qerror.c

   1 /*
   2  * QError: QEMU Error data-type.
   3  *
   4  * Copyright (C) 2009 Red Hat Inc.
   5  *
   6  * Authors:
   7  *  Luiz Capitulino <lcapitulino@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
  10  * See the COPYING.LIB file in the top-level directory.
  11  */
  12 #include "qjson.h"
  13 #include "qerror.h"
  14 #include "qstring.h"
  15 #include "sysemu.h"
  16 #include "qemu-common.h"
  17
  18 static void qerror_destroy_obj(QObject *obj);
  19
  20 static const QType qerror_type = {
  21     .code = QTYPE_QERROR,
  22     .destroy = qerror_destroy_obj,
  23 };
  24
  25 /**
  26  * The 'desc' parameter is a printf-like string, the format of the format
  27  * string is:
  28  *
  29  * %(KEY)
  30  *
  31  * Where KEY is a QDict key, which has to be passed to qerror_from_info().
  32  *
  33  * Example:
  34  *
  35  * "foo error on device: %(device) slot: %(slot_nr)"
  36  *
  37  * A single percent sign can be printed if followed by a second one,
  38  * for example:
  39  *
  40  * "running out of foo: %(foo)%%"
  41  */
  42 static const QErrorStringTable qerror_table[] = {
  43     {
  44         .error_fmt   = QERR_COMMAND_NOT_FOUND,
  45         .desc        = "The command %(name) has not been found",
  46     },
  47     {
  48         .error_fmt = QERR_DEVICE_NOT_FOUND,
  49         .desc      = "The %(device) device has not been found",
  50     },
  51     {
  52         .error_fmt = QERR_DEVICE_NOT_ACTIVE,
  53         .desc      = "The %(device) device has not been activated by the guest",
  54     },
  55     {
  56         .error_fmt   = QERR_INVALID_PARAMETER_TYPE,
  57         .desc        = "Invalid parameter type, expected: %(expected)",
  58     },
  59     {
  60         .error_fmt = QERR_KVM_MISSING_CAP,
  61         .desc      = "Using KVM without %(capability), %(feature) unavailable",
  62     },
  63     {
  64         .error_fmt = QERR_MISSING_PARAMETER,
  65         .desc      = "Parameter %(name) is missing",
  66     },
  67     {
  68         .error_fmt = QERR_QMP_BAD_INPUT_OBJECT,
  69         .desc      = "Bad QMP input object",
  70     },
  71     {
  72         .error_fmt = QERR_JSON_PARSING,
  73         .desc      = "Invalid JSON synaxt",
  74     },
  75     {
  76         .error_fmt   = QERR_UNDEFINED_ERROR,
  77         .desc        = "An undefined error has ocurred",
  78     },
  79     {}
  80 };
  81
  82 /**
  83  * qerror_new(): Create a new QError
  84  *
  85  * Return strong reference.
  86  */
  87 QError *qerror_new(void)
  88 {
  89     QError *qerr;
  90
  91     qerr = qemu_mallocz(sizeof(*qerr));
  92     QOBJECT_INIT(qerr, &qerror_type);
  93
  94     return qerr;
  95 }
  96
  97 static void qerror_abort(const QError *qerr, const char *fmt, ...)
  98 {
  99     va_list ap;
 100
 101     fprintf(stderr, "qerror: bad call in function '%s':\n", qerr->func);
 102     fprintf(stderr, "qerror: -> ");
 103
 104     va_start(ap, fmt);
 105     vfprintf(stderr, fmt, ap);
 106     va_end(ap);
 107
 108     fprintf(stderr, "\nqerror: call at %s:%d\n", qerr->file, qerr->linenr);
 109     abort();
 110 }
 111
 112 static void qerror_set_data(QError *qerr, const char *fmt, va_list *va)
 113 {
 114     QObject *obj;
 115
 116     obj = qobject_from_jsonv(fmt, va);
 117     if (!obj) {
 118         qerror_abort(qerr, "invalid format '%s'", fmt);
 119     }
 120     if (qobject_type(obj) != QTYPE_QDICT) {
 121         qerror_abort(qerr, "error format is not a QDict '%s'", fmt);
 122     }
 123
 124     qerr->error = qobject_to_qdict(obj);
 125
 126     obj = qdict_get(qerr->error, "class");
 127     if (!obj) {
 128         qerror_abort(qerr, "missing 'class' key in '%s'", fmt);
 129     }
 130     if (qobject_type(obj) != QTYPE_QSTRING) {
 131         qerror_abort(qerr, "'class' key value should be a QString");
 132     }
 133
 134     obj = qdict_get(qerr->error, "data");
 135     if (!obj) {
 136         qerror_abort(qerr, "missing 'data' key in '%s'", fmt);
 137     }
 138     if (qobject_type(obj) != QTYPE_QDICT) {
 139         qerror_abort(qerr, "'data' key value should be a QDICT");
 140     }
 141 }
 142
 143 static void qerror_set_desc(QError *qerr, const char *fmt)
 144 {
 145     int i;
 146
 147     // FIXME: inefficient loop
 148
 149     for (i = 0; qerror_table[i].error_fmt; i++) {
 150         if (strcmp(qerror_table[i].error_fmt, fmt) == 0) {
 151             qerr->entry = &qerror_table[i];
 152             return;
 153         }
 154     }
 155
 156     qerror_abort(qerr, "error format '%s' not found", fmt);
 157 }
 158
 159 /**
 160  * qerror_from_info(): Create a new QError from error information
 161  *
 162  * The information consists of:
 163  *
 164  * - file   the file name of where the error occurred
 165  * - linenr the line number of where the error occurred
 166  * - func   the function name of where the error occurred
 167  * - fmt    JSON printf-like dictionary, there must exist keys 'class' and
 168  *          'data'
 169  * - va     va_list of all arguments specified by fmt
 170  *
 171  * Return strong reference.
