X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=gdb%2Fevent-top.c;h=5feb2928e22eb3e72bb8248a5abae337a28c48b0;hb=9d084466d740e40c655609f9c04b3bb2b9b9ca76;hp=fc1a6c607531b705c9750893937496e2b8f2d88f;hpb=585a46a2d01d25181926329f258f1d1374f93e99;p=deliverable%2Fbinutils-gdb.git

diff --git a/gdb/event-top.c b/gdb/event-top.c
index fc1a6c6075..5feb2928e2 100644
--- a/gdb/event-top.c
+++ b/gdb/event-top.c
@@ -1,6 +1,6 @@
 /* Top level stuff for GDB, the GNU debugger.
 
-   Copyright (C) 1999-2016 Free Software Foundation, Inc.
+   Copyright (C) 1999-2019 Free Software Foundation, Inc.
 
    Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions.
 
@@ -24,7 +24,7 @@
 #include "inferior.h"
 #include "infrun.h"
 #include "target.h"
-#include "terminal.h"		/* for job_control */
+#include "terminal.h"
 #include "event-loop.h"
 #include "event-top.h"
 #include "interps.h"
@@ -32,14 +32,15 @@
 #include "cli/cli-script.h"     /* for reset_command_nest_depth */
 #include "main.h"
 #include "gdbthread.h"
-#include "observer.h"
+#include "observable.h"
 #include "continuations.h"
 #include "gdbcmd.h"		/* for dont_repeat() */
 #include "annotate.h"
 #include "maint.h"
-#include "buffer.h"
+#include "gdbsupport/buffer.h"
 #include "ser-event.h"
 #include "gdb_select.h"
+#include "gdbsupport/gdb-sigmask.h"
 
 /* readline include files.  */
 #include "readline/readline.h"
@@ -48,10 +49,7 @@
 /* readline defines this.  */
 #undef savestring
 
-static void rl_callback_read_char_wrapper (gdb_client_data client_data);
-static void command_line_handler (char *rl);
-static void change_line_handler (void);
-static char *top_level_prompt (void);
+static std::string top_level_prompt ();
 
 /* Signal handlers.  */
 #ifdef SIGQUIT
@@ -71,33 +69,15 @@ static void async_do_nothing (gdb_client_data);
 static void async_disconnect (gdb_client_data);
 #endif
 static void async_float_handler (gdb_client_data);
-#ifdef STOP_SIGNAL
-static void async_stop_sig (gdb_client_data);
+#ifdef SIGTSTP
+static void async_sigtstp_handler (gdb_client_data);
 #endif
 static void async_sigterm_handler (gdb_client_data arg);
 
-/* Readline offers an alternate interface, via callback
-   functions.  These are all included in the file callback.c in the
-   readline distribution.  This file provides (mainly) a function, which
-   the event loop uses as callback (i.e. event handler) whenever an event
-   is detected on the standard input file descriptor.
-   readline_callback_read_char is called (by the GDB event loop) whenever
-   there is a new character ready on the input stream.  This function
-   incrementally builds a buffer internal to readline where it
-   accumulates the line read up to the point of invocation.  In the
-   special case in which the character read is newline, the function
-   invokes a GDB supplied callback routine, which does the processing of
-   a full command line.  This latter routine is the asynchronous analog
-   of the old command_line_input in gdb.  Instead of invoking (and waiting
-   for) readline to read the command line and pass it back to
-   command_loop for processing, the new command_line_handler function has
-   the command line already available as its parameter.  INPUT_HANDLER is
-   to be set to the function that readline will invoke when a complete
-   line of input is ready.  CALL_READLINE is to be set to the function
-   that readline offers as callback to the event_loop.  */
-
-void (*input_handler) (char *);
-void (*call_readline) (gdb_client_data);
+/* Instead of invoking (and waiting for) readline to read the command
+   line and pass it back for processing, we use readline's alternate
+   interface, via callback functions, so that the event loop can react
+   to other event sources while we wait for input.  */
 
 /* Important variables for the event loop.  */
 
@@ -107,15 +87,11 @@ void (*call_readline) (gdb_client_data);
    ezannoni: as of 1999-04-29 I expect that this
    variable will not be used after gdb is changed to use the event
    loop as default engine, and event-top.c is merged into top.c.  */
-int async_command_editing_p;
+bool set_editing_cmd_var;
 
 /* This is used to display the notification of the completion of an
    asynchronous execution command.  */
-int exec_done_display_p = 0;
-
-/* This is the file descriptor for the input stream that GDB uses to
-   read commands from.  */
-int input_fd;
+bool exec_done_display_p = false;
 
 /* Used by the stdin event handler to compensate for missed stdin events.
    Setting this to a non-zero value inside an stdin callback makes the callback
@@ -136,38 +112,125 @@ static struct async_signal_handler *sighup_token;
 static struct async_signal_handler *sigquit_token;
 #endif
 static struct async_signal_handler *sigfpe_token;
-#ifdef STOP_SIGNAL
+#ifdef SIGTSTP
 static struct async_signal_handler *sigtstp_token;
 #endif
 static struct async_signal_handler *async_sigterm_token;
 
-/* This hook is called by rl_callback_read_char_wrapper after each
+/* This hook is called by gdb_rl_callback_read_char_wrapper after each
    character is processed.  */
 void (*after_char_processing_hook) (void);
 
