Re: [RFA] Fix for thread apply

[Michael Snyder <msnyder at redhat dot com>]

Christopher Faylor wrote:
> 
> The problem below was suggested by a net contributor.
> 
> Here is their description of the problem:
> 
> There is a bug in the 'thread apply' command: it does not save
> the command string before switching the thread and executing
> the command on it. There effect is that when you do:
> 
>         thread apply all x/i $pc
> 
> to disassemble one instruction for each thread, the PC is not
> changed between threads. This is because the first time the
> command is executed, the command string is modified and a \0
> is inserted before the '$pc'. Execution on other threads will
> then to a 'x/i' which means to use the previous disassembly
> position.
> 
> The fix for this is pretty simple.  Ok to apply?

Excuse the delay.  The fix is approved, modulo your
discretion as to whether to use malloc or alloca.

Michael

> 
> (A test suite addition to test for this problem is being prepared
> separately)
> 
> cgf
> 
> 2000-11-08  Christopher Faylor  <cgf@redhat.com>
> 
>         * thread.c (thread_apply_all_command): Save the command before
>         executing it because it may be modified.  Restore the saved command so
>         that the same command is executed on next thread.
>         (thread_apply_command): Same correction.
> 
> Index: thread.c
> ===================================================================
> RCS file: /cvs/uberbaum/gdb/thread.c,v
> retrieving revision 1.7
> diff -u -p -r1.7 thread.c
> --- thread.c    2000/10/28 22:15:09     1.7
> +++ thread.c    2000/11/08 20:15:04
> @@ -517,6 +517,7 @@ thread_apply_all_command (char *cmd, int
>  {
>    struct thread_info *tp;
>    struct cleanup *old_chain;
> +  char *saved_cmd;
> 
>    if (cmd == NULL || *cmd == '\000')
>      error ("Please specify a command following the thread ID list");
> @@ -527,9 +528,14 @@ thread_apply_all_command (char *cmd, int
>       traversing it for "thread apply all".  MVS */
>    target_find_new_threads ();
> 
> +  /* Save a copy of the command in case it is clobbered by
> +     execute_command */
> +  saved_cmd = alloca (strlen (cmd) + 1);
> +  strcpy (saved_cmd, cmd);
>    for (tp = thread_list; tp; tp = tp->next)
>      if (thread_alive (tp))
>        {
> +       struct cleanup *chain;
>         switch_to_thread (tp->pid);
>  #ifdef HPUXHPPA
>         printf_filtered ("\nThread %d (%s):\n",
> @@ -540,6 +546,8 @@ thread_apply_all_command (char *cmd, int
>                          target_pid_to_str (inferior_pid));
>  #endif
>         execute_command (cmd, from_tty);
> +
> +       strcpy (cmd, saved_cmd); /* Restore exact command used previously */
>        }
> 
>    do_cleanups (old_chain);
> @@ -551,6 +559,7 @@ thread_apply_command (char *tidlist, int
>    char *cmd;
>    char *p;
>    struct cleanup *old_chain;
> +  char *saved_cmd;
> 
>    if (tidlist == NULL || *tidlist == '\000')
>      error ("Please specify a thread ID list");
> @@ -562,6 +571,10 @@ thread_apply_command (char *tidlist, int
> 
>    old_chain = make_cleanup_restore_current_thread (inferior_pid);
> 
> +  /* Save a copy of the command in case it is clobbered by
> +     execute_command */
> +  saved_cmd = alloca (strlen (cmd) + 1);
> +  strcpy (saved_cmd, cmd);
>    while (tidlist < cmd)
>      {
>        struct thread_info *tp;
> @@ -608,6 +621,7 @@ thread_apply_command (char *tidlist, int
>                                target_pid_to_str (inferior_pid));
>  #endif
>               execute_command (cmd, from_tty);
> +             strcpy (cmd, saved_cmd);  /* Restore exact command used previously */
>             }
>         }
>      }