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NAME    [Toc]    [Back]

       err - error codes

LIBRARY    [Toc]    [Back]

       libcrypto, -lcrypto

SYNOPSIS    [Toc]    [Back]

        #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    [Toc]    [Back]

       When a call to the OpenSSL library fails, this is usually
       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

       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 humanreadable
 error messages is described in

       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.


       See ERR_put_error(3) if you want to record error codes in
       the OpenSSL error system from within your application.

       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    [Toc]    [Back]

       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 descriptions.
       For example, the function ssl23_read() reports a "handshake
 failure" as follows:


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

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

       When you are using new function or reason codes, run make
       errors.  The necessary #defines will then automatically 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    [Toc]    [Back]

       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 Makefile.
  Running make errors will then generate a file
       xxx_err.c, and add all error codes used in the library to

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

        #ifndef HEADER_XXX_H
        #define HEADER_XXX_H

        #ifdef __cplusplus
        extern "C" {

        /* 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 automatically
 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.


       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    [Toc]    [Back]

       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_table(void) and
       ERR_get_string_table(void) respectively.

SEE ALSO    [Toc]    [Back]

       CRYPTO_set_id_callback(3), CRYPTO_set_locking_callback(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)

2002-07-31                    0.9.6g                       err(3)
[ Back ]
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