 
-/* Wrapper function for calling into the readline library.  The event
-   loop expects the callback function to have a paramter, while
-   readline expects none.  */
+/* Wrapper function for calling into the readline library.  This takes
+   care of a couple things:
+
+   - The event loop expects the callback function to have a parameter,
+     while readline expects none.
+
+   - Propagation of GDB exceptions/errors thrown from INPUT_HANDLER
+     across readline requires special handling.
+
+   On the exceptions issue:
+
+   DWARF-based unwinding cannot cross code built without -fexceptions.
+   Any exception that tries to propagate through such code will fail
+   and the result is a call to std::terminate.  While some ABIs, such
+   as x86-64, require all code to be built with exception tables,
+   others don't.
+
+   This is a problem when GDB calls some non-EH-aware C library code,
+   that calls into GDB again through a callback, and that GDB callback
+   code throws a C++ exception.  Turns out this is exactly what
+   happens with GDB's readline callback.
+
+   In such cases, we must catch and save any C++ exception that might
+   be thrown from the GDB callback before returning to the
+   non-EH-aware code.  When the non-EH-aware function itself returns
+   back to GDB, we then rethrow the original C++ exception.
+
+   In the readline case however, the right thing to do is to longjmp
+   out of the callback, rather than do a normal return -- there's no
+   way for the callback to return to readline an indication that an
+   error happened, so a normal return would have rl_callback_read_char
+   potentially continue processing further input, redisplay the
+   prompt, etc.  Instead of raw setjmp/longjmp however, we use our
+   sjlj-based TRY/CATCH mechanism, which knows to handle multiple
+   levels of active setjmp/longjmp frames, needed in order to handle
+   the readline callback recursing, as happens with e.g., secondary
+   prompts / queries, through gdb_readline_wrapper.  This must be
+   noexcept in order to avoid problems with mixing sjlj and
+   (sjlj-based) C++ exceptions.  */
+
+static struct gdb_exception
+gdb_rl_callback_read_char_wrapper_noexcept () noexcept
+{
+  struct gdb_exception gdb_expt;
+
+  /* C++ exceptions can't normally be thrown across readline (unless
+     it is built with -fexceptions, but it won't by default on many
+     ABIs).  So we instead wrap the readline call with a sjlj-based
+     TRY/CATCH, and rethrow the GDB exception once back in GDB.  */
+  TRY_SJLJ
+    {
+      rl_callback_read_char ();
+      if (after_char_processing_hook)
+	(*after_char_processing_hook) ();
+    }
+  CATCH_SJLJ (ex, RETURN_MASK_ALL)
+    {
+      gdb_expt = std::move (ex);
+    }
+  END_CATCH_SJLJ
+
+  return gdb_expt;
+}
+
 static void
-rl_callback_read_char_wrapper (gdb_client_data client_data)
+gdb_rl_callback_read_char_wrapper (gdb_client_data client_data)
 {
-  rl_callback_read_char ();
-  if (after_char_processing_hook)
-    (*after_char_processing_hook) ();
+  struct gdb_exception gdb_expt
+    = gdb_rl_callback_read_char_wrapper_noexcept ();
+
+  /* Rethrow using the normal EH mechanism.  */
+  if (gdb_expt.reason < 0)
+    throw_exception (std::move (gdb_expt));
 }
 
-/* Initialize all the necessary variables, start the event loop,
-   register readline, and stdin, start the loop.  The DATA is the
-   interpreter data cookie, ignored for now.  */
+/* GDB's readline callback handler.  Calls the current INPUT_HANDLER,
+   and propagates GDB exceptions/errors thrown from INPUT_HANDLER back
+   across readline.  See gdb_rl_callback_read_char_wrapper.  This must
+   be noexcept in order to avoid problems with mixing sjlj and
+   (sjlj-based) C++ exceptions.  */
 
-void
-cli_command_loop (void *data)
+static void
+gdb_rl_callback_handler (char *rl) noexcept
 {
-  display_gdb_prompt (0);
+  /* This is static to avoid undefined behavior when calling longjmp
+     -- gdb_exception has a destructor with side effects.  */
+  static struct gdb_exception gdb_rl_expt;
+  struct ui *ui = current_ui;
+
+  try
+    {
+      /* Ensure the exception is reset on each call.  */
+      gdb_rl_expt = {};
+      ui->input_handler (gdb::unique_xmalloc_ptr<char> (rl));
+    }
+  catch (gdb_exception &ex)
+    {
+      gdb_rl_expt = std::move (ex);
+    }
 
-  /* Now it's time to start the event loop.  */
-  start_event_loop ();
+  /* If we caught a GDB exception, longjmp out of the readline
+     callback.  There's no other way for the callback to signal to
+     readline that an error happened.  A normal return would have
+     readline potentially continue processing further input, redisplay
+     the prompt, etc.  (This is what GDB historically did when it was
+     a C program.)  Note that since we're long jumping, local variable
+     dtors are NOT run automatically.  */
+  if (gdb_rl_expt.reason < 0)
+    throw_exception_sjlj (gdb_rl_expt);
 }
 
