1 /* 2 * QEMU Error Objects 3 * 4 * Copyright IBM, Corp. 2011 5 * Copyright (C) 2011-2015 Red Hat, Inc. 6 * 7 * Authors: 8 * Anthony Liguori <aliguori@us.ibm.com> 9 * Markus Armbruster <armbru@redhat.com> 10 * 11 * This work is licensed under the terms of the GNU LGPL, version 2. See 12 * the COPYING.LIB file in the top-level directory. 13 */ 14 15 /* 16 * Error reporting system loosely patterned after Glib's GError. 17 * 18 * Create an error: 19 * error_setg(&err, "situation normal, all fouled up"); 20 * 21 * Create an error and add additional explanation: 22 * error_setg(&err, "invalid quark"); 23 * error_append_hint(&err, "Valid quarks are up, down, strange, " 24 * "charm, top, bottom.\n"); 25 * 26 * Do *not* contract this to 27 * error_setg(&err, "invalid quark\n" 28 * "Valid quarks are up, down, strange, charm, top, bottom."); 29 * 30 * Report an error to the current monitor if we have one, else stderr: 31 * error_report_err(err); 32 * This frees the error object. 33 * 34 * Likewise, but with additional text prepended: 35 * error_reportf_err(err, "Could not frobnicate '%s': ", name); 36 * 37 * Report an error somewhere else: 38 * const char *msg = error_get_pretty(err); 39 * do with msg what needs to be done... 40 * error_free(err); 41 * Note that this loses hints added with error_append_hint(). 42 * 43 * Handle an error without reporting it (just for completeness): 44 * error_free(err); 45 * 46 * Assert that an expected error occurred, but clean it up without 47 * reporting it (primarily useful in testsuites): 48 * error_free_or_abort(&err); 49 * 50 * Pass an existing error to the caller: 51 * error_propagate(errp, err); 52 * where Error **errp is a parameter, by convention the last one. 53 * 54 * Pass an existing error to the caller with the message modified: 55 * error_propagate(errp, err); 56 * error_prepend(errp, "Could not frobnicate '%s': ", name); 57 * 58 * Create a new error and pass it to the caller: 59 * error_setg(errp, "situation normal, all fouled up"); 60 * 61 * Call a function and receive an error from it: 62 * Error *err = NULL; 63 * foo(arg, &err); 64 * if (err) { 65 * handle the error... 66 * } 67 * 68 * Call a function ignoring errors: 69 * foo(arg, NULL); 70 * 71 * Call a function aborting on errors: 72 * foo(arg, &error_abort); 73 * 74 * Call a function treating errors as fatal: 75 * foo(arg, &error_fatal); 76 * 77 * Receive an error and pass it on to the caller: 78 * Error *err = NULL; 79 * foo(arg, &err); 80 * if (err) { 81 * handle the error... 82 * error_propagate(errp, err); 83 * } 84 * where Error **errp is a parameter, by convention the last one. 85 * 86 * Do *not* "optimize" this to 87 * foo(arg, errp); 88 * if (*errp) { // WRONG! 89 * handle the error... 90 * } 91 * because errp may be NULL! 92 * 93 * But when all you do with the error is pass it on, please use 94 * foo(arg, errp); 95 * for readability. 96 * 97 * Receive and accumulate multiple errors (first one wins): 98 * Error *err = NULL, *local_err = NULL; 99 * foo(arg, &err); 100 * bar(arg, &local_err); 101 * error_propagate(&err, local_err); 102 * if (err) { 103 * handle the error... 104 * } 105 * 106 * Do *not* "optimize" this to 107 * foo(arg, &err); 108 * bar(arg, &err); // WRONG! 109 * if (err) { 110 * handle the error... 111 * } 112 * because this may pass a non-null err to bar(). 113 */ 114 115 #ifndef ERROR_H 116 #define ERROR_H 117 118 #include "qapi/qapi-types-common.h" 119 120 /* 121 * Overall category of an error. 122 * Based on the qapi type QapiErrorClass, but reproduced here for nicer 123 * enum names. 