From af21c579c860d10da1b0620e3d5d14abdc0b5fff Mon Sep 17 00:00:00 2001
From: Jiri Olsa <jolsa@kernel.org>
Date: Thu, 26 Nov 2020 18:00:11 +0100
Subject: [PATCH] perf build-id: 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@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201126170026.2619053-11-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/build-id.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 2aacc8b29f7e..4a391f13f40d 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -755,8 +755,25 @@ 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];
+		ssize_t len;
+
+		len = readlink(linkname, path, sizeof(path) - 1);
+		if (len <= 0) {
+			pr_err("Cant read link: %s\n", linkname);
+			goto out_free;
+		}
+		path[len] = '\0';
+
+		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 &&
-- 
2.20.1