 /* Change the function to be invoked every time there is a character
@@ -175,32 +238,45 @@ cli_command_loop (void *data)
    therefore bypassing readline, and letting gdb handle the input
    itself, via gdb_readline_no_editing_callback.  Also it is used in
    the opposite case in which the user sets editing on again, by
-   restoring readline handling of the input.  */
-static void
-change_line_handler (void)
+   restoring readline handling of the input.
+
+   NOTE: this operates on input_fd, not instream.  If we are reading
+   commands from a file, instream will point to the file.  However, we
+   always read commands from a file with editing off.  This means that
+   the 'set editing on/off' will have effect only on the interactive
+   session.  */
+
+void
+change_line_handler (int editing)
 {
-  /* NOTE: this operates on input_fd, not instream.  If we are reading
-     commands from a file, instream will point to the file.  However in
-     async mode, we always read commands from a file with editing
-     off.  This means that the 'set editing on/off' will have effect
-     only on the interactive session.  */
+  struct ui *ui = current_ui;
+
+  /* We can only have one instance of readline, so we only allow
+     editing on the main UI.  */
+  if (ui != main_ui)
+    return;
 
-  if (async_command_editing_p)
+  /* Don't try enabling editing if the interpreter doesn't support it
+     (e.g., MI).  */
+  if (!interp_supports_command_editing (top_level_interpreter ())
+      || !interp_supports_command_editing (command_interp ()))
+    return;
+
+  if (editing)
     {
+      gdb_assert (ui == main_ui);
+
       /* Turn on editing by using readline.  */
-      call_readline = rl_callback_read_char_wrapper;
-      input_handler = command_line_handler;
+      ui->call_readline = gdb_rl_callback_read_char_wrapper;
     }
   else
     {
       /* Turn off editing by using gdb_readline_no_editing_callback.  */
-      gdb_rl_callback_handler_remove ();
-      call_readline = gdb_readline_no_editing_callback;
-
-      /* Set up the command handler as well, in case we are called as
-         first thing from .gdbinit.  */
-      input_handler = command_line_handler;
+      if (ui->command_editing)
+	gdb_rl_callback_handler_remove ();
+      ui->call_readline = gdb_readline_no_editing_callback;
     }
+  ui->command_editing = editing;
 }
 
 /* The functions below are wrappers for rl_callback_handler_remove and
@@ -221,6 +297,8 @@ static int callback_handler_installed;
 void
 gdb_rl_callback_handler_remove (void)
 {
+  gdb_assert (current_ui == main_ui);
+
   rl_callback_handler_remove ();
   callback_handler_installed = 0;
 }
@@ -232,12 +310,14 @@ gdb_rl_callback_handler_remove (void)
 void
 gdb_rl_callback_handler_install (const char *prompt)
 {
+  gdb_assert (current_ui == main_ui);
+
   /* Calling rl_callback_handler_install resets readline's input
      buffer.  Calling this when we were already processing input
      therefore loses input.  */
   gdb_assert (!callback_handler_installed);
 
-  rl_callback_handler_install (prompt, input_handler);
+  rl_callback_handler_install (prompt, gdb_rl_callback_handler);
   callback_handler_installed = 1;
 }
 
@@ -246,6 +326,8 @@ gdb_rl_callback_handler_install (const char *prompt)
 void
 gdb_rl_callback_handler_reinstall (void)
 {
+  gdb_assert (current_ui == main_ui);
+
   if (!callback_handler_installed)
     {
       /* Passing NULL as prompt argument tells readline to not display
@@ -274,22 +356,23 @@ gdb_rl_callback_handler_reinstall (void)
 void
 display_gdb_prompt (const char *new_prompt)
 {
-  char *actual_gdb_prompt = NULL;
-  struct cleanup *old_chain;
+  std::string actual_gdb_prompt;
 
   annotate_display_prompt ();
 
   /* Reset the nesting depth used when trace-commands is set.  */
   reset_command_nest_depth ();
 
-  old_chain = make_cleanup (free_current_contents, &actual_gdb_prompt);
-
   /* Do not call the python hook on an explicit prompt change as
      passed to this function, as this forms a secondary/local prompt,
      IE, displayed but not set.  */
   if (! new_prompt)
     {
-      if (sync_execution)
+      struct ui *ui = current_ui;
+
+      if (ui->prompt_state == PROMPTED)
+	internal_error (__FILE__, __LINE__, _("double prompt"));
+      else if (ui->prompt_state == PROMPT_BLOCKED)
 	{
 	  /* This is to trick readline into not trying to display the
 	     prompt.  Even though we display the prompt using this
@@ -307,23 +390,24 @@ display_gdb_prompt (const char *new_prompt)
 	     the above two functions.  Calling
 	     rl_callback_handler_remove(), does the job.  */
 
-	  gdb_rl_callback_handler_remove ();
-	  do_cleanups (old_chain);
+	  if (current_ui->command_editing)
+	    gdb_rl_callback_handler_remove ();
 	  return;
 	}
-      else
+      else if (ui->prompt_state == PROMPT_NEEDED)
 	{
 	  /* Display the top level prompt.  */
 	  actual_gdb_prompt = top_level_prompt ();
+	  ui->prompt_state = PROMPTED;
 	}
     }
   else
-    actual_gdb_prompt = xstrdup (new_prompt);
+    actual_gdb_prompt = new_prompt;
 
