| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | SEE ALSO | COLOPHON | The Linux Programming Interface |
RANDOM_R(3) Linux Programmer's Manual RANDOM_R(3)
random_r, srandom_r, initstate_r, setstate_r - reentrant random number genera-
tor
#include <stdlib.h>
int random_r(struct random_data *buf, int32_t *result);
int srandom_r(unsigned int seed, struct random_data *buf);
int initstate_r(unsigned int seed, char *statebuf,
size_t statelen, struct random_data *buf);
int setstate_r(char *statebuf, struct random_data *buf);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
random_r(), srandom_r(), initstate_r(), setstate_r():
_SVID_SOURCE || _BSD_SOURCE
These functions are the reentrant equivalents of the functions described in
random(3). They are suitable for use in multithreaded programs where each
thread needs to obtain an independent, reproducible sequence of random
numbers.
The random_r() function is like random(3), except that instead of using state
information maintained in a global variable, it uses the state information in
the argument pointed to by buf. The generated random number is returned in
the argument result.
The srandom_r() function is like srandom(3), except that it initializes the
seed for the random number generator whose state is maintained in the object
pointed to by buf, instead of the seed associated with the global state
variable.
The initstate_r() function is like initstate(3) except that it initializes the
state in the object pointed to by buf, rather than initializing the global
state variable.
The setstate_r() function is like setstate(3) except that it modifies the
state in the object pointer to by buf, rather than modifying the global state
variable.
All of these functions return 0 on success, or -1 on error.
EINVAL A state array of less than 8 bytes was specified to initstate_r().
EINVAL The statebuf or buf argument to setstate_r() was NULL.
EINVAL The buf or result argument to random_r() was NULL.
These functions are nonstandard glibc extensions.
drand48(3), rand(3), random(3)
This page is part of release 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
GNU 2008-03-07 RANDOM_R(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface