Re: [PATCH] tools: Fix str_error_r() Werror=restrict build

Jiri Olsa
2018-03-19T07:18:24Z

On Mon, Mar 19, 2018 at 02:55:04PM +0900, Sergey Senozhatsky wrote:
> Commit c8b5f2c96d1bf6c ("tools: Introduce str_error_r()") added
> an str_error_r() wrapper which makes gcc8 unhappy due to
> restrict-qualified parameter aliasing violation:
>
> ../lib/str_error_r.c: In function ‘str_error_r’:
> ../lib/str_error_r.c:25:3: error: passing argument 1 to restrict-qualified parameter aliases with argument 5 [-Werror=restrict]
> snprintf(buf, buflen, "INTERNAL ERROR: strerror_r(%d, %p, %zd)=%d", errnum, buf, buflen, err);
> ^~~~~~~~
> cc1: all warnings being treated as errors
>
> Workaround that aliasing error by creating an additional stack
> variable which holds the buf pointer value we passed to strerror_r().
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

Josh posted another way to fix it:
https://marc.info/?l=linux-kernel&m=152116992412107&w=2

your patch keeps the same output, I dont mind either way ;-)

jirka

> ---
> tools/lib/str_error_r.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/tools/lib/str_error_r.c b/tools/lib/str_error_r.c
> index d6d65537b0d9..11c3425f272b 100644
> --- a/tools/lib/str_error_r.c
> +++ b/tools/lib/str_error_r.c
> @@ -21,7 +21,12 @@
> char *str_error_r(int errnum, char *buf, size_t buflen)
> {
> int err = strerror_r(errnum, buf, buflen);
> - if (err)
> - snprintf(buf, buflen, "INTERNAL ERROR: strerror_r(%d, %p, %zd)=%d", errnum, buf, buflen, err);
> + if (err) {
> + char *err_buf = buf;
> +
> + snprintf(err_buf, buflen,
> + "INTERNAL ERROR: strerror_r(%d, %p, %zd)=%d",
> + errnum, buf, buflen, err);
> + }
> return buf;
> }
> --
> 2.16.2
>