[tip:perf/core] perf parse-events: Fix unchecked usage of strncpy()

[tip-bot for Arnaldo Carvalho de Melo]

Commit-ID:  bd8d57fb7e25e9fcf67a9eef5fa13aabe2016e07
Gitweb:     https://git.kernel.org/tip/bd8d57fb7e25e9fcf67a9eef5fa13aabe2016e07
Author:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Thu, 6 Dec 2018 13:52:13 -0300
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 17 Dec 2018 14:59:30 -0300

perf parse-events: Fix unchecked usage of strncpy()

The strncpy() function may leave the destination string buffer
unterminated, better use strlcpy() that we have a __weak fallback
implementation for systems without it.

This fixes this warning on an Alpine Linux Edge system with gcc 8.2:

  util/parse-events.c: In function 'print_symbol_events':
  util/parse-events.c:2465:4: error: 'strncpy' specified bound 100 equals destination size [-Werror=stringop-truncation]
      strncpy(name, syms->symbol, MAX_NAME_LEN);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  In function 'print_symbol_events.constprop',
      inlined from 'print_events' at util/parse-events.c:2508:2:
  util/parse-events.c:2465:4: error: 'strncpy' specified bound 100 equals destination size [-Werror=stringop-truncation]
      strncpy(name, syms->symbol, MAX_NAME_LEN);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  In function 'print_symbol_events.constprop',
      inlined from 'print_events' at util/parse-events.c:2511:2:
  util/parse-events.c:2465:4: error: 'strncpy' specified bound 100 equals destination size [-Werror=stringop-truncation]
      strncpy(name, syms->symbol, MAX_NAME_LEN);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Fixes: 947b4ad1d198 ("perf list: Fix max event string size")
Link: https://lkml.kernel.org/n/tip-b663e33bm6x8hrkie4uxh7u2@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/parse-events.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 59be3466d64d..920e1e6551dd 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -2462,7 +2462,7 @@ restart:
 		if (!name_only && strlen(syms->alias))
 			snprintf(name, MAX_NAME_LEN, "%s OR %s", syms->symbol, syms->alias);
 		else
-			strncpy(name, syms->symbol, MAX_NAME_LEN);
+			strlcpy(name, syms->symbol, MAX_NAME_LEN);
 
 		evt_list[evt_i] = strdup(name);
 		if (evt_list[evt_i] == NULL)