From e1a3aad31c3b4b4d3cbd38bc010bb63ba9f63dfa Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Wed, 23 Aug 2023 01:08:05 -0700 Subject: [PATCH] perf pmu: Avoid a path name copy Rather than read a base path and append into a 2nd path, read the base path directly into output buffer and append to that. Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Gaosheng Cui Cc: Ingo Molnar Cc: James Clark Cc: Jing Zhang Cc: Jiri Olsa Cc: John Garry Cc: Kajol Jain Cc: Kan Liang Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Rob Herring Link: https://lore.kernel.org/r/20230823080828.1460376-3-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/pmu.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c index a7f05e4..7683c67 100644 --- a/tools/perf/util/pmu.c +++ b/tools/perf/util/pmu.c @@ -1756,17 +1756,19 @@ int perf_pmu__event_source_devices_fd(void) * then pathname will be filled with * "/sys/bus/event_source/devices/cs_etm/format" * - * Return 0 if the sysfs mountpoint couldn't be found or if no - * characters were written. + * Return 0 if the sysfs mountpoint couldn't be found, if no characters were + * written or if the buffer size is exceeded. */ int perf_pmu__pathname_scnprintf(char *buf, size_t size, const char *pmu_name, const char *filename) { - char base_path[PATH_MAX]; + size_t len; - if (!perf_pmu__event_source_devices_scnprintf(base_path, sizeof(base_path))) + len = perf_pmu__event_source_devices_scnprintf(buf, size); + if (!len || (len + strlen(pmu_name) + strlen(filename) + 1) >= size) return 0; - return scnprintf(buf, size, "%s%s/%s", base_path, pmu_name, filename); + + return scnprintf(buf + len, size - len, "%s/%s", pmu_name, filename); } int perf_pmu__pathname_fd(int dirfd, const char *pmu_name, const char *filename, int flags) -- 2.7.4