Re: [PATCH v2 2/2] mi-out: Implement mi redirection using a stack.

[Adrian Sendroiu <adrian dot sendroiu at freescale dot com>]

I implemented the test case. A couple of issues I encountered:

- skip_python_tests doesn't work with MI, because it searches for $gdb_prompt.
I implemented another one called mi_skip_python_tests which uses $mi_gdb_prompt.

- executing "python gdb.execute("break main", ... ) directly doesn't work,
because "python" is a cli command, and before running it the current_uiout will
be temporarily changed to cli_uiout, so the first redirection won't be done
on mi_uiout. To bypass this I implemented a small workaround: set a breakpoint,
then set the python command to be executed when the breakpoint hits.

- when running the test on a gdb without the redirection fix, the test will be
reported as UNRESOLVED, because gdb crashes.

--- 8< ---
Subject: [PATCH] mi-out: Implement mi redirection using a stack.

The current implementation doesn't support nested redirections because it only
has an "original_buffer" where it saves the current stream when a redirection is
done. To overcome this limitation, this patch reimplements it using a stack of
streams.

gdb/
2014-07-23  Adrian Sendroiu  <adrian.sendroiu@freescale.com>

	* mi/mi-out.c (ui_filep): New typedef.
	(DEF_VEC_P (ui_filep)): New type.
	(struct ui_out_data): <buffer> Remove field.
	<original_buffer> Remove field.
	<streams>: New field.
	(mi_field_string): Get the output stream from the top of the
	stack of streams.
	(mi_field_fmt): Likewise.
	(mi_flush): Likewise.
	(field_separator): Likewise.
	(mi_open): Likewise.
	(mi_close): Likewise.
	(mi_out_buffered): Likewise.
	(mi_out_rewind): Likewise.
	(mi_out_put): Likewise.
	(mi_out_new): Initialize the stack of streams. Push a newly
	created stream on the stack. Remove obsolete comment.
	(mi_redirect): Reimplement using push and pop operations.

gdb/testsuite/
2014-07-30  Adrian Sendroiu  <adrian.sendroiu@freescale.com>

	* gdb.mi/mi-logging.exp: Add test for nested mi redirection.
	* lib/mi-support.exp: (mi_skip_python_tests): New function.
---
 gdb/mi/mi-out.c                     |   77 ++++++++++++++++++++---------------
 gdb/testsuite/gdb.mi/mi-logging.exp |   14 +++++++
 gdb/testsuite/lib/mi-support.exp    |   37 +++++++++++++++++
 3 files changed, 95 insertions(+), 33 deletions(-)

diff --git a/gdb/mi/mi-out.c b/gdb/mi/mi-out.c
index 6ec41e6..6731509 100644
--- a/gdb/mi/mi-out.c
+++ b/gdb/mi/mi-out.c
@@ -22,14 +22,17 @@
 #include "defs.h"
 #include "ui-out.h"
 #include "mi-out.h"
+#include "vec.h"
+
+typedef struct ui_file *ui_filep;
+DEF_VEC_P (ui_filep);
 
 struct ui_out_data
   {
     int suppress_field_separator;
     int suppress_output;
     int mi_version;
-    struct ui_file *buffer;
-    struct ui_file *original_buffer;
+    VEC (ui_filep) *streams;
   };
 typedef struct ui_out_data mi_out_data;
 
@@ -215,17 +218,20 @@ mi_field_string (struct ui_out *uiout, int fldno, int width,
 		 enum ui_align align, const char *fldname, const char *string)
 {
   mi_out_data *data = ui_out_data (uiout);
+  struct ui_file *stream;
 
   if (data->suppress_output)
     return;
 
+  stream = VEC_last (ui_filep, data->streams);
+
   field_separator (uiout);
   if (fldname)
-    fprintf_unfiltered (data->buffer, "%s=", fldname);
-  fprintf_unfiltered (data->buffer, "\"");
+    fprintf_unfiltered (stream, "%s=", fldname);
+  fprintf_unfiltered (stream, "\"");
   if (string)
-    fputstr_unfiltered (string, '"', data->buffer);
-  fprintf_unfiltered (data->buffer, "\"");
+    fputstr_unfiltered (string, '"', stream);
+  fprintf_unfiltered (stream, "\"");
 }
 
