linux-kernel - [PATCH 09/24] perf tools: Add check for existing link in buildid dir

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Message-Id: <20201117110053.1303113-10-jolsa@kernel.org>
Date:   Tue, 17 Nov 2020 12:00:38 +0100
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>,
        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 09/24] 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 output debug message
that the build id is already linked.

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/perf/util/build-id.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 7d9ecc37849c..ef9a31b54ba2 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -754,8 +754,21 @@ 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_debug("build <%s> already linked to %s\n",
+				 sbuild_id, linkname);
+		}
+		err = 0;
+	}
 
 	/* Update SDT cache : error is just warned */
 	if (realname &&
-- 
2.26.2