Check public key is not NULL.

[thirdparty/openssl.git] / doc / crypto / 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. The seed file is $RANDFILE if that environment variable is
set, $HOME/.rnd otherwise. If $HOME 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 to B<max_bytes> are read; starting with OpenSSL 0.9.5,
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)|rand(3)>, L<RAND_add(3)|RAND_add(3)>, L<RAND_cleanup(3)|RAND_cleanup(3)>

=head1 HISTORY

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

=cut