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.

8 files changed, 136 insertions, 181 deletions

diff --git a/gdb/mi/mi-cmd-stack.c b/gdb/mi/mi-cmd-stack.c
index efaf49dfbe..acb44a28ee 100644
--- a/gdb/mi/mi-cmd-stack.c
+++ b/gdb/mi/mi-cmd-stack.c
@@ -488,7 +488,6 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
 {
   struct cleanup *old_chain;
   struct ui_out *uiout = current_uiout;
-  struct ui_file *stb;
 
   gdb_assert (!arg->val || !arg->error);
   gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
@@ -511,15 +510,16 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
 					 TYPE_LENGTH (value_type (arg->val))))))
     return;
 
-  stb = mem_fileopen ();
-  old_chain = make_cleanup_ui_file_delete (stb);
+  old_chain = make_cleanup (null_cleanup, NULL);
 
   if (values != PRINT_NO_VALUES || what == all)
     make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
 
-  fputs_filtered (SYMBOL_PRINT_NAME (arg->sym), stb);
+  string_file stb;
+
+  stb.puts (SYMBOL_PRINT_NAME (arg->sym));
   if (arg->entry_kind == print_entry_values_only)
-    fputs_filtered ("@entry", stb);
+    stb.puts ("@entry");
   uiout->field_stream ("name", stb);
 
   if (what == all && SYMBOL_IS_ARGUMENT (arg->sym))
@@ -528,7 +528,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
   if (values == PRINT_SIMPLE_VALUES)
     {
       check_typedef (arg->sym->type);
-      type_print (arg->sym->type, "", stb, -1);
+      type_print (arg->sym->type, "", &stb, -1);
       uiout->field_stream ("type", stb);
     }
 
@@ -546,7 +546,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
 
 	      get_no_prettyformat_print_options (&opts);
 	      opts.deref_ref = 1;
-	      common_val_print (arg->val, stb, 0, &opts,
+	      common_val_print (arg->val, &stb, 0, &opts,
 				language_def (SYMBOL_LANGUAGE (arg->sym)));
 	    }
 	  CATCH (except, RETURN_MASK_ERROR)
@@ -556,8 +556,7 @@ list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
 	  END_CATCH
 	}
       if (error_message != NULL)
-	fprintf_filtered (stb, _("<error reading variable: %s>"),
-			  error_message);
+	stb.printf (_("<error reading variable: %s>"), error_message);
       uiout->field_stream ("value", stb);
     }
 
diff --git a/gdb/mi/mi-common.h b/gdb/mi/mi-common.h
index 0d39cb718a..e82b4a3dab 100644
--- a/gdb/mi/mi-common.h
+++ b/gdb/mi/mi-common.h
@@ -19,6 +19,8 @@
 #ifndef MI_COMMON_H
 #define MI_COMMON_H
 
+struct mi_console_file;
+
 /* Represents the reason why GDB is sending an asynchronous command to
    the front end.  NOTE: When modifing this, don't forget to update
    gdb.texinfo!  */
@@ -51,11 +53,11 @@ const char *async_reason_lookup (enum async_reply_reason reason);
 struct mi_interp
 {
   /* MI's output channels */
-  struct ui_file *out;
-  struct ui_file *err;
-  struct ui_file *log;
-  struct ui_file *targ;
-  struct ui_file *event_channel;
+  mi_console_file *out;
+  mi_console_file *err;
+  mi_console_file *log;
+  mi_console_file *targ;
+  mi_console_file *event_channel;
 
   /* Raw console output.  */
   struct ui_file *raw_stdout;
diff --git a/gdb/mi/mi-console.c b/gdb/mi/mi-console.c
index afb5e94c1a..7c1c2acc37 100644
--- a/gdb/mi/mi-console.c
+++ b/gdb/mi/mi-console.c
@@ -26,118 +26,56 @@
 
