CentOS 7.0 - man page for rand_file_name (centos section 3)

RAND_load_file(3)			     OpenSSL				RAND_load_file(3)

NAME
       RAND_load_file, RAND_write_file, RAND_file_name - PRNG seed file

SYNOPSIS
	#include <openssl/rand.h>

	const char *RAND_file_name(char *buf, size_t num);

	int RAND_load_file(const char *filename, long max_bytes);

	int RAND_write_file(const char *filename);

DESCRIPTION
       RAND_file_name() generates a default path for the random seed file. buf points to a buffer
       of size num in which to store the filename. The seed file is $RANDFILE if that environment
       variable is set, $HOME/.rnd otherwise. If $HOME is not set either, or num is too small for
       the path name, an error occurs.

       RAND_load_file() reads a number of bytes from file filename and adds them to the PRNG. If
       max_bytes is non-negative, up to to max_bytes are read; starting with OpenSSL 0.9.5, if
       max_bytes is -1, the complete file is read.

       RAND_write_file() writes a number of random bytes (currently 1024) to file filename which
       can be used to initialize the PRNG by calling RAND_load_file() in a later session.

RETURN VALUES
       RAND_load_file() returns the number of bytes read.

       RAND_write_file() returns the number of bytes written, and -1 if the bytes written were
       generated without appropriate seed.

       RAND_file_name() returns a pointer to buf on success, and NULL on error.

SEE ALSO
       rand(3), RAND_add(3), RAND_cleanup(3)

HISTORY
       RAND_load_file(), RAND_write_file() and RAND_file_name() are available in all versions of
       SSLeay and OpenSSL.

1.0.1e					    2013-02-11				RAND_load_file(3)