 /* This is the only field function that does not align.  */
@@ -236,17 +242,20 @@ mi_field_fmt (struct ui_out *uiout, int fldno, int width,
 	      const char *format, va_list args)
 {
   mi_out_data *data = ui_out_data (uiout);
+  struct ui_file *stream;
 
   if (data->suppress_output)
     return;
 
+  stream = VEC_last (ui_filep, data->streams);
+
   field_separator (uiout);
   if (fldname)
-    fprintf_unfiltered (data->buffer, "%s=\"", fldname);
+    fprintf_unfiltered (stream, "%s=\"", fldname);
   else
-    fputs_unfiltered ("\"", data->buffer);
-  vfprintf_unfiltered (data->buffer, format, args);
-  fputs_unfiltered ("\"", data->buffer);
+    fputs_unfiltered ("\"", stream);
+  vfprintf_unfiltered (stream, format, args);
+  fputs_unfiltered ("\"", stream);
 }
 
 void
@@ -275,8 +284,9 @@ void
 mi_flush (struct ui_out *uiout)
 {
   mi_out_data *data = ui_out_data (uiout);
+  struct ui_file *stream = VEC_last (ui_filep, data->streams);
 
-  gdb_flush (data->buffer);
+  gdb_flush (stream);
 }
 
 int
@@ -285,15 +295,9 @@ mi_redirect (struct ui_out *uiout, struct ui_file *outstream)
   mi_out_data *data = ui_out_data (uiout);
 
   if (outstream != NULL)
-    {
-      data->original_buffer = data->buffer;
-      data->buffer = outstream;
-    }
-  else if (data->original_buffer != NULL)
-    {
-      data->buffer = data->original_buffer;
-      data->original_buffer = NULL;
-    }
+    VEC_safe_push (ui_filep, data->streams, outstream);
+  else
+    VEC_pop (ui_filep, data->streams);
 
   return 0;
 }
@@ -306,29 +310,31 @@ static void
 field_separator (struct ui_out *uiout)
 {
   mi_out_data *data = ui_out_data (uiout);
+  struct ui_file *stream = VEC_last (ui_filep, data->streams);
 
   if (data->suppress_field_separator)
     data->suppress_field_separator = 0;
   else
-    fputc_unfiltered (',', data->buffer);
+    fputc_unfiltered (',', stream);
 }
 
 static void
 mi_open (struct ui_out *uiout, const char *name, enum ui_out_type type)
 {
   mi_out_data *data = ui_out_data (uiout);
+  struct ui_file *stream = VEC_last (ui_filep, data->streams);
 
   field_separator (uiout);
   data->suppress_field_separator = 1;
   if (name)
-    fprintf_unfiltered (data->buffer, "%s=", name);
+    fprintf_unfiltered (stream, "%s=", name);
   switch (type)
     {
     case ui_out_type_tuple:
-      fputc_unfiltered ('{', data->buffer);
+      fputc_unfiltered ('{', stream);
       break;
     case ui_out_type_list:
-      fputc_unfiltered ('[', data->buffer);
+      fputc_unfiltered ('[', stream);
       break;
     default:
       internal_error (__FILE__, __LINE__, _("bad switch"));
@@ -339,14 +345,15 @@ static void
 mi_close (struct ui_out *uiout, enum ui_out_type type)
 {
   mi_out_data *data = ui_out_data (uiout);
+  struct ui_file *stream = VEC_last (ui_filep, data->streams);
 
   switch (type)
     {
     case ui_out_type_tuple:
-      fputc_unfiltered ('}', data->buffer);
+      fputc_unfiltered ('}', stream);
       break;
     case ui_out_type_list:
-      fputc_unfiltered (']', data->buffer);
+      fputc_unfiltered (']', stream);
       break;
     default:
       internal_error (__FILE__, __LINE__, _("bad switch"));
@@ -360,8 +367,9 @@ void
 mi_out_buffered (struct ui_out *uiout, char *string)
 {
   mi_out_data *data = ui_out_data (uiout);
+  struct ui_file *stream = VEC_last (ui_filep, data->streams);
 
-  fprintf_unfiltered (data->buffer, "%s", string);
+  fprintf_unfiltered (stream, "%s", string);
 }
 
