libmmanager/mm-string-utils.c

   1 /* MManager - a Desktop wide manager for multimedia applications.
   2  *
   3  * Copyright (C) 2008 Cosimo Cecchi <cosimoc@gnome.org>
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the
  17  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18  * Boston, MA 02111-1307, USA.
  19  */
  20
  21 #include <glib.h>
  22 #include <string.h>
  23 #include <libxml/tree.h>
  24 #include <libxml/xmlwriter.h>
  25 #include <libxml/xmlreader.h>
  26 #include <libxml/xmlerror.h>
  27 #include "mm-string-utils.h"
  28 #include "mm-utils.h"
  29 #include "mm-hit.h"
  30 #include "mm-error.h"
  31
  32 typedef struct {
  33   MMComparisionOperator op;
  34   const char *string;
  35 } OperatorGrid;
  36
  37 typedef struct {
  38   xmlTextWriterPtr writer;
  39   GError **error;
  40 } SerializeData;
  41
  42 static OperatorGrid operator_grid[] =
  43 {
  44   { MM_COMP_EQUAL, "EQ" },
  45   { MM_COMP_GREATER, "GR" },
  46   { MM_COMP_GREATER_EQUAL, "GRQ" },
  47   { MM_COMP_LESS, "LS" },
  48   { MM_COMP_LESS_EQUAL, "LSQ" },
  49   { MM_COMP_NONE, "" }
  50 };
  51
  52 static void
  53 set_error (int res, GError **error, const char *obj_name)
  54 {
  55   xmlErrorPtr xml_error;
  56
  57   if (res == -1) {
  58     xml_error = xmlGetLastError ();
  59     g_set_error (error, MM_XML_ERROR_QUARK, MM_XML_ERROR_UNSERIALIZE_FAILED,
  60                  "Error while parsing the serialized xml %s: %s",
  61                  obj_name, (xml_error != NULL) ? (xml_error->message) : "");
  62   } else if (res == 0) {
  63     g_set_error (error, MM_XML_ERROR_QUARK, MM_XML_ERROR_UNEXPECTED_EOF,
  64                  "Error while parsing the serialized xml %s: unexpected "
  65                  "end of the xml buffer.", obj_name);
  66   }
  67 }
  68
  69 static void
  70 set_hit_error (int res, GError **error)
  71 {
  72   set_error (res, error, "Hit");
  73 }
  74
  75 static void
  76 set_hit_collection_error (int res, GError **error)
  77 {
  78   set_error (res, error, "HitCollection");
  79 }
  80
  81 static void
  82 set_value_error (int res, GError **error)
  83 {
  84   set_error (res, error, "Value");
  85 }
  86
  87 static void
  88 set_filter_param_error (int res, GError **error)
  89 {
  90   set_error (res, error, "FilterParam");
  91 }
  92
  93 static void
  94 set_operator_error (int res, GError **error)
  95 {
  96   set_error (res, error, "ComparisionOperator");
  97 }
  98
  99 static void
 100 set_filter_error (int res, GError **error)
 101 {
 102   set_error (res, error, "Filter");
 103 }
 104
 105 static void
 106 set_pair_error (int res, GError **error)
 107 {
 108   set_error (res, error, "Pair");
 109 }
 110
 111 static void
 112 set_attribute_error (int res, GError **error)
 113 {
 114   set_error (res, error, "Attribute");
 115 }
 116
 117 static void
 118 serialize_value (xmlTextWriterPtr writer, GValue *v, GError **error)
 119 {
 120   xmlChar *safe;
 121   int res;
 122   char *ret = NULL;
 123
 124   ret = mm_gvalue_to_string (v);
 125   if (!ret) {
 126     return;
 127   }
 128
 129   safe = xmlCharStrdup (ret);
 130   g_free (ret);
 131
 132   res = xmlTextWriterWriteElement (writer, BAD_CAST ("value"), safe);
 133   g_free (safe);
 134   if (res == -1) {
 135     set_value_error (res, error);
 136     return;
 137   }
 138 }
 139
 140 static void
 141 serialize_op (xmlTextWriterPtr writer, MMComparisionOperator op, GError **error)
 142 {
 143   int idx, res;
 144   xmlChar *str = NULL;
 145
 146   for (idx = 0; idx < G_N_ELEMENTS (operator_grid); idx++) {
 147     if (op == operator_grid[idx].op) {
 148       str = xmlCharStrdup (operator_grid[idx].string);
 149     }
 150   }
 151
 152   if (str) {
 153     res = xmlTextWriterWriteElement (writer, BAD_CAST ("op"), str);
 154     g_free (str);
 155     if (res == -1) {
 156       set_operator_error (res, error);
