Re: [PATCH 07/26] perf tools: Add check for existing link in buildid dir

Namhyung Kim
2020-09-14T05:54:51Z

On Mon, Sep 14, 2020 at 6:05 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> When adding new build id link we fail if the link is already
> there. Adding check for existing link and warn/replace the
> link with new target.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> tools/perf/util/build-id.c | 20 +++++++++++++++++++-
> 1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> index bdee4e08e60d..ecdc167aa1a0 100644
> --- a/tools/perf/util/build-id.c
> +++ b/tools/perf/util/build-id.c
> @@ -751,8 +751,26 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
> tmp = dir_name + strlen(buildid_dir) - 5;
> memcpy(tmp, "../..", 5);
>
> - if (symlink(tmp, linkname) == 0)
> + if (symlink(tmp, linkname) == 0) {
> err = 0;
> + } else if (errno == EEXIST) {
> + char path[PATH_MAX];
> +
> + if (readlink(linkname, path, sizeof(path)) == -1) {
> + pr_err("Cant read link: %s\n", linkname);

typo

> + goto out_free;
> + }
> + if (strcmp(tmp, path)) {
> + pr_err("Inconsistent .debug record, updating [%s]\n",
> + linkname);

But isn't it ok to copy a binary to another location?
There can be multiple binaries with the same build-id..

Thanks
Namhyung

> +
> + unlink(linkname);
> +
> + if (symlink(tmp, linkname))
> + goto out_free;
> + }
> + err = 0;
> + }
>
> /* Update SDT cache : error is just warned */
> if (realname &&
> --
> 2.26.2
>