Have 'thread|frame apply' style their output.

'thread|frame apply CMD' launches CMD so that CMD output goes to a string_file.
This patch ensures that string_file for such CMD output contains
style escape sequences that 'thread|frame apply' will later on
output on the real terminal, so as to have CMD output properly styled.

The idea is to have the class ui_file having overridable methods
to indicate that the output to this ui_file should be done using
'terminal' behaviour such as styling.
Then these methods are overriden in string_file so that a specially
constructed string_file will get output with style escape sequences.

After this patch, the output of CMD by thread|frame apply CMD is styled
similarly as when CMD is launched directly.
Note that string_file (term_out true) could also support wrapping,
but this is not done (yet?).

Tested on debian/amd64.

gdb/ChangeLog
2019-04-27  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	Support style in 'frame|thread apply'

	* gdbcmd.h (execute_command_to_string): New term_out parameter.
	* record.c (record_start, record_stop): Update callers of
	execute_command_to_string with false.
	* ui-file.h (class ui_file): New term_out and can_emit_style_escape
	methods.
	(class string_file): New constructor with term_out parameter.
	Override methods term_out and can_emit_style_escape.  New member
	term_out.
	(class stdio_file): Override can_emit_style_escape.
	(class tee_file): Override term_out and can_emit_style_escape.
	* utils.h (can_emit_style_escape): Remove.
	* utils.c (can_emit_style_escape): Likewise.
	Update all callers of can_emit_style_escape (SOMESTREAM) to
	SOMESTREAM->can_emit_style_escape.
	* source-cache.c (source_cache::get_source_lines): Likewise.
	* stack.c (frame_apply_command_count): Call execute_command_to_string
	passing the term_out characteristic of the current gdb_stdout.
	* thread.c (thr_try_catch_cmd): Likewise.
	* top.c (execute_command_to_string): pass term_out parameter
	to construct the string_file for the command output.
	* ui-file.c (term_cli_styling): New function (most code moved
	from utils.c can_emit_style_escape).
	(string_file::string_file, string_file::can_emit_style_escape,
	stdio_file::can_emit_style_escape, tee_file::term_out,
	tee_file::can_emit_style_escape): New functions.

1 files changed, 71 insertions, 0 deletions

diff --git a/gdb/ui-file.c b/gdb/ui-file.c
index 77f6b31..4139b5d 100644
--- a/gdb/ui-file.c
+++ b/gdb/ui-file.c
@@ -101,6 +101,33 @@ ui_file_isatty (struct ui_file *file)
   return file->isatty ();
 }
 
+/* true if the gdb terminal supports styling, and styling is enabled.  */
+
+static bool
+term_cli_styling ()
+{
+  extern int cli_styling;
+
+  if (!cli_styling)
+    return false;
+
+  const char *term = getenv ("TERM");
+  /* Windows doesn't by default define $TERM, but can support styles
+     regardless.  */
+#ifndef _WIN32
+  if (term == nullptr || !strcmp (term, "dumb"))
+    return false;
+#else
+  /* But if they do define $TERM, let us behave the same as on Posix
+     platforms, for the benefit of programs which invoke GDB as their
+     back-end.  */
+  if (term && !strcmp (term, "dumb"))
+    return false;
+#endif
+  return true;
+}
+
+
 void
 ui_file_write (struct ui_file *file,
 		const char *buf,
@@ -140,6 +167,22 @@ string_file::write (const char *buf, long length_buf)
   m_string.append (buf, length_buf);
 }
 
+/* See ui-file.h.  */
+
+bool
+string_file::term_out ()
+{
+  return m_term_out;
+}
+
+/* See ui-file.h.  */
+
+bool
+string_file::can_emit_style_escape ()
+{
+  return m_term_out && term_cli_styling ();
+}
+
 
 
 stdio_file::stdio_file (FILE *file, bool close_p)
@@ -255,6 +298,16 @@ stdio_file::isatty ()
   return ::isatty (m_fd);
 }
 
+/* See ui-file.h.  */
+
+bool
+stdio_file::can_emit_style_escape ()
+{
+  return (this == gdb_stdout
+	  && this->isatty ()
+	  && term_cli_styling ());
+}
+
 
 
 /* This is the implementation of ui_file method 'write' for stderr.
@@ -332,3 +385,21 @@ tee_file::isatty ()
 {
   return m_one->isatty ();
 }
+
+/* See ui-file.h.  */
+
+bool
+tee_file::term_out ()
+{
+  return m_one->term_out ();
+}
+
+/* See ui-file.h.  */
+
+bool
+tee_file::can_emit_style_escape ()
+{
+  return (this == gdb_stdout
+	  && m_one->term_out ()
+	  && term_cli_styling ());
+}