[PATCH 06/16] Reset terminal styles

[Tom Tromey <tom@tromey.com>]

This adds a function that can be used to reset terminal styles,
regardless of what style the low-levle output routines currently think
is applied.

This is used to make "echo" and "printf" work properly when emitting
ANSI terminal escapes -- now gdb will reset the style at the end of
the command.

gdb/ChangeLog
2018-11-27  Tom Tromey  <tom@tromey.com>

	* utils.h (reset_terminal_style): Declare.
	* utils.c (can_emit_style_escape): New function.
	(set_output_style): Use it.
	(reset_terminal_style): New function.
	* printcmd.c (printf_command): Call reset_terminal_style.
	* cli/cli-cmds.c (echo_command): Call reset_terminal_style.
---
 gdb/ChangeLog      |  9 +++++++++
 gdb/cli/cli-cmds.c |  2 ++
 gdb/printcmd.c     |  2 ++
 gdb/utils.c        | 37 +++++++++++++++++++++++++++++++------
 gdb/utils.h        |  4 ++++
 5 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index 135f550b80..12ac74c7e9 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -689,6 +689,8 @@ echo_command (const char *text, int from_tty)
 	  printf_filtered ("%c", c);
       }
 
+  reset_terminal_style (gdb_stdout);
+
   /* Force this output to appear now.  */
   wrap_here ("");
   gdb_flush (gdb_stdout);
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index 8c999188d7..79c3d2d2ff 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -2609,6 +2609,8 @@ static void
 printf_command (const char *arg, int from_tty)
 {
   ui_printf (arg, gdb_stdout);
+  reset_terminal_style (gdb_stdout);
+  wrap_here ("");
   gdb_flush (gdb_stdout);
 }
 
diff --git a/gdb/utils.c b/gdb/utils.c
index 69c9e76576..85b0fb14e3 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -1444,25 +1444,50 @@ emit_style_escape (const ui_file_style &style)
   wrap_buffer.append (style.to_ansi ());
 }
 
-/* Set the current output style.  This will affect future uses of the
-   _filtered output functions.  */
+/* Return true if ANSI escapes can be used on STREAM.  */
 
-static void
-set_output_style (struct ui_file *stream, const ui_file_style &style)
+static bool
+can_emit_style_escape (struct ui_file *stream)
 {
   if (stream != gdb_stdout
       || !cli_styling
-      || style == desired_style
       || !ui_file_isatty (stream))
-    return;
+    return false;
   const char *term = getenv ("TERM");
   if (term == nullptr || !strcmp (term, "dumb"))
+    return false;
+  return true;
+}
+
+/* Set the current output style.  This will affect future uses of the
+   _filtered output functions.  */
+
+static void
+set_output_style (struct ui_file *stream, const ui_file_style &style)
+{
+  if (!can_emit_style_escape (stream)
+      || style == desired_style)
     return;
 
   desired_style = style;
   emit_style_escape (style);
 }
 
+/* See utils.h.  */
+
+void
+reset_terminal_style (struct ui_file *stream)
+{
+  if (can_emit_style_escape (stream))
+    {
+      /* Force the setting, regardless of what we think the setting
+	 might already be.  */
+      desired_style = ui_file_style ();
+      applied_style = desired_style;
+      wrap_buffer.append (desired_style.to_ansi ());
+    }
+}
+
 /* Wait, so the user can read what's on the screen.  Prompt the user
    to continue by pressing RETURN.  'q' is also provided because
    telling users what to do in the prompt is more user-friendly than
diff --git a/gdb/utils.h b/gdb/utils.h
index 9872a15fd7..1f09ec2d47 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -439,6 +439,10 @@ extern void fputs_styled (const char *linebuffer,
 			  const ui_file_style &style,
 			  struct ui_file *stream);
 
+/* Reset the terminal style to the default, if needed.  */
+
+extern void reset_terminal_style (struct ui_file *stream);
+
 /* Display the host ADDR on STREAM formatted as ``0x%x''.  */
 extern void gdb_print_host_address_1 (const void *addr, struct ui_file *stream);
 
-- 
2.17.2