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Re: [PATCH perf/core v10 09/23] perf probe: Show all cached probes

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On Thu, 9 Jun 2016 11:22:55 -0300
Arnaldo Carvalho de Melo <acme@kernel.org> wrote:

> Em Wed, Jun 08, 2016 at 06:30:30PM +0900, Masami Hiramatsu escreveu:
> > +char *build_id_cache__origname(const char *sbuild_id)
> > +{
> > +	char *linkname;
> > +	char buf[PATH_MAX];
> > +	char *ret = NULL, *p;
> > +	size_t offs = 5;	/* == strlen("../..") */
> > +
> > +	linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
> > +	if (!linkname)
> > +		return NULL;
> > +
> > +	if (readlink(linkname, buf, PATH_MAX) < 0)
> > +		goto out;
> > +	/* The link should be "../..<origpath>/<sbuild_id>" */
> > +	p = strrchr(buf, '/');	/* Cut off the "/<sbuild_id>" */
> > +	if (p && (p > buf + offs)) {
> > +		*p = '\0';
> > +		if (buf[offs + 1] == '[')
> > +			offs++;	/*
> > +				 * This is a DSO name, like [kernel.kallsyms].
> > +				 * Skip the first '/', since this is not the
> > +				 * cache of a regular file.
> > +				 */
> > +		ret = strdup(buf + offs);	/* Skip "../..[/]" */
> 
> strdup can fail.

Ah, right.

> 
> > +	}
> > +out:
> > +	free(linkname);
> > +	return ret;
> > +}
> > +
> >  static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso)
> >  {
> >  	return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : "elf");
> > @@ -390,6 +419,59 @@ void disable_buildid_cache(void)
> >  	no_buildid_cache = true;
> >  }
> >  
> > +int build_id_cache__list_all(struct strlist **result)
> > +{
> > +	struct strlist *toplist, *list, *bidlist;
> > +	struct str_node *nd, *nd2;
> > +	char *topdir, *linkdir;
> > +	char sbuild_id[SBUILD_ID_SIZE];
> > +	int ret = 0;
> > +
> > +	/* Open the top-level directory */
> > +	if (asprintf(&topdir, "%s/.build-id/", buildid_dir) < 0)
> > +		return -errno;
> 
> Wouldn't be better to just return -1 and leave the caller to look at
> errno? I know that there is code that does that, but better stick to the
> errno convention?

Hmm, IMHO, that may depends on case. This case is possible,
but in below case, pr_debug() also calls libc function and
it can override the errno. This can also happen when we run
some cleanup code before returning.

So, I think it will be good for enough small functions, but
not good for complex bigger functions.

From the viewpoint of debugging, maybe it is also possible
to return -N, where N is based on the place where the error
happens :)

> > +	toplist = lsdir(topdir, lsdir_no_dot_filter);
> > +	if (!toplist) {
> > +		pr_debug("Failed to opendir %s\n", topdir);
> > +		ret = -errno;
> 
> ditto
> 
> > +		goto out;
> > +	}
> > +	bidlist = strlist__new(NULL, NULL);
> > +	strlist__for_each(nd, toplist) {
> > +		if (asprintf(&linkdir, "%s/%s", topdir, nd->s) < 0) {
> > +			ret = -errno;
> > +			goto out;
> > +		}
> > +		/* Open the lower-level directory */
> > +		list = lsdir(linkdir, lsdir_no_dot_filter);
> > +		if (!list) {
> > +			pr_debug("Failed to open %s: %d\n", linkdir, -errno);
> > +			goto next;
> > +		}
> > +		strlist__for_each(nd2, list) {
> > +			ret = snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
> > +					nd->s, nd2->s);
> > +			if (ret != SBUILD_ID_SIZE - 1) {
> > +				pr_debug("%s/%s is not buildid cache\n",
> > +					nd->s, nd2->s);
> > +				continue;
> > +			}
> > +			strlist__add(bidlist, sbuild_id);
> 
> strlist__add() can fail, please check its result.

Ah, I forgot to update that...

> 
> > +		}
> > +		strlist__delete(list);
> > +next:
> > +		free(linkdir);
> > +	}
> > +
> > +	*result = bidlist;
> > +out:
> > +	if (toplist)
> > +		strlist__delete(toplist);
> 
> No need for checking toplist.