-  if (async_command_editing_p)
+  if (current_ui->command_editing)
     {
       gdb_rl_callback_handler_remove ();
-      gdb_rl_callback_handler_install (actual_gdb_prompt);
+      gdb_rl_callback_handler_install (actual_gdb_prompt.c_str ());
     }
   /* new_prompt at this point can be the top of the stack or the one
      passed in.  It can't be NULL.  */
@@ -332,26 +416,23 @@ display_gdb_prompt (const char *new_prompt)
       /* Don't use a _filtered function here.  It causes the assumed
          character position to be off, since the newline we read from
          the user is not accounted for.  */
-      fputs_unfiltered (actual_gdb_prompt, gdb_stdout);
+      fputs_unfiltered (actual_gdb_prompt.c_str (), gdb_stdout);
       gdb_flush (gdb_stdout);
     }
-
-  do_cleanups (old_chain);
 }
 
 /* Return the top level prompt, as specified by "set prompt", possibly
-   overriden by the python gdb.prompt_hook hook, and then composed
-   with the prompt prefix and suffix (annotations).  The caller is
-   responsible for freeing the returned string.  */
+   overridden by the python gdb.prompt_hook hook, and then composed
+   with the prompt prefix and suffix (annotations).  */
 
-static char *
+static std::string
 top_level_prompt (void)
 {
   char *prompt;
 
   /* Give observers a chance of changing the prompt.  E.g., the python
      `gdb.prompt_hook' is installed as an observer.  */
-  observer_notify_before_prompt (get_prompt ());
+  gdb::observers::before_prompt.notify (get_prompt ());
 
   prompt = get_prompt ();
 
@@ -364,28 +445,25 @@ top_level_prompt (void)
 	 beginning.  */
       const char suffix[] = "\n\032\032prompt\n";
 
-      return concat (prefix, prompt, suffix, NULL);
+      return std::string (prefix) + prompt + suffix;
     }
 
-  return xstrdup (prompt);
+  return prompt;
 }
 
-/* Get a pointer to the command line buffer.  This is used to
+/* See top.h.  */
+
+struct ui *main_ui;
+struct ui *current_ui;
+struct ui *ui_list;
+
+/* Get a pointer to the current UI's line buffer.  This is used to
    construct a whole line of input from partial input.  */
 
 static struct buffer *
 get_command_line_buffer (void)
 {
-  static struct buffer line_buffer;
-  static int line_buffer_initialized;
-
-  if (!line_buffer_initialized)
-    {
-      buffer_init (&line_buffer);
-      line_buffer_initialized = 1;
-    }
-
-  return &line_buffer;
+  return &current_ui->line_buffer;
 }
 
 /* When there is an event ready on the stdin file descriptor, instead
@@ -396,32 +474,66 @@ get_command_line_buffer (void)
 void
 stdin_event_handler (int error, gdb_client_data client_data)
 {
+  struct ui *ui = (struct ui *) client_data;
+
   if (error)
     {
-      printf_unfiltered (_("error detected on stdin\n"));
-      delete_file_handler (input_fd);
-      /* If stdin died, we may as well kill gdb.  */
-      quit_command ((char *) 0, stdin == instream);
+      /* Switch to the main UI, so diagnostics always go there.  */
+      current_ui = main_ui;
+
+      delete_file_handler (ui->input_fd);
+      if (main_ui == ui)
+	{
+	  /* If stdin died, we may as well kill gdb.  */
+	  printf_unfiltered (_("error detected on stdin\n"));
+	  quit_command ((char *) 0, 0);
+	}
+      else
+	{
+	  /* Simply delete the UI.  */
+	  delete ui;
+	}
     }
   else
     {
-    /* This makes sure a ^C immediately followed by further input is
-       always processed in that order.  E.g,. with input like
-       "^Cprint 1\n", the SIGINT handler runs, marks the async signal
-       handler, and then select/poll may return with stdin ready,
-       instead of -1/EINTR.  The
-       gdb.base/double-prompt-target-event-error.exp test exercises
-       this.  */
+      /* Switch to the UI whose input descriptor woke up the event
+	 loop.  */
+      current_ui = ui;
+
+      /* This makes sure a ^C immediately followed by further input is
+	 always processed in that order.  E.g,. with input like
+	 "^Cprint 1\n", the SIGINT handler runs, marks the async
+	 signal handler, and then select/poll may return with stdin
+	 ready, instead of -1/EINTR.  The
+	 gdb.base/double-prompt-target-event-error.exp test exercises
+	 this.  */
       QUIT;
 
       do
 	{
 	  call_stdin_event_handler_again_p = 0;
-	  (*call_readline) (client_data);
-	} while (call_stdin_event_handler_again_p != 0);
+	  ui->call_readline (client_data);
+	}
+      while (call_stdin_event_handler_again_p != 0);
     }
 }
 
+/* See top.h.  */
+
+void
+ui_register_input_event_handler (struct ui *ui)
+{
+  add_file_handler (ui->input_fd, stdin_event_handler, ui);
+}
+
+/* See top.h.  */
+
+void
+ui_unregister_input_event_handler (struct ui *ui)
+{
+  delete_file_handler (ui->input_fd);
+}
+
 /* Re-enable stdin after the end of an execution command in
    synchronous mode, or after an error from the target, and we aborted
    the exec operation.  */
@@ -429,14 +541,13 @@ stdin_event_handler (int error, gdb_client_data client_data)
 void
 async_enable_stdin (void)
 {
-  if (sync_execution)
+  struct ui *ui = current_ui;
+
+  if (ui->prompt_state == PROMPT_BLOCKED)
     {
-      /* See NOTE in async_disable_stdin().  */
-      /* FIXME: cagney/1999-09-27: Call this before clearing
-	 sync_execution.  Current target_terminal_ours() implementations
-	 check for sync_execution before switching the terminal.  */
-      target_terminal_ours ();
-      sync_execution = 0;
+      target_terminal::ours ();
+      ui_register_input_event_handler (ui);
+      ui->prompt_state = PROMPT_NEEDED;
     }
 }
 
