[RFA,08/11] Use string and unique_xmalloc_ptr in mi-main.c

  Change a couple of spots in mi-main.c to use std::string or
unique_xmalloc_ptr.  unique_xmalloc_ptr is used here where the string
is writeable; I generally prefer to pretend that string is read-only,
perhaps not for a good resaon.

ChangeLog
2017-09-12  Tom Tromey  <tom@tromey.com>

	* mi/mi-main.c (mi_execute_cli_command): Use unique_xmalloc_ptr.
	(mi_execute_async_cli_command): Likewise.
	(mi_cmd_trace_frame_collected): Use std::string.
---
 gdb/ChangeLog    |  6 ++++++
 gdb/mi/mi-main.c | 40 +++++++++++-----------------------------
 2 files changed, 17 insertions(+), 29 deletions(-)
  

On 09/12/2017 07:57 PM, Tom Tromey wrote:
> Change a couple of spots in mi-main.c to use std::string or
> unique_xmalloc_ptr.  unique_xmalloc_ptr is used here where the string
> is writeable; I generally prefer to pretend that string is read-only,
> perhaps not for a good resaon.

Yes, I think not for a good reason.  :-)  You can
pass &str[0] to execute_command get access to the underlying
modifiable raw string.  See b064640146bb for example.

> diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
> index c8c4a97..0147fb9 100644
> --- a/gdb/mi/mi-main.c
> +++ b/gdb/mi/mi-main.c
> @@ -2264,41 +2264,31 @@ mi_execute_cli_command (const char *cmd, int args_p, const char *args)
>  {
>    if (cmd != 0)
>      {
> -      struct cleanup *old_cleanups;
> -      char *run;
> +      gdb::unique_xmalloc_ptr<char> run;
>  
>        if (args_p)
> -	run = xstrprintf ("%s %s", cmd, args);
> +	run.reset (xstrprintf ("%s %s", cmd, args));
>        else
> -	run = xstrdup (cmd);
> +	run.reset (xstrdup (cmd));
>        if (mi_debug_p)
>  	/* FIXME: gdb_???? */
>  	fprintf_unfiltered (gdb_stdout, "cli=%s run=%s\n",
> -			    cmd, run);
> -      old_cleanups = make_cleanup (xfree, run);
> -      execute_command (run, 0 /* from_tty */ );
> -      do_cleanups (old_cleanups);
> -      return;
> +			    cmd, run.get ());
> +      execute_command (run.get (), 0 /* from_tty */ );
>      }
>  }
>  
>  void
>  mi_execute_async_cli_command (const char *cli_command, char **argv, int argc)
>  {
> -  struct cleanup *old_cleanups;
> -  char *run;
> +  gdb::unique_xmalloc_ptr<char> run;
>  
>    if (mi_async_p ())
> -    run = xstrprintf ("%s %s&", cli_command, argc ? *argv : "");
> +    run.reset (xstrprintf ("%s %s&", cli_command, argc ? *argv : ""));
>    else
> -    run = xstrprintf ("%s %s", cli_command, argc ? *argv : "");
> -  old_cleanups = make_cleanup (xfree, run);
> -
> -  execute_command (run, 0 /* from_tty */ );
> +    run.reset (xstrprintf ("%s %s", cli_command, argc ? *argv : ""));
>  
> -  /* Do this before doing any printing.  It would appear that some
> -     print code leaves garbage around in the buffer.  */
> -  do_cleanups (old_cleanups);
> +  execute_command (run.get (), 0 /* from_tty */ );
>  }
>  

I think the above would look better with std::string + string_printf.


>  	struct trace_state_variable *tsv;
> @@ -2822,10 +2808,8 @@ mi_cmd_trace_frame_collected (const char *command, char **argv, int argc)
>  
>  	if (tsv != NULL)
>  	  {
> -	    tsvname = (char *) xrealloc (tsvname, strlen (tsv->name) + 2);
> -	    tsvname[0] = '$';
> -	    strcpy (tsvname + 1, tsv->name);
> -	    uiout->field_string ("name", tsvname);
> +	    std::string tsvname = std::string ("$") + tsv->name;
> +	    uiout->field_string ("name", tsvname.c_str ());

How about replacing this string building + field_string with a single
call to:

	    uiout->field_fmt ("name", "$%s", tsv->name);

Thanks,
Pedro Alves