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    Subject[PATCH 01/14] perf data: Fix 'strncat may truncate' build failure with recent gcc
    Date
    From: Shawn Landden <shawn@git.icu>

    This strncat() is safe because the buffer was allocated with zalloc(),
    however gcc doesn't know that. Since the string always has 4 non-null
    bytes, just use memcpy() here.

    CC /home/shawn/linux/tools/perf/util/data-convert-bt.o
    In file included from /usr/include/string.h:494,
    from /home/shawn/linux/tools/lib/traceevent/event-parse.h:27,
    from util/data-convert-bt.c:22:
    In function ‘strncat’,
    inlined from ‘string_set_value’ at util/data-convert-bt.c:274:4:
    /usr/include/powerpc64le-linux-gnu/bits/string_fortified.h:136:10: error: ‘__builtin_strncat’ output may be truncated copying 4 bytes from a string of length 4 [-Werror=stringop-truncation]
    136 | return __builtin___strncat_chk (__dest, __src, __len, __bos (__dest));
    | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    Signed-off-by: Shawn Landden <shawn@git.icu>
    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Wang Nan <wangnan0@huawei.com>
    LPU-Reference: 20190518183238.10954-1-shawn@git.icu
    Link: https://lkml.kernel.org/n/tip-289f1jice17ta7tr3tstm9jm@git.kernel.org
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/util/data-convert-bt.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
    index e0311c9750ad..9097543a818b 100644
    --- a/tools/perf/util/data-convert-bt.c
    +++ b/tools/perf/util/data-convert-bt.c
    @@ -271,7 +271,7 @@ static int string_set_value(struct bt_ctf_field *field, const char *string)
    if (i > 0)
    strncpy(buffer, string, i);
    }
    - strncat(buffer + p, numstr, 4);
    + memcpy(buffer + p, numstr, 4);
    p += 3;
    }
    }
    --
    2.20.1
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