@@ -446,7 +557,10 @@ async_enable_stdin (void)
 void
 async_disable_stdin (void)
 {
-  sync_execution = 1;
+  struct ui *ui = current_ui;
+
+  ui->prompt_state = PROMPT_BLOCKED;
+  delete_file_handler (ui->input_fd);
 }
 
 
@@ -455,38 +569,36 @@ async_disable_stdin (void)
    a whole command.  */
 
 void
-command_handler (char *command)
+command_handler (const char *command)
 {
-  struct cleanup *stat_chain;
-  char *c;
+  struct ui *ui = current_ui;
+  const char *c;
 
-  if (instream == stdin)
+  if (ui->instream == ui->stdin_stream)
     reinitialize_more_filter ();
 
-  stat_chain = make_command_stats_cleanup (1);
+  scoped_command_stats stat_reporter (true);
 
   /* Do not execute commented lines.  */
   for (c = command; *c == ' ' || *c == '\t'; c++)
     ;
   if (c[0] != '#')
     {
-      execute_command (command, instream == stdin);
+      execute_command (command, ui->instream == ui->stdin_stream);
 
       /* Do any commands attached to breakpoint we stopped at.  */
       bpstat_do_actions ();
     }
-
-  do_cleanups (stat_chain);
 }
 
 /* Append RL, an input line returned by readline or one of its
    emulations, to CMD_LINE_BUFFER.  Returns the command line if we
    have a whole command line ready to be processed by the command
    interpreter or NULL if the command line isn't complete yet (input
-   line ends in a backslash).  Takes ownership of RL.  */
+   line ends in a backslash).  */
 
 static char *
-command_line_append_input_line (struct buffer *cmd_line_buffer, char *rl)
+command_line_append_input_line (struct buffer *cmd_line_buffer, const char *rl)
 {
   char *cmd;
   size_t len;
@@ -507,9 +619,6 @@ command_line_append_input_line (struct buffer *cmd_line_buffer, char *rl)
       cmd = cmd_line_buffer->buffer;
     }
 
-  /* Allocated in readline.  */
-  xfree (rl);
-
   return cmd;
 }
 
@@ -526,17 +635,19 @@ command_line_append_input_line (struct buffer *cmd_line_buffer, char *rl)
    If REPEAT, handle command repetitions:
 
      - If the input command line is NOT empty, the command returned is
-       copied into the global 'saved_command_line' var so that it can
-       be repeated later.
+       saved using save_command_line () so that it can be repeated later.
 
-     - OTOH, if the input command line IS empty, return the previously
-       saved command instead of the empty input line.
+     - OTOH, if the input command line IS empty, return the saved
+       command instead of the empty input line.
 */
 
 char *
 handle_line_of_input (struct buffer *cmd_line_buffer,
-		      char *rl, int repeat, char *annotation_suffix)
+		      const char *rl, int repeat,
+		      const char *annotation_suffix)
 {
+  struct ui *ui = current_ui;
+  int from_tty = ui->instream == ui->stdin_stream;
   char *p1;
   char *cmd;
 
@@ -551,7 +662,7 @@ handle_line_of_input (struct buffer *cmd_line_buffer,
      command, but leave ownership of memory to the buffer .  */
   cmd_line_buffer->used_size = 0;
 
-  if (annotation_level > 1 && instream == stdin)
+  if (from_tty && annotation_level > 1)
     {
       printf_unfiltered (("\n\032\032post-"));
       puts_unfiltered (annotation_suffix);
@@ -559,43 +670,41 @@ handle_line_of_input (struct buffer *cmd_line_buffer,
     }
 
 #define SERVER_COMMAND_PREFIX "server "
-  if (startswith (cmd, SERVER_COMMAND_PREFIX))
+  server_command = startswith (cmd, SERVER_COMMAND_PREFIX);
+  if (server_command)
     {
-      /* Note that we don't set `saved_command_line'.  Between this
+      /* Note that we don't call `save_command_line'.  Between this
          and the check in dont_repeat, this insures that repeating
          will still do the right thing.  */
       return cmd + strlen (SERVER_COMMAND_PREFIX);
     }
 
   /* Do history expansion if that is wished.  */
-  if (history_expansion_p && instream == stdin
-      && ISATTY (instream))
+  if (history_expansion_p && from_tty && input_interactive_p (current_ui))
     {
-      char *history_value;
+      char *cmd_expansion;
       int expanded;
 
-      expanded = history_expand (cmd, &history_value);
+      expanded = history_expand (cmd, &cmd_expansion);
+      gdb::unique_xmalloc_ptr<char> history_value (cmd_expansion);
       if (expanded)
 	{
 	  size_t len;
 
