Re: RFC: Fix unpaginated backtrace and various other corrupted output

[Elena Zannoni <ezannoni at redhat dot com>]

Daniel Jacobowitz writes:
 > I've noticed recently that backtraces aren't paginating.  The immediate
 > problem is this code in fputs_maybe_filtered:
 > 
 >   /* Don't do any filtering if it is disabled.  */
 >   if ((stream != gdb_stdout) || !pagination_enabled
 >       || (lines_per_page == UINT_MAX && chars_per_line == UINT_MAX))
 > 
 > It turns out that cli_text's saved stream is NOT equal to gdb_stdout.  Why
 > not?  Well, captured_main first initializes gdb_stdout:
 >   gdb_stdout = stdio_fileopen (stdout);
 > 
 > Then _initialize_cli_interp creates the CLI output object:
 > #1  0x0807ef6d in _initialize_cli_interp () at /opt/src/gdb/src/gdb/cli/cli-interp.c:136
 > 136       cli_uiout = cli_out_new (gdb_stdout);
 > 
 > and then:
 > #0  gdb_setup_readline () at /opt/src/gdb/src/gdb/event-top.c:1123
 > #1  0x0807ee6b in cli_interpreter_resume (data=0x0) at /opt/src/gdb/src/gdb/cli/cli-interp.c:57
 > #2  0x080bbb78 in interp_set (interp=0x8271df8) at /opt/src/gdb/src/gdb/interps.c:203
 > 
 > 1122          gdb_stdout = stdio_fileopen (stdout);
 > 
 > Oops!  We've changed gdb_stdout.  Now all CLI output using ui_out is
 > considered unfiltered.  This leads to broken pagination, bad interleaving,
 > et cetera.
 > 
 > Possible solutions: change the test, change stdio_fileopen to return the
 > same stream, update the CLI's stream value.  I chose door #3.  The
 > resulting patch isn't pretty, but door #1 was even worse and door #2 has
 > some surprising warts unless I introduce reference counting.
 > 
 > Does anyone have comments on this patch?
 > 

Does this fix the problem in this thread (on which I dropped the ball)?
http://sources.redhat.com/ml/gdb-patches/2003-04/msg00284.html

elena



 > -- 
 > Daniel Jacobowitz
 > MontaVista Software                         Debian GNU/Linux Developer
 > 
 > 2003-06-28  Daniel Jacobowitz  <drow@mvista.com>
 > 
 > 	* cli/cli-interp.c (cli_interpreter_resume): Update the
 > 	cli_uiout's stream to gdb_stdout.
 > 
 > Index: cli-interp.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/cli/cli-interp.c,v
 > retrieving revision 1.3
 > diff -u -p -r1.3 cli-interp.c
 > --- cli-interp.c	8 Jun 2003 18:27:14 -0000	1.3
 > +++ cli-interp.c	28 Jun 2003 17:57:08 -0000
 > @@ -53,8 +53,25 @@ cli_interpreter_init (void)
 >  static int
 >  cli_interpreter_resume (void *data)
 >  {
 > +  struct ui_file *stream;
 > +
 >    /*sync_execution = 1; */
 > +
 > +  /* gdb_setup_readline will change gdb_stdout.  If the CLI was previously
 > +     writing to gdb_stdout, then set it to the new gdb_stdout afterwards.  */
 > +
 > +  stream = cli_out_set_stream (cli_uiout, gdb_stdout);
 > +  if (stream != gdb_stdout)
 > +    {
 > +      cli_out_set_stream (cli_uiout, stream);
 > +      stream = NULL;
 > +    }
 > +
 >    gdb_setup_readline ();
 > +
 > +  if (stream != NULL)
 > +    cli_out_set_stream (cli_uiout, gdb_stdout);
 > +
 >    return 1;
 >  }
 >