 #include "defs.h"
 #include "mi-console.h"
-static ui_file_fputs_ftype mi_console_file_fputs;
-static ui_file_flush_ftype mi_console_file_flush;
-static ui_file_delete_ftype mi_console_file_delete;
-
-struct mi_console_file
-  {
-    int *magic;
-    struct ui_file *raw;
-    struct ui_file *buffer;
-    const char *prefix;
-    char quote;
-  };
-
-/* Use the address of this otherwise-unused global as a magic number
-   identifying this class of ui_file objects.  */
-static int mi_console_file_magic;
 
 /* Create a console that wraps the given output stream RAW with the
    string PREFIX and quoting it with QUOTE.  */
 
-struct ui_file *
-mi_console_file_new (struct ui_file *raw, const char *prefix, char quote)
-{
-  struct ui_file *ui_file = ui_file_new ();
-  struct mi_console_file *mi_console = XNEW (struct mi_console_file);
-
-  mi_console->magic = &mi_console_file_magic;
-  mi_console->raw = raw;
-  mi_console->buffer = mem_fileopen ();
-  mi_console->prefix = prefix;
-  mi_console->quote = quote;
-  set_ui_file_fputs (ui_file, mi_console_file_fputs);
-  set_ui_file_flush (ui_file, mi_console_file_flush);
-  set_ui_file_data (ui_file, mi_console, mi_console_file_delete);
-
-  return ui_file;
-}
-
-static void
-mi_console_file_delete (struct ui_file *file)
-{
-  struct mi_console_file *mi_console
-    = (struct mi_console_file *) ui_file_data (file);
-
-  if (mi_console->magic != &mi_console_file_magic)
-    internal_error (__FILE__, __LINE__,
-		    _("mi_console_file_delete: bad magic number"));
+mi_console_file::mi_console_file (ui_file *raw, const char *prefix, char quote)
+  : m_raw (raw),
+    m_prefix (prefix),
+    m_quote (quote)
+{}
 
-  xfree (mi_console);
-}
-
-static void
-mi_console_file_fputs (const char *buf, struct ui_file *file)
+void
+mi_console_file::write (const char *buf, long length_buf)
 {
-  struct mi_console_file *mi_console
-    = (struct mi_console_file *) ui_file_data (file);
-
-  if (mi_console->magic != &mi_console_file_magic)
-    internal_error (__FILE__, __LINE__,
-		    "mi_console_file_fputs: bad magic number");
-
+  size_t prev_size = m_buffer.size ();
   /* Append the text to our internal buffer.  */
-  fputs_unfiltered (buf, mi_console->buffer);
-  /* Flush when an embedded newline is present anywhere in the buffer.  */
-  if (strchr (buf, '\n') != NULL)
-    gdb_flush (file);
+  m_buffer.write (buf, length_buf);
+  /* Flush when an embedded newline is present anywhere in the
+     buffer.  */
+  if (strchr (m_buffer.c_str () + prev_size, '\n') != NULL)
+    this->flush ();
 }
 
-/* Transform a byte sequence into a console output packet.  */
-
-static void
-mi_console_raw_packet (void *data, const char *buf, long length_buf)
+void
+mi_console_file::flush ()
 {
-  struct mi_console_file *mi_console = (struct mi_console_file *) data;
-
-  if (mi_console->magic != &mi_console_file_magic)
-    internal_error (__FILE__, __LINE__,
-		    _("mi_console_raw_packet: bad magic number"));
+  const std::string &str = m_buffer.string ();
 
