1=pod 2 3=head1 NAME 4 5err - error codes 6 7=head1 SYNOPSIS 8 9 #include <openssl/err.h> 10 11 unsigned long ERR_get_error(void); 12 unsigned long ERR_peek_error(void); 13 unsigned long ERR_get_error_line(const char **file, int *line); 14 unsigned long ERR_peek_error_line(const char **file, int *line); 15 unsigned long ERR_get_error_line_data(const char **file, int *line, 16 const char **data, int *flags); 17 unsigned long ERR_peek_error_line_data(const char **file, int *line, 18 const char **data, int *flags); 19 20 int ERR_GET_LIB(unsigned long e); 21 int ERR_GET_FUNC(unsigned long e); 22 int ERR_GET_REASON(unsigned long e); 23 24 void ERR_clear_error(void); 25 26 char *ERR_error_string(unsigned long e, char *buf); 27 const char *ERR_lib_error_string(unsigned long e); 28 const char *ERR_func_error_string(unsigned long e); 29 const char *ERR_reason_error_string(unsigned long e); 30 31 void ERR_print_errors(BIO *bp); 32 void ERR_print_errors_fp(FILE *fp); 33 34 void ERR_load_crypto_strings(void); 35 void ERR_free_strings(void); 36 37 void ERR_remove_state(unsigned long pid); 38 39 void ERR_put_error(int lib, int func, int reason, const char *file, 40 int line); 41 void ERR_add_error_data(int num, ...); 42 43 void ERR_load_strings(int lib,ERR_STRING_DATA str[]); 44 unsigned long ERR_PACK(int lib, int func, int reason); 45 int ERR_get_next_error_library(void); 46 47=head1 DESCRIPTION 48 49When a call to the OpenSSL library fails, this is usually signalled 50by the return value, and an error code is stored in an error queue 51associated with the current thread. The B<err> library provides 52functions to obtain these error codes and textual error messages. 53 54The L<ERR_get_error(3)|ERR_get_error(3)> manpage describes how to 55access error codes. 56 57Error codes contain information about where the error occurred, and 58what went wrong. L<ERR_GET_LIB(3)|ERR_GET_LIB(3)> describes how to 59extract this information. A method to obtain human-readable error 60messages is described in L<ERR_error_string(3)|ERR_error_string(3)>. 61 62L<ERR_clear_error(3)|ERR_clear_error(3)> can be used to clear the 63error queue. 64 65Note that L<ERR_remove_state(3)|ERR_remove_state(3)> should be used to 66avoid memory leaks when threads are terminated. 67 68=head1 ADDING NEW ERROR CODES TO OPENSSL 69 70See L<ERR_put_error(3)> if you want to record error codes in the 71OpenSSL error system from within your application. 72 73The remainder of this section is of interest only if you want to add 74new error codes to OpenSSL or add error codes from external libraries. 75 76=head2 Reporting errors 77 78Each sub-library has a specific macro XXXerr() that is used to report 79errors. Its first argument is a function code B<XXX_F_...>, the second 80argument is a reason code B<XXX_R_...>. Function codes are derived 81from the function names; reason codes consist of textual error 82descriptions. For example, the function ssl23_read() reports a 83"handshake failure" as follows: 84 85 SSLerr(SSL_F_SSL23_READ, SSL_R_SSL_HANDSHAKE_FAILURE); 86 87Function and reason codes should consist of upper case characters, 88numbers and underscores only. The error file generation script translates 89function codes into function names by looking in the header files 90for an appropriate function name, if none is found it just uses 91the capitalized form such as "SSL23_READ" in the above example. 92 93The trailing section of a reason code (after the "_R_") is translated 94into lower case and underscores changed to spaces. 95 96When you are using new function or reason codes, run B<make errors>. 97The necessary B<#define>s will then automatically be added to the 98sub-library's header file. 99 100Although a library will normally report errors using its own specific 101XXXerr macro, another library's macro can be used. This is normally 102only done when a library wants to include ASN1 code which must use 103the ASN1err() macro. 104 105=head2 Adding new libraries 106 107When adding a new sub-library to OpenSSL, assign it a library number 108B<ERR_LIB_XXX>, define a macro XXXerr() (both in B<err.h>), add its 109name to B<ERR_str_libraries[]> (in B<crypto/err/err.c>), and add 110C<ERR_load_XXX_strings()> to the ERR_load_crypto_strings() function 111(in B<crypto/err/err_all.c>). Finally, add an entry 112 113 L XXX xxx.h xxx_err.c 114 115to B<crypto/err/openssl.ec>, and add B<xxx_err.c> to the Makefile. 116Running B<make errors> will then generate a file B<xxx_err.c>, and 117add all error codes used in the library to B<xxx.h>. 118 119Additionally the library include file must have a certain form. 120Typically it will initially look like this: 121 122 #ifndef HEADER_XXX_H 123 #define HEADER_XXX_H 124 125 #ifdef __cplusplus 126 extern "C" { 127 #endif 128 129 /* Include files */ 130 131 #include <openssl/bio.h> 132 #include <openssl/x509.h> 133 134 /* Macros, structures and function prototypes */ 135 136 137 /* BEGIN ERROR CODES */ 138 139The B<BEGIN ERROR CODES> sequence is used by the error code 140generation script as the point to place new error codes, any text 141after this point will be overwritten when B<make errors> is run. 142The closing #endif etc will be automatically added by the script. 143 144The generated C error code file B<xxx_err.c> will load the header 145files B<stdio.h>, B<openssl/err.h> and B<openssl/xxx.h> so the 146header file must load any additional header files containing any 147definitions it uses. 148 149=head1 USING ERROR CODES IN EXTERNAL LIBRARIES 150 151It is also possible to use OpenSSL's error code scheme in external 152libraries. The library needs to load its own codes and call the OpenSSL 153error code insertion script B<mkerr.pl> explicitly to add codes to 154the header file and generate the C error code file. This will normally 155be done if the external library needs to generate new ASN1 structures 156but it can also be used to add more general purpose error code handling. 157 158TBA more details 159 160=head1 INTERNALS 161 162The error queues are stored in a hash table with one B<ERR_STATE> 163entry for each pid. ERR_get_state() returns the current thread's 164B<ERR_STATE>. An B<ERR_STATE> can hold up to B<ERR_NUM_ERRORS> error 165codes. When more error codes are added, the old ones are overwritten, 166on the assumption that the most recent errors are most important. 167 168Error strings are also stored in hash table. The hash tables can 169be obtained by calling ERR_get_err_state_table(void) and 170ERR_get_string_table(void) respectively. 171 172=head1 SEE ALSO 173 174L<CRYPTO_set_id_callback(3)|CRYPTO_set_id_callback(3)>, 175L<CRYPTO_set_locking_callback(3)|CRYPTO_set_locking_callback(3)>, 176L<ERR_get_error(3)|ERR_get_error(3)>, 177L<ERR_GET_LIB(3)|ERR_GET_LIB(3)>, 178L<ERR_clear_error(3)|ERR_clear_error(3)>, 179L<ERR_error_string(3)|ERR_error_string(3)>, 180L<ERR_print_errors(3)|ERR_print_errors(3)>, 181L<ERR_load_crypto_strings(3)|ERR_load_crypto_strings(3)>, 182L<ERR_remove_state(3)|ERR_remove_state(3)>, 183L<ERR_put_error(3)|ERR_put_error(3)>, 184L<ERR_load_strings(3)|ERR_load_strings(3)>, 185L<SSL_get_error(3)|SSL_get_error(3)> 186 187=cut 188