err(3)                      OpenSSL                      err(3)





NAME
       err - error codes

SYNOPSIS
        #include <openssl/err.h>

        unsigned long ERR_get_error(void);
        unsigned long ERR_peek_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_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);

        int ERR_GET_LIB(unsigned long e);
        int ERR_GET_FUNC(unsigned long e);
        int ERR_GET_REASON(unsigned long e);

        void ERR_clear_error(void);

        char *ERR_error_string(unsigned long e, char *buf);
        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);

        void ERR_print_errors(BIO *bp);
        void ERR_print_errors_fp(FILE *fp);

        void ERR_load_crypto_strings(void);
        void ERR_free_strings(void);

        void ERR_remove_state(unsigned long pid);

        void ERR_put_error(int lib, int func, int reason, const char *file,
                int line);
        void ERR_add_error_data(int num, ...);

        void ERR_load_strings(int lib,ERR_STRING_DATA str[]);
        unsigned long ERR_PACK(int lib, int func, int reason);
        int ERR_get_next_error_library(void);

DESCRIPTION
       When a call to the OpenSSL library fails, this is usu-
       ally signalled by the return value, and an error code is
       stored in an error queue associated with the current
       thread. The err library provides functions to obtain
       these error codes and textual error messages.

       The ERR_get_error(3) manpage describes how to access
       error codes.

       Error codes contain information about where the error
       occurred, and what went wrong. ERR_GET_LIB(3) describes
       how to extract this information. A method to obtain
       human-readable error messages is described in
       ERR_error_string(3).

       ERR_clear_error(3) can be used to clear the error queue.

       Note that ERR_remove_state(3) should be used to avoid
       memory leaks when threads are terminated.

ADDING NEW ERROR CODES TO OPENSSL
       See ERR_put_error(3) if you want to record error codes
       in the OpenSSL error system from within your applica-
       tion.

       The remainder of this section is of interest only if you
       want to add new error codes to OpenSSL or add error
       codes from external libraries.

       Reporting errors

       Each sub-library has a specific macro XXXerr() that is
       used to report errors. Its first argument is a function
       code XXX_F_..., the second argument is a reason code
       XXX_R_.... Function codes are derived from the function
       names; reason codes consist of textual error descrip-
       tions. For example, the function ssl23_read() reports a
       "handshake failure" as follows:

        SSLerr(SSL_F_SSL23_READ, SSL_R_SSL_HANDSHAKE_FAILURE);

       Function and reason codes should consist of upper case
       characters, numbers and underscores only. The error file
       generation script translates function codes into func-
       tion names by looking in the header files for an appro-
       priate function name, if none is found it just uses the
       capitalized form such as "SSL23_READ" in the above exam-
       ple.

       The trailing section of a reason code (after the "_R_")
       is translated into lower case and underscores changed to
       spaces.

       When you are using new function or reason codes, run
       make errors.  The necessary #defines will then automati-
       cally be added to the sub-library's header file.

       Although a library will normally report errors using its
       own specific XXXerr macro, another library's macro can
       be used. This is normally only done when a library wants
       to include ASN1 code which must use the ASN1err() macro.

       Adding new libraries

       When adding a new sub-library to OpenSSL, assign it a
       library number ERR_LIB_XXX, define a macro XXXerr()
       (both in err.h), add its name to ERR_str_libraries[] (in
       crypto/err/err.c), and add "ERR_load_XXX_strings()" to
       the ERR_load_crypto_strings() function (in
       crypto/err/err_all.c). Finally, add an entry

        L      XXX     xxx.h   xxx_err.c

       to crypto/err/openssl.ec, and add xxx_err.c to the Make-
       file.  Running make errors will then generate a file
       xxx_err.c, and add all error codes used in the library
       to xxx.h.

       Additionally the library include file must have a cer-
       tain form.  Typically it will initially look like this:

        #ifndef HEADER_XXX_H
        #define HEADER_XXX_H

        #ifdef __cplusplus
        extern "C" {
        #endif

        /* Include files */


        #include <openssl/bio.h>
        #include <openssl/x509.h>

        /* Macros, structures and function prototypes */

        /* BEGIN ERROR CODES */

       The BEGIN ERROR CODES sequence is used by the error code
       generation script as the point to place new error codes,
       any text after this point will be overwritten when make
       errors is run.  The closing #endif etc will be automati-
       cally added by the script.

       The generated C error code file xxx_err.c will load the
       header files stdio.h, openssl/err.h and openssl/xxx.h so
       the header file must load any additional header files
       containing any definitions it uses.

USING ERROR CODES IN EXTERNAL LIBRARIES
       It is also possible to use OpenSSL's error code scheme
       in external libraries. The library needs to load its own
       codes and call the OpenSSL error code insertion script
       mkerr.pl explicitly to add codes to the header file and
       generate the C error code file. This will normally be
       done if the external library needs to generate new ASN1
       structures but it can also be used to add more general
       purpose error code handling.

       TBA more details

INTERNALS
       The error queues are stored in a hash table with one
       ERR_STATE entry for each pid. ERR_get_state() returns
       the current thread's ERR_STATE. An ERR_STATE can hold up
       to ERR_NUM_ERRORS error codes. When more error codes are
       added, the old ones are overwritten, on the assumption
       that the most recent errors are most important.

       Error strings are also stored in hash table. The hash
       tables can be obtained by calling ERR_get_err_state_ta-
       ble(void) and ERR_get_string_table(void) respectively.

SEE ALSO
       CRYPTO_set_id_callback(3), CRYPTO_set_locking_call-
       back(3), ERR_get_error(3), ERR_GET_LIB(3),
       ERR_clear_error(3), ERR_error_string(3),
       ERR_print_errors(3), ERR_load_crypto_strings(3),
       ERR_remove_state(3), ERR_put_error(3),
       ERR_load_strings(3), SSL_get_error(3)



0.9.7c                     2002-07-10                    err(3)
