ERR_get_error(3)

     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

     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);


     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 ERR_GET_LIB(3) for obtaining information about location
          and reason of the error, and 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 *file and *line, unless these are
          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 *data and *flags,
          unless these are NULL. *data contains a string if
          *flags&ERR_TXT_STRING. If it has been allocated by
          OPENSSL_malloc(), *flags&ERR_TXT_MALLOCED is true.

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

     SEE ALSO
          err(3), ERR_error_string(3), ERR_GET_LIB(3)

     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.