From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E2EF2405ED for ; Thu, 19 Feb 2026 01:13:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771463604; cv=none; b=gxJIwrAABHxOqU//JrmQ05jmwvRKdwWJ+jVbwPHfe9aScARrbjPd6xJ8XlwYONePhQfmw/TrAgPdeda2ql8Q8R2zOAzgR/VfJ8ElwxSIwnFkWTjyCLKa5B6o32YoPc/IClTFuXDqzyiNo+VmYXskBFrd+/PafhSyhWW83jBBP38= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771463604; c=relaxed/simple; bh=A+VT5+BsIR/a3Qzvhm7j+Pf2wFJv6fT9CMBrm9wXpYM=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=eeazlYlcA26wAarHj0WlW+vEf2ZR4l+n1o3ldmZ3/V4uNM6sPjZBKnbBZcfzTsMfaNJDS+BwHvnaODZYBUWrgLmWVUvd5B4tatmPozuVIFUxcrKBLI4t1RgM5UdJZ7c1X0ud4hUr/3hMtRU7W2PEs6frgbisp4JnRXy+7t4+2kw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=BvQgQcNM; arc=none smtp.client-ip=95.215.58.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="BvQgQcNM" Message-ID: <54cffd1f-df2f-4a01-a07d-0509425558d9@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1771463590; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lPMTLBQvRNETuIrCkCAVjc0UXZ7p6OpQAPvFEm5Rxig=; b=BvQgQcNMUEnxnJB5aByo3kYo/UeIKNNSjc5/AjMk8uciZt1j7tuwRkAt4yOYw3PEe9QHzx iEZ/Nq9/YmMhTFhGzAya+Xo8mH/FlM4WAi8P1qvYQZr19JK6C6fHmPwB1xZtV4+9AqiaIl DS+0/GqnKVWhBfU9/o4/DVyYUt9mhMo= Date: Wed, 18 Feb 2026 17:12:52 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf v2 14/15] selftests/bpf: Check BPFTOOL env var in detect_bpftool_path() X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Ihor Solodrai To: Alexei Starovoitov Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , Jiri Olsa , Mykyta Yatsenko , =?UTF-8?Q?Alexis_Lothor=C3=A9?= , Amery Hung , bpf , LKML , Kernel Team References: <20260218003041.1156774-1-ihor.solodrai@linux.dev> <20260218003041.1156774-15-ihor.solodrai@linux.dev> <84ba9764-5ba2-4e9b-af81-3fea2682d161@linux.dev> Content-Language: en-US In-Reply-To: <84ba9764-5ba2-4e9b-af81-3fea2682d161@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 2/18/26 10:17 AM, Ihor Solodrai wrote: > On 2/18/26 9:38 AM, Alexei Starovoitov wrote: >> On Tue, Feb 17, 2026 at 4:31 PM Ihor Solodrai wrote: >>> >>> [...] >>> >>> /* 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); >> >> I guess it's ok for user space, but >> >> git log --oneline|grep "snprintf with strscpy" >> ad789a85b163 mm/cma: replace snprintf with strscpy in cma_new_area >> 674fb053e95d sparc: vio: Replace snprintf with strscpy in vio_create_one >> 2dfc417414c6 genirq/proc: Replace snprintf with strscpy in register_handler_proc >> f46ebb910989 block: Replace snprintf with strscpy in check_partition >> b66215e7b780 media: verisilicon: replace snprintf with strscpy+strlcat >> a86028f8e3ee staging: most: sound: replace snprintf with strscpy >> >> and many others... >> So.. should we introduce strscpy() in selftests/bpf ? > > I guess we can, but: > > $ grep -r 'snprintf(' --include="*.[ch]" tools/testing/selftests/bpf/ | wc -l > 238 > > The reason to prefer strscpy() is speed, right? > Can we use kernel implementation in userspace directly? > > In tools/include I only see this: > > #define strscpy strcpy > I think we can add a simple implementation to tools/lib/string.c See a diff below: essentially a copy from arch/s390/boot/string.c [1] I suppose it's faster than snprintf(). However I am not sure about going through all 238 usages, as that would touch many files. But at least we can make actual strscpy available in selftests. I can add this in v3. Alexei, wdyt? [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/s390/boot/string.c?h=v6.19#n32 diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h index 51ad3cf4fa82..ca183a0e846a 100644 --- a/tools/include/linux/string.h +++ b/tools/include/linux/string.h @@ -3,6 +3,7 @@ #define _TOOLS_LINUX_STRING_H_ #include /* for size_t */ +#include /* for ssize_t */ #include void *memdup(const void *src, size_t len); @@ -12,7 +13,7 @@ void argv_free(char **argv); int strtobool(const char *s, bool *res); -#define strscpy strcpy +ssize_t strscpy(char *dest, const char *src, size_t count); /* * glibc based builds needs the extern while uClibc doesn't. diff --git a/tools/lib/string.c b/tools/lib/string.c index 3126d2cff716..54c9163fa2b0 100644 --- a/tools/lib/string.c +++ b/tools/lib/string.c @@ -239,3 +239,17 @@ void *memchr_inv(const void *start, int c, size_t bytes) return check_bytes8(start, value, bytes % 8); } + +ssize_t strscpy(char *dst, const char *src, size_t count) +{ + size_t len; + + if (count == 0) + return -E2BIG; + + len = strnlen(src, count - 1); + memcpy(dst, src, len); + dst[len] = '\0'; + + return src[len] ? -E2BIG : len; +}