 	  /* Print the changes.  */
-	  printf_unfiltered ("%s\n", history_value);
+	  printf_unfiltered ("%s\n", history_value.get ());
 
 	  /* If there was an error, call this function again.  */
 	  if (expanded < 0)
-	    {
-	      xfree (history_value);
-	      return cmd;
-	    }
+	    return cmd;
 
 	  /* history_expand returns an allocated string.  Just replace
 	     our buffer with it.  */
-	  len = strlen (history_value);
+	  len = strlen (history_value.get ());
 	  xfree (buffer_finish (cmd_line_buffer));
-	  cmd_line_buffer->buffer = history_value;
+	  cmd_line_buffer->buffer = history_value.get ();
 	  cmd_line_buffer->buffer_size = len + 1;
-	  cmd = history_value;
+	  cmd = history_value.release ();
 	}
     }
 
@@ -604,7 +713,7 @@ handle_line_of_input (struct buffer *cmd_line_buffer,
   for (p1 = cmd; *p1 == ' ' || *p1 == '\t'; p1++)
     ;
   if (repeat && *p1 == '\0')
-    return saved_command_line;
+    return get_saved_command_line ();
 
   /* Add command to history if appropriate.  Note: lines consisting
      solely of comments are also added to the command history.  This
@@ -613,15 +722,14 @@ handle_line_of_input (struct buffer *cmd_line_buffer,
      and then later fetch it from the value history and remove the
      '#'.  The kill ring is probably better, but some people are in
      the habit of commenting things out.  */
-  if (*cmd != '\0' && input_from_terminal_p ())
+  if (*cmd != '\0' && from_tty && input_interactive_p (current_ui))
     gdb_add_history (cmd);
 
   /* Save into global buffer if appropriate.  */
   if (repeat)
     {
-      xfree (saved_command_line);
-      saved_command_line = xstrdup (cmd);
-      return saved_command_line;
+      save_command_line (cmd);
+      return get_saved_command_line ();
     }
   else
     return cmd;
@@ -636,12 +744,13 @@ handle_line_of_input (struct buffer *cmd_line_buffer,
    function.  */
 
 void
-command_line_handler (char *rl)
+command_line_handler (gdb::unique_xmalloc_ptr<char> &&rl)
 {
   struct buffer *line_buffer = get_command_line_buffer ();
+  struct ui *ui = current_ui;
   char *cmd;
 
-  cmd = handle_line_of_input (line_buffer, rl, instream == stdin, "prompt");
+  cmd = handle_line_of_input (line_buffer, rl.get (), 1, "prompt");
   if (cmd == (char *) EOF)
     {
       /* stdin closed.  The connection with the terminal is gone.
@@ -649,7 +758,7 @@ command_line_handler (char *rl)
 	 hung up but GDB is still alive.  In such a case, we just quit
 	 gdb killing the inferior program too.  */
       printf_unfiltered ("quit\n");
-      execute_command ("quit", stdin == instream);
+      execute_command ("quit", 1);
     }
   else if (cmd == NULL)
     {
@@ -658,8 +767,12 @@ command_line_handler (char *rl)
     }
   else
     {
+      ui->prompt_state = PROMPT_NEEDED;
+
       command_handler (cmd);
-      display_gdb_prompt (0);
+
+      if (ui->prompt_state != PROMPTED)
+	display_gdb_prompt (0);
     }
 }
 
@@ -674,6 +787,7 @@ gdb_readline_no_editing_callback (gdb_client_data client_data)
   char *result;
   struct buffer line_buffer;
   static int done_once = 0;
+  struct ui *ui = current_ui;
 
   buffer_init (&line_buffer);
 
@@ -683,9 +797,9 @@ gdb_readline_no_editing_callback (gdb_client_data client_data)
      stream after '\n'.  If we buffer the input and fgetc drains the
      stream, getting stuff beyond the newline as well, a select, done
      afterwards will not trigger.  */
-  if (!done_once && !ISATTY (instream))
+  if (!done_once && !ISATTY (ui->instream))
     {
-      setbuf (instream, NULL);
+      setbuf (ui->instream, NULL);
       done_once = 1;
     }
 
@@ -701,7 +815,7 @@ gdb_readline_no_editing_callback (gdb_client_data client_data)
     {
       /* Read from stdin if we are executing a user defined command.
          This is the right thing for prompt_for_continue, at least.  */
-      c = fgetc (instream ? instream : stdin);
+      c = fgetc (ui->instream != NULL ? ui->instream : ui->stdin_stream);
 
       if (c == EOF)
 	{
@@ -713,7 +827,7 @@ gdb_readline_no_editing_callback (gdb_client_data client_data)
 	      break;
 	    }
 	  xfree (buffer_finish (&line_buffer));
-	  (*input_handler) (0);
+	  ui->input_handler (NULL);
 	  return;
 	}
 
