[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-ppc] [PATCH] fdt_ro.c: implement strnlen
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [PATCH] fdt_ro.c: implement strnlen |
Date: |
Thu, 19 Oct 2017 12:31:26 +1100 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
On Wed, Oct 18, 2017 at 06:31:16PM -0400, John Arbuckle wrote:
> Implement the strnlen() function if it isn't implemented.
>
> Signed-off-by: John Arbuckle <address@hidden>
Nice idea, but this won't work.
> ---
> libfdt/fdt_ro.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
> index 3d00d2e..a7986fb 100644
> --- a/libfdt/fdt_ro.c
> +++ b/libfdt/fdt_ro.c
> @@ -55,6 +55,30 @@
>
> #include "libfdt_internal.h"
>
> +/* if the current environment does not define strnlen */
> +#ifndef strnlen
This will only trigger if strnlen is defined as a macro. The C
library (or other environment) *might* do that, but there's no
guarantee, whether or not it defines strnlen as a function. With
extra complications if the compiler has a strnlen builtin like gcc.
> +
> +/* This eliminates the missing prototype warning */
> +int strnlen(const char *string, int max_count);
> +
> +/*
> + * strnlen: return the length of a string or max_count
> + * which ever is shortest
> + */
> +
> +int strnlen(const char *string, int max_count)
Also strnlen is supposed to take and return size_t, not int.
> +{
> + int count;
> + for(count = 0; count < max_count; count++) {
> + if (string[count] == '\0') {
> + break;
> + }
> + }
> + return count;
> +}
> +
> +#endif /* strnlen */
> +
> static int _fdt_nodename_eq(const void *fdt, int offset,
> const char *s, int len)
> {
In any case, this sort of compatibility munging is the job of
libfdt_env.h. It's purpose is to provide all the external things that
libfdt needs - there's not that many of them and strnlen() is one.
The included libfdt_env.h is intended for POSIXy userspace
environments, which should already include strnlen() in string.h.
If your environment does not provide strnlen(), you probably need your
own version of libfdt_env.h, which will need to define it.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
signature.asc
Description: PGP signature