NAME
randomr, srandomr, initstater, setstater - reentrant random number generator SYNOPSIS
#include
int randomr(struct randomdata *buf, int32t *result); int srandomr(unsigned int seed, struct randomdata *buf); int initstater(unsigned int seed, char *statebuf, sizet statelen, struct randomdata *buf); int setstater(char *statebuf, struct randomdata *buf); Feature Test Macro Requirements for glibc (see featuretestmacros(7)): randomr(), srandomr(), initstater(), setstater(): SVIDSOURCE || BSDSOURCE 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 randomr() 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 srandomr() 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 initstater() 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 setstater() 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‐ stater(). EINVAL The statebuf or buf argument to setstater() was NULL. EINVAL The buf or result argument to randomr() was NULL. ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). ┌────────────────────────────┬───────────────┬──────────────────┐ │Interface │ Attribute │ Value │ ├────────────────────────────┼───────────────┼──────────────────┤
│randomr(), srandomr(), │ Thread safety │ MT-Safe race:buf │ │initstater(), setstater() │ │ │ └────────────────────────────┴───────────────┴──────────────────┘ CONFORMING TO These functions are nonstandard glibc extensions. SEE ALSO drand48(3), rand(3), random(3) COLOPHON
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GNU 2013-04-19 RANDOMR(3)