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[122.61.176.117]) by smtp.gmail.com with ESMTPSA id ls16sm13380079pjb.49.2021.08.07.19.18.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 07 Aug 2021 19:18:51 -0700 (PDT) Cc: mtk.manpages@gmail.com, linux-man@vger.kernel.org, Jonny Grant Subject: Re: [PATCH 30/32] strlen.3, wcslen.3: Add recommendations for safer variants To: "Alejandro Colomar (man-pages)" References: <20210728202008.3158-1-alx.manpages@gmail.com> <20210728202008.3158-31-alx.manpages@gmail.com> <0b8006d4-82d3-3896-5ee9-c1efe04a8583@gmail.com> <16dc1629-f2f7-68c2-8e20-66c2598b7f39@gmail.com> From: "Michael Kerrisk (man-pages)" Message-ID: <81d0ccbf-4c85-118d-97ca-3ca34d05ab57@gmail.com> Date: Sun, 8 Aug 2021 04:18:46 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <16dc1629-f2f7-68c2-8e20-66c2598b7f39@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org Hi Alex, On 8/8/21 3:24 AM, Alejandro Colomar (man-pages) wrote: > Hi Michael, > > On 8/8/21 3:20 AM, Michael Kerrisk (man-pages) wrote: >>> I have some doubts about this patch, but in a completely different sense: >>> >>> I don't know if I'm being a bit paranoid in treating user input. I've >>> always been taught that I should program deffensively, but as time >>> passes by, I realize myself that I was programming too much >>> deffensively, and even introducing bugs in the error handling code. And >>> in many cases, strings will always be NUL-terminated, so maybe I'm just >>> passing around a wrong recommendation. >>> >>> What do you think about this? >> >> How about a sentence something like: >> >> [[ >> In cases where the input buffer may not contain a terminating null byte, >> .BR strnlen (3) >> should be used instead. >> ]] >> >> What do you think? > > Yes, that's much better. Thanks! Okay. I applied the patch below. Thanks, Michael diff --git a/man3/strlen.3 b/man3/strlen.3 index dea4c1050..ca7a7d188 100644 --- a/man3/strlen.3 +++ b/man3/strlen.3 @@ -64,6 +64,11 @@ T} Thread safety MT-Safe .hy .ad .sp 1 +.SH NOTES +In cases where the input buffer may not contain +a terminating null byte, +.BR strnlen (3) +should be used instead. .SH CONFORMING TO POSIX.1-2001, POSIX.1-2008, C89, C99, C11, SVr4, 4.3BSD. .SH SEE ALSO diff --git a/man3/wcslen.3 b/man3/wcslen.3 index af3fcb9ca..24dca8e55 100644 --- a/man3/wcslen.3 +++ b/man3/wcslen.3 @@ -56,6 +56,11 @@ T} Thread safety MT-Safe .hy .ad .sp 1 +.SH NOTES +In cases where the input buffer may not contain +a terminating null wide character, +.BR wcsnlen (3) +should be used instead. .SH CONFORMING TO POSIX.1-2001, POSIX.1-2008, C99. .SH SEE ALSO -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/