from small one page howto to huge articles all in one place
 

search text in:





Poll
Which screen resolution do you use?










poll results

Last additions:
using iotop to find disk usage hogs

using iotop to find disk usage hogs

words:

887

views:

125020

userrating:

average rating: 1.7 (86 votes) (1=very good 6=terrible)


May 25th. 2007:
Words

486

Views

235523

why adblockers are bad


Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

words:

161

views:

116136

userrating:

average rating: 1.3 (28 votes) (1=very good 6=terrible)


April, 26th. 2006:

Druckversion
You are here: manpages





GETENTROPY

Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
Index Return to Main Contents
 

NAME

getentropy - fill a buffer with random bytes  

SYNOPSIS

#include <unistd.h>

int getentropy(void *buffer, size_t length);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

getentropy():

_DEFAULT_SOURCE
 

DESCRIPTION

The getentropy() function writes length bytes of high-quality random data to the buffer starting at the location pointed to by buffer. The maximum permitted value for the length argument is 256.

A successful call to getentropy() always provides the requested number of bytes of entropy.  

RETURN VALUE

On success, this function returns zero. On error, -1 is returned, and errno is set appropriately.  

ERRORS

EFAULT
Part or all of the buffer specified by buffer and length is not in valid addressable memory.
EIO
length is greater than 256.
EIO
An unspecified error occurred while trying to overwrite buffer with random data.
ENOSYS
This kernel version does not implement the getrandom(2) system call required to implement this function.
 

VERSIONS

The getentropy() function first appeared in glibc 2.25.  

CONFORMING TO

This function is nonstandard. It is also present on OpenBSD.  

NOTES

The getentropy() function is implemented using getrandom(2).

Whereas the glibc wrapper makes getrandom(2) a cancellation point, getentropy() is not a cancellation point.

getentropy() is also declared in <sys/random.h>. (No feature test macro need be defined to obtain the declaration from that header file.)

A call to getentropy() may block if the system has just booted and the kernel has not yet collected enough randomness to initialize the entropy pool. In this case, getentropy() will keep blocking even if a signal is handled, and will return only once the entropy pool has been initialized.  

SEE ALSO

getrandom(2), urandom(4), random(7)  

COLOPHON

This page is part of release 4.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
VERSIONS
CONFORMING TO
NOTES
SEE ALSO
COLOPHON





Other free services
toURL.org
Shorten long
URLs to short
links like
http://tourl.org/2
tourl.org
.
Reverse DNS lookup
Find out which hostname(s)
resolve to a
given IP or other hostnames for the server
www.reversednslookup.org
rdf newsfeed | rss newsfeed | Atom newsfeed
- Powered by LeopardCMS - Running on Gentoo -
Copyright 2004-2018 Sascha Nitsch Unternehmensberatung UG(haftungsbeschränkt)
Valid XHTML1.1 : Valid CSS : buttonmaker
- Level Triple-A Conformance to Web Content Accessibility Guidelines 1.0 -
- Copyright and legal notices -
Time to create this page: 3.3 ms