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 * Report an error to stderr: 22 * error_report_err(err); 23 * This frees the error object. 24 * 25 * Report an error somewhere else: 26 * const char *msg = error_get_pretty(err); 27 * do with msg what needs to be done... 28 * error_free(err); 29 * 30 * Handle an error without reporting it (just for completeness): 31 * error_free(err); 32 * 33 * Pass an existing error to the caller: 34 * error_propagate(errp, err); 35 * where Error **errp is a parameter, by convention the last one. 36 * 37 * Create a new error and pass it to the caller: 38 * error_setg(errp, "situation normal, all fouled up"); 39 * 40 * Call a function and receive an error from it: 41 * Error *err = NULL; 42 * foo(arg, &err); 43 * if (err) { 44 * handle the error... 45 * } 46 * 47 * Call a function ignoring errors: 48 * foo(arg, NULL); 49 * 50 * Call a function aborting on errors: 51 * foo(arg, &error_abort); 52 * 53 * Receive an error and pass it on to the caller: 54 * Error *err = NULL; 55 * foo(arg, &err); 56 * if (err) { 57 * handle the error... 58 * error_propagate(errp, err); 59 * } 60 * where Error **errp is a parameter, by convention the last one. 61 * 62 * Do *not* "optimize" this to 63 * foo(arg, errp); 64 * if (*errp) { // WRONG! 65 * handle the error... 66 * } 67 * because errp may be NULL! 68 * 69 * But when all you do with the error is pass it on, please use 70 * foo(arg, errp); 71 * for readability. 72 */ 73 74 #ifndef ERROR_H 75 #define ERROR_H 76 77 #include "qemu/compiler.h" 78 #include "qapi-types.h" 79 #include <stdbool.h> 80 81 /* 82 * Opaque error object. 83 */ 84 typedef struct Error Error; 85 86 /* 87 * Get @err's human-readable error message. 88 */ 89 const char *error_get_pretty(Error *err); 90 91 /* 92 * Get @err's error class. 93 * Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is 94 * strongly discouraged. 95 */ 96 ErrorClass error_get_class(const Error *err); 97 98 /* 99 * Create a new error object and assign it to *@errp. 100 * If @errp is NULL, the error is ignored. Don't bother creating one 101 * then. 102 * If @errp is &error_abort, print a suitable message and abort(). 103 * If @errp is anything else, *@errp must be NULL. 104 * The new error's class is ERROR_CLASS_GENERIC_ERROR, and its 105 * human-readable error message is made from printf-style @fmt, ... 106 */ 107 #define error_setg(errp, fmt, ...) \ 108 error_setg_internal((errp), __FILE__, __LINE__, __func__, \ 109 (fmt), ## __VA_ARGS__) 110 void error_setg_internal(Error **errp, 111 const char *src, int line, const char *func, 112 const char *fmt, ...) 113 GCC_FMT_ATTR(5, 6); 114 115 /* 116 * Just like error_setg(), with @os_error info added to the message. 117 * If @os_error is non-zero, ": " + strerror(os_error) is appended to 118 * the human-readable error message. 119 */ 120 #define error_setg_errno(errp, os_error, fmt, ...) \ 121 error_setg_errno_internal((errp), __FILE__, __LINE__, __func__, \ 122 (os_error), (fmt), ## __VA_ARGS__) 123 void error_setg_errno_internal(Error **errp, 124 const char *fname, int line, const char *func, 125 int os_error, const char *fmt, ...) 126 GCC_FMT_ATTR(6, 7); 127 128 #ifdef _WIN32 129 /* 130 * Just like error_setg(), with @win32_error info added to the message. 131 * If @win32_error is non-zero, ": " + g_win32_error_message(win32_err) 132 * is appended to the human-readable error message. 133 */ 134 #define error_setg_win32(errp, win32_err, fmt, ...) \ 135 error_setg_win32_internal((errp), __FILE__, __LINE__, __func__, \ 136 (win32_err), (fmt), ## __VA_ARGS__) 137 void error_setg_win32_internal(Error **errp, 138 const char *src, int line, const char *func, 139 int win32_err, const char *fmt, ...) 140 GCC_FMT_ATTR(6, 7); 141 #endif 142 143 /* 144 * Propagate error object (if any) from @local_err to @dst_errp. 145 * If @local_err is NULL, do nothing (because there's nothing to 146 * propagate). 147 * Else, if @dst_errp is NULL, errors are being ignored. Free the 148 * error object. 149 * Else, if @dst_errp is &error_abort, print a suitable message and 150 * abort(). 151 * Else, if @dst_errp already contains an error, ignore this one: free 152 * the error object. 153 * Else, move the error object from @local_err to *@dst_errp. 154 * On return, @local_err is invalid. 155 */ 156 void error_propagate(Error **dst_errp, Error *local_err); 157 158 /* 159 * Convenience function to report open() failure. 160 */ 161 #define error_setg_file_open(errp, os_errno, filename) \ 162 error_setg_file_open_internal((errp), __FILE__, __LINE__, __func__, \ 163 (os_errno), (filename)) 164 void error_setg_file_open_internal(Error **errp, 165 const char *src, int line, const char *func, 166 int os_errno, const char *filename); 167 168 /* 169 * Return an exact copy of @err. 170 */ 171 Error *error_copy(const Error *err); 172 173 /* 174 * Free @err. 175 * @err may be NULL. 176 */ 177 void error_free(Error *err); 178 179 /* 180 * Convenience function to error_report() and free @err. 181 */ 182 void error_report_err(Error *); 183 184 /* 185 * Just like error_setg(), except you get to specify the error class. 186 * Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is 187 * strongly discouraged. 188 */ 189 #define error_set(errp, err_class, fmt, ...) \ 190 error_set_internal((errp), __FILE__, __LINE__, __func__, \ 191 (err_class), (fmt), ## __VA_ARGS__) 192 void error_set_internal(Error **errp, 193 const char *src, int line, const char *func, 194 ErrorClass err_class, const char *fmt, ...) 195 GCC_FMT_ATTR(6, 7); 196 197 /* 198 * Pass to error_setg() & friends to abort() on error. 199 */ 200 extern Error *error_abort; 201 202 #endif 203