Convert inflow to type-safe registry API

This changes inflow.c to use the type-safe registry API.  This fixes a
latent bug in swap_terminal_info, which previously said:

  terminal_info *info_a
    = (terminal_info *) inferior_data (a, inflow_inferior_data);
  terminal_info *info_b
    = (terminal_info *) inferior_data (a, inflow_inferior_data);

... both of which examine 'a'.

gdb/ChangeLog
2019-05-08  Tom Tromey  <tom@tromey.com>

	* inflow.c (struct terminal_info): Add destructor and
	initializers.
	(inflow_inferior_data): Change type.
	(~terminal_info): Rename from inflow_inferior_data_cleanup.
	(get_inflow_inferior_data, inflow_inferior_exit)
	(swap_terminal_info, _initialize_inflow): Update.

2 files changed, 27 insertions, 37 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5c8680b..e461a06 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,14 @@
 2019-05-08  Tom Tromey  <tom@tromey.com>
 
+	* inflow.c (struct terminal_info): Add destructor and
+	initializers.
+	(inflow_inferior_data): Change type.
+	(~terminal_info): Rename from inflow_inferior_data_cleanup.
+	(get_inflow_inferior_data, inflow_inferior_exit)
+	(swap_terminal_info, _initialize_inflow): Update.
+
+2019-05-08  Tom Tromey  <tom@tromey.com>
+
 	* target-dcache.c (target_dcache_cleanup): Remove.
 	(target_dcache_aspace_key): Change type.
 	(target_dcache_init_p, target_dcache_invalidate)
diff --git a/gdb/inflow.c b/gdb/inflow.c
index b715113..339b55c 100644
--- a/gdb/inflow.c
+++ b/gdb/inflow.c
@@ -58,13 +58,16 @@ static struct serial *stdin_serial;
    the inferior is resumed in the foreground.  */
 struct terminal_info
 {
+  terminal_info () = default;
+  ~terminal_info ();
+
   /* The name of the tty (from the `tty' command) that we gave to the
      inferior when it was started.  */
-  char *run_terminal;
+  char *run_terminal = nullptr;
 
   /* TTY state.  We save it whenever the inferior stops, and restore
      it when it resumes in the foreground.  */
-  serial_ttystate ttystate;
+  serial_ttystate ttystate {};
 
 #ifdef HAVE_TERMIOS_H
   /* The terminal's foreground process group.  Saved whenever the
@@ -80,11 +83,11 @@ struct terminal_info
      inf2's pgrp in the foreground instead of inf1's (which would be
      problematic since it would be left stopped: Ctrl-C wouldn't work,
      for example).  */
-  pid_t process_group;
+  pid_t process_group = 0;
 #endif
 
   /* fcntl flags.  Saved and restored just like ttystate.  */
-  int tflags;
+  int tflags = 0;
 };
 
 /* Our own tty state, which we restore every time we need to deal with
@@ -623,16 +626,12 @@ child_pass_ctrlc (struct target_ops *self)
 }
 
 /* Per-inferior data key.  */
-static const struct inferior_data *inflow_inferior_data;
+static const struct inferior_key<terminal_info> inflow_inferior_data;
 
-static void
-inflow_inferior_data_cleanup (struct inferior *inf, void *arg)
+terminal_info::~terminal_info ()
 {
-  struct terminal_info *info = (struct terminal_info *) arg;
-
-  xfree (info->run_terminal);
-  xfree (info->ttystate);
-  xfree (info);
+  xfree (run_terminal);
+  xfree (ttystate);
 }
 
 /* Get the current svr4 data.  If none is found yet, add it now.  This
@@ -643,12 +642,9 @@ get_inflow_inferior_data (struct inferior *inf)
 {
   struct terminal_info *info;
 
-  info = (struct terminal_info *) inferior_data (inf, inflow_inferior_data);
+  info = inflow_inferior_data.get (inf);
   if (info == NULL)
-    {
-      info = XCNEW (struct terminal_info);
-      set_inferior_data (inf, inflow_inferior_data, info);
-    }
+    info = inflow_inferior_data.emplace (inf);
 
   return info;
 }
@@ -662,18 +658,8 @@ get_inflow_inferior_data (struct inferior *inf)
 static void
 inflow_inferior_exit (struct inferior *inf)
 {
-  struct terminal_info *info;
-
   inf->terminal_state = target_terminal_state::is_ours;
-
-  info = (struct terminal_info *) inferior_data (inf, inflow_inferior_data);
-  if (info != NULL)
-    {
-      xfree (info->run_terminal);
-      xfree (info->ttystate);
-      xfree (info);
-      set_inferior_data (inf, inflow_inferior_data, NULL);
-    }
+  inflow_inferior_data.clear (inf);
 }
 
 void
@@ -705,13 +691,11 @@ copy_terminal_info (struct inferior *to, struct inferior *from)
 void
 swap_terminal_info (inferior *a, inferior *b)
 {
-  terminal_info *info_a
-    = (terminal_info *) inferior_data (a, inflow_inferior_data);
-  terminal_info *info_b
-    = (terminal_info *) inferior_data (a, inflow_inferior_data);
+  terminal_info *info_a = inflow_inferior_data.get (a);
+  terminal_info *info_b = inflow_inferior_data.get (b);
 
-  set_inferior_data (a, inflow_inferior_data, info_b);
-  set_inferior_data (b, inflow_inferior_data, info_a);
+  inflow_inferior_data.set (a, info_b);
+  inflow_inferior_data.set (b, info_a);
 
   std::swap (a->terminal_state, b->terminal_state);
 }
@@ -1006,7 +990,4 @@ _initialize_inflow (void)
   have_job_control ();
 
   gdb::observers::inferior_exit.attach (inflow_inferior_exit);
-
-  inflow_inferior_data
-    = register_inferior_data_with_cleanup (NULL, inflow_inferior_data_cleanup);
 }