-  if (length_buf > 0)
+  /* Transform a byte sequence into a console output packet.  */
+  if (!str.empty ())
     {
-      fputs_unfiltered (mi_console->prefix, mi_console->raw);
-      if (mi_console->quote)
+      size_t length_buf = str.size ();
+      const char *buf = str.data ();
+
+      fputs_unfiltered (m_prefix, m_raw);
+      if (m_quote)
 	{
-	  fputc_unfiltered (mi_console->quote, mi_console->raw);
-	  fputstrn_unfiltered (buf, length_buf,
-			       mi_console->quote, mi_console->raw);
-	  fputc_unfiltered (mi_console->quote, mi_console->raw);
-	  fputc_unfiltered ('\n', mi_console->raw);
+	  fputc_unfiltered (m_quote, m_raw);
+	  fputstrn_unfiltered (buf, length_buf, m_quote, m_raw);
+	  fputc_unfiltered (m_quote, m_raw);
+	  fputc_unfiltered ('\n', m_raw);
 	}
       else
 	{
-	  fputstrn_unfiltered (buf, length_buf, 0, mi_console->raw);
-	  fputc_unfiltered ('\n', mi_console->raw);
+	  fputstrn_unfiltered (buf, length_buf, 0, m_raw);
+	  fputc_unfiltered ('\n', m_raw);
 	}
-      gdb_flush (mi_console->raw);
+      gdb_flush (m_raw);
     }
-}
-
-static void
-mi_console_file_flush (struct ui_file *file)
-{
-  struct mi_console_file *mi_console
-    = (struct mi_console_file *) ui_file_data (file);
-
-  if (mi_console->magic != &mi_console_file_magic)
-    internal_error (__FILE__, __LINE__,
-		    _("mi_console_file_flush: bad magic number"));
-
-  ui_file_put (mi_console->buffer, mi_console_raw_packet, mi_console);
-  ui_file_rewind (mi_console->buffer);
 
+  m_buffer.clear ();
 }
 
 /* Change the underlying stream of the console directly; this is
@@ -145,14 +83,7 @@ mi_console_file_flush (struct ui_file *file)
    logging enable/disable.  */
 
 void
-mi_console_set_raw (struct ui_file *file, struct ui_file *raw)
+mi_console_file::set_raw (ui_file *raw)
 {
-  struct mi_console_file *mi_console
-    = (struct mi_console_file *) ui_file_data (file);
-
-  if (mi_console->magic != &mi_console_file_magic)
-    internal_error (__FILE__, __LINE__,
-		    _("mi_console_file_set_raw: bad magic number"));
-
-  mi_console->raw = raw;
+  m_raw = raw;
 }
diff --git a/gdb/mi/mi-console.h b/gdb/mi/mi-console.h
index 64355a710d..289013f955 100644
--- a/gdb/mi/mi-console.h
+++ b/gdb/mi/mi-console.h
@@ -20,11 +20,37 @@
 #ifndef MI_CONSOLE_H
 #define MI_CONSOLE_H
 
-extern struct ui_file *mi_console_file_new (struct ui_file *raw,
-					    const char *prefix,
-					    char quote);
+/* An output stream for MI.  Wraps a given output stream with a prefix
+   and handles quoting.  This stream is locally buffered.  */
 
-extern void mi_console_set_raw (struct ui_file *console,
-				struct ui_file *raw);
+class mi_console_file : public ui_file
+{
+public:
+  /* Create a console that wraps the given output stream RAW with the
+     string PREFIX and quoting it with QUOTE.  */
+  mi_console_file (ui_file *raw, const char *prefix, char quote);
+
+  /* MI-specific API.  */
+  void set_raw (ui_file *raw);
+
+  /* ui_file-specific methods.  */
+
+  void flush () override;
+
+  void write (const char *buf, long length_buf) override;
+
+private:
+  /* The wrapped raw output stream.  */
+  ui_file *m_raw;
+
+  /* The local buffer.  */
+  string_file m_buffer;
+
+  /* The prefix.  */
+  const char *m_prefix;
+
+  /* The quote char.  */
+  char m_quote;
+};
 
 #endif
diff --git a/gdb/mi/mi-interp.c b/gdb/mi/mi-interp.c
index 76f4f8ceea..f167a535bc 100644
--- a/gdb/mi/mi-interp.c
+++ b/gdb/mi/mi-interp.c
@@ -126,11 +126,11 @@ mi_interpreter_init (struct interp *interp, int top_level)
 
