=pod

=head1 NAME

ERR_get_error, ERR_peek_error, ERR_peek_last_error,
ERR_get_error_line, ERR_peek_error_line, ERR_peek_last_error_line,
ERR_get_error_line_data, ERR_peek_error_line_data,
ERR_peek_last_error_line_data - obtain error code and data

=head1 SYNOPSIS

 #include <openssl/err.h>

 unsigned long ERR_get_error(void);
 unsigned long ERR_peek_error(void);
 unsigned long ERR_peek_last_error(void);

 unsigned long ERR_get_error_line(const char **file, int *line);
 unsigned long ERR_peek_error_line(const char **file, int *line);
 unsigned long ERR_peek_last_error_line(const char **file, int *line);

 unsigned long ERR_get_error_line_data(const char **file, int *line,
         const char **data, int *flags);
 unsigned long ERR_peek_error_line_data(const char **file, int *line,
         const char **data, int *flags);
 unsigned long ERR_peek_last_error_line_data(const char **file, int *line,
         const char **data, int *flags);

=head1 DESCRIPTION

ERR_get_error() returns the earliest error code from the thread's error
queue and removes the entry. This function can be called repeatedly
until there are no more error codes to return.

ERR_peek_error() returns the earliest error code from the thread's
error queue without modifying it.

ERR_peek_last_error() returns the latest error code from the thread's
error queue without modifying it.

See L<ERR_GET_LIB(3)|ERR_GET_LIB(3)> for obtaining information about
location and reason of the error, and
L<ERR_error_string(3)|ERR_error_string(3)> for human-readable error
messages.

ERR_get_error_line(), ERR_peek_error_line() and
ERR_peek_last_error_line() are the same as the above, but they
additionally store the file name and line number where
the error occurred in *B<file> and *B<line>, unless these are B<NULL>.

ERR_get_error_line_data(), ERR_peek_error_line_data() and
ERR_get_last_error_line_data() store additional data and flags
associated with the error code in *B<data>
and *B<flags>, unless these are B<NULL>. *B<data> contains a string
if *B<flags>&B<ERR_TXT_STRING> is true. 

An application B<MUST NOT> free the *B<data> pointer (or any other pointers
returned by these functions) with OPENSSL_free() as freeing is handled
automatically by the error library.

=head1 RETURN VALUES

The error code, or 0 if there is no error in the queue.

=head1 SEE ALSO

L<err(3)|err(3)>, L<ERR_error_string(3)|ERR_error_string(3)>,
L<ERR_GET_LIB(3)|ERR_GET_LIB(3)>

=head1 HISTORY

ERR_get_error(), ERR_peek_error(), ERR_get_error_line() and
ERR_peek_error_line() are available in all versions of SSLeay and
OpenSSL. ERR_get_error_line_data() and ERR_peek_error_line_data()
were added in SSLeay 0.9.0.
ERR_peek_last_error(), ERR_peek_last_error_line() and
ERR_peek_last_error_line_data() were added in OpenSSL 0.9.7.

=cut