Re: [PATCH v2] gdb: CTF support

[Wei-min Pan <weimin dot pan at oracle dot com>]

On 10/3/2019 11:53 AM, Wei-min Pan wrote:
> On 10/3/2019 11:31 AM, Simon Marchi wrote:
> > On 2019-10-03 2:21 p.m., Wei-min Pan wrote:
> > > Let's use an example (checking omitted):
> > >
> > > We're replacing:
> > >    name = ctf_type_aname_raw (fp, tid);
> > >    TYPE_NAME (type) = obstack_strdup (&of->objfile_obstack, name);
> > >    free (name);
> > >
> > > with
> > >    gdb::unique_xmalloc_ptr<char> name (ctf_type_aname_raw (fp, tid));
> > >    TYPE_NAME (type) = obstack_strdup (&of->objfile_obstack, name.get ()); 
> > >
> > >
> > > The allocated copy from ctf_type_aname_raw is not freed. Or did I 
> > > miss something?
> > >
> > > Weimin
> > Yes, the second snippet frees the copy returned by ctf_type_aname_raw.
> >
> > It might just be that you are not familiar with the concept of 
> > std::unique_ptr in C++:
> >
> >    https://en.cppreference.com/w/cpp/memory/unique_ptr
> >
> > It's a wrapper around a simple pointer that automatically calls a 
> > deleter function
> > when it goes out of scope.  gdb::unique_xmalloc_ptr is a 
> > specialization of std::unique_ptr
> > that uses xfree as the deleter function.
> >
> > Here's a similar use:
> >
> > https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=gdb/fbsd-tdep.c;h=9422e3c1a7e1a65c76b088f42bb5986bd13a089f;hb=HEAD#l1530
> >
> > `fbsd_core_vnode_path` return a pointer to an allocated C String, 
> > which `cwd` wraps.  When
> > it goes out of scope, `cwd` automatically calls `xfree` with the 
> > pointer.
>
> Oh, thanks for the explanation, reference and example. Will switch to 
> using gdb::unique_xmalloc_ptr<> instead.

Hi Simon,

I've switched to using gdb::unique_xmalloc_ptr, please see the attached 
patch, and ran
the CTF test suite successfully. Will submit a revised patch upstream 
shortly.

Thanks again for your reviews and help.

Weimin

Attachment: 0001-updated2.patch
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