linux-kernel - [PATCH 3.16 39/99] perf help: Remove needless use of strncpy()

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Date:   Tue, 02 Apr 2019 14:38:27 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Adrian Hunter" <adrian.hunter@...el.com>,
        "Arnaldo Carvalho de Melo" <acme@...hat.com>,
        "Jiri Olsa" <jolsa@...nel.org>,
        "Namhyung Kim" <namhyung@...nel.org>
Subject: [PATCH 3.16 39/99] perf help: Remove needless use of strncpy()

3.16.65-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Arnaldo Carvalho de Melo <acme@...hat.com>

commit b6313899f4ed2e76b8375cf8069556f5b94fbff0 upstream.

Since we make sure the destination buffer has at least strlen(orig) + 1,
no need to do a strncpy(dest, orig, strlen(orig)), just use strcpy(dest,
orig).

This silences this gcc 8.2 warning on Alpine Linux:

  In function 'add_man_viewer',
      inlined from 'perf_help_config' at builtin-help.c:284:3:
  builtin-help.c:192:2: error: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]
    strncpy((*p)->name, name, len);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  builtin-help.c: In function 'perf_help_config':
  builtin-help.c:187:15: note: length computed here
    size_t len = strlen(name);
                 ^~~~~~~~~~~~

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Fixes: 078006012401 ("perf_counter tools: add in basic glue from Git")
Link: https://lkml.kernel.org/n/tip-2f69l7drca427ob4km8i7kvo@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 tools/perf/builtin-help.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/perf/builtin-help.c
+++ b/tools/perf/builtin-help.c
@@ -166,7 +166,7 @@ static void add_man_viewer(const char *n
 	while (*p)
 		p = &((*p)->next);
 	*p = zalloc(sizeof(**p) + len + 1);
-	strncpy((*p)->name, name, len);
+	strcpy((*p)->name, name);
 }
 
 static int supported_man_viewer(const char *name, size_t len)