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124 .\" ========================================================================
125 .\"
126 .IX Title "err 3"
127 .TH err 3 "2014-04-07" "1.0.1g" "OpenSSL"
128 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
129 .\" way too many mistakes in technical documents.
130 .if n .ad l
131 .nh
132 .SH "NAME"
133 err \- error codes
134 .SH "SYNOPSIS"
135 .IX Header "SYNOPSIS"
136 .Vb 1
137 \& #include <openssl/err.h>
138 \&
139 \& unsigned long ERR_get_error(void);
140 \& unsigned long ERR_peek_error(void);
141 \& unsigned long ERR_get_error_line(const char **file, int *line);
142 \& unsigned long ERR_peek_error_line(const char **file, int *line);
143 \& unsigned long ERR_get_error_line_data(const char **file, int *line,
144 \& const char **data, int *flags);
145 \& unsigned long ERR_peek_error_line_data(const char **file, int *line,
146 \& const char **data, int *flags);
147 \&
148 \& int ERR_GET_LIB(unsigned long e);
149 \& int ERR_GET_FUNC(unsigned long e);
150 \& int ERR_GET_REASON(unsigned long e);
151 \&
152 \& void ERR_clear_error(void);
153 \&
154 \& char *ERR_error_string(unsigned long e, char *buf);
155 \& const char *ERR_lib_error_string(unsigned long e);
156 \& const char *ERR_func_error_string(unsigned long e);
157 \& const char *ERR_reason_error_string(unsigned long e);
158 \&
159 \& void ERR_print_errors(BIO *bp);
160 \& void ERR_print_errors_fp(FILE *fp);
161 \&
162 \& void ERR_load_crypto_strings(void);
163 \& void ERR_free_strings(void);
164 \&
165 \& void ERR_remove_state(unsigned long pid);
166 \&
167 \& void ERR_put_error(int lib, int func, int reason, const char *file,
168 \& int line);
169 \& void ERR_add_error_data(int num, ...);
170 \&
171 \& void ERR_load_strings(int lib,ERR_STRING_DATA str[]);
172 \& unsigned long ERR_PACK(int lib, int func, int reason);
173 \& int ERR_get_next_error_library(void);
174 .Ve
175 .SH "DESCRIPTION"
176 .IX Header "DESCRIPTION"
177 When a call to the OpenSSL library fails, this is usually signalled
178 by the return value, and an error code is stored in an error queue
179 associated with the current thread. The \fBerr\fR library provides
180 functions to obtain these error codes and textual error messages.
181 .PP
182 The \fIERR_get_error\fR\|(3) manpage describes how to
183 access error codes.
184 .PP
185 Error codes contain information about where the error occurred, and
186 what went wrong. \s-1\fIERR_GET_LIB\s0\fR\|(3) describes how to
187 extract this information. A method to obtain human-readable error
188 messages is described in \fIERR_error_string\fR\|(3).
189 .PP
190 \&\fIERR_clear_error\fR\|(3) can be used to clear the
191 error queue.
192 .PP
193 Note that \fIERR_remove_state\fR\|(3) should be used to
194 avoid memory leaks when threads are terminated.
195 .SH "ADDING NEW ERROR CODES TO OPENSSL"
196 .IX Header "ADDING NEW ERROR CODES TO OPENSSL"
197 See \fIERR_put_error\fR\|(3) if you want to record error codes in the
198 OpenSSL error system from within your application.
199 .PP
200 The remainder of this section is of interest only if you want to add
201 new error codes to OpenSSL or add error codes from external libraries.
202 .SS "Reporting errors"
203 .IX Subsection "Reporting errors"
204 Each sub-library has a specific macro \fIXXXerr()\fR that is used to report
205 errors. Its first argument is a function code \fB\s-1XXX_F_\s0...\fR, the second
206 argument is a reason code \fB\s-1XXX_R_\s0...\fR. Function codes are derived
207 from the function names; reason codes consist of textual error
208 descriptions. For example, the function \fIssl23_read()\fR reports a
209 \&\*(L"handshake failure\*(R" as follows:
210 .PP
211 .Vb 1
212 \& SSLerr(SSL_F_SSL23_READ, SSL_R_SSL_HANDSHAKE_FAILURE);
213 .Ve
214 .PP
215 Function and reason codes should consist of upper case characters,
216 numbers and underscores only. The error file generation script translates
217 function codes into function names by looking in the header files
218 for an appropriate function name, if none is found it just uses
219 the capitalized form such as \*(L"\s-1SSL23_READ\s0\*(R" in the above example.
220 .PP
221 The trailing section of a reason code (after the \*(L"_R_\*(R") is translated
222 into lower case and underscores changed to spaces.