OK.

> 
> > +	free(topdir);
> > +
> > +	return ret;
> > +}
> 
> <SNIP>
> 
> - Arnaldo

Thank you!

-- 
Masami Hiramatsu <mhiramat@kernel.org>

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[PATCH perf/core v10 00/23] perf-probe --cache and SDT support Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:30 +0200
  [PATCH perf/core v10 02/23] perf-probe: Fix to add NULL check for strndup Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:30 +0200
    [tip:perf/core] perf probe: Fix to add NULL check for strndup tip-bot for Masami Hiramatsu <tipbot@zytor.com> - 2016-06-16 10:40 +0200
  [PATCH perf/core v10 05/23] perf probe: Recover and export synthesize_perf_probe_point() Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
    [tip:perf/core] perf probe: Uncomment and export  synthesize_perf_probe_point() tip-bot for Masami Hiramatsu <tipbot@zytor.com> - 2016-06-16 10:40 +0200
  [PATCH perf/core v10 14/23] perf probe: Accept %sdt and %cached event name Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 18/23] perf probe: Allow wildcard for cached events Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 22/23] perf build: Add sdt feature detection Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 15/23] perf-list: Show SDT and pre-cached events Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 10/23] perf probe: Remove caches when --cache is given Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
    Re: [PATCH perf/core v10 10/23] perf probe: Remove caches when  --cache is given Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-06-09 16:30 +0200
      Re: [PATCH perf/core v10 10/23] perf probe: Remove caches when  --cache is given Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-11 03:20 +0200
  [PATCH perf/core v10 09/23] perf probe: Show all cached probes Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
    Re: [PATCH perf/core v10 09/23] perf probe: Show all cached probes Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-06-09 16:30 +0200
      Re: [PATCH perf/core v10 09/23] perf probe: Show all cached probes Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-11 02:30 +0200
        Re: [PATCH perf/core v10 09/23] perf probe: Show all cached probes Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-12 05:30 +0200
  [PATCH perf/core v10 08/23] perf probe: Use cache entry if possible Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 12/23] perf probe: Add group name support Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 11/23] perf/sdt: ELF support for SDT Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 04/23] perf probe: Add perf_probe_event__copy() Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
    [tip:perf/core] perf probe: Add perf_probe_event__copy() tip-bot for Masami Hiramatsu <tipbot@zytor.com> - 2016-06-16 10:40 +0200
  [PATCH perf/core v10 21/23] perf probe: Support a special SDT probe format Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 16/23] perf-list: Skip SDTs placed in invalid binaries Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 13/23] perf buildid-cache: Scan and import user SDT events to probe cache Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 17/23] perf: probe-cache: Add for_each_probe_cache_entry() wrapper Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 23/23] perf-test: Add a test case for SDT event Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 19/23] perf probe: Search SDT/cached event from all probe caches Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 20/23] perf probe: Support @BUILDID or @FILE suffix for SDT events Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
  [PATCH perf/core v10 07/23] perf probe: Add --cache option to cache the probe definitions Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
    Re: [PATCH perf/core v10 07/23] perf probe: Add --cache option to  cache the probe definitions Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-06-09 16:20 +0200
      Re: [PATCH perf/core v10 07/23] perf probe: Add --cache option to  cache the probe definitions Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-11 01:40 +0200
  [PATCH perf/core v10 06/23] perf probe-file: Introduce perf_cache interfaces Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 11:40 +0200
    Re: [PATCH perf/core v10 06/23] perf probe-file: Introduce  perf_cache interfaces Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-06-09 16:20 +0200
      Re: [PATCH perf/core v10 06/23] perf probe-file: Introduce  perf_cache interfaces Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-11 00:20 +0200
  [PATCH perf/core v10 23/23] perf-test: Add a test case for SDT event Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 13:20 +0200
  Re: [PATCH perf/core v10 00/23] perf-probe --cache and SDT support Masami Hiramatsu <masami.hiramatsu@gmail.com> - 2016-06-08 13:20 +0200
  [PATCH perf/core v10 22/23] perf build: Add sdt feature detection Masami Hiramatsu <mhiramat@kernel.org> - 2016-06-08 13:20 +0200

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