   /* Create MI console channels, each with a different prefix so they
      can be distinguished.  */
-  mi->out = mi_console_file_new (mi->raw_stdout, "~", '"');
-  mi->err = mi_console_file_new (mi->raw_stdout, "&", '"');
+  mi->out = new mi_console_file (mi->raw_stdout, "~", '"');
+  mi->err = new mi_console_file (mi->raw_stdout, "&", '"');
   mi->log = mi->err;
-  mi->targ = mi_console_file_new (mi->raw_stdout, "@", '"');
-  mi->event_channel = mi_console_file_new (mi->raw_stdout, "=", 0);
+  mi->targ = new mi_console_file (mi->raw_stdout, "@", '"');
+  mi->event_channel = new mi_console_file (mi->raw_stdout, "=", 0);
 
   name = interp_name (interp);
   /* INTERP_MI selects the most recent released version.  "mi2" was
@@ -1391,8 +1391,8 @@ mi_set_logging (struct interp *interp, int start_log,
 	 it), and create one based on raw_stdout instead.  */
       if (logfile)
 	{
-	  ui_file_delete (out);
-	  out = tee_file_new (mi->raw_stdout, 0, logfile, 0);
+	  delete out;
+	  out = new tee_file (mi->raw_stdout, false, logfile, false);
 	}
 
       mi->saved_raw_stdout = mi->raw_stdout;
@@ -1404,11 +1404,11 @@ mi_set_logging (struct interp *interp, int start_log,
       mi->saved_raw_stdout = NULL;
     }
   
-  mi_console_set_raw (mi->out, mi->raw_stdout);
-  mi_console_set_raw (mi->err, mi->raw_stdout);
-  mi_console_set_raw (mi->log, mi->raw_stdout);
-  mi_console_set_raw (mi->targ, mi->raw_stdout);
-  mi_console_set_raw (mi->event_channel, mi->raw_stdout);
+  mi->out->set_raw (mi->raw_stdout);
+  mi->err->set_raw (mi->raw_stdout);
+  mi->log->set_raw (mi->raw_stdout);
+  mi->targ->set_raw (mi->raw_stdout);
+  mi->event_channel->set_raw (mi->raw_stdout);
 
   return 1;
 }
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index 57c23ebf5d..b249f2d7cc 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -1267,7 +1267,6 @@ output_register (struct frame_info *frame, int regnum, int format,
   struct value *val = value_of_register (regnum, frame);
   struct cleanup *tuple_cleanup;
   struct value_print_options opts;
-  struct ui_file *stb;
 
   if (skip_unavailable && !value_entirely_available (val))
     return;
@@ -1281,14 +1280,13 @@ output_register (struct frame_info *frame, int regnum, int format,
   if (format == 'r')
     format = 'z';
 
-  stb = mem_fileopen ();
-  make_cleanup_ui_file_delete (stb);
+  string_file stb;
 
   get_formatted_print_options (&opts, format);
   opts.deref_ref = 1;
   val_print (value_type (val),
 	     value_embedded_offset (val), 0,
-	     stb, 0, val, &opts, current_language);
+	     &stb, 0, val, &opts, current_language);
   uiout->field_stream ("value", stb);
 
   do_cleanups (tuple_cleanup);
@@ -1358,15 +1356,10 @@ mi_cmd_data_write_register_values (char *command, char **argv, int argc)
 void
 mi_cmd_data_evaluate_expression (char *command, char **argv, int argc)
 {
-  struct cleanup *old_chain;
   struct value *val;
-  struct ui_file *stb;
   struct value_print_options opts;
   struct ui_out *uiout = current_uiout;
 
-  stb = mem_fileopen ();
-  old_chain = make_cleanup_ui_file_delete (stb);
-
   if (argc != 1)
     error (_("-data-evaluate-expression: "
 	     "Usage: -data-evaluate-expression expression"));
@@ -1375,14 +1368,14 @@ mi_cmd_data_evaluate_expression (char *command, char **argv, int argc)
 
   val = evaluate_expression (expr.get ());
 
+  string_file stb;
+
   /* Print the result of the expression evaluation.  */
   get_user_print_options (&opts);
   opts.deref_ref = 0;
-  common_val_print (val, stb, 0, &opts, current_language);
+  common_val_print (val, &stb, 0, &opts, current_language);
 
   uiout->field_stream ("value", stb);
-
-  do_cleanups (old_chain);
 }
 
 /* This is the -data-read-memory command.
@@ -1522,15 +1515,13 @@ mi_cmd_data_read_memory (char *command, char **argv, int argc)
 
