* guile/scm-disasm.c (gdbscm_print_insn_from_port): Take a
	'string_file *' instead of a 'ui_file *'.
	(gdbscm_arch_disassemble): Use string_file.
	* guile/scm-frame.c (frscm_print_frame_smob): Use string_file.
	* guile/scm-ports.c (class ioscm_file_port): Now a class that
	inherits from ui_file.
	(ioscm_file_port_delete, ioscm_file_port_rewind)
	(ioscm_file_port_put): Delete.
	(ioscm_file_port_write): Rename to ...
	(ioscm_file_port::write): ... this.  Remove file_port_magic
	checks.
	(ioscm_file_port_new): Delete.
	(ioscm_with_output_to_port_worker): Use ioscm_file_port and
	ui_file_up.
	* guile/scm-type.c (tyscm_type_name): Use string_file.
	* guile/scm-value.c (vlscm_print_value_smob, gdbscm_value_print):
	Use string_file.
	* infcmd.c (print_return_value_1): Use string_file.
	* infrun.c (print_target_wait_results): Use string_file.
	* language.c (add_language): Use string_file.
	* location.c (explicit_to_string_internal): Use string_file.
	* main.c (captured_main_1): Use null_file.
	* maint.c (maintenance_print_architecture): Use stdio_file.
	* mi/mi-cmd-stack.c (list_arg_or_local): Use string_file.
	* mi/mi-common.h (struct mi_interp) <out, err, log, targ,
	event_channel>: Change type to mi_console_file pointer.
	* mi/mi-console.c (mi_console_file_fputs, mi_console_file_flush)
	(mi_console_file_delete): Delete.
	(struct mi_console_file): Delete.
	(mi_console_file_magic): Delete.
	(mi_console_file_new): Delete.
	(mi_console_file::mi_console_file): New.
	(mi_console_file_delete): Delete.
	(mi_console_file_fputs): Delete.
	(mi_console_file::write): New.
	(mi_console_raw_packet): Delete.
	(mi_console_file::flush): New.
	(mi_console_file_flush): Delete.
	(mi_console_set_raw): Rename to ...
	(mi_console_file::set_raw): ... this.
	* mi/mi-console.h (class mi_console_file): New class.
	(mi_console_file_new, mi_console_set_raw): Delete.
	* mi/mi-interp.c (mi_interpreter_init): Use mi_console_file.
	(mi_set_logging): Use delete and tee_file.  Adjust.
	* mi/mi-main.c (output_register): Use string_file.
	(mi_cmd_data_evaluate_expression): Use string_file.
	(mi_cmd_data_read_memory): Use string_file.
	(mi_cmd_execute, print_variable_or_computed): Use string_file.
	* mi/mi-out.c (mi_ui_out::main_stream): New.
	(mi_ui_out::rewind): Use main_stream and
	string_file.
	(mi_ui_out::put): Use main_stream and string_file.
	(mi_ui_out::mi_ui_out): Remove 'stream' parameter.
	Allocate a 'string_file' instead.
	(mi_out_new): Don't allocate a mem_fileopen stream here.
	* mi/mi-out.h (mi_ui_out::mi_ui_out): Remove 'stream' parameter.
	(mi_ui_out::main_stream): Declare method.
	* printcmd.c (eval_command): Use string_file.
	* psymtab.c (maintenance_print_psymbols): Use stdio_file.
	* python/py-arch.c (archpy_disassemble): Use string_file.
	* python/py-breakpoint.c (bppy_get_commands): Use string_file.
	* python/py-frame.c (frapy_str): Use string_file.
	* python/py-framefilter.c (py_print_type, py_print_single_arg):
	Use string_file.
	* python/py-type.c (typy_str): Use string_file.
	* python/py-unwind.c (unwind_infopy_str): Use string_file.
	* python/py-value.c (valpy_str): Use string_file.
	* record-btrace.c (btrace_insn_history): Use string_file.
	* regcache.c (regcache_print): Use stdio_file.