 157       return;
 158     }
 159   }
 160 }
 161
 162 static void
 163 serialize_attribute (xmlTextWriterPtr writer,
 164                      MMAttribute *attribute,
 165                      GError **error)
 166 {
 167   xmlChar *safe_str;
 168   int res;
 169
 170   res = xmlTextWriterStartElement (writer, BAD_CAST ("attribute"));
 171   if (res == -1) {
 172     set_attribute_error (res, error);
 173     return;
 174   }
 175
 176   safe_str = xmlCharStrdup (mm_attribute_get_id (attribute));
 177   res = xmlTextWriterWriteAttribute (writer, BAD_CAST ("id"), safe_str);
 178   g_free (safe_str);
 179   if (res == -1) {
 180     set_attribute_error (res, error);
 181     return;
 182   }
 183
 184   safe_str = xmlCharStrdup (mm_attribute_get_name (attribute));
 185   xmlTextWriterWriteAttribute (writer, BAD_CAST ("name"), safe_str);
 186   g_free (safe_str);
 187   if (res == -1) {
 188     set_attribute_error (res, error);
 189     return;
 190   }
 191
 192   safe_str = xmlCharStrdup (mm_attribute_get_description (attribute));
 193   xmlTextWriterWriteAttribute (writer, BAD_CAST ("description"), safe_str);
 194   g_free (safe_str);
 195   if (res == -1) {
 196     set_attribute_error (res, error);
 197     return;
 198   }
 199
 200   res = xmlTextWriterWriteAttribute (writer, BAD_CAST ("type"),
 201                                      BAD_CAST (g_type_name (mm_attribute_get_value_type (attribute))));
 202   if (res == -1) {
 203     set_attribute_error (res, error);
 204     return;
 205   }
 206
 207   /* close "attribute" */
 208   res = xmlTextWriterEndElement (writer);
 209   if (res == -1) {
 210     set_attribute_error (res, error);
 211     return;
 212   }
 213 }
 214
 215 static void
 216 serialize_filter_param (MMFilterParam *fp,
 217                         SerializeData *data)
 218 {
 219   MMAttribute *attribute;
 220   GValue *val;
 221   MMComparisionOperator op;
 222   int res;
 223   xmlTextWriterPtr writer = data->writer;
 224   GError **error = data->error;
 225
 226   attribute = mm_filter_param_get_attribute (fp);
 227   val = mm_filter_param_get_value (fp);
 228   op = mm_filter_param_get_operator (fp);
 229
 230   res = xmlTextWriterStartElement (writer, BAD_CAST ("filter-param"));
 231   if (res == -1) {
 232     set_filter_param_error (res, error);
 233     return;
 234   }
 235
 236   serialize_attribute (writer, attribute, error);
 237   if (*error) {
 238     return;
 239   }
 240   serialize_value (writer, val, error);
 241   if (*error) {
 242     return;
 243   }
 244   serialize_op (writer, op, error);
 245   if (*error) {
 246     return;
 247   }
 248
 249   /* close "filter-param" */
 250   res = xmlTextWriterEndElement (writer);
 251   if (res == -1) {
 252     set_filter_param_error (res, error);
 253     return;
 254   }
 255 }
 256
 257 static void
 258 unserialize_operator (xmlTextReaderPtr reader, MMComparisionOperator *op,
 259                       GError **error)
 260 {
 261   const xmlChar * op_string;
 262   gboolean found = FALSE;
 263   int idx, res;
 264
 265   /* we should be on <op> */
 266   if (xmlStrcmp (xmlTextReaderConstName (reader), BAD_CAST ("op")) != 0) {
 267     g_set_error (error, MM_XML_ERROR_QUARK, MM_XML_ERROR_UNEXPECTED_NODE,
 268                  "Error while parsing the serialized xml opeator: the xml reader "
 269                  "does not point to a ComparisionOperator");
 270     return;
 271   }
 272
 273   /* move on to the content */
 274   res = xmlTextReaderRead (reader);
 275   if (res <= 0) {
 276     set_operator_error (res, error);
 277     return;
 278   }
 279
 280   op_string = xmlTextReaderConstValue (reader);
 281   for (idx = 0; idx < G_N_ELEMENTS (operator_grid); idx++) {
 282     if (xmlStrcmp (op_string, BAD_CAST (operator_grid[idx].string)) == 0) {
 283       found = TRUE;
 284       break;
 285     }
 286   }
 287
