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perf ui helpline: Use strlcpy() as a shorter form of strncpy() + explicit set nul

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commit 4d0f16d059ddb91424480d88473f7392f24aebdc upstream.

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

In this case we are actually setting the null byte at the right place,
but since we pass the buffer size as the limit to strncpy() and not
it minus one, gcc ends up warning us about that, see below. So, lets
just switch to the shorter form provided by strlcpy().

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

  ui/tui/helpline.c: In function 'tui_helpline__push':
  ui/tui/helpline.c:27:2: error: 'strncpy' specified bound 512 equals destination size [-Werror=stringop-truncation]
    strncpy(ui_helpline__current, msg, sz)[sz - 1] = '\0';
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Fixes: e6e904687949 ("perf ui: Introduce struct ui_helpline")
Link: https://lkml.kernel.org/n/tip-d1wz0hjjsh19xbalw69qpytj@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Arnaldo Carvalho de Melo 2018-12-06 11:41:03 -03:00 committed by Greg Kroah-Hartman
parent c7c680979b
commit e1f60e369a
1 changed files with 1 additions and 1 deletions
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tools/perf/ui/tui/helpline.c
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@ -23,7 +23,7 @@ static void tui_helpline__push(const char *msg)
SLsmg_set_color(0);
SLsmg_write_nstring((char *)msg, SLtt_Screen_Cols);
SLsmg_refresh();
strncpy(ui_helpline__current, msg, sz)[sz - 1] = '\0';
strlcpy(ui_helpline__current, msg, sz);
}
static int tui_helpline__show(const char *format, va_list ap)