[Patch] Get trace file name when using 'target tfile'

["Abid, Hafiz" <hafiz_abid at mentor dot com>]

Hi All,
When using 'target tfile', commands like 'info target' and 'info files'  
don't show the name of the trace file. This patch adds this  
information. It also add a new field in the output of the -trace-status  
command so that frontends can get this inforamtion.

This patch was originally written by Pedro. I have updated and  
regtested it.

Regards,
Abid

Before:
(gdb) info target
Local trace dump file:
Looking at a trace file.
(gdb) interpreter-exec mi -trace-status
^done,supported="file",running="0",stop-reason="request",frames="7215",frames-created="7215",buffer-size="5242880",buffer-free="2833070",disconnected="0",circular="0",user-name="",notes="",start-time="0.000000",stop-time="0.000000"

After:
(gdb) info target
Local trace dump file:
	`/home/abidh/trace.txt'
(gdb) interpreter-exec mi -trace-status
^done,supported="file",trace-file="/home/abidh/trace.txt",running="0",stop-reason="request",frames="7215",frames-created="7215",buffer-size="5242880",buffer-free="2833070",disconnected="0",circular="0",user-name="",notes="",start-time="0.000000",stop-time="0.000000"


2013-02-13  Pedro Alves  <pedro@codesourcery.com>
	    Hafiz Abid Qadeer  <abidh@codesourcery.com>

	gdb/
	* tracepoint.c (trace_status_mi): Output "trace-file" field.
	(tfile_open): Record the trace file's filename in the trace
	status.
	(tfile_files_info): Mention the name of the trace file.
	* tracepoint.h (struct trace_status) <from_file>: Make it hold  
the
	trace file's filename instead of a boolean.

	gdb/doc/
	* gdb.texinfo (GDB/MI Tracepoint Commands) <-trace-status>:
	Document the "trace-file" field.

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index e3f336e..e8ac8c5 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -32094,6 +32094,10 @@ The value of the disconnected tracing flag.  @code{1} means that
 tracing will continue after @value{GDBN} disconnects, @code{0} means
 that the trace run will stop.
 
+@item trace-file
+The filename of the trace file being examined.  This field is
+optional, and only present when examining a trace file.
+
 @end table
 
 @subsubheading @value{GDBN} Command
diff --git a/gdb/tracepoint.c b/gdb/tracepoint.c
index b45863e..848a1b1 100644
--- a/gdb/tracepoint.c
+++ b/gdb/tracepoint.c
@@ -2094,6 +2094,9 @@ trace_status_mi (int on_stop)
   else if (!on_stop)
     ui_out_field_string (uiout, "supported", "1");
 
+  if (ts->from_file)
+    ui_out_field_string (uiout, "trace-file", ts->from_file);
+
   gdb_assert (ts->running_known);
 
   if (ts->running)
@@ -3745,8 +3748,8 @@ tfile_open (char *filename, int from_tty)
 
   trace_regblock_size = 0;
   ts = current_trace_status ();
-  /* We know we're working with a file.  */
-  ts->from_file = 1;
+  /* We know we're working with a file. Record its name.  */
+  ts->from_file = trace_filename;
   /* Set defaults in case there is no status line.  */
   ts->running_known = 0;
   ts->stop_reason = trace_stop_reason_unknown;
@@ -4196,8 +4199,7 @@ tfile_close (int quitting)
 static void
 tfile_files_info (struct target_ops *t)
 {
-  /* (it would be useful to mention the name of the file).  */
-  printf_filtered ("Looking at a trace file.\n");
+  printf_filtered ("\t`%s'\n", trace_filename);
 }
 
 /* The trace status for a file is that tracing can never be run.  */
diff --git a/gdb/tracepoint.h b/gdb/tracepoint.h
index 2e1d83a..f407046 100644
--- a/gdb/tracepoint.h
+++ b/gdb/tracepoint.h
@@ -72,9 +72,9 @@ enum trace_stop_reason
 
 struct trace_status
 {
-  /* This is true if the status is coming from a file rather
-     than a live target.  */
-  int from_file;
+  /* If the status is coming from a file rather than a live target,
+     this points at the file's filename.  Otherwise, this is NULL.  */
+  const char *from_file;
 
   /* This is true if the value of the running field is known.  */
   int running_known;