 288   /* move to </op> */
 289   res = xmlTextReaderRead (reader);
 290   if (res <= 0) {
 291     set_operator_error (res, error);
 292     return;
 293   }
 294
 295   if (found) {
 296     *op = operator_grid[idx].op;
 297   }
 298 }
 299
 300 static void
 301 unserialize_value (xmlTextReaderPtr reader, GValue *v, GError **error)
 302 {
 303   int res;
 304   GType type;
 305   const char *val_string;
 306   gboolean result;
 307
 308   /* we should be on <value> */
 309   if (xmlStrcmp (xmlTextReaderConstName (reader), BAD_CAST ("value")) != 0) {
 310     g_set_error (error, MM_XML_ERROR_QUARK, MM_XML_ERROR_UNEXPECTED_NODE,
 311                  "Error while parsing the serialized xml value: the xml reader "
 312                  " does not point to a value");
 313     return;
 314   }
 315
 316   /* move on to the content node */
 317   res = xmlTextReaderRead (reader);
 318   if (res <= 0) {
 319     set_value_error (res, error);
 320     return;
 321   }
 322
 323   type = G_VALUE_TYPE (v);
 324   val_string = (const char *) xmlTextReaderConstValue (reader);
 325
 326   result = mm_gvalue_from_string (val_string, type, v);
 327   if (!result) {
 328     g_set_error (error, MM_XML_ERROR_QUARK, MM_XML_ERROR_UNKNOWN_GTYPE,
 329                  "Can't convert the string to a value: unhandled type");
 330     return;
 331   }
 332
 333   /* move over </value> */
 334   res = xmlTextReaderRead (reader);
 335   if (res <= 0) {
 336     set_value_error (res, error);
 337     g_value_unset (v);
 338     g_free (v);
 339     v = NULL;
 340   }
 341 }
 342
 343 static void
 344 unserialize_attribute (xmlTextReaderPtr reader, MMAttribute **attribute, GError **error)
 345 {
 346   xmlChar *id, *name, *desc, *type_name;
 347   GType type;
 348
 349   /* we should be on <attribute> */
 350   if (xmlStrcmp (xmlTextReaderConstName (reader), BAD_CAST ("attribute")) != 0) {
 351     g_set_error (error, MM_XML_ERROR_QUARK, MM_XML_ERROR_UNEXPECTED_NODE,
 352                  "Error while parsing the serialized xml attribute: the xml reader"
 353                  " does not point to an attribute.");
 354     return;
 355   }
 356
 357   id = xmlTextReaderGetAttribute (reader, BAD_CAST ("id"));
 358   name = xmlTextReaderGetAttribute (reader, BAD_CAST ("name"));
 359   desc = xmlTextReaderGetAttribute (reader, BAD_CAST ("desc"));
 360   type_name = xmlTextReaderGetAttribute (reader, BAD_CAST ("type"));
 361
 362   type = g_type_from_name ((const char *) type_name);
 363   if (type == 0) {
 364     g_set_error (error, MM_XML_ERROR_QUARK, MM_XML_ERROR_UNKNOWN_GTYPE,
 365                  "Error while parsing the serialized xml attribute: cannot get a GType"
 366                  " for the name %s.", (const char *) type_name);
 367     goto out;
 368   }
 369
 370   *attribute = mm_attribute_new (type,
 371                                  (const char *) id,
 372                                  (const char *) name,
 373                                  (const char *) desc);
 374 out:
 375   g_free (id);
 376   g_free (name);
 377   g_free (desc);
 378   g_free (type_name);
 379 }
 380
 381 static MMFilterParam *
 382 unserialize_filter_param (xmlTextReaderPtr reader, GError **error)
 383 {
 384   int res;
 385   MMAttribute *attribute = NULL;
 386   MMComparisionOperator op = MM_COMP_NONE;
 387   GValue *val = NULL;
 388   MMFilterParam *fp = NULL;
 389
 390   res = xmlTextReaderRead (reader);
 391   if (res <= 0) {
 392     set_filter_param_error (res, error);
 393     goto out;
 394   }
 395
 396   /* we're either on <attribute> or </filter-param> if the object is empty */
 397   while (!((xmlTextReaderNodeType (reader) == XML_READER_TYPE_END_ELEMENT) &&
 398            xmlStrcmp (xmlTextReaderConstName (reader), BAD_CAST ("filter-param")) == 0) && res > 0) {
 399     unserialize_attribute (reader, &attribute, error);
 400     if (*error) {