	* reggroups.c (maintenance_print_reggroups): Use stdio_file.
	* remote.c (escape_buffer): Use string_file.
	* rust-lang.c (rust_get_disr_info): Use string_file.
	* serial.c (serial_open_ops_1): Use stdio_file.
	(do_serial_close): Use delete.
	* stack.c (print_frame_arg): Use string_file.
	(print_frame_args): Remove local mem_fileopen stream, not used.
	(print_frame): Use string_file.
	* symmisc.c (maintenance_print_symbols): Use stdio_file.
	* symtab.h (struct symbol_computed_ops) <generate_c_location>:
	Take a 'string_file *' instead of a 'ui_file *'.
	* top.c (new_ui): Use stdio_file and stderr_file.
	(free_ui): Use delete.
	(execute_command_to_string): Use string_file.
	(quit_confirm): Use string_file.
	* tracepoint.c (collection_list::append_exp): Use string_file.
	* tui/tui-disasm.c (tui_disassemble): Use string_file.
	* tui/tui-file.c: Don't include "ui-file.h".
	(enum streamtype, struct tui_stream): Delete.
	(tui_file_new, tui_file_delete, tui_fileopen, tui_sfileopen)
	(tui_file_isatty, tui_file_rewind, tui_file_put): Delete.
	(tui_file::tui_file): New method.
	(tui_file_fputs): Delete.
	(tui_file_get_strbuf): Delete.
	(tui_file::puts): New method.
	(tui_file_adjust_strbuf): Delete.
	(tui_file_flush): Delete.
	(tui_file::flush): New method.
	* tui/tui-file.h: Tweak intro comment.
	Include ui-file.h.
	(tui_fileopen, tui_sfileopen, tui_file_get_strbuf)
	(tui_file_adjust_strbuf): Delete declarations.
	(class tui_file): New class.
	* tui/tui-io.c (tui_initialize_io): Use tui_file.
	* tui/tui-regs.c (tui_restore_gdbout): Use delete.
	(tui_register_format): Use string_stream.
	* tui/tui-stack.c (tui_make_status_line): Use string_file.
	(tui_get_function_from_frame): Use string_file.
	* typeprint.c (type_to_string): Use string_file.
	* ui-file.c (struct ui_file, ui_file_magic, ui_file_new): Delete.
	(null_stream): New global.
	(ui_file_delete): Delete.
	(ui_file::ui_file): New.
	(null_file_isatty): Delete.
	(ui_file::~ui_file): New.
	(null_file_rewind): Delete.
	(ui_file::printf): New.
	(null_file_put): Delete.
	(null_file_flush): Delete.
	(ui_file::putstr): New.
	(null_file_write): Delete.
	(ui_file::putstrn): New.
	(null_file_read): Delete.
	(ui_file::putc): New.
	(null_file_fputs): Delete.
	(null_file_write_async_safe): Delete.
	(ui_file::vprintf): New.
	(null_file_delete): Delete.
	(null_file::write): New.
	(null_file_fseek): Delete.
	(null_file::puts): New.
	(ui_file_data): Delete.
	(null_file::write_async_safe): New.
	(gdb_flush, ui_file_isatty): Adjust.
	(ui_file_put, ui_file_rewind): Delete.
	(ui_file_write): Adjust.
	(ui_file_write_for_put): Delete.
	(ui_file_write_async_safe, ui_file_read): Adjust.
	(ui_file_fseek): Delete.
	(fputs_unfiltered): Adjust.
	(set_ui_file_flush, set_ui_file_isatty, set_ui_file_rewind)
	(set_ui_file_put, set_ui_file_write, set_ui_file_write_async_safe)
	(set_ui_file_read, set_ui_file_fputs, set_ui_file_fseek)
	(set_ui_file_data): Delete.
	(string_file::~string_file, string_file::write)
	(struct accumulated_ui_file, do_ui_file_xstrdup, ui_file_xstrdup)
	(do_ui_file_as_string, ui_file_as_string): Delete.
	(do_ui_file_obsavestring, ui_file_obsavestring): Delete.
	(struct mem_file): Delete.
	(mem_file_new): Delete.
	(stdio_file::stdio_file): New.