124 */ 125 typedef enum ErrorClass { 126 ERROR_CLASS_GENERIC_ERROR = QAPI_ERROR_CLASS_GENERICERROR, 127 ERROR_CLASS_COMMAND_NOT_FOUND = QAPI_ERROR_CLASS_COMMANDNOTFOUND, 128 ERROR_CLASS_DEVICE_NOT_ACTIVE = QAPI_ERROR_CLASS_DEVICENOTACTIVE, 129 ERROR_CLASS_DEVICE_NOT_FOUND = QAPI_ERROR_CLASS_DEVICENOTFOUND, 130 ERROR_CLASS_KVM_MISSING_CAP = QAPI_ERROR_CLASS_KVMMISSINGCAP, 131 } ErrorClass; 132 133 /* 134 * Get @err's human-readable error message. 135 */ 136 const char *error_get_pretty(const Error *err); 137 138 /* 139 * Get @err's error class. 140 * Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is 141 * strongly discouraged. 142 */ 143 ErrorClass error_get_class(const Error *err); 144 145 /* 146 * Create a new error object and assign it to *@errp. 147 * If @errp is NULL, the error is ignored. Don't bother creating one 148 * then. 149 * If @errp is &error_abort, print a suitable message and abort(). 150 * If @errp is &error_fatal, print a suitable message and exit(1). 151 * If @errp is anything else, *@errp must be NULL. 152 * The new error's class is ERROR_CLASS_GENERIC_ERROR, and its 153 * human-readable error message is made from printf-style @fmt, ... 154 * The resulting message should be a single phrase, with no newline or 155 * trailing punctuation. 156 * Please don't error_setg(&error_fatal, ...), use error_report() and 157 * exit(), because that's more obvious. 158 * Likewise, don't error_setg(&error_abort, ...), use assert(). 159 */ 160 #define error_setg(errp, fmt, ...) \ 161 error_setg_internal((errp), __FILE__, __LINE__, __func__, \ 162 (fmt), ## __VA_ARGS__) 163 void error_setg_internal(Error **errp, 164 const char *src, int line, const char *func, 165 const char *fmt, ...) 166 GCC_FMT_ATTR(5, 6); 167 168 /* 169 * Just like error_setg(), with @os_error info added to the message. 170 * If @os_error is non-zero, ": " + strerror(os_error) is appended to 171 * the human-readable error message. 172 * 173 * The value of errno (which usually can get clobbered by almost any 174 * function call) will be preserved. 175 */ 176 #define error_setg_errno(errp, os_error, fmt, ...) \ 177 error_setg_errno_internal((errp), __FILE__, __LINE__, __func__, \ 178 (os_error), (fmt), ## __VA_ARGS__) 179 void error_setg_errno_internal(Error **errp, 180 const char *fname, int line, const char *func, 181 int os_error, const char *fmt, ...) 182 GCC_FMT_ATTR(6, 7); 183 184 #ifdef _WIN32 185 /* 186 * Just like error_setg(), with @win32_error info added to the message. 187 * If @win32_error is non-zero, ": " + g_win32_error_message(win32_err) 188 * is appended to the human-readable error message. 189 */ 190 #define error_setg_win32(errp, win32_err, fmt, ...) \ 191 error_setg_win32_internal((errp), __FILE__, __LINE__, __func__, \ 192 (win32_err), (fmt), ## __VA_ARGS__) 193 void error_setg_win32_internal(Error **errp, 194 const char *src, int line, const char *func, 195 int win32_err, const char *fmt, ...) 196 GCC_FMT_ATTR(6, 7); 197 #endif 198 199 /* 200 * Propagate error object (if any) from @local_err to @dst_errp. 201 * If @local_err is NULL, do nothing (because there's nothing to 202 * propagate). 203 * Else, if @dst_errp is NULL, errors are being ignored. Free the 204 * error object. 205 * Else, if @dst_errp is &error_abort, print a suitable message and 206 * abort(). 207 * Else, if @dst_errp is &error_fatal, print a suitable message and 208 * exit(1). 209 * Else, if @dst_errp already contains an error, ignore this one: free 210 * the error object. 211 * Else, move the error object from @local_err to *@dst_errp. 212 * On return, @local_err is invalid. 