[review] Fix the "winheight" command

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 18a7906..392ffd9 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,13 @@ 
 2019-10-27  Tom Tromey  <tom@tromey.com>
 
+	* tui/tui-win.c (tui_partial_win_by_name): Move from tui-data.c.
+	Now static.  Change type of "name".
+	(tui_set_win_height_command): Don't copy "arg".
+	* tui/tui-data.h (tui_partial_win_by_name): Don't declare.
+	* tui/tui-data.c (tui_partial_win_by_name): Move to tui-win.c.
+
+2019-10-27  Tom Tromey  <tom@tromey.com>
+
 	* tui/tui-win.c (tui_set_win_height_command): Call
 	tui_adjust_window_height.
 	(tui_adjust_win_heights, new_height_ok): Remove.
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 238432d..da242b5 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,9 @@ 
 2019-10-27  Tom Tromey  <tom@tromey.com>
 
+	* gdb.tui/winheight.exp: New file.
+
+2019-10-27  Tom Tromey  <tom@tromey.com>
+
 	* gdb.tui/resize.exp: Update.
 	* gdb.tui/empty.exp (layouts): Update.
 
diff --git a/gdb/testsuite/gdb.tui/winheight.exp b/gdb/testsuite/gdb.tui/winheight.exp
new file mode 100644
index 0000000..cf65c75
--- /dev/null
+++ b/gdb/testsuite/gdb.tui/winheight.exp
@@ -0,0 +1,37 @@ 
+# Copyright 2019 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test the "winheight" command.
+
+load_lib "tuiterm.exp"
+
+standard_testfile tui-layout.c
+
+if {[build_executable "failed to prepare" ${testfile} ${srcfile}] == -1} {
+    return -1
+}
+
+Term::clean_restart 24 80 $testfile
+if {![Term::enter_tui]} {
+    unsupported "TUI not supported"
+}
+
+Term::check_box "source box" 0 0 80 15
+
+Term::command "winheight cmd +5"
+Term::check_box "smaller source box" 0 0 80 10
+
+Term::command "winheight cmd -5"
+Term::check_box "larger source box" 0 0 80 15
diff --git a/gdb/tui/tui-data.c b/gdb/tui/tui-data.c
index 522bb9a..8f79658 100644
--- a/gdb/tui/tui-data.c
+++ b/gdb/tui/tui-data.c
@@ -158,25 +158,6 @@ 
 }
 
 
-/* Answer the window represented by name.  */
-struct tui_win_info *
-tui_partial_win_by_name (const char *name)
-{
-  if (name != NULL)
-    {
-      for (tui_win_info *item : all_tui_windows ())
-	{
-	  const char *cur_name = item->name ();
-
-	  if (strlen (name) <= strlen (cur_name)
-	      && startswith (cur_name, name))
-	    return item;
-	}
-    }
-
-  return NULL;
-}
-
 /* See tui-data.h.  */
 
 void
diff --git a/gdb/tui/tui-data.h b/gdb/tui/tui-data.h
index 3bfb55a..459d7b4 100644
--- a/gdb/tui/tui-data.h
+++ b/gdb/tui/tui-data.h
@@ -302,7 +302,6 @@ 
 
 
 /* Data Manipulation Functions.  */
-extern struct tui_win_info *tui_partial_win_by_name (const char *);
 extern enum tui_layout_type tui_current_layout (void);
 extern int tui_term_height (void);
 extern void tui_set_term_height_to (int);
diff --git a/gdb/tui/tui-win.c b/gdb/tui/tui-win.c
index 57b0eba..bda9595 100644
--- a/gdb/tui/tui-win.c
+++ b/gdb/tui/tui-win.c
@@ -51,6 +51,7 @@ 
 #include "gdb_curses.h"
 #include <ctype.h>
 #include "readline/readline.h"
+#include "gdbsupport/gdb_string_view.h"
 
 #include <signal.h>
 
@@ -686,6 +687,24 @@ 
 }
 
 
+/* Answer the window represented by name.  */
+static struct tui_win_info *
+tui_partial_win_by_name (gdb::string_view name)
+{
+  if (name != NULL)
+    {
+      for (tui_win_info *item : all_tui_windows ())
+	{
+	  const char *cur_name = item->name ();
+
+	  if (startswith (cur_name, name))
+	    return item;
+	}
+    }
+
+  return NULL;
+}
+
 /* Set focus to the window named by 'arg'.  */
 static void
 tui_set_focus_command (const char *arg, int from_tty)
@@ -833,20 +852,16 @@ 
   tui_enable ();
   if (arg != NULL)
     {
-      std::string copy = arg;
-      char *buf = &copy[0];
-      char *buf_ptr = buf;
-      char *wname = NULL;
+      const char *buf = arg;
+      const char *buf_ptr = buf;
       int new_height;
       struct tui_win_info *win_info;
 
-      wname = buf_ptr;
       buf_ptr = strchr (buf_ptr, ' ');
       if (buf_ptr != NULL)
 	{
-	  *buf_ptr = '\0';
-
 	  /* Validate the window name.  */
+	  gdb::string_view wname (buf, buf_ptr - buf);
 	  win_info = tui_partial_win_by_name (wname);
 
 	  if (win_info == NULL)