	(mem_file_delete): Delete.
	(stdio_file::stdio_file): New.
	(mem_fileopen): Delete.
	(stdio_file::~stdio_file): New.
	(mem_file_rewind): Delete.
	(stdio_file::set_stream): New.
	(mem_file_put): Delete.
	(stdio_file::open): New.
	(mem_file_write): Delete.
	(stdio_file_magic, struct stdio_file): Delete.
	(stdio_file_new, stdio_file_delete, stdio_file_flush): Delete.
	(stdio_file::flush): New.
	(stdio_file_read): Rename to ...
	(stdio_file::read): ... this.  Adjust.
	(stdio_file_write): Rename to ...
	(stdio_file::write): ... this.  Adjust.
	(stdio_file_write_async_safe): Rename to ...
	(stdio_file::write_async_safe) ... this.  Adjust.
	(stdio_file_fputs): Rename to ...
	(stdio_file::puts) ... this.  Adjust.
	(stdio_file_isatty): Delete.
	(stdio_file_fseek): Delete.
	(stdio_file::isatty): New.
	(stderr_file_write): Rename to ...
	(stderr_file::write) ... this.  Adjust.
	(stderr_file_fputs): Rename to ...
	(stderr_file::puts) ... this.  Adjust.
	(stderr_fileopen, stdio_fileopen, gdb_fopen): Delete.
	(stderr_file::stderr_file): New.
	(tee_file_magic): Delete.
	(struct tee_file): Delete.
	(tee_file::tee_file): New.
	(tee_file_new): Delete.
	(tee_file::~tee_file): New.
	(tee_file_delete): Delete.
	(tee_file_flush): Rename to ...
	(tee_file::flush): ... this.  Adjust.
	(tee_file_write): Rename to ...
	(tee_file::write): ... this.  Adjust.
	(tee_file::write_async_safe): New.
	(tee_file_fputs): Rename to ...
	(tee_file::puts): ... this.  Adjust.
	(tee_file_isatty): Rename to ...
	(tee_file::isatty): ... this.  Adjust.
	* ui-file.h (struct obstack, struct ui_file): Don't
	forward-declare.
	(ui_file_new, ui_file_flush_ftype, set_ui_file_flush)
	(ui_file_write_ftype)
	(set_ui_file_write, ui_file_fputs_ftype, set_ui_file_fputs)
	(ui_file_write_async_safe_ftype, set_ui_file_write_async_safe)
	(ui_file_read_ftype, set_ui_file_read, ui_file_isatty_ftype)
	(set_ui_file_isatty, ui_file_rewind_ftype, set_ui_file_rewind)
	(ui_file_put_method_ftype, ui_file_put_ftype, set_ui_file_put)
	(ui_file_delete_ftype, set_ui_file_data, ui_file_fseek_ftype)
	(set_ui_file_fseek): Delete.
	(ui_file_data, ui_file_delete, ui_file_rewind)
	(struct ui_file): New.
	(ui_file_up): New.
	(class null_file): New.
	(null_stream): Declare.
	(ui_file_write_for_put, ui_file_put): Delete.
	(ui_file_xstrdup, ui_file_as_string, ui_file_obsavestring):
	Delete.
	(ui_file_fseek, mem_fileopen, stdio_fileopen, stderr_fileopen)
	(gdb_fopen, tee_file_new): Delete.
	(struct string_file): New.
	(struct stdio_file): New.
	(stdio_file_up): New.
	(struct stderr_file): New.
	(class tee_file): New.
	* ui-out.c (ui_out::field_stream): Take a 'string_file &' instead
	of a 'ui_file *'.  Adjust.
	* ui-out.h (class ui_out) <field_stream>: Likewise.
	* utils.c (do_ui_file_delete, make_cleanup_ui_file_delete)
	(null_stream): Delete.
	(error_stream): Take a 'string_file &' instead of a 'ui_file *'.
	Adjust.
	* utils.h (struct ui_file): Delete forward declaration..
	(make_cleanup_ui_file_delete, null_stream): Delete declarations.
	(error_stream): Take a 'string_file &' instead of a
	'ui_file *'.
	* varobj.c (varobj_value_get_print_value): Use string_file.
	* xtensa-tdep.c (xtensa_verify_config): Use string_file.
	* gdbarch.c: Regenerate.

