1 files changed, 66 insertions, 48 deletions

diff --git a/src/lib/libc/stdlib/random.3 b/src/lib/libc/stdlib/random.3
index 38c15a9803..ed05df162b 100644
--- a/src/lib/libc/stdlib/random.3
+++ b/src/lib/libc/stdlib/random.3
@@ -9,11 +9,7 @@
 .\" 2. Redistributions in binary form must reproduce the above copyright
 .\"    notice, this list of conditions and the following disclaimer in the
 .\"    documentation and/or other materials provided with the distribution.
-.\" 3. All advertising materials mentioning features or use of this software
-.\"    must display the following acknowledgement:
-.\"     This product includes software developed by the University of
-.\"     California, Berkeley and its contributors.
-.\" 4. Neither the name of the University nor the names of its contributors
+.\" 3. Neither the name of the University nor the names of its contributors
 .\"    may be used to endorse or promote products derived from this software
 .\"    without specific prior written permission.
 .\"
@@ -29,97 +25,105 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"     from: @(#)random.3      6.5 (Berkeley) 4/19/91
-.\"     $Id: random.3,v 1.1.1.1 1995/10/18 08:42:19 deraadt Exp $
+.\"     $OpenBSD: random.3,v 1.19 2007/05/31 19:19:31 jmc Exp $
 .\"
-.Dd April 19, 1991
+.Dd $Mdocdate: May 31 2007 $
 .Dt RANDOM 3
-.Os BSD 4.2
+.Os
 .Sh NAME
 .Nm random ,
 .Nm srandom ,
+.Nm srandomdev ,
 .Nm initstate ,
 .Nm setstate
 .Nd better random number generator; routines for changing generators
 .Sh SYNOPSIS
 .Fd #include <stdlib.h>
-.Ft long 
+.Ft long
 .Fn random void
 .Ft void
-.Fn srandom "unsigned seed"
+.Fn srandom "unsigned int seed"
+.Ft void
+.Fn srandomdev void
 .Ft char *
-.Fn initstate "unsigned seed" "char *state" "int n"
+.Fn initstate "unsigned int seed" "char *state" "size_t n"
 .Ft char *
-.Fn setstate "char *state"
+.Fn setstate "const char *state"
 .Sh DESCRIPTION
 The
 .Fn random
-function
-uses a non-linear 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
-.if t 2\u\s731\s10\d\(mi1.
-.if n (2**31)\(mi1.
+function uses a non-linear 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 (2**31)\-1.
 The period of this random number generator is very large, approximately
-.if t 16\(mu(2\u\s731\s10\d\(mi1).
-.if n 16*((2**31)\(mi1).
+16*((2**31)\-1).
 .Pp
 The
-.Fn random Ns / Fn srandom
-have (almost) the same calling sequence and initialization properties as
-.Xr rand 3 Ns / Xr srand 3 .
+.Fn random
+and
+.Fn srandom
+functions have (almost) the same calling sequence and initialization
+properties as
+.Xr rand 3 Ns / Ns Xr srand 3 .
 The difference is that
 .Xr rand
 produces a much less random sequence \(em in fact, the low dozen bits
-generated by rand go through a cyclic pattern.  All the bits generated by
+generated by rand go through a cyclic pattern.
+All the bits generated by
 .Fn random
-are usable.  For example,
+are usable.
+For example,
 .Sq Li random()&01
 will produce a random binary
 value.
 .Pp
-Unlike
-.Xr srand ,
-.Fn srandom
-does not return the old seed; the reason for this is that the amount of
-state information used is much more than a single word.  (Two other
-routines are provided to deal with restarting/changing random
-number generators).  Like
+Like
 .Xr rand 3 ,
-however,
 .Fn random
 will by default produce a sequence of numbers that can be duplicated
 by calling
 .Fn srandom
-with 
+with
 .Ql 1
 as the seed.
 .Pp
 The
+.Fn srandomdev
+routine initializes a state array using
+random numbers obtained from the kernel,
+suitable for cryptographic use.
+Note that this particular seeding procedure can generate
+states which are impossible to reproduce by calling
+.Fn srandom
+with any value, since the succeeding terms in the
+state buffer are no longer derived from the LC algorithm applied to
+a fixed seed.
+.Pp
+The
 .Fn initstate
 routine allows a state array, passed in as an argument, to be initialized
-for future use.  The size of the state array (in bytes) is used by
+for future use.
+The size of the state array (in bytes) is used by
 .Fn initstate
 to decide how sophisticated a random number generator it should use \(em the
 more state, the better the random numbers will be.
 (Current "optimal" values for the amount of state information are
 8, 32, 64, 128, and 256 bytes; other amounts will be rounded down to
-the nearest known amount.  Using less than 8 bytes will cause an error.)
+the nearest known amount.
+Using less than 8 bytes will cause an error.)
 The seed for the initialization (which specifies a starting point for
 the random number sequence, and provides for restarting at the same
 point) is also an argument.
 The
 .Fn initstate
-function
-returns a pointer to the previous state information array.
+function returns a pointer to the previous state information array.
 .Pp
 Once a state has been initialized, the
 .Fn setstate
 routine provides for rapid switching between states.
 The
 .Fn setstate
-function
-returns a pointer to the previous state array; its
+function returns a pointer to the previous state array; its
 argument state array is used for further random number generation
 until the next call to
 .Fn initstate
@@ -143,12 +147,8 @@ is that the size of the state array does not have to be remembered after
 it is initialized.
 .Pp
 With 256 bytes of state information, the period of the random number
-generator is greater than
-.if t 2\u\s769\s10\d,
-.if n 2**69
+generator is greater than 2**69
 which should be sufficient for most purposes.
-.Sh AUTHOR
-Earl T. Cohen
 .Sh DIAGNOSTICS
 If
 .Fn initstate
@@ -157,11 +157,29 @@ is called with less than 8 bytes of state information, or if
 detects that the state information has been garbled, error
 messages are printed on the standard error output.
 .Sh SEE ALSO
-.Xr rand 3
+.Xr arc4random 3 ,
+.Xr drand48 3 ,
+.Xr rand 3 ,
+.Xr random 4
+.Sh STANDARDS
+The
+.Fn random ,
+.Fn srandom ,
+.Fn initstate ,
+and
+.Fn setstate
+functions conform to
+.St -xpg4.2 .
+.Pp
+The
+.Fn srandomdev
+function is an extension.
 .Sh HISTORY
 These
-functions appeared in 
+functions appeared in
 .Bx 4.2 .
+.Sh AUTHORS
+.An Earl T. Cohen
 .Sh BUGS
 About 2/3 the speed of
 .Xr rand 3 .