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 const QErrorStringTable qerror_table[] = {
  43     {
  44         .error_fmt = QERR_DEVICE_NOT_FOUND,
  45         .desc      = "The %(device) device has not been found",
  46     },
  47     {
  48         .error_fmt = QERR_DEVICE_NOT_ACTIVE,
  49         .desc      = "The %(device) device has not been activated by the guest",
  50     },
  51     {
  52         .error_fmt = QERR_KVM_MISSING_CAP,
  53         .desc      = "Using KVM without %(capability), %(feature) unavailable",
  54     },
  55     {}
  56 };
  57
  58 /**
  59  * qerror_new(): Create a new QError
  60  *
  61  * Return strong reference.
  62  */
  63 QError *qerror_new(void)
  64 {
  65     QError *qerr;
  66
  67     qerr = qemu_mallocz(sizeof(*qerr));
  68     QOBJECT_INIT(qerr, &qerror_type);
  69
  70     return qerr;
  71 }
  72
  73 static void qerror_abort(const QError *qerr, const char *fmt, ...)
  74 {
  75     va_list ap;
  76
  77     fprintf(stderr, "qerror: bad call in function '%s':\n", qerr->func);
  78     fprintf(stderr, "qerror: -> ");
  79
  80     va_start(ap, fmt);
  81     vfprintf(stderr, fmt, ap);
  82     va_end(ap);
  83
  84     fprintf(stderr, "\nqerror: call at %s:%d\n", qerr->file, qerr->linenr);
  85     abort();
  86 }
  87
  88 static void qerror_set_data(QError *qerr, const char *fmt, va_list *va)
  89 {
  90     QObject *obj;
  91
  92     obj = qobject_from_jsonv(fmt, va);
  93     if (!obj) {
  94         qerror_abort(qerr, "invalid format '%s'", fmt);
  95     }
  96     if (qobject_type(obj) != QTYPE_QDICT) {
  97         qerror_abort(qerr, "error format is not a QDict '%s'", fmt);
  98     }
  99
 100     qerr->error = qobject_to_qdict(obj);
 101
 102     obj = qdict_get(qerr->error, "class");
 103     if (!obj) {
 104         qerror_abort(qerr, "missing 'class' key in '%s'", fmt);
 105     }
 106     if (qobject_type(obj) != QTYPE_QSTRING) {
 107         qerror_abort(qerr, "'class' key value should be a QString");
 108     }
 109
 110     obj = qdict_get(qerr->error, "data");
 111     if (!obj) {
 112         qerror_abort(qerr, "missing 'data' key in '%s'", fmt);
 113     }
 114     if (qobject_type(obj) != QTYPE_QDICT) {
 115         qerror_abort(qerr, "'data' key value should be a QDICT");
 116     }
 117 }
 118
 119 static void qerror_set_desc(QError *qerr, const char *fmt)
 120 {
 121     int i;
 122
 123     // FIXME: inefficient loop
 124
 125     for (i = 0; qerror_table[i].error_fmt; i++) {
 126         if (strcmp(qerror_table[i].error_fmt, fmt) == 0) {
 127             qerr->entry = &qerror_table[i];
 128             return;
 129         }
 130     }
 131
 132     qerror_abort(qerr, "error format '%s' not found", fmt);
 133 }
 134
 135 /**
 136  * qerror_from_info(): Create a new QError from error information
 137  *
 138  * The information consists of:
 139  *
 140  * - file   the file name of where the error occurred
 141  * - linenr the line number of where the error occurred
 142  * - func   the function name of where the error occurred
 143  * - fmt    JSON printf-like dictionary, there must exist keys 'class' and
 144  *          'data'
 145  * - va     va_list of all arguments specified by fmt
 146  *
 147  * Return strong reference.
 148  */
 149 QError *qerror_from_info(const char *file, int linenr, const char *func,
 150                          const char *fmt, va_list *va)
 151 {
 152     QError *qerr;
 153
 154     qerr = qerror_new();
 155     qerr->linenr = linenr;
 156     qerr->file = file;
 157     qerr->func = func;
 158
 159     if (!fmt) {
 160         qerror_abort(qerr, "QDict not specified");
 161     }
 162
 163     qerror_set_data(qerr, fmt, va);
 164     qerror_set_desc(qerr, fmt);
 165
 166     return qerr;
 167 }
 168
 169 static void parse_error(const QError *qerror, int c)
 170 {
 171     qerror_abort(qerror, "expected '%c' in '%s'", c, qerror->entry->desc);
 172 }
 173
 174 static const char *append_field(QString *outstr, const QError *qerror,
 175                                 const char *start)
 176 {
 177     QObject *obj;
 178     QDict *qdict;
 179     QString *key_qs;
 180     const char *end, *key;
 181
 182     if (*start != '%')
 183         parse_error(qerror, '%');
 184     start++;
 185     if (*start != '(')
 186         parse_error(qerror, '(');
 187     start++;
 188
 189     end = strchr(start, ')');
 190     if (!end)
 191         parse_error(qerror, ')');
 192
 193     key_qs = qstring_from_substr(start, 0, end - start - 1);
 194     key = qstring_get_str(key_qs);
 195
 196     qdict = qobject_to_qdict(qdict_get(qerror->error, "data"));
 197     obj = qdict_get(qdict, key);
 198     if (!obj) {
 199         qerror_abort(qerror, "key '%s' not found in QDict", key);
 200     }
 201
 202     switch (qobject_type(obj)) {
 203         case QTYPE_QSTRING:
 204             qstring_append(outstr, qdict_get_str(qdict, key));
 205             break;
 206         case QTYPE_QINT:
 207             qstring_append_int(outstr, qdict_get_int(qdict, key));
 208             break;
 209         default:
 210             qerror_abort(qerror, "invalid type '%c'", qobject_type(obj));
 211     }
 212
 213     QDECREF(key_qs);
 214     return ++end;
 215 }
 216
 217 /**
 218  * qerror_print(): Print QError data
 219  *
 220  * This function will print the member 'desc' of the specified QError object,
 221  * it uses qemu_error() for this, so that the output is routed to the right
 222  * place (ie. stderr or Monitor's device).
 223  */
 224 void qerror_print(const QError *qerror)
 225 {
 226     const char *p;
 227     QString *qstring;
 228
 229     assert(qerror->entry != NULL);
 230
 231     qstring = qstring_new();
 232
 233     for (p = qerror->entry->desc; *p != '\0';) {
 234         if (*p != '%') {
 235             qstring_append_chr(qstring, *p++);
 236         } else if (*(p + 1) == '%') {
 237             qstring_append_chr(qstring, '%');
 238             p += 2;
 239         } else {
 240             p = append_field(qstring, qerror, p);
 241         }
 242     }
 243
 244     qemu_error("%s\n", qstring_get_str(qstring));
 245     QDECREF(qstring);
 246 }
 247
 248 /**
 249  * qobject_to_qerror(): Convert a QObject into a QError
 250  */
 251 QError *qobject_to_qerror(const QObject *obj)
 252 {
 253     if (qobject_type(obj) != QTYPE_QERROR) {
 254         return NULL;
 255     }
 256
 257     return container_of(obj, QError, base);
 258 }
 259
 260 /**
 261  * qerror_destroy_obj(): Free all memory allocated by a QError
 262  */
 263 static void qerror_destroy_obj(QObject *obj)
 264 {
 265     QError *qerr;
 266
 267     assert(obj != NULL);
 268     qerr = qobject_to_qerror(obj);
 269
 270     QDECREF(qerr->error);
 271     qemu_free(qerr);
 272 }