   /* Build the result as a two dimentional table.  */
   {
-    struct ui_file *stream;
-    struct cleanup *cleanup_stream;
     int row;
     int row_byte;
+    struct cleanup *cleanup_list;
 
-    stream = mem_fileopen ();
-    cleanup_stream = make_cleanup_ui_file_delete (stream);
+    string_file stream;
 
-    make_cleanup_ui_out_list_begin_end (uiout, "memory");
+    cleanup_list = make_cleanup_ui_out_list_begin_end (uiout, "memory");
     for (row = 0, row_byte = 0;
 	 row < nr_rows;
 	 row++, row_byte += nr_cols * word_size)
@@ -1557,9 +1548,9 @@ mi_cmd_data_read_memory (char *command, char **argv, int argc)
 	      }
 	    else
 	      {
-		ui_file_rewind (stream);
+		stream.clear ();
 		print_scalar_formatted (&mbuf[col_byte], word_type, &opts,
-					word_asize, stream);
+					word_asize, &stream);
 		uiout->field_stream (NULL, stream);
 	      }
 	  }
@@ -1568,22 +1559,22 @@ mi_cmd_data_read_memory (char *command, char **argv, int argc)
 	  {
 	    int byte;
 
-	    ui_file_rewind (stream);
+	    stream.clear ();
 	    for (byte = row_byte;
 		 byte < row_byte + word_size * nr_cols; byte++)
 	      {
 		if (byte >= nr_bytes)
-		  fputc_unfiltered ('X', stream);
+		  stream.putc ('X');
 		else if (mbuf[byte] < 32 || mbuf[byte] > 126)
-		  fputc_unfiltered (aschar, stream);
+		  stream.putc (aschar);
 		else
-		  fputc_unfiltered (mbuf[byte], stream);
+		  stream.putc (mbuf[byte]);
 	      }
 	    uiout->field_stream ("ascii", stream);
 	  }
 	do_cleanups (cleanup_tuple);
       }
-    do_cleanups (cleanup_stream);
+    do_cleanups (cleanup_list);
   }
 }
 
@@ -2317,15 +2308,12 @@ mi_cmd_execute (struct mi_parse *parse)
   else
     {
       /* FIXME: DELETE THIS.  */
-      struct ui_file *stb;
-
-      stb = mem_fileopen ();
+      string_file stb;
 
-      fputs_unfiltered ("Undefined mi command: ", stb);
-      fputstr_unfiltered (parse->command, '"', stb);
-      fputs_unfiltered (" (missing implementation)", stb);
+      stb.puts ("Undefined mi command: ");
+      stb.putstr (parse->command, '"');
+      stb.puts (" (missing implementation)");
 
-      make_cleanup_ui_file_delete (stb);
       error_stream (stb);
     }
   do_cleanups (cleanup);
@@ -2705,12 +2693,10 @@ print_variable_or_computed (const char *expression, enum print_values values)
 {
   struct cleanup *old_chain;
   struct value *val;
-  struct ui_file *stb;
   struct type *type;
   struct ui_out *uiout = current_uiout;
 
-  stb = mem_fileopen ();
-  old_chain = make_cleanup_ui_file_delete (stb);
+  string_file stb;
 
   expression_up expr = parse_expression (expression);
 
@@ -2719,6 +2705,7 @@ print_variable_or_computed (const char *expression, enum print_values values)
   else
     val = evaluate_expression (expr.get ());
 