 401       goto out;
 402     }
 403
 404     res = xmlTextReaderRead (reader);
 405     if (res <= 0) {
 406       set_filter_param_error (res, error);
 407       goto out;
 408     }
 409     /* we're now on <value> */
 410     val = mm_create_gvalue_for_attribute (attribute);
 411     unserialize_value (reader, val, error);
 412     if (*error) {
 413       goto out;
 414     }
 415
 416     res = xmlTextReaderRead (reader);
 417     if (res <= 0) {
 418       set_filter_param_error (res, error);
 419       goto out;
 420     }
 421     /* we're now on <op> */
 422     unserialize_operator (reader, &op, error);
 423     if (*error) {
 424       goto out;
 425     }
 426
 427     /* move after </op> */
 428     res = xmlTextReaderRead (reader);
 429     if (res <= 0) {
 430       set_filter_param_error (res, error);
 431       goto out;
 432     }
 433   }
 434
 435   /* if we're here, everything in the unserialize sub-operations went well */
 436   fp = mm_filter_param_new (attribute, val, op);
 437
 438 out:
 439   if (val) {
 440     g_value_unset (val);
 441     g_free (val);
 442   }
 443
 444   return fp;
 445 }
 446
 447 static void
 448 serialize_pair (MMAttribute *attr,
 449                 GValue *val,
 450                 SerializeData *pair_data)
 451 {
 452   xmlTextWriterPtr writer = pair_data->writer;
 453   GError **error = pair_data->error;
 454   int res;
 455
 456   if (*error) {
 457     /* an error occurred in a previous iteration of this function, don't do
 458      * anything.
 459      */
 460     return;
 461   }
 462
 463   xmlTextWriterStartElement (writer, BAD_CAST ("pair"));
 464   serialize_attribute (writer, attr, error);
 465   if (*error) {
 466     return;
 467   }
 468
 469   serialize_value (writer, val, error);
 470   if (*error) {
 471     return;
 472   }
 473
 474   /* end "pair" */
 475   res = xmlTextWriterEndElement (writer);
 476   if (res == -1) {
 477     set_pair_error (res, error);
 478   }
 479 }
 480
 481 static MMHit *
 482 unserialize_hit (xmlTextReaderPtr reader, GError **error)
 483 {
 484   int res;
 485   MMAttribute *attribute = NULL;
 486   GValue *v;
 487   MMHit *hit = NULL;
 488
 489   hit = g_object_new (MM_TYPE_HIT, NULL);
 490
 491   do {
 492     /* skip <pair> */
 493     res = xmlTextReaderRead (reader);
 494     if (res <= 0) {
 495       set_hit_error (res, error);
 496       g_object_unref (hit);
 497       hit = NULL;
 498       break;
 499     }
 500     res = xmlTextReaderRead (reader);
 501     /* now we should be on "attribute" */
 502     if (res <= 0) {
 503       set_hit_error (res, error);
 504       g_object_unref (hit);
 505       hit = NULL;
 506       break;
 507     }
 508     unserialize_attribute (reader, &attribute, error);
 509     if (*error) {
 510       g_object_unref (hit);
 511       hit = NULL;
 512       break;
 513     }
 514     res = xmlTextReaderRead (reader);
 515     /* we're now on "value" */
 516     if (res <= 0) {
 517       set_hit_error (res, error);
 518       g_object_unref (hit);
 519       hit = NULL;
 520       break;
 521     }
 522
 523     v = mm_create_gvalue_for_attribute (attribute);
 524     unserialize_value (reader, v, error);
 525     if (*error) {
 526       g_object_unref (hit);
 527       hit = NULL;
 528       break;
 529     }
 530
 531     mm_hit_set_value (hit, attribute, v);
 532
 533     res = xmlTextReaderRead (reader);
 534     /* now we're on </pair> */
 535     if (res <= 0) {
 536       set_hit_error (res, error);
 537       g_object_unref (hit);
 538       hit = NULL;
 539       break;
 540     }
 541
 542     res = xmlTextReaderRead (reader);
 543     if (res <= 0) {
 544       set_hit_error (res, error);
 545       g_object_unref (hit);
 546       hit = NULL;
 547       break;
 548     }
 549     /* now we're either on <pair> again or </hit>. we must end they cycle
 550      * on </hit>.
