mojave man page for err_error_string_n

ERR_error_string(3SSL)                                                OpenSSL                                               ERR_error_string(3SSL)

NAME
       ERR_error_string, ERR_error_string_n, ERR_lib_error_string, ERR_func_error_string, ERR_reason_error_string - obtain human-readable error
       message

SYNOPSIS
        #include <openssl/err.h>

        char *ERR_error_string(unsigned long e, char *buf);
        void ERR_error_string_n(unsigned long e, char *buf, size_t len);

        const char *ERR_lib_error_string(unsigned long e);
        const char *ERR_func_error_string(unsigned long e);
        const char *ERR_reason_error_string(unsigned long e);

DESCRIPTION
       ERR_error_string() generates a human-readable string representing the error code e, and places it at buf. buf must be at least 120 bytes
       long. If buf is NULL, the error string is placed in a static buffer.  ERR_error_string_n() is a variant of ERR_error_string() that writes
       at most len characters (including the terminating 0) and truncates the string if necessary.  For ERR_error_string_n(), buf may not be NULL.

       The string will have the following format:

        error:[error code]:[library name]:[function name]:[reason string]

       error code is an 8 digit hexadecimal number, library name, function name and reason string are ASCII text.

       ERR_lib_error_string(), ERR_func_error_string() and ERR_reason_error_string() return the library name, function name and reason string
       respectively.

       The OpenSSL error strings should be loaded by calling ERR_load_crypto_strings(3) or, for SSL applications, SSL_load_error_strings(3) first.
       If there is no text string registered for the given error code, the error string will contain the numeric code.

       ERR_print_errors(3) can be used to print all error codes currently in the queue.

RETURN VALUES
       ERR_error_string() returns a pointer to a static buffer containing the string if buf == NULL, buf otherwise.

       ERR_lib_error_string(), ERR_func_error_string() and ERR_reason_error_string() return the strings, and NULL if none is registered for the
       error code.

SEE ALSO
       err(3), ERR_get_error(3), ERR_load_crypto_strings(3), SSL_load_error_strings(3) ERR_print_errors(3)

HISTORY
       ERR_error_string() is available in all versions of SSLeay and OpenSSL.  ERR_error_string_n() was added in OpenSSL 0.9.6.

1.0.1e                                                              2013-02-11                                              ERR_error_string(3SSL)