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

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Message-Id: <20200913210313.1985612-8-jolsa@kernel.org>
Date:   Sun, 13 Sep 2020 23:02:54 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Song Liu <songliubraving@...com>,
        "Frank Ch. Eigler" <fche@...hat.com>,
        Ian Rogers <irogers@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: [PATCH 07/26] perf tools: Add check for existing link in buildid dir

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@...nel.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);
+			goto out_free;
+		}
+		if (strcmp(tmp, path)) {
+			pr_err("Inconsistent .debug record, updating [%s]\n",
+				linkname);
+
+			unlink(linkname);
+
+			if (symlink(tmp, linkname))
+				goto out_free;
+		}
+		err = 0;
+	}
 
 	/* Update SDT cache : error is just warned */
 	if (realname &&
-- 
2.26.2