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[122.61.176.117]) by smtp.gmail.com with ESMTPSA id 65sm17067605pgi.12.2021.08.07.16.45.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 07 Aug 2021 16:45:26 -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 References: <20210728202008.3158-1-alx.manpages@gmail.com> <20210728202008.3158-31-alx.manpages@gmail.com> From: "Michael Kerrisk (man-pages)" Message-ID: <0b8006d4-82d3-3896-5ee9-c1efe04a8583@gmail.com> Date: Sun, 8 Aug 2021 01:45:22 +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: <20210728202008.3158-31-alx.manpages@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 Hello Alex, I see there was a rather long mail thread that led to this patch. The patch definitely deserves a commit message. See also below. On 7/28/21 10:20 PM, Alejandro Colomar wrote: > Reported-by: Jonny Grant > Signed-off-by: Alejandro Colomar > --- > man3/strlen.3 | 6 ++++++ > man3/wcslen.3 | 9 ++++++++- > 2 files changed, 14 insertions(+), 1 deletion(-) > > diff --git a/man3/strlen.3 b/man3/strlen.3 > index dea4c1050..78783c446 100644 > --- a/man3/strlen.3 > +++ b/man3/strlen.3 > @@ -66,6 +66,12 @@ T} Thread safety MT-Safe > .sp 1 > .SH CONFORMING TO > POSIX.1-2001, POSIX.1-2008, C89, C99, C11, SVr4, 4.3BSD. > +.SH NOTES > +.SS strnlen(3) > +If the input buffer size is known, > +it is probably better to use > +.BR strnlen (3), > +which can prevent reading past the end of the array. I hesitate slightly about this. strlen() is in the C standard, but strnlen() is not. What do you think; do we need to care? Thanks, Michael > .SH SEE ALSO > .BR string (3), > .BR strnlen (3), > diff --git a/man3/wcslen.3 b/man3/wcslen.3 > index af3fcb9ca..fe1d6331b 100644 > --- a/man3/wcslen.3 > +++ b/man3/wcslen.3 > @@ -58,5 +58,12 @@ T} Thread safety MT-Safe > .sp 1 > .SH CONFORMING TO > POSIX.1-2001, POSIX.1-2008, C99. > +.SH NOTES > +.SS wcsnlen(3) > +If the input buffer size is known, > +it is probably better to use > +.BR wcsnlen (3), > +which can prevent reading past the end of the array. > .SH SEE ALSO > -.BR strlen (3) > +.BR strlen (3), > +.BR wcsnlen (3) > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/