Re: [RFA 2/2] Remove some clanups from solib-svr4.c

[Simon Marchi <simon dot marchi at polymtl dot ca>]

On 2018-03-30 15:04, Tom Tromey wrote:
> > > -  newobj = XCNEW (struct so_list);
> > > -  old_chain = make_cleanup (xfree, newobj);
> > > -  lm_info_svr4 *li = lm_info_read (ldsomap);
> > > -  newobj->lm_info = li;
> > > -  make_cleanup (xfree, newobj->lm_info);
> > > +  gdb::unique_xmalloc_ptr<lm_info_svr4> li (lm_info_read (ldsomap));
>
> Simon> This is not an error because lm_info_svr4 is trivially 
> destructible,
> Simon> but since we allocate it with "new", we might as well use a
> Simon> unique_ptr, it's more future-proof.
>
> Good catch, thanks.
>
> Simon> How about making lm_info_read return an 
> std::unique_ptr<lm_info_svr4>?
>
> Simon> The patch LGTM with or without those changes.
>
> How's this?

LGTM, I just noted two nits:

> @@ -168,28 +168,24 @@ svr4_same (struct so_list *gdb, struct so_list 
> *inferior)
>    return (svr4_same_1 (gdb->so_original_name, 
> inferior->so_original_name));
>  }
>
> -static lm_info_svr4 *
> +static std::unique_ptr<lm_info_svr4>
>  lm_info_read (CORE_ADDR lm_addr)
>  {
>    struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
> -  gdb_byte *lm;
> -  lm_info_svr4 *lm_info;
> -  struct cleanup *back_to;
> +  std::unique_ptr<lm_info_svr4> lm_info;
>
> -  lm = (gdb_byte *) xmalloc (lmo->link_map_size);
> -  back_to = make_cleanup (xfree, lm);
> +  gdb::byte_vector lm (lmo->link_map_size);
>
> -  if (target_read_memory (lm_addr, lm, lmo->link_map_size) != 0)
> +  if (target_read_memory (lm_addr, lm.data (), lmo->link_map_size) != 
> 0)
>      {
>        warning (_("Error reading shared library list entry at %s"),
> -	       paddress (target_gdbarch (), lm_addr)),
> -      lm_info = NULL;
> +	       paddress (target_gdbarch (), lm_addr));
>      }

Curly braces can be removed here.

> @@ -973,13 +965,8 @@ svr4_keep_data_in_core (CORE_ADDR vaddr, unsigned
> long size)
>    if (!ldsomap)
>      return 0;
>
> -  newobj = XCNEW (struct so_list);
> -  old_chain = make_cleanup (xfree, newobj);
> -  lm_info_svr4 *li = lm_info_read (ldsomap);
> -  newobj->lm_info = li;
> -  make_cleanup (xfree, newobj->lm_info);
> +  std::unique_ptr<lm_info_svr4> li (lm_info_read (ldsomap));

I think it's clearer to use the assignment operator in that case:

std::unique_ptr<lm_info_svr4> li = lm_info_read (ldsomap);

Simon