RE: [PATCH v10 2/9] test: add new function to get current file-prefix arg

[Marat Khalili <marat.khalili@huawei.com>]

> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Monday 29 December 2025 21:59
> To: dev@dpdk.org
> Cc: Stephen Hemminger <stephen@networkplumber.org>
> Subject: [PATCH v10 2/9] test: add new function to get current file-prefix arg
> 
> Refactor so that there is one function to get current argument
> for "--file-prefix=XXX".
> 
> The code does not need to initialize all these 4K buffers since
> they are directly used by functions that set them.
> The maximum sizeof of the current DPDK prefix is NAME_MAX (128)
> not PATH_MAX(4096) so save a significant amount of space.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  app/test/process.h | 38 ++++++++++++++++++++++++++++++++------
>  1 file changed, 32 insertions(+), 6 deletions(-)
> 
> diff --git a/app/test/process.h b/app/test/process.h
> index f948a89786..251262d948 100644
> --- a/app/test/process.h
> +++ b/app/test/process.h
> @@ -199,15 +199,22 @@ process_dup(const char *const argv[], int numargs, const char *env_value)
>  	return status;
>  }
> 
> -/* FreeBSD doesn't support file prefixes, so force compile failures for any
> - * tests attempting to use this function on FreeBSD.
> - */
> +/* FreeBSD doesn't support file prefixes, so no argument passed. */
> +#ifdef RTE_EXEC_ENV_FREEBSD
> +static inline const char *
> +file_prefix_arg(void)
> +{
> +	/* BSD target doesn't support prefixes at this point */
> +	return "";
> +}
> +#else
> +
>  #ifdef RTE_EXEC_ENV_LINUX
>  static inline char *
>  get_current_prefix(char *prefix, int size)
>  {
> -	char path[PATH_MAX] = {0};
> -	char buf[PATH_MAX] = {0};
> +	char path[64];
> +	char buf[PATH_MAX];
> 
>  	/* get file for config (fd is always 3) */
>  	snprintf(path, sizeof(path), "/proc/self/fd/%d", 3);

I wonder if we ever learn what stood behind this.

> @@ -216,10 +223,29 @@ get_current_prefix(char *prefix, int size)
>  	if (readlink(path, buf, sizeof(buf)) == -1)
>  		return NULL;
> 
> -	/* get the prefix */
> +	/*
> +	 * path should be something like "/var/run/dpdk/config"

JFYI it's /run/dpdk/my-prefix/config on my system, although example correctly demonstrates the algorithm.

> +	 * which results in prefix of "dpdk"
> +	 */
>  	rte_basename(dirname(buf), prefix, size);
> +	return prefix;
> +}
> +
> +/* Return a --file-prefix=XXXX argument or NULL */
> +static inline const char *
> +file_prefix_arg(void)
> +{
> +	static char prefix[NAME_MAX + sizeof("--file-prefix=")];
> +	char tmp[NAME_MAX];

Can current prefix change? Can we verify that it is filled already and return immediately?

> 
> +	if (get_current_prefix(tmp, sizeof(tmp)) == NULL) {
> +		fprintf(stderr, "Error - unable to get current prefix!\n");
> +		return NULL;
> +	}
> +
> +	snprintf(prefix, sizeof(prefix), "--file-prefix=%s", tmp);
>  	return prefix;
> +#endif
>  }
>  #endif
> 
> --
> 2.51.0

Considering the refactor in the next commit, with or without suggested optimization,

Acked-by: Marat Khalili <marat.khalili@huawei.com>