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-types.h" 119 120 /* 121 * Opaque error object. 122 */ 123 typedef struct Error Error; 124 125 /* 126 * Overall category of an error. 127 * Based on the qapi type QapiErrorClass, but reproduced here for nicer 128 * enum names. 129 */ 130 typedef enum ErrorClass { 131 ERROR_CLASS_GENERIC_ERROR = QAPI_ERROR_CLASS_GENERICERROR, 132 ERROR_CLASS_COMMAND_NOT_FOUND = QAPI_ERROR_CLASS_COMMANDNOTFOUND, 133 ERROR_CLASS_DEVICE_ENCRYPTED = QAPI_ERROR_CLASS_DEVICEENCRYPTED, 134 ERROR_CLASS_DEVICE_NOT_ACTIVE = QAPI_ERROR_CLASS_DEVICENOTACTIVE, 135 ERROR_CLASS_DEVICE_NOT_FOUND = QAPI_ERROR_CLASS_DEVICENOTFOUND, 136 ERROR_CLASS_KVM_MISSING_CAP = QAPI_ERROR_CLASS_KVMMISSINGCAP, 137 } ErrorClass; 138 139 /* 140 * Get @err's human-readable error message. 141 */ 142 const char *error_get_pretty(Error *err); 143 144 /* 145 * Get @err's error class. 146 * Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is 147 * strongly discouraged. 148 */ 149 ErrorClass error_get_class(const Error *err); 150 151 /* 152 * Create a new error object and assign it to *@errp. 153 * If @errp is NULL, the error is ignored. Don't bother creating one 154 * then. 155 * If @errp is &error_abort, print a suitable message and abort(). 156 * If @errp is &error_fatal, print a suitable message and exit(1). 157 * If @errp is anything else, *@errp must be NULL. 158 * The new error's class is ERROR_CLASS_GENERIC_ERROR, and its 159 * human-readable error message is made from printf-style @fmt, ... 160 * The resulting message should be a single phrase, with no newline or 161 * trailing punctuation. 162 * Please don't error_setg(&error_fatal, ...), use error_report() and 163 * exit(), because that's more obvious. 164 * Likewise, don't error_setg(&error_abort, ...), use assert(). 165 */ 166 #define error_setg(errp, fmt, ...) \ 167 error_setg_internal((errp), __FILE__, __LINE__, __func__, \ 168 (fmt), ## __VA_ARGS__) 169 void error_setg_internal(Error **errp, 170 const char *src, int line, const char *func, 171 const char *fmt, ...) 172 GCC_FMT_ATTR(5, 6); 173 174 /* 175 * Just like error_setg(), with @os_error info added to the message. 176 * If @os_error is non-zero, ": " + strerror(os_error) is appended to 177 * the human-readable error message. 178 */ 179 #define error_setg_errno(errp, os_error, fmt, ...) \ 180 error_setg_errno_internal((errp), __FILE__, __LINE__, __func__, \ 181 (os_error), (fmt), ## __VA_ARGS__) 182 void error_setg_errno_internal(Error **errp, 183 const char *fname, int line, const char *func, 184 int os_error, const char *fmt, ...) 185 GCC_FMT_ATTR(6, 7); 186 187 #ifdef _WIN32 188 /* 189 * Just like error_setg(), with @win32_error info added to the message. 190 * If @win32_error is non-zero, ": " + g_win32_error_message(win32_err) 191 * is appended to the human-readable error message. 192 */ 193 #define error_setg_win32(errp, win32_err, fmt, ...) \ 194 error_setg_win32_internal((errp), __FILE__, __LINE__, __func__, \ 195 (win32_err), (fmt), ## __VA_ARGS__) 196 void error_setg_win32_internal(Error **errp, 197 const char *src, int line, const char *func, 198 int win32_err, const char *fmt, ...) 199 GCC_FMT_ATTR(6, 7); 200 #endif 201 202 /* 203 * Propagate error object (if any) from @local_err to @dst_errp. 204 * If @local_err is NULL, do nothing (because there's nothing to 205 * propagate). 206 * Else, if @dst_errp is NULL, errors are being ignored. Free the 207 * error object. 208 * Else, if @dst_errp is &error_abort, print a suitable message and 209 * abort(). 210 * Else, if @dst_errp is &error_fatal, print a suitable message and 211 * exit(1). 212 * Else, if @dst_errp already contains an error, ignore this one: free 213 * the error object. 214 * Else, move the error object from @local_err to *@dst_errp. 215 * On return, @local_err is invalid. 216 * Please don't error_propagate(&error_fatal, ...), use 217 * error_report_err() and exit(), because that's more obvious. 218 */ 219 void error_propagate(Error **dst_errp, Error *local_err); 220 221 /* 222 * Prepend some text to @errp's human-readable error message. 223 * The text is made by formatting @fmt, @ap like vprintf(). 224 */ 225 void error_vprepend(Error **errp, const char *fmt, va_list ap); 226 227 /* 228 * Prepend some text to @errp's human-readable error message. 229 * The text is made by formatting @fmt, ... like printf(). 230 */ 231 void error_prepend(Error **errp, const char *fmt, ...) 232 GCC_FMT_ATTR(2, 3); 233 234 /* 235 * Append a printf-style human-readable explanation to an existing error. 236 * @errp may be NULL, but not &error_fatal or &error_abort. 237 * Trivially the case if you call it only after error_setg() or 238 * error_propagate(). 239 * May be called multiple times. The resulting hint should end with a 240 * newline. 241 */ 242 void error_append_hint(Error **errp, const char *fmt, ...) 243 GCC_FMT_ATTR(2, 3); 244 245 /* 246 * Convenience function to report open() failure. 247 */ 248 #define error_setg_file_open(errp, os_errno, filename) \ 249 error_setg_file_open_internal((errp), __FILE__, __LINE__, __func__, \ 250 (os_errno), (filename)) 251 void error_setg_file_open_internal(Error **errp, 252 const char *src, int line, const char *func, 253 int os_errno, const char *filename); 254 255 /* 256 * Return an exact copy of @err. 257 */ 258 Error *error_copy(const Error *err); 259 260 /* 261 * Free @err. 262 * @err may be NULL. 263 */ 264 void error_free(Error *err); 265 266 /* 267 * Convenience function to assert that *@errp is set, then silently free it. 268 */ 269 void error_free_or_abort(Error **errp); 270 271 /* 272 * Convenience function to error_report() and free @err. 273 */ 274 void error_report_err(Error *err); 275 276 /* 277 * Convenience function to error_prepend(), error_report() and free @err. 278 */ 279 void error_reportf_err(Error *err, const char *fmt, ...) 280 GCC_FMT_ATTR(2, 3); 281 282 /* 283 * Just like error_setg(), except you get to specify the error class. 284 * Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is 285 * strongly discouraged. 286 */ 287 #define error_set(errp, err_class, fmt, ...) \ 288 error_set_internal((errp), __FILE__, __LINE__, __func__, \ 289 (err_class), (fmt), ## __VA_ARGS__) 290 void error_set_internal(Error **errp, 291 const char *src, int line, const char *func, 292 ErrorClass err_class, const char *fmt, ...) 293 GCC_FMT_ATTR(6, 7); 294 295 /* 296 * Special error destination to abort on error. 297 * See error_setg() and error_propagate() for details. 298 */ 299 extern Error *error_abort; 300 301 /* 302 * Special error destination to exit(1) on error. 303 * See error_setg() and error_propagate() for details. 304 */ 305 extern Error *error_fatal; 306 307 #endif 308