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Date: Wed, 24 Aug 2016 09:30:10 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com>
Cc: acme@redhat.com, linux-kernel@vger.kernel.org,
        Namhyung Kim <namhyung@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH RFC RESEND] Perf: lookup dwarf unwind stack info in debug
 file pointed by .gnu_debuglink
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On Tue, Aug 23, 2016 at 06:18:10PM +0200, Matija Glavinic Pecotic wrote:

SNIP

> -		ret = filename__read_debuglink(filename, debuglink,
> -					       size - (debuglink - filename));
> +		ret = filename__read_debuglink(filename, symfile, PATH_MAX);
> +		if (ret)
> +			break;
> +
> +		/* Check predefined locations where debug file might reside:
> +		 *  - if debuglink is absolute path, check only that one
> +		 * If debuglink provides name w/o path, look for debug file:
> +		 *  - in the same directory as dso
> +		 *  - in the .debug subdirectory of dso directory
> +		 *  - in the /usr/lib/debug/[dso directory]
> +		 *  */
> +		ret = 0;
> +		if (symfile[0] == '/') {
> +			if (!is_regular_file(symfile))
> +				ret = -1;
> +			else
> +				strncpy(filename, symfile, size);
> +			break;
>  		}
> +
> +		snprintf(filename, size, "%s/%s", dso_dir, symfile);
> +		if(is_regular_file(filename))
> +			break;
> +
> +		snprintf(filename, size, "%s/.debug/%s", dso_dir, symfile);
> +		if(is_regular_file(filename))
> +			break;
> +
> +		snprintf(filename, size, "/usr/lib/debug/%s/%s",
> +				dso_dir, symfile);
> +		if(is_regular_file(filename))
> +			break;

it might be more clear to follow the same way we do for vmlinux search,
like array of possible paths and generic code to check.. search for
vmlinux_path in symbol.c

jirka