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([2001:a61:253c:8201:b2fb:3ef8:ca:1604]) by smtp.gmail.com with ESMTPSA id h188sm628034wmh.2.2020.06.08.13.27.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 08 Jun 2020 13:27:06 -0700 (PDT) Cc: mtk.manpages@gmail.com, linux-man@vger.kernel.org, walter harms Subject: Re: [patch] random.3: wfix: RAND_MAX is for rand(3) To: John Marshall References: <02185B3C-F6E5-4674-BB34-E549E04C5B37@glasgow.ac.uk> <627c601ec03b4da9b1ce98ee0e61a6ba@bfs.de> <20200608110416.GA21314@Johns-MacBook-Pro.local> From: "Michael Kerrisk (man-pages)" Message-ID: Date: Mon, 8 Jun 2020 22:27:04 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200608110416.GA21314@Johns-MacBook-Pro.local> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-man-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org On 6/8/20 1:04 PM, John Marshall wrote: > POSIX fixes random()'s range at 2^31-1; RAND_MAX may be smaller on some > platforms (even though with glibc or musl on Linux they are the same). > --- > > On Sat, Jun 06, 2020 at 12:45:58PM +0000, Walter Harms wrote: >> that RAND_MAX is 2^31-1 in some cases does not matter. IMHO >> it is wrong to mention RAND_MAX in the random page. it can >> simply be replaced with (2**31-1) > > Thanks for confirming, Walter. I forgot to mention I was happy to > provide a patch -- suggested fix in this git-format-patch message. > > John > > man3/random.3 | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/man3/random.3 b/man3/random.3 > index 76b076f42..e3550f802 100644 > --- a/man3/random.3 > +++ b/man3/random.3 > @@ -69,7 +69,7 @@ The > function uses a nonlinear additive feedback random > number generator employing a default table of size 31 long integers to > return successive pseudo-random numbers in > -the range from 0 to \fBRAND_MAX\fR. > +the range from 0 to 2^31\ \-\ 1. > The period of this random number generator is very large, approximately > .IR "16\ *\ ((2^31)\ \-\ 1)" . > .PP > @@ -125,7 +125,9 @@ or be the result of a previous call of > The > .BR random () > function returns a value between 0 and > -.BR RAND_MAX . > +.BR INT32_MAX , > +i.e., > +.IR "(2^31)\ \-\ 1" . > The > .BR srandom () > function returns no value. Hello John, Thanks. I applied this patch. I also agree with Walter. There's no real need to mention INT32_MAX, so I removed that piece. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/