Re: [PATCH v2] modpost: remove use of non-standard strsep() in HOSTCC code

From: Masahiro Yamada
Date: Wed Jul 01 2020 - 11:51:38 EST


On Wed, Jul 1, 2020 at 3:18 PM H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> wrote:
>
> strsep() is neither standard C nor POSIX and used outside
> the kernel code here. Using it here requires that the
> build host supports it out of the box which is e.g.
> not true for a Darwin build host and using a cross-compiler.
> This leads to:
>
> scripts/mod/modpost.c:145:2: warning: implicit declaration of function 'strsep' [-Wimplicit-function-declaration]
> return strsep(stringp, "\n");
> ^
>
> and a segfault when running MODPOST.
>
> See also: https://stackoverflow.com/a/7219504
>
> So let's replace this by strchr() instead of using strsep().
> It does not hurt kernel size or speed since this code is run
> on the build host.
>
> Fixes: ac5100f5432967 ("modpost: add read_text_file() and get_line() helpers")
> Co-developed-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>
> ---

Applied to linux-kbuild.
Thanks.


> scripts/mod/modpost.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 6aea65c657454..45f2ab2ec2d46 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -138,11 +138,19 @@ char *read_text_file(const char *filename)
>
> char *get_line(char **stringp)
> {
> + char *orig = *stringp, *next;
> +
> /* do not return the unwanted extra line at EOF */
> - if (*stringp && **stringp == '\0')
> + if (!orig || *orig == '\0')
> return NULL;
>
> - return strsep(stringp, "\n");
> + next = strchr(orig, '\n');
> + if (next)
> + *next++ = '\0';
> +
> + *stringp = next;
> +
> + return orig;
> }
>
> /* A list of all modules we processed */
> --
> 2.26.2
>


--
Best Regards
Masahiro Yamada