7 files changed, 41 insertions, 102 deletions

diff --git a/gdb/python/py-arch.c b/gdb/python/py-arch.c
index 13cc9baf639..8d0ec3330cc 100644
--- a/gdb/python/py-arch.c
+++ b/gdb/python/py-arch.c
@@ -193,54 +193,38 @@ archpy_disassemble (PyObject *self, PyObject *args, PyObject *kw)
        || (end_obj == NULL && count_obj == NULL && pc == start);)
     {
       int insn_len = 0;
-      struct ui_file *memfile = mem_fileopen ();
       gdbpy_ref insn_dict (PyDict_New ());
 
       if (insn_dict == NULL)
-        {
-          ui_file_delete (memfile);
-
-          return NULL;
-        }
+	return NULL;
       if (PyList_Append (result_list.get (), insn_dict.get ()))
-        {
-          ui_file_delete (memfile);
+	return NULL;  /* PyList_Append Sets the exception.  */
 
-          return NULL;  /* PyList_Append Sets the exception.  */
-        }
+      string_file stb;
 
       TRY
         {
-          insn_len = gdb_print_insn (gdbarch, pc, memfile, NULL);
+          insn_len = gdb_print_insn (gdbarch, pc, &stb, NULL);
         }
       CATCH (except, RETURN_MASK_ALL)
         {
-          ui_file_delete (memfile);
-
 	  gdbpy_convert_exception (except);
 	  return NULL;
         }
       END_CATCH
 
-      std::string as = ui_file_as_string (memfile);
-
       if (PyDict_SetItemString (insn_dict.get (), "addr",
                                 gdb_py_long_from_ulongest (pc))
           || PyDict_SetItemString (insn_dict.get (), "asm",
-                                   PyString_FromString (!as.empty ()
-							? as.c_str ()
+                                   PyString_FromString (!stb.empty ()
+							? stb.c_str ()
 							: "<unknown>"))
           || PyDict_SetItemString (insn_dict.get (), "length",
                                    PyInt_FromLong (insn_len)))
-        {
-          ui_file_delete (memfile);
-
-          return NULL;
-        }
+	return NULL;
 
       pc += insn_len;
       i++;
-      ui_file_delete (memfile);
     }
 
   return result_list.release ();
diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index f268b2bb446..ac649000ab8 100644
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -485,19 +485,16 @@ bppy_get_commands (PyObject *self, void *closure)
   gdbpy_breakpoint_object *self_bp = (gdbpy_breakpoint_object *) self;
   struct breakpoint *bp = self_bp->bp;
   long length;
-  struct ui_file *string_file;
   PyObject *result;
-  struct cleanup *chain;
 
   BPPY_REQUIRE_VALID (self_bp);
 
   if (! self_bp->bp->commands)
     Py_RETURN_NONE;
 
-  string_file = mem_fileopen ();
-  chain = make_cleanup_ui_file_delete (string_file);
+  string_file stb;
 
-  current_uiout->redirect (string_file);
+  current_uiout->redirect (&stb);
   TRY
     {
       print_command_lines (current_uiout, breakpoint_commands (bp), 0);
@@ -505,17 +502,13 @@ bppy_get_commands (PyObject *self, void *closure)
   CATCH (except, RETURN_MASK_ALL)
     {
       current_uiout->redirect (NULL);
-      do_cleanups (chain);
       gdbpy_convert_exception (except);
       return NULL;
     }
   END_CATCH
 
   current_uiout->redirect (NULL);
-  std::string cmdstr = ui_file_as_string (string_file);
-  result = host_string_to_python_string (cmdstr.c_str ());
-  do_cleanups (chain);
-  return result;
+  return host_string_to_python_string (stb.c_str ());
 }
 
 /* Python function to get the breakpoint type.  */
diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index 048e7c1a88a..8f5ddd04f0b 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -80,13 +80,10 @@ frame_object_to_frame_info (PyObject *obj)
 static PyObject *
 frapy_str (PyObject *self)
 {
-  PyObject *result;
-  struct ui_file *strfile;
+  string_file strfile;
 
