Fwd: [PATCH 2/4] covoar: Use DWARF to map addresses to source files and lines.

[Joel Sherrill]

On Mon, May 7, 2018 at 3:58 PM, Chris Johns <chrisj at rtems.org> wrote:

> On 08/05/2018 03:56, Joel Sherrill wrote:
> >
> > I have attached a workaround.
>
> Looks like a solution to me.
>

Good enough for now. All basename() calls should come from rld.

Eventually all dirname() calls should also.

Luckily no file uses both so we don't have to include libgen.h when
for dirname() and screw up basename().


>
> > It seems that libgen.h has this:
> >
> > ========================================================
> > /* Return final component of PATH.
> >
> >    This is the weird XPG version of this function.  It sometimes will
> >    modify its argument.  Therefore we normally use the GNU version (in
> >    <string.h>) and only if this header is included make the XPG
> >    version available under the real name.  */
> > extern char *__xpg_basename (char *__path) __THROW;
> > #define basename        __xpg_basename
> > ========================================================
> >
>
> Oh yuck, who would ever work in standards. ;)
>
> Is this function allowed to be redefined as a macro?
>

http://pubs.opengroup.org/onlinepubs/9699919799/functions/basename.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/dirname.html

Neither seems to say anything about that. Both have language like this:

" The *dirname*() function may modify the string pointed to by *path*, and
may return a pointer to static storage that may then be overwritten by a
subsequent call to *dirname*()."

It really would be better to have our own implementations and not
use the standard basename() and dirname(). The POSIX ones
are not thread-safe.


>
> > Chris has used basename as a method name and even though that should
> > be perfectly acceptable, the macro above gets expanded, the name
> > gets changed (in some places) to rld::path::__xpg_basename()
> >
> >       r.lowSourceLine = rld::path::basename (location);
> >
> > IMO the fix is to add dirname to rld-files, use rld basename and dirname
> > exclusively, and avoid libgen.h at all costs.
>
> Wouldn't the world be so much simpler if there was only Linux? ;)
>

The methods as defined by POSIX aren't thread-safe and can
modify the caller's string. Suck by design. :)

Having one mono-culture is easy but it doesn't make it right
even when conformant. :)


> > I didn't do that much work. I got lucky in a couple of files by removing
> the
> > include of libgen.h since it wasn't needed but I had to leave it in one
> place.
> >
> > $ grep dirname *.cc
> > GcovData.cc:    dirname( path );
> >
> > Hopefully this lets you all proceed with Chris' patches and my slight
> hack
> > in place.
> >
> > Ultimate solution is probably simple. We just need to hear from Chris.
>
> This is fine. I am slowing move covoar to use more and more of the
> rtemstoolkit.
>
> I will merge these changes into a v2 patch set.
>

Are you adding dirname()? Or does that need a ticket?

--joel


>
> Chris
>
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