 551      */
 552   } while (!((xmlTextReaderNodeType (reader) == XML_READER_TYPE_END_ELEMENT) &&
 553              xmlStrcmp (xmlTextReaderConstName (reader), BAD_CAST ("hit"))));
 554
 555   return hit;
 556 }
 557
 558 /* public functions */
 559
 560 /**
 561  * mm_filter_serialize:
 562  * @filter: a #MMFilter object.
 563  * @error: a #GError.
 564  *
 565  * Builds a serialized XML version of @filter.
 566  *
 567  * Return value: a newly allocated string buffer containing the serialized
 568  * #MMFilter.
 569  */
 570
 571 char *
 572 mm_filter_serialize (MMFilter *filter, GError **error)
 573 {
 574   char *serialized = NULL;
 575   xmlBufferPtr buffer;
 576   xmlTextWriterPtr writer;
 577   GList *filter_params;
 578   SerializeData *fp_data;
 579   int res;
 580
 581   buffer = xmlBufferCreate ();
 582   writer = xmlNewTextWriterMemory (buffer, 0);
 583
 584   res = xmlTextWriterStartDocument (writer, NULL, NULL, NULL);
 585   if (res == -1) {
 586     set_filter_error (res, error);
 587     goto out;
 588   }
 589
 590   res = xmlTextWriterStartElement (writer, BAD_CAST ("filter"));
 591   if (res == -1) {
 592     set_filter_error (res, error);
 593     goto out;
 594   }
 595
 596   filter_params = mm_filter_get_filtering_params (filter);
 597   fp_data = g_new0 (SerializeData, 1);
 598   fp_data->writer = writer;
 599   fp_data->error = error;
 600   g_list_foreach (filter_params, (GFunc) serialize_filter_param, fp_data);
 601   g_free (fp_data);
 602   if (*error) {
 603     goto out;
 604   }
 605
 606   /* close "filter" */
 607   res = xmlTextWriterEndElement (writer);
 608   if (res == -1) {
 609     set_filter_error (res, error);
 610     goto out;
 611   }
 612
 613   res = xmlTextWriterEndDocument (writer);
 614   if (res == -1) {
 615     set_filter_error (res, error);
 616     goto out;
 617   }
 618
 619   /* everything went well */
 620   serialized = g_strdup ((char *) xmlBufferContent (buffer));
 621
 622 out:
 623   xmlFreeTextWriter (writer);
 624   xmlBufferFree (buffer);
 625
 626   return serialized;
 627 }
 628
 629 /**
 630  * mm_hit_collection_serialize:
 631  * @hc: a #MMHitCollection object.
 632  * @error: a #GError.
 633  *
 634  * Builds a serialized XML version of the #MMHitCollection.
 635  *
 636  * Return value: a newly allocated string buffer containing the serialized
 637  * #MMHitCollection.
