Re: [PATCH] Use strlen instead of sizeof on char* string

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 11/13/2012 04:47 PM, Alexander Stein wrote:
> This bug was detected by the clang warning:
> libsocketcan.c:384:16: warning: argument to 'sizeof' in 'strncmp' call
> is the same expression as the source; did you mean to provide an
> explicit length? [-Wsizeof-pointer-memaccess]
> sizeof(name)) != 0)
> ~~~~~~~^~~~~~
> 
> Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
> ---
>  src/libsocketcan.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/src/libsocketcan.c b/src/libsocketcan.c
> index fedcbdc..3ad2a6c 100644
> --- a/src/libsocketcan.c
> +++ b/src/libsocketcan.c
> @@ -364,6 +364,7 @@ static int do_get_nl_link(int fd, __u8 acquire, const char *name, void *res)
>  		     nl_msg = NLMSG_NEXT(nl_msg, u_msglen)) {
>  			int type = nl_msg->nlmsg_type;
>  			int len;
> +			int namelen = strlen(name);
>  
>  			if (type == NLMSG_DONE) {
>  				done++;
> @@ -381,7 +382,7 @@ static int do_get_nl_link(int fd, __u8 acquire, const char *name, void *res)
>  
>  			if (strncmp
>  			    ((char *)RTA_DATA(tb[IFLA_IFNAME]), name,
> -			     sizeof(name)) != 0)
> +			     namelen) != 0)

What about using strcmp() instead. AFAIK it will compare until it finds
the end of the string in one of the strings, so it should be no
difference here?

>  				continue;
>  
>  			if (tb[IFLA_LINKINFO])
> 

Marc

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