+  old_chain = make_cleanup (null_cleanup, NULL);
   if (values != PRINT_NO_VALUES)
     make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
   uiout->field_string ("name", expression);
@@ -2727,7 +2714,7 @@ print_variable_or_computed (const char *expression, enum print_values values)
     {
     case PRINT_SIMPLE_VALUES:
       type = check_typedef (value_type (val));
-      type_print (value_type (val), "", stb, -1);
+      type_print (value_type (val), "", &stb, -1);
       uiout->field_stream ("type", stb);
       if (TYPE_CODE (type) != TYPE_CODE_ARRAY
 	  && TYPE_CODE (type) != TYPE_CODE_STRUCT
@@ -2737,7 +2724,7 @@ print_variable_or_computed (const char *expression, enum print_values values)
 
 	  get_no_prettyformat_print_options (&opts);
 	  opts.deref_ref = 1;
-	  common_val_print (val, stb, 0, &opts, current_language);
+	  common_val_print (val, &stb, 0, &opts, current_language);
 	  uiout->field_stream ("value", stb);
 	}
       break;
@@ -2747,7 +2734,7 @@ print_variable_or_computed (const char *expression, enum print_values values)
 
 	get_no_prettyformat_print_options (&opts);
 	opts.deref_ref = 1;
-	common_val_print (val, stb, 0, &opts, current_language);
+	common_val_print (val, &stb, 0, &opts, current_language);
 	uiout->field_stream ("value", stb);
       }
       break;
diff --git a/gdb/mi/mi-out.c b/gdb/mi/mi-out.c
index 5a5aef95d6..6181140c3b 100644
--- a/gdb/mi/mi-out.c
+++ b/gdb/mi/mi-out.c
@@ -236,23 +236,31 @@ mi_ui_out::close (ui_out_type type)
   m_suppress_field_separator = false;
 }
 
+string_file *
+mi_ui_out::main_stream ()
+{
+  gdb_assert (m_streams.size () == 1);
+
+  return (string_file *) m_streams.back ();
+}
+
 /* Clear the buffer.  */
 
 void
 mi_ui_out::rewind ()
 {
-  ui_file_rewind (m_streams.back ());
+  main_stream ()->clear ();
 }
 
 /* Dump the buffer onto the specified stream.  */
 
 void
-mi_ui_out::put (ui_file *stream)
+mi_ui_out::put (ui_file *where)
 {
-  ui_file *outstream = m_streams.back ();
+  string_file *mi_stream = main_stream ();
 
-  ui_file_put (outstream, ui_file_write_for_put, stream);
-  ui_file_rewind (outstream);
+  where->write (mi_stream->data (), mi_stream->size ());
+  mi_stream->clear ();
 }
 
 /* Return the current MI version.  */
@@ -265,13 +273,12 @@ mi_ui_out::version ()
 
 /* Constructor for an `mi_out_data' object.  */
 
-mi_ui_out::mi_ui_out (int mi_version, ui_file *stream)
+mi_ui_out::mi_ui_out (int mi_version)
 : m_suppress_field_separator (false),
   m_suppress_output (false),
   m_mi_version (mi_version)
 {
-  gdb_assert (stream != NULL);
-
+  string_file *stream = new string_file ();
   m_streams.push_back (stream);
 }
 
@@ -284,9 +291,7 @@ mi_ui_out::~mi_ui_out ()
 mi_ui_out *
 mi_out_new (int mi_version)
 {
-  ui_file *stream = mem_fileopen ();
-
-  return new mi_ui_out (mi_version, stream);
+  return new mi_ui_out (mi_version);
 }
 
 /* Helper function to return the given UIOUT as an mi_ui_out.  It is an error
diff --git a/gdb/mi/mi-out.h b/gdb/mi/mi-out.h
index e82d44d2ce..fea94f20ba 100644
--- a/gdb/mi/mi-out.h
+++ b/gdb/mi/mi-out.h
@@ -30,7 +30,7 @@ class mi_ui_out : public ui_out
 {
 public:
 
-  explicit mi_ui_out (int mi_version, ui_file *stream);
+  explicit mi_ui_out (int mi_version);
   virtual ~mi_ui_out ();
 
   /* MI-specific */
@@ -78,6 +78,11 @@ private:
   void open (const char *name, ui_out_type type);
   void close (ui_out_type type);
 
+  /* Convenience method that returns the MI out's string stream cast
+     to its appropriate type.  Assumes/asserts that output was not
+     redirected.  */
+  string_file *main_stream ();
+
   bool m_suppress_field_separator;
   bool m_suppress_output;
   int m_mi_version;