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RANDOM_R(3)                Linux Programmer's Manual               RANDOM_R(3)

NAME
       random_r,  srandom_r, initstate_r, setstate_r - reentrant random number
       generator
SYNOPSIS
       #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
DESCRIPTION
       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 initial-
       izes the state in the object pointed to by buf, rather than  initializ-
       ing 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.
RETURN VALUE
       All  of these functions return 0 on success.  On error, -1 is returned,
       with errno set to indicate the cause of the error.
ERRORS
       EINVAL A state array of less  than  8  bytes  was  specified  to  init-
              state_r().
       EINVAL The statebuf or buf argument to setstate_r() was NULL.
       EINVAL The buf or result argument to random_r() was NULL.
CONFORMING TO
       These functions are nonstandard glibc extensions.
SEE ALSO
       drand48(3), rand(3), random(3)
COLOPHON
       This  page  is  part of release 3.53 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                               2013-04-19                       RANDOM_R(3)