@@ -730,8 +844,47 @@ gdb_readline_no_editing_callback (gdb_client_data client_data)
 
   buffer_grow_char (&line_buffer, '\0');
   result = buffer_finish (&line_buffer);
-  (*input_handler) (result);
+  ui->input_handler (gdb::unique_xmalloc_ptr<char> (result));
+}
+
+
+/* See event-top.h.  */
+
+thread_local void (*thread_local_segv_handler) (int);
+
+static void handle_sigsegv (int sig);
+
+/* Install the SIGSEGV handler.  */
+static void
+install_handle_sigsegv ()
+{
+#if defined (HAVE_SIGACTION)
+  struct sigaction sa;
+  sa.sa_handler = handle_sigsegv;
+  sigemptyset (&sa.sa_mask);
+#ifdef HAVE_SIGALTSTACK
+  sa.sa_flags = SA_ONSTACK;
+#else
+  sa.sa_flags = 0;
+#endif
+  sigaction (SIGSEGV, &sa, nullptr);
+#else
+  signal (SIGSEGV, handle_sigsegv);
+#endif
 }
+
+/* Handler for SIGSEGV.  */
+
+static void
+handle_sigsegv (int sig)
+{
+  install_handle_sigsegv ();
+
+  if (thread_local_segv_handler == nullptr)
+    abort ();			/* ARI: abort */
+  thread_local_segv_handler (sig);
+}
+
 
 
 /* The serial event associated with the QUIT flag.  set_quit_flag sets
@@ -797,10 +950,12 @@ async_init_signals (void)
   sigfpe_token =
     create_async_signal_handler (async_float_handler, NULL);
 
-#ifdef STOP_SIGNAL
+#ifdef SIGTSTP
   sigtstp_token =
-    create_async_signal_handler (async_stop_sig, NULL);
+    create_async_signal_handler (async_sigtstp_handler, NULL);
 #endif
+
+  install_handle_sigsegv ();
 }
 
 /* See defs.h.  */
@@ -835,7 +990,7 @@ default_quit_handler (void)
 {
   if (check_quit_flag ())
     {
-      if (target_terminal_is_ours ())
+      if (target_terminal::is_ours ())
 	quit ();
       else
 	target_pass_ctrlc ();
@@ -845,51 +1000,6 @@ default_quit_handler (void)
 /* See defs.h.  */
 quit_handler_ftype *quit_handler = default_quit_handler;
 
-/* Data for make_cleanup_override_quit_handler.  Wrap the previous
-   handler pointer in a data struct because it's not portable to cast
-   a function pointer to a data pointer, which is what make_cleanup
-   expects.  */
-struct quit_handler_cleanup_data
-{
-  /* The previous quit handler.  */
-  quit_handler_ftype *prev_handler;
-};
-
-/* Cleanup call that restores the previous quit handler.  */
-
-static void
-restore_quit_handler (void *arg)
-{
-  struct quit_handler_cleanup_data *data
-    = (struct quit_handler_cleanup_data *) arg;
-
-  quit_handler = data->prev_handler;
-}
-
-/* Destructor for the quit handler cleanup.  */
-
-static void
-restore_quit_handler_dtor (void *arg)
-{
-  xfree (arg);
-}
-
-/* See defs.h.  */
-
-struct cleanup *
-make_cleanup_override_quit_handler (quit_handler_ftype *new_quit_handler)
-{
-  struct cleanup *old_chain;
-  struct quit_handler_cleanup_data *data;
-
-  data = XNEW (struct quit_handler_cleanup_data);
-  data->prev_handler = quit_handler;
-  old_chain = make_cleanup_dtor (restore_quit_handler, data,
-				 restore_quit_handler_dtor);
-  quit_handler = new_quit_handler;
-  return old_chain;
-}
-
 /* Handle a SIGINT.  */
 
 void
@@ -949,7 +1059,7 @@ interruptible_select (int n,
 static void
 async_sigterm_handler (gdb_client_data arg)
 {
-  quit_force (NULL, stdin == instream);
+  quit_force (NULL, 0);
 }
 
 /* See defs.h.  */
@@ -1015,63 +1125,57 @@ static void
 async_disconnect (gdb_client_data arg)
 {
 
-  TRY
+  try
     {
       quit_cover ();
     }
 
-  CATCH (exception, RETURN_MASK_ALL)
+  catch (const gdb_exception &exception)
     {
       fputs_filtered ("Could not kill the program being debugged",
 		      gdb_stderr);
       exception_print (gdb_stderr, exception);
     }
-  END_CATCH
 
-  TRY
+  try
     {
       pop_all_targets ();
     }
-  CATCH (exception, RETURN_MASK_ALL)
+  catch (const gdb_exception &exception)
     {
     }
-  END_CATCH
 
   signal (SIGHUP, SIG_DFL);	/*FIXME: ???????????  */
   raise (SIGHUP);
 }
 #endif
 
-#ifdef STOP_SIGNAL
+#ifdef SIGTSTP
 void
-handle_stop_sig (int sig)
+handle_sigtstp (int sig)
 {
   mark_async_signal_handler (sigtstp_token);
-  signal (sig, handle_stop_sig);
+  signal (sig, handle_sigtstp);
 }
 
 static void
-async_stop_sig (gdb_client_data arg)
+async_sigtstp_handler (gdb_client_data arg)
 {
   char *prompt = get_prompt ();
 
-#if STOP_SIGNAL == SIGTSTP
   signal (SIGTSTP, SIG_DFL);
 #if HAVE_SIGPROCMASK
   {
     sigset_t zero;
 
     sigemptyset (&zero);
-    sigprocmask (SIG_SETMASK, &zero, 0);
+    gdb_sigmask (SIG_SETMASK, &zero, 0);
   }
 #elif HAVE_SIGSETMASK
   sigsetmask (0);
 #endif
   raise (SIGTSTP);
-  signal (SIGTSTP, handle_stop_sig);
-#else
-  signal (STOP_SIGNAL, handle_stop_sig);
-#endif
+  signal (SIGTSTP, handle_sigtstp);
   printf_unfiltered ("%s", prompt);
   gdb_flush (gdb_stdout);
 