 /* Clear the buffer.  */
@@ -370,8 +378,9 @@ void
 mi_out_rewind (struct ui_out *uiout)
 {
   mi_out_data *data = ui_out_data (uiout);
+  struct ui_file *stream = VEC_last (ui_filep, data->streams);
 
-  ui_file_rewind (data->buffer);
+  ui_file_rewind (stream);
 }
 
 /* Dump the buffer onto the specified stream.  */
@@ -386,9 +395,10 @@ void
 mi_out_put (struct ui_out *uiout, struct ui_file *stream)
 {
   mi_out_data *data = ui_out_data (uiout);
+  struct ui_file *current_stream = VEC_last (ui_filep, data->streams);
 
-  ui_file_put (data->buffer, do_write, stream);
-  ui_file_rewind (data->buffer);
+  ui_file_put (current_stream, do_write, stream);
+  ui_file_rewind (current_stream);
 }
 
 /* Return the current MI version.  */
@@ -407,13 +417,14 @@ struct ui_out *
 mi_out_new (int mi_version)
 {
   int flags = 0;
+  struct ui_file *new_stream;
 
   mi_out_data *data = XNEW (mi_out_data);
   data->suppress_field_separator = 0;
   data->suppress_output = 0;
   data->mi_version = mi_version;
-  /* FIXME: This code should be using a ``string_file'' and not the
-     TUI buffer hack. */
-  data->buffer = mem_fileopen ();
+  data->streams = NULL;
+  new_stream = mem_fileopen ();
+  VEC_safe_push (ui_filep, data->streams, new_stream);
   return ui_out_new (&mi_ui_out_impl, data, flags);
 }
diff --git a/gdb/testsuite/gdb.mi/mi-logging.exp b/gdb/testsuite/gdb.mi/mi-logging.exp
index d5e4193..063ea97 100644
--- a/gdb/testsuite/gdb.mi/mi-logging.exp
+++ b/gdb/testsuite/gdb.mi/mi-logging.exp
@@ -82,6 +82,20 @@ if [regexp "1001\\^done\[\r\n\]+$mi_log_prompt.*1002\\^running\[\r\n\]+\\*runnin
     fail "Redirect log file contents"
 }
 
+# This triggers a nested mi_ui_out redirection, by disabling a breakpoint
+# inside a python command that has to_string = True.
+if ![mi_skip_python_tests] {
+    mi_gdb_test "-break-insert do_nothing" ".*"
+    mi_gdb_test "-break-commands 2 \"python gdb.execute('disable 2', True, True)\"" ".*"
+
+    mi_gdb_test "-exec-continue" ".*"
+
+    set s [string repeat "A" 100]
+
+    # This will crash gdb if redirection is not done properly.
+    mi_gdb_test "echo $s" ".*\\^done" "mi nested redirect"
+}
+
 mi_gdb_exit
 
 remote_file host delete $milogfile
diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index 204f1e8..23a5b80 100644
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -2491,3 +2491,40 @@ proc mi_make_breakpoint_table {bp_list} {
     # Assemble the final regexp.
     return "BreakpointTable={nr_rows=\"$nr\",nr_cols=\"$nc\",$header,$body}"
 }
+
+proc mi_skip_python_tests {} {
+    global mi_gdb_prompt
+    global gdb_py_is_py3k
+    global gdb_py_is_py24
+
+    gdb_test_multiple "python print ('test')" "verify python support" {
+	-re "not supported.*$mi_gdb_prompt$"	{
+	    unsupported "Python support is disabled."
+	    return 1
+	}
+	-re "$mi_gdb_prompt$"	{}
+    }
+
+    set gdb_py_is_py24 0
+    gdb_test_multiple "python print (sys.version_info\[0\])" "check if python 3" {
+	-re "3.*$mi_gdb_prompt$"	{
+            set gdb_py_is_py3k 1
+        }
+	-re ".*$mi_gdb_prompt$"	{
+            set gdb_py_is_py3k 0
+        }
+
+    }
+    if { $gdb_py_is_py3k == 0 } {
+        gdb_test_multiple "python print (sys.version_info\[1\])" "check if python 2.4" {
+	    -re "\[45\].*$mi_gdb_prompt$" {
+                set gdb_py_is_py24 1
+            }
+	    -re ".*$mi_gdb_prompt$" {
+                set gdb_py_is_py24 0
+            }
+        }
+    }
+
+    return 0
+}
-- 
1.7.9.5