-  strfile = mem_fileopen ();
-  fprint_frame_id (strfile, ((frame_object *) self)->frame_id);
-  std::string s = ui_file_as_string (strfile);
-  return PyString_FromString (s.c_str ());
+  fprint_frame_id (&strfile, ((frame_object *) self)->frame_id);
+  return PyString_FromString (strfile.c_str ());
 }
 
 /* Implementation of gdb.Frame.is_valid (self) -> Boolean.
diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
index bdd991158a3..9dc01bad14a 100644
--- a/gdb/python/py-framefilter.c
+++ b/gdb/python/py-framefilter.c
@@ -208,15 +208,11 @@ py_print_type (struct ui_out *out, struct value *val)
 
   TRY
     {
-      struct ui_file *stb;
-      struct cleanup *cleanup;
-
-      stb = mem_fileopen ();
-      cleanup = make_cleanup_ui_file_delete (stb);
       check_typedef (value_type (val));
-      type_print (value_type (val), "", stb, -1);
+
+      string_file stb;
+      type_print (value_type (val), "", &stb, -1);
       out->field_stream ("type", stb);
-      do_cleanups (cleanup);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -280,14 +276,10 @@ py_print_value (struct ui_out *out, struct value *val,
     {
       TRY
 	{
-	  struct ui_file *stb;
-	  struct cleanup *cleanup;
+	  string_file stb;
 
-	  stb = mem_fileopen ();
-	  cleanup = make_cleanup_ui_file_delete (stb);
-	  common_val_print (val, stb, indent, opts, language);
+	  common_val_print (val, &stb, indent, opts, language);
 	  out->field_stream ("value", stb);
-	  do_cleanups (cleanup);
 	}
       CATCH (except, RETURN_MASK_ALL)
 	{
@@ -393,26 +385,22 @@ py_print_single_arg (struct ui_out *out,
 	 entry value options.  */
       if (fa != NULL)
 	{
-	  struct ui_file *stb;
+	  string_file stb;
 
-	  stb = mem_fileopen ();
-	  make_cleanup_ui_file_delete (stb);
-	  fprintf_symbol_filtered (stb, SYMBOL_PRINT_NAME (fa->sym),
+	  fprintf_symbol_filtered (&stb, SYMBOL_PRINT_NAME (fa->sym),
 				   SYMBOL_LANGUAGE (fa->sym),
 				   DMGL_PARAMS | DMGL_ANSI);
 	  if (fa->entry_kind == print_entry_values_compact)
 	    {
-	      fputs_filtered ("=", stb);
+	      stb.puts ("=");
 
-	      fprintf_symbol_filtered (stb, SYMBOL_PRINT_NAME (fa->sym),
+	      fprintf_symbol_filtered (&stb, SYMBOL_PRINT_NAME (fa->sym),
 				       SYMBOL_LANGUAGE (fa->sym),
 				       DMGL_PARAMS | DMGL_ANSI);
 	    }
 	  if (fa->entry_kind == print_entry_values_only
 	      || fa->entry_kind == print_entry_values_compact)
-	    {
-	      fputs_filtered ("@entry", stb);
-	    }
+	    stb.puts ("@entry");
 	  out->field_stream ("name", stb);
 	}
       else
diff --git a/gdb/python/py-type.c b/gdb/python/py-type.c
index 7862829f176..f6e8dd6e155 100644
--- a/gdb/python/py-type.c
+++ b/gdb/python/py-type.c
@@ -967,22 +967,13 @@ typy_template_argument (PyObject *self, PyObject *args)
 static PyObject *
 typy_str (PyObject *self)
 {
-  std::string thetype;
+  string_file thetype;
   PyObject *result;
 
   TRY
     {
-      struct cleanup *old_chain;
-      struct ui_file *stb;
-
-      stb = mem_fileopen ();
-      old_chain = make_cleanup_ui_file_delete (stb);
-
-      LA_PRINT_TYPE (type_object_to_type (self), "", stb, -1, 0,
+      LA_PRINT_TYPE (type_object_to_type (self), "", &thetype, -1, 0,
 		     &type_print_raw_options);
-
-      thetype = ui_file_as_string (stb);
-      do_cleanups (old_chain);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -990,10 +981,8 @@ typy_str (PyObject *self)
     }
   END_CATCH
 
