19d12795fSRobert Mustacchi.\" $OpenBSD: getentropy.2,v 1.7 2014/12/10 19:19:00 schwarze Exp $ 29d12795fSRobert Mustacchi.\" 39d12795fSRobert Mustacchi.\" Copyright (c) 2014 Theo de Raadt 49d12795fSRobert Mustacchi.\" Copyright (c) 2015 Joyent, Inc. 59d12795fSRobert Mustacchi.\" 69d12795fSRobert Mustacchi.\" Permission to use, copy, modify, and distribute this software for any 79d12795fSRobert Mustacchi.\" purpose with or without fee is hereby granted, provided that the above 89d12795fSRobert Mustacchi.\" copyright notice and this permission notice appear in all copies. 99d12795fSRobert Mustacchi.\" 109d12795fSRobert Mustacchi.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 119d12795fSRobert Mustacchi.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 129d12795fSRobert Mustacchi.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 139d12795fSRobert Mustacchi.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 149d12795fSRobert Mustacchi.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 159d12795fSRobert Mustacchi.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 169d12795fSRobert Mustacchi.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 179d12795fSRobert Mustacchi.\" 189d12795fSRobert Mustacchi.Dd "Dec 31, 2014" 199d12795fSRobert Mustacchi.Dt GETENTROPY 3C 209d12795fSRobert Mustacchi.Os 219d12795fSRobert Mustacchi.Sh NAME 229d12795fSRobert Mustacchi.Nm getentropy 239d12795fSRobert Mustacchi.Nd get entropy 249d12795fSRobert Mustacchi.Sh SYNOPSIS 259d12795fSRobert Mustacchi.Fd #include <unistd.h> 269d12795fSRobert Mustacchi.Ft int 279d12795fSRobert Mustacchi.Fn getentropy "void *buf" "size_t buflen" 289d12795fSRobert Mustacchi.Sh DESCRIPTION 299d12795fSRobert Mustacchi.Nm 309d12795fSRobert Mustacchifills a buffer with high-quality entropy, which can be used 319d12795fSRobert Mustacchias input for process-context pseudorandom generators like 329d12795fSRobert Mustacchi.Xr arc4random 3C . 339d12795fSRobert Mustacchi.Pp 349d12795fSRobert MustacchiThe maximum buffer size permitted is 256 bytes. 359d12795fSRobert MustacchiIf 369d12795fSRobert Mustacchi.Va buflen 379d12795fSRobert Mustacchiexceeds this, an error of 389d12795fSRobert Mustacchi.Er EIO 399d12795fSRobert Mustacchiwill be indicated. 409d12795fSRobert Mustacchi.Pp 419d12795fSRobert Mustacchi.Nm 429d12795fSRobert Mustacchiis not intended for regular code; please use the 439d12795fSRobert Mustacchi.Xr arc4random 3C 449d12795fSRobert Mustacchifamily of functions instead. 459d12795fSRobert Mustacchi.Sh RETURN VALUES 469d12795fSRobert Mustacchi.Rv -std 479d12795fSRobert Mustacchi.Sh ERRORS 489d12795fSRobert Mustacchi.Fn getentropy 499d12795fSRobert Mustacchiwill succeed unless: 509d12795fSRobert Mustacchi.Bl -tag -width Er 519d12795fSRobert Mustacchi.It Er EFAULT 529d12795fSRobert MustacchiThe 539d12795fSRobert Mustacchi.Fa buf 549d12795fSRobert Mustacchiparameter points to an 559d12795fSRobert Mustacchiinvalid address. 569d12795fSRobert Mustacchi.It Er EIO 579d12795fSRobert MustacchiToo many bytes requested, or some other fatal error occurred. 589d12795fSRobert Mustacchi.El 599d12795fSRobert Mustacchi.Sh INTERFACE STABILITY 609d12795fSRobert Mustacchi.Sy Comitted 619d12795fSRobert Mustacchi.Sh MT-LEVEL 629d12795fSRobert Mustacchi.Sy Async-Signal-Safe 639d12795fSRobert Mustacchi.Sh SEE ALSO 643a005aadSYuri Pankov.Xr arc4random 3C , 65*bbf21555SRichard Lowe.Xr attributes 7 66