Re: [PATCH bpf v2 14/15] selftests/bpf: Check BPFTOOL env var in detect_bpftool_path()

[Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>]

On 2/18/26 00:30, Ihor Solodrai wrote:
> The bpftool_maps_access and bpftool_metadata tests may fail on BPF CI
> with "command not found", depending on a workflow.
> This happens because detect_bpftool_path() only checks two hardcoded
> relative paths:
>    - ./tools/sbin/bpftool
>    - ../tools/sbin/bpftool
>
> Add support for a BPFTOOL environment variable that allows specifying
> the exact path to the bpftool binary.
>
> Also replace strncpy() with snprintf() for proper null-termination.
>
> Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
> ---
>   tools/testing/selftests/bpf/bpftool_helpers.c | 19 +++++++++++++++----
>   1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/bpftool_helpers.c b/tools/testing/selftests/bpf/bpftool_helpers.c
> index a5824945a4a5..d810e73da6c8 100644
> --- a/tools/testing/selftests/bpf/bpftool_helpers.c
> +++ b/tools/testing/selftests/bpf/bpftool_helpers.c
> @@ -1,5 +1,6 @@
>   // SPDX-License-Identifier: GPL-2.0-only
>   #include "bpftool_helpers.h"
> +#include <stdio.h>
>   #include <unistd.h>
>   #include <string.h>
>   #include <stdbool.h>
> @@ -12,13 +13,24 @@
>   static int detect_bpftool_path(char *buffer)
>   {
>   	char tmp[BPFTOOL_PATH_MAX_LEN];
> +	const char *env_path;
> +
> +	/* First, check if BPFTOOL environment variable is set */
> +	env_path = getenv("BPFTOOL");
> +	if (env_path && access(env_path, X_OK) == 0) {
> +		snprintf(buffer, BPFTOOL_PATH_MAX_LEN, "%s", env_path);
> +		return 0;
> +	} else if (env_path) {
> +		fprintf(stderr, "bpftool '%s' doesn't exist or is not executable\n", env_path);
> +		return 1;
> +	}
>   
>   	/* Check default bpftool location (will work if we are running the
>   	 * default flavor of test_progs)
>   	 */
>   	snprintf(tmp, BPFTOOL_PATH_MAX_LEN, "./%s", BPFTOOL_DEFAULT_PATH);
>   	if (access(tmp, X_OK) == 0) {
> -		strncpy(buffer, tmp, BPFTOOL_PATH_MAX_LEN);
> +		snprintf(buffer, BPFTOOL_PATH_MAX_LEN, "%s", tmp);
>   		return 0;
>   	}
>   
> @@ -27,11 +39,11 @@ static int detect_bpftool_path(char *buffer)
>   	 */
>   	snprintf(tmp, BPFTOOL_PATH_MAX_LEN, "../%s", BPFTOOL_DEFAULT_PATH);
>   	if (access(tmp, X_OK) == 0) {
> -		strncpy(buffer, tmp, BPFTOOL_PATH_MAX_LEN);
> +		snprintf(buffer, BPFTOOL_PATH_MAX_LEN, "%s", tmp);
>   		return 0;
>   	}
>   
> -	/* Failed to find bpftool binary */
> +	fprintf(stderr, "Failed to detect bpftool path, use BPFTOOL env var to override\n");
>   	return 1;
>   }
>   
> @@ -71,4 +83,3 @@ int get_bpftool_command_output(char *args, char *output_buf, size_t output_max_l
>   {
>   	return run_command(args, output_buf, output_max_len);
>   }
> -