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Message-ID: <3D359FDE.4453EA90@cae.wisc.edu>
Date: Wed, 17 Jul 2002 09:50:00 -0000
From: Jason Kraftcheck <kraftche@cae.wisc.edu>
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Organization: University of Wisconsin (http://www.wisc.edu)
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To: gdb@sources.redhat.com
Subject: environment for 'shell' command
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X-SW-Source: 2002-07/txt/msg00169.txt.bz2

Hi,

I would like the ability to pass the file name and line number of the
source corresponding to the selected stack frame to a program started
via the 'shell' command.  I could not find any way to do this in gdb. 
If there is a way to do this, please let me know (and disregard the rest
of this message.)  I decided to add this functionality but I am
unfimiliar with the internal workings of gdb.  The following is a
description of what I did to implement this.  I'd really appreciate any
suggestions on better ways to implement this, error conditions I'm not
handling, etc.

The simplest way I could come up with to do this is to put the values in
environmental variables immediately before executing the command. 
Specifically, setting gdb_stack_dir, gdb_stack_file, and gdb_stack_line
to the values from a struct symtab_and_line.  I use this for defining
things like a 'view' command that highlights the current location in the
source in a text editor:

 define view
   shell if [ x$gdb_stack_file != x ]; then \ 
            nc -line $gdb_stack_line $gdb_stack_dir$gdb_stack_file; \
         fi
 end

I added the following function to stack.c to get a symtab_and_line
struct for the selected frame:

 /* Get a symtab_and_line for the selected stack frame. */
 struct symtab_and_line 
 find_selected_line (void)
 {
   struct symtab_and_line sal;
   INIT_SAL( &sal );
   if( selected_frame != NULL )
     sal = find_pc_line(selected_frame->pc, 
                        selected_frame->next
                        && !selected_frame->next->signal_handler_caller 
                        && !frame_in_dummy (selected_frame->next));
   return sal;
 }


I added a function 'set_shell_environment' to cli/cli-cmds.c and added
calls to that function in 'shell_escape'.

 #define SHELL_ENV "gdb_stack_"

 static void
 set_shell_environment()
 {
   char buffer[16];
   struct symtab_and_line sal = find_selected_line();
   
   unsetenv (SHELL_ENV "file");
   unsetenv (SHELL_ENV "dir");
   unsetenv (SHELL_ENV "line");
   
   if (sal.symtab && sal.symtab->filename && sal.symtab->dirname)
     {
       sprintf (buffer, "%d", sal.line);
       setenv (SHELL_ENV "line", buffer, 1);
       setenv (SHLLL_ENV "dir", sal.symtab->dirname, 1);
       setenv (SHELL_ENV "file", sal.symtab->filename, 1);
     } 
 }      

thanks,

-- 
Jason Kraftcheck