213 * Please don't error_propagate(&error_fatal, ...), use 214 * error_report_err() and exit(), because that's more obvious. 215 */ 216 void error_propagate(Error **dst_errp, Error *local_err); 217 218 /* 219 * Prepend some text to @errp's human-readable error message. 220 * The text is made by formatting @fmt, @ap like vprintf(). 221 */ 222 void error_vprepend(Error **errp, const char *fmt, va_list ap); 223 224 /* 225 * Prepend some text to @errp's human-readable error message. 226 * The text is made by formatting @fmt, ... like printf(). 227 */ 228 void error_prepend(Error **errp, const char *fmt, ...) 229 GCC_FMT_ATTR(2, 3); 230 231 /* 232 * Append a printf-style human-readable explanation to an existing error. 233 * If the error is later reported to a human user with 234 * error_report_err() or warn_report_err(), the hints will be shown, 235 * too. If it's reported via QMP, the hints will be ignored. 236 * Intended use is adding helpful hints on the human user interface, 237 * e.g. a list of valid values. It's not for clarifying a confusing 238 * error message. 239 * @errp may be NULL, but not &error_fatal or &error_abort. 240 * Trivially the case if you call it only after error_setg() or 241 * error_propagate(). 242 * May be called multiple times. The resulting hint should end with a 243 * newline. 244 */ 245 void error_append_hint(Error **errp, const char *fmt, ...) 246 GCC_FMT_ATTR(2, 3); 247 248 /* 249 * Convenience function to report open() failure. 250 */ 251 #define error_setg_file_open(errp, os_errno, filename) \ 252 error_setg_file_open_internal((errp), __FILE__, __LINE__, __func__, \ 253 (os_errno), (filename)) 254 void error_setg_file_open_internal(Error **errp, 255 const char *src, int line, const char *func, 256 int os_errno, const char *filename); 257 258 /* 259 * Return an exact copy of @err. 260 */ 261 Error *error_copy(const Error *err); 262 263 /* 264 * Free @err. 265 * @err may be NULL. 266 */ 267 void error_free(Error *err); 268 269 /* 270 * Convenience function to assert that *@errp is set, then silently free it. 271 */ 272 void error_free_or_abort(Error **errp); 273 274 /* 275 * Convenience function to warn_report() and free @err. 276 * The report includes hints added with error_append_hint(). 277 */ 278 void warn_report_err(Error *err); 279 280 /* 281 * Convenience function to error_report() and free @err. 282 * The report includes hints added with error_append_hint(). 283 */ 284 void error_report_err(Error *err); 285 286 /* 287 * Convenience function to error_prepend(), warn_report() and free @err. 288 */ 289 void warn_reportf_err(Error *err, const char *fmt, ...) 290 GCC_FMT_ATTR(2, 3); 291 292 /* 293 * Convenience function to error_prepend(), error_report() and free @err. 294 */ 295 void error_reportf_err(Error *err, const char *fmt, ...) 296 GCC_FMT_ATTR(2, 3); 297 298 /* 299 * Just like error_setg(), except you get to specify the error class. 300 * Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is 301 * strongly discouraged. 302 */ 303 #define error_set(errp, err_class, fmt, ...) \ 304 error_set_internal((errp), __FILE__, __LINE__, __func__, \ 305 (err_class), (fmt), ## __VA_ARGS__) 306 void error_set_internal(Error **errp, 307 const char *src, int line, const char *func, 308 ErrorClass err_class, const char *fmt, ...) 309 GCC_FMT_ATTR(6, 7); 310 311 /* 312 * Special error destination to abort on error. 313 * See error_setg() and error_propagate() for details. 314 */ 315 extern Error *error_abort; 316 317 /* 318 * Special error destination to exit(1) on error. 319 * See error_setg() and error_propagate() for details. 320 */ 321 extern Error *error_fatal; 322 323 #endif 324