Re: [dpdk-dev] [PATCH] eal: support strlcat function

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 1/16/2019 12:48 PM, Bruce Richardson wrote:
> Add the strlcat function to DPDK to exist alongside the strlcpy one.  While
> strncat is generally safe for use for concatenation, the API for the
> strlcat function is perhaps a little nicer to use, and supports truncation
> detection.
> 
> See commit: 5364de644a4b ("eal: support strlcpy function") for more
> details on the function selection logic, since we only should be using the
> DPDK-provided version when no system-provided version is present.
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
>  .../common/include/rte_string_fns.h           | 15 +++++++
>  test/test/test_string_fns.c                   | 45 +++++++++++++++++++
>  2 files changed, 60 insertions(+)
> 
> diff --git a/lib/librte_eal/common/include/rte_string_fns.h b/lib/librte_eal/common/include/rte_string_fns.h
> index 9a2a1ff90..e7a1656f0 100644
> --- a/lib/librte_eal/common/include/rte_string_fns.h
> +++ b/lib/librte_eal/common/include/rte_string_fns.h
> @@ -59,10 +59,24 @@ rte_strlcpy(char *dst, const char *src, size_t size)
>  	return (size_t)snprintf(dst, size, "%s", src);
>  }
>  
> +/**
> + * @internal
> + * DPDK-specific version of strlcat for systems without
> + * libc or libbsd copies of the function
> + */
> +static inline size_t
> +rte_strlcat(char *dst, const char *src, size_t size)
> +{
> +	size_t l = strnlen(dst, size);
> +	return l + ((l < size) ?
> +		rte_strlcpy(&dst[l], src, size - l) : strlen(src));

I think operation is complex for ternary operation, regular if check can be
simpler, other than that looks good to me.

> +}
> +
>  /* pull in a strlcpy function */
>  #ifdef RTE_EXEC_ENV_BSDAPP
>  #ifndef __BSD_VISIBLE /* non-standard functions are hidden */
>  #define strlcpy(dst, src, size) rte_strlcpy(dst, src, size)
> +#define strlcat(dst, src, size) rte_strlcat(dst, src, size)
>  #endif
>  
>  #else /* non-BSD platforms */
> @@ -71,6 +85,7 @@ rte_strlcpy(char *dst, const char *src, size_t size)
>  
>  #else /* no BSD header files, create own */
>  #define strlcpy(dst, src, size) rte_strlcpy(dst, src, size)
> +#define strlcat(dst, src, size) rte_strlcat(dst, src, size)
>  
>  #endif /* RTE_USE_LIBBSD */
>  #endif /* BSDAPP */
> diff --git a/test/test/test_string_fns.c b/test/test/test_string_fns.c
> index 3f091ab92..3bd8ed5d8 100644
> --- a/test/test/test_string_fns.c
> +++ b/test/test/test_string_fns.c
> @@ -129,11 +129,56 @@ test_rte_strsplit(void)
>  	return 0;
>  }
>  
> +int
> +test_rte_strlcat(void)
> +{
> +	/* only run actual unit tests if we have system-provided strlcat */
> +#if defined(__BSD_VISIBLE) || defined(RTE_USE_LIBBSD)
> +#define BUF_LEN 32
> +	const char dst[BUF_LEN] = "Test string";
> +	const char src[] = " appended";
> +	char bsd_dst[BUF_LEN];
> +	char rte_dst[BUF_LEN];
> +	size_t i, bsd_ret, rte_ret;
> +
> +	LOG("dst = '%s', strlen(dst) = %zu\n", dst, strlen(dst));
> +	LOG("src = '%s', strlen(src) = %zu\n", src, strlen(src));
> +	LOG("---\n");
> +
> +	for (i = 0; i < BUF_LEN; i++) {
> +		/* initialize destination buffers */
> +		memcpy(bsd_dst, dst, BUF_LEN);
> +		memcpy(rte_dst, dst, BUF_LEN);
> +		/* compare implementations */
> +		bsd_ret = strlcat(bsd_dst, src, i);
> +		rte_ret = rte_strlcat(rte_dst, src, i);
> +		if (bsd_ret != rte_ret) {
> +			LOG("Incorrect retval for buf length = %zu\n", i);
> +			LOG("BSD: '%zu', rte: '%zu'\n", bsd_ret, rte_ret);
> +			return -1;
> +		}
> +		if (memcmp(bsd_dst, rte_dst, BUF_LEN) != 0) {
> +			LOG("Resulting buffers don't match\n");
> +			LOG("BSD: '%s', rte: '%s'\n", bsd_dst, rte_dst);
> +			return -1;
> +		}
> +		LOG("buffer size = %zu: dst = '%s', ret = %zu\n",
> +			i, rte_dst, rte_ret);
> +	}
> +	LOG("Checked %zu combinations\n", i);
> +#undef BUF_LEN
> +#endif /* defined(__BSD_VISIBLE) || defined(RTE_USE_LIBBSD) */
> +
> +	return 0;
> +}
> +
>  static int
>  test_string_fns(void)
>  {
>  	if (test_rte_strsplit() < 0)
>  		return -1;
> +	if (test_rte_strlcat() < 0)
> +		return -1;
>  	return 0;
>  }
>  
>