RAND_load_file.pod

=pod

=head1 NAME

RAND_load_file, RAND_write_file, RAND_file_name - PRNG seed file

=head1 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);

=head1 DESCRIPTION

RAND_file_name() generates a default path for the random seed
file. B<buf> points to a buffer of size B<num> in which to store the
filename.

On Windows the seed file is %RANDFILE% if that environment variable is set.
Otherwise the file is called ".rnd" in one of the following locations (in order
of preference): %TMP%, %TEMP%, %USERPROFILE%, %SYSTEMROOT%, %HOME%, "C:".

On all other systems the seed file is $RANDFILE if that environment variable is
set, $HOME/.rnd otherwise.

If $HOME (on non Windows systems) is not set either, or B<num> is
too small for the path name, an error occurs.

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

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

=head1 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 B<buf> on success, and NULL on
error.

=head1 SEE ALSO

L<rand(3)>, L<RAND_add(3)>, L<RAND_cleanup(3)>

=head1 COPYRIGHT

Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.

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