223 .PP
224 When you are using new function or reason codes, run \fBmake errors\fR.
225 The necessary \fB#define\fRs will then automatically be added to the
226 sub-library's header file.
227 .PP
228 Although a library will normally report errors using its own specific
229 XXXerr macro, another library's macro can be used. This is normally
230 only done when a library wants to include \s-1ASN1\s0 code which must use
231 the \fIASN1err()\fR macro.
232 .SS "Adding new libraries"
233 .IX Subsection "Adding new libraries"
234 When adding a new sub-library to OpenSSL, assign it a library number
235 \&\fB\s-1ERR_LIB_XXX\s0\fR, define a macro \fIXXXerr()\fR (both in \fBerr.h\fR), add its
236 name to \fBERR_str_libraries[]\fR (in \fBcrypto/err/err.c\fR), and add
237 \&\f(CW\*(C`ERR_load_XXX_strings()\*(C'\fR to the \fIERR_load_crypto_strings()\fR function
238 (in \fBcrypto/err/err_all.c\fR). Finally, add an entry
239 .PP
240 .Vb 1
241 \& L XXX xxx.h xxx_err.c
242 .Ve
243 .PP
244 to \fBcrypto/err/openssl.ec\fR, and add \fBxxx_err.c\fR to the Makefile.
245 Running \fBmake errors\fR will then generate a file \fBxxx_err.c\fR, and
246 add all error codes used in the library to \fBxxx.h\fR.
247 .PP
248 Additionally the library include file must have a certain form.
249 Typically it will initially look like this:
250 .PP
251 .Vb 2
252 \& #ifndef HEADER_XXX_H
253 \& #define HEADER_XXX_H
254 \&
255 \& #ifdef _\|_cplusplus
256 \& extern "C" {
257 \& #endif
258 \&
259 \& /* Include files */
260 \&
261 \& #include <openssl/bio.h>
262 \& #include <openssl/x509.h>
263 \&
264 \& /* Macros, structures and function prototypes */
265 \&
266 \&
267 \& /* BEGIN ERROR CODES */
268 .Ve
269 .PP
270 The \fB\s-1BEGIN\s0 \s-1ERROR\s0 \s-1CODES\s0\fR sequence is used by the error code
271 generation script as the point to place new error codes, any text
272 after this point will be overwritten when \fBmake errors\fR is run.
273 The closing #endif etc will be automatically added by the script.
274 .PP
275 The generated C error code file \fBxxx_err.c\fR will load the header
276 files \fBstdio.h\fR, \fBopenssl/err.h\fR and \fBopenssl/xxx.h\fR so the
277 header file must load any additional header files containing any
278 definitions it uses.
279 .SH "USING ERROR CODES IN EXTERNAL LIBRARIES"
280 .IX Header "USING ERROR CODES IN EXTERNAL LIBRARIES"
281 It is also possible to use OpenSSL's error code scheme in external
282 libraries. The library needs to load its own codes and call the OpenSSL
283 error code insertion script \fBmkerr.pl\fR explicitly to add codes to
284 the header file and generate the C error code file. This will normally
285 be done if the external library needs to generate new \s-1ASN1\s0 structures
286 but it can also be used to add more general purpose error code handling.
287 .PP
288 \&\s-1TBA\s0 more details
289 .SH "INTERNALS"
290 .IX Header "INTERNALS"
291 The error queues are stored in a hash table with one \fB\s-1ERR_STATE\s0\fR
292 entry for each pid. \fIERR_get_state()\fR returns the current thread's
293 \&\fB\s-1ERR_STATE\s0\fR. An \fB\s-1ERR_STATE\s0\fR can hold up to \fB\s-1ERR_NUM_ERRORS\s0\fR error
294 codes. When more error codes are added, the old ones are overwritten,
295 on the assumption that the most recent errors are most important.
296 .PP
297 Error strings are also stored in hash table. The hash tables can
298 be obtained by calling ERR_get_err_state_table(void) and
299 ERR_get_string_table(void) respectively.
300 .SH "SEE ALSO"
301 .IX Header "SEE ALSO"
302 \&\fICRYPTO_set_id_callback\fR\|(3),
303 \&\fICRYPTO_set_locking_callback\fR\|(3),
304 \&\fIERR_get_error\fR\|(3),
305 \&\s-1\fIERR_GET_LIB\s0\fR\|(3),
306 \&\fIERR_clear_error\fR\|(3),
307 \&\fIERR_error_string\fR\|(3),
308 \&\fIERR_print_errors\fR\|(3),
309 \&\fIERR_load_crypto_strings\fR\|(3),
310 \&\fIERR_remove_state\fR\|(3),
311 \&\fIERR_put_error\fR\|(3),
312 \&\fIERR_load_strings\fR\|(3),
313 \&\fISSL_get_error\fR\|(3)