@@ -1079,7 +1183,7 @@ async_stop_sig (gdb_client_data arg)
      nothing.  */
   dont_repeat ();
 }
-#endif /* STOP_SIGNAL */
+#endif /* SIGTSTP */
 
 /* Tell the event loop what to do if SIGFPE is received.
    See event-signal.c.  */
@@ -1090,7 +1194,7 @@ handle_sigfpe (int sig)
   signal (sig, handle_sigfpe);
 }
 
-/* Event loop will call this functin to process a SIGFPE.  */
+/* Event loop will call this function to process a SIGFPE.  */
 static void
 async_float_handler (gdb_client_data arg)
 {
@@ -1100,78 +1204,66 @@ async_float_handler (gdb_client_data arg)
 }
 
 
-/* Called by do_setshow_command.  */
-void
-set_async_editing_command (char *args, int from_tty,
-			   struct cmd_list_element *c)
-{
-  change_line_handler ();
-}
-
 /* Set things up for readline to be invoked via the alternate
-   interface, i.e. via a callback function (rl_callback_read_char),
-   and hook up instream to the event loop.  */
+   interface, i.e. via a callback function
+   (gdb_rl_callback_read_char), and hook up instream to the event
+   loop.  */
+
 void
-gdb_setup_readline (void)
+gdb_setup_readline (int editing)
 {
+  struct ui *ui = current_ui;
+
   /* This function is a noop for the sync case.  The assumption is
      that the sync setup is ALL done in gdb_init, and we would only
      mess it up here.  The sync stuff should really go away over
      time.  */
   if (!batch_silent)
-    gdb_stdout = stdio_fileopen (stdout);
-  gdb_stderr = stderr_fileopen ();
+    gdb_stdout = new stdio_file (ui->outstream);
+  gdb_stderr = new stderr_file (ui->errstream);
   gdb_stdlog = gdb_stderr;  /* for moment */
   gdb_stdtarg = gdb_stderr; /* for moment */
   gdb_stdtargerr = gdb_stderr; /* for moment */
 
-  /* If the input stream is connected to a terminal, turn on
-     editing.  */
-  if (ISATTY (instream))
+  /* If the input stream is connected to a terminal, turn on editing.
+     However, that is only allowed on the main UI, as we can only have
+     one instance of readline.  */
+  if (ISATTY (ui->instream) && editing && ui == main_ui)
     {
       /* Tell gdb that we will be using the readline library.  This
 	 could be overwritten by a command in .gdbinit like 'set
 	 editing on' or 'off'.  */
-      async_command_editing_p = 1;
-	  
+      ui->command_editing = 1;
+
       /* When a character is detected on instream by select or poll,
 	 readline will be invoked via this callback function.  */
-      call_readline = rl_callback_read_char_wrapper;
+      ui->call_readline = gdb_rl_callback_read_char_wrapper;
+
+      /* Tell readline to use the same input stream that gdb uses.  */
+      rl_instream = ui->instream;
     }
   else
     {
-      async_command_editing_p = 0;
-      call_readline = gdb_readline_no_editing_callback;
+      ui->command_editing = 0;
+      ui->call_readline = gdb_readline_no_editing_callback;
     }
-  
-  /* When readline has read an end-of-line character, it passes the
-     complete line to gdb for processing; command_line_handler is the
-     function that does this.  */
-  input_handler = command_line_handler;
-      
-  /* Tell readline to use the same input stream that gdb uses.  */
-  rl_instream = instream;
-
-  /* Get a file descriptor for the input stream, so that we can
-     register it with the event loop.  */
-  input_fd = fileno (instream);
-
-  /* Now we need to create the event sources for the input file
-     descriptor.  */
-  /* At this point in time, this is the only event source that we
-     register with the even loop.  Another source is going to be the
-     target program (inferior), but that must be registered only when
-     it actually exists (I.e. after we say 'run' or after we connect
-     to a remote target.  */
-  add_file_handler (input_fd, stdin_event_handler, 0);
+
+  /* Now create the event source for this UI's input file descriptor.
+     Another source is going to be the target program (inferior), but
+     that must be registered only when it actually exists (I.e. after
+     we say 'run' or after we connect to a remote target.  */
+  ui_register_input_event_handler (ui);
 }
 
 /* Disable command input through the standard CLI channels.  Used in
    the suspend proc for interpreters that use the standard gdb readline
    interface, like the cli & the mi.  */
+
 void
 gdb_disable_readline (void)
 {
+  struct ui *ui = current_ui;
+
   /* FIXME - It is too heavyweight to delete and remake these every
      time you run an interpreter that needs readline.  It is probably
      better to have the interpreters cache these, which in turn means
@@ -1185,6 +1277,7 @@ gdb_disable_readline (void)
   gdb_stdtargerr = NULL;
 #endif
 
-  gdb_rl_callback_handler_remove ();
-  delete_file_handler (input_fd);
+  if (ui->command_editing)
+    gdb_rl_callback_handler_remove ();
+  delete_file_handler (ui->input_fd);
 }