-  result = PyUnicode_Decode (thetype.c_str (), thetype.length (),
-			     host_charset (), NULL);
-
-  return result;
+  return PyUnicode_Decode (thetype.c_str (), thetype.size (),
+			   host_charset (), NULL);
 }
 
 /* Implement the richcompare method.  */
diff --git a/gdb/python/py-unwind.c b/gdb/python/py-unwind.c
index 690412a0ecb..d1b63adfbcd 100644
--- a/gdb/python/py-unwind.c
+++ b/gdb/python/py-unwind.c
@@ -198,12 +198,11 @@ pyuw_object_attribute_to_pointer (PyObject *pyo, const char *attr_name,
 static PyObject *
 unwind_infopy_str (PyObject *self)
 {
-  struct ui_file *strfile = mem_fileopen ();
   unwind_info_object *unwind_info = (unwind_info_object *) self;
-  PyObject *result;
+  string_file stb;
 
-  fprintf_unfiltered (strfile, "Frame ID: ");
-  fprint_frame_id (strfile, unwind_info->frame_id);
+  stb.puts ("Frame ID: ");
+  fprint_frame_id (&stb, unwind_info->frame_id);
   {
     char *sep = "";
     int i;
@@ -211,18 +210,18 @@ unwind_infopy_str (PyObject *self)
     saved_reg *reg;
 
     get_user_print_options (&opts);
-    fprintf_unfiltered (strfile, "\nSaved registers: (");
+    stb.printf ("\nSaved registers: (");
     for (i = 0; VEC_iterate (saved_reg, unwind_info->saved_regs, i, reg); i++)
       {
         struct value *value = value_object_to_value (reg->value);
 
-        fprintf_unfiltered (strfile, "%s(%d, ", sep, reg->number);
+        stb.printf ("%s(%d, ", sep, reg->number);
         if (value != NULL)
           {
             TRY
               {
-                value_print (value, strfile, &opts);
-                fprintf_unfiltered (strfile, ")");
+                value_print (value, &stb, &opts);
+                stb.puts (")");
               }
             CATCH (except, RETURN_MASK_ALL)
               {
@@ -231,16 +230,13 @@ unwind_infopy_str (PyObject *self)
             END_CATCH
           }
         else
-          fprintf_unfiltered (strfile, "<BAD>)");
+          stb.puts ("<BAD>)");
         sep = ", ";
       }
-    fprintf_unfiltered (strfile, ")");
+    stb.puts (")");
   }
 
-  std::string s = ui_file_as_string (strfile);
-  result = PyString_FromString (s.c_str ());
-  ui_file_delete (strfile);
-  return result;
+  return PyString_FromString (stb.c_str ());
 }
 
 /* Create UnwindInfo instance for given PendingFrame and frame ID.
diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c
index 8f3164b53c4..8e4d06d8683 100644
--- a/gdb/python/py-value.c
+++ b/gdb/python/py-value.c
@@ -867,23 +867,17 @@ valpy_call (PyObject *self, PyObject *args, PyObject *keywords)
 static PyObject *
 valpy_str (PyObject *self)
 {
-  std::string s;
-  PyObject *result;
   struct value_print_options opts;
 
   get_user_print_options (&opts);
   opts.deref_ref = 0;
 
+  string_file stb;
+
   TRY
     {
-      struct ui_file *stb = mem_fileopen ();
-      struct cleanup *old_chain = make_cleanup_ui_file_delete (stb);
-
-      common_val_print (((value_object *) self)->value, stb, 0,
+      common_val_print (((value_object *) self)->value, &stb, 0,
 			&opts, python_language);
-      s = ui_file_as_string (stb);
-
-      do_cleanups (old_chain);
     }
   CATCH (except, RETURN_MASK_ALL)
     {
@@ -891,9 +885,7 @@ valpy_str (PyObject *self)
     }
   END_CATCH
 
-  result = PyUnicode_Decode (s.c_str (), s.length (), host_charset (), NULL);
-
-  return result;
+  return PyUnicode_Decode (stb.c_str (), stb.size (), host_charset (), NULL);
 }
 
 /* Implements gdb.Value.is_optimized_out.  */