 172  */
 173 QError *qerror_from_info(const char *file, int linenr, const char *func,
 174                          const char *fmt, va_list *va)
 175 {
 176     QError *qerr;
 177
 178     qerr = qerror_new();
 179     qerr->linenr = linenr;
 180     qerr->file = file;
 181     qerr->func = func;
 182
 183     if (!fmt) {
 184         qerror_abort(qerr, "QDict not specified");
 185     }
 186
 187     qerror_set_data(qerr, fmt, va);
 188     qerror_set_desc(qerr, fmt);
 189
 190     return qerr;
 191 }
 192
 193 static void parse_error(const QError *qerror, int c)
 194 {
 195     qerror_abort(qerror, "expected '%c' in '%s'", c, qerror->entry->desc);
 196 }
 197
 198 static const char *append_field(QString *outstr, const QError *qerror,
 199                                 const char *start)
 200 {
 201     QObject *obj;
 202     QDict *qdict;
 203     QString *key_qs;
 204     const char *end, *key;
 205
 206     if (*start != '%')
 207         parse_error(qerror, '%');
 208     start++;
 209     if (*start != '(')
 210         parse_error(qerror, '(');
 211     start++;
 212
 213     end = strchr(start, ')');
 214     if (!end)
 215         parse_error(qerror, ')');
 216
 217     key_qs = qstring_from_substr(start, 0, end - start - 1);
 218     key = qstring_get_str(key_qs);
 219
 220     qdict = qobject_to_qdict(qdict_get(qerror->error, "data"));
 221     obj = qdict_get(qdict, key);
 222     if (!obj) {
 223         qerror_abort(qerror, "key '%s' not found in QDict", key);
 224     }
 225
 226     switch (qobject_type(obj)) {
 227         case QTYPE_QSTRING:
 228             qstring_append(outstr, qdict_get_str(qdict, key));
 229             break;
 230         case QTYPE_QINT:
 231             qstring_append_int(outstr, qdict_get_int(qdict, key));
 232             break;
 233         default:
 234             qerror_abort(qerror, "invalid type '%c'", qobject_type(obj));
 235     }
 236
 237     QDECREF(key_qs);
 238     return ++end;
 239 }
 240
 241 /**
 242  * qerror_print(): Print QError data
 243  *
 244  * This function will print the member 'desc' of the specified QError object,
 245  * it uses qemu_error() for this, so that the output is routed to the right
 246  * place (ie. stderr or Monitor's device).
 247  */
 248 void qerror_print(const QError *qerror)
 249 {
 250     const char *p;
 251     QString *qstring;
 252
 253     assert(qerror->entry != NULL);
 254
 255     qstring = qstring_new();
 256
 257     for (p = qerror->entry->desc; *p != '\0';) {
 258         if (*p != '%') {
 259             qstring_append_chr(qstring, *p++);
 260         } else if (*(p + 1) == '%') {
 261             qstring_append_chr(qstring, '%');
 262             p += 2;
 263         } else {
 264             p = append_field(qstring, qerror, p);
 265         }
 266     }
 267
 268     qemu_error("%s\n", qstring_get_str(qstring));
 269     QDECREF(qstring);
 270 }
 271
 272 /**
 273  * qobject_to_qerror(): Convert a QObject into a QError
 274  */
 275 QError *qobject_to_qerror(const QObject *obj)
 276 {
 277     if (qobject_type(obj) != QTYPE_QERROR) {
 278         return NULL;
 279     }
 280
 281     return container_of(obj, QError, base);
 282 }
 283
 284 /**
 285  * qerror_destroy_obj(): Free all memory allocated by a QError
 286  */
 287 static void qerror_destroy_obj(QObject *obj)
 288 {
 289     QError *qerr;
 290
 291     assert(obj != NULL);
 292     qerr = qobject_to_qerror(obj);
 293
 294     QDECREF(qerr->error);
 295     qemu_free(qerr);
 296 }