 638  */
 639
 640 char *
 641 mm_hit_collection_serialize (MMHitCollection *hc, GError **error)
 642 {
 643   char *serialized = NULL;
 644   int res;
 645   xmlBufferPtr buffer;
 646   xmlTextWriterPtr writer;
 647   MMHit *hit;
 648   GHashTable *attrs_and_values;
 649   SerializeData *pair_data;
 650
 651   buffer = xmlBufferCreate ();
 652   writer = xmlNewTextWriterMemory (buffer, 0);
 653
 654   res = xmlTextWriterStartDocument (writer, NULL, NULL, NULL);
 655   if (res == -1) {
 656     set_hit_collection_error (res, error);
 657     goto out;
 658   }
 659
 660   res = xmlTextWriterStartElement (writer, BAD_CAST ("hit-collection"));
 661   if (res == -1) {
 662     set_hit_collection_error (res, error);
 663     goto out;
 664   }
 665
 666   while ((hit = mm_hit_collection_get_next_hit (hc)) != NULL) {
 667     res = xmlTextWriterStartElement (writer, BAD_CAST ("hit"));
 668     if (res == -1) {
 669       g_object_unref (hit);
 670       set_hit_collection_error (res, error);
 671       goto out;
 672     }
 673
 674     attrs_and_values = mm_hit_get_all_values (hit);
 675     g_object_unref (hit);
 676
 677     pair_data = g_slice_new0 (SerializeData);
 678     pair_data->writer = writer;
 679     pair_data->error = error;
 680
 681     g_hash_table_foreach (attrs_and_values,
 682                           (GHFunc) serialize_pair,
 683                           pair_data);
 684     g_slice_free (SerializeData, pair_data);
 685     g_hash_table_destroy (attrs_and_values);
 686
 687     if (*error) {
 688       /* an error occurred somewhere in one of the sub-functions */
 689       goto out;
 690     }
 691
 692     /* close "hit" */
 693     res = xmlTextWriterEndElement (writer);
 694     if (res == -1) {
 695       set_hit_collection_error (res, error);
 696       goto out;
 697     }
 698   }
 699
 700   /* close "hit-collection" */
 701   res = xmlTextWriterEndElement (writer);
 702   if (res == -1) {
 703     set_hit_collection_error (res, error);
 704     goto out;
 705   }
 706   res = xmlTextWriterEndDocument (writer);
 707   if (res == -1) {
 708     set_hit_collection_error (res, error);
 709     goto out;
 710   }
 711
 712   /* it seems everything has gone well */
 713   serialized = g_strdup ((char *) xmlBufferContent (buffer));
 714
 715 out:
 716   xmlFreeTextWriter (writer);
 717   xmlBufferFree (buffer);
 718
 719   return serialized;
 720 }
 721
 722 /**
 723  * mm_filter_unserialize:
 724  * @s: a serialized #MMFilter, obtained with
 725  * #mm_filter_serialize.
 726  * @error: a #GError.
 727  *
 728  * Builds a #MMFilter object from a serialized XML string.
 729  *
 730  * Return value: a #MMFilter object. Unref it when done.
 731  */
 732
 733 MMFilter *
 734 mm_filter_unserialize (const char *s, GError **error)
 735 {
 736   MMFilter *f = NULL;
 737   MMFilterParam *fp;
 738   xmlTextReaderPtr reader;
 739   int res;
 740   const xmlChar *node_name;
 741
 742   reader = xmlReaderForMemory (s, strlen (s), NULL, NULL, 0);
 743
 744   /* cut all the elements before <filter> */
 745   do {
 746     res = xmlTextReaderRead (reader);
 747     node_name = xmlTextReaderConstName (reader);
 748   } while (xmlStrcmp (node_name, BAD_CAST ("filter")) != 0);
 749
 750   /* do the error checking here and not in each iteration of the cycle */
 751   if (res <= 0) {
 752     set_filter_error (res, error);
 753     goto out;
 754   }
 755
 756   res = xmlTextReaderRead (reader);
 757   node_name = xmlTextReaderConstName (reader);
 758   f = mm_filter_new ();
 759
 760   /* we're either on the first <filter-param> or on </filter> if the
 761    * object is empty. cycle until we're on </filter>.
 762    */
 763   while (!((xmlTextReaderNodeType (reader) == XML_READER_TYPE_END_ELEMENT) &&
 764            xmlStrcmp (node_name, BAD_CAST ("filter")) == 0) && res > 0) {
 765     fp = unserialize_filter_param (reader, error);
 766     if (*error) {
 767       g_object_unref (f);
 768       f = NULL;
 769       goto out;
 770     }
 771     mm_filter_add_filtering_param (f, fp);
 772     g_object_unref (fp);
 773     res = xmlTextReaderRead (reader);
 774     node_name = xmlTextReaderConstName (reader);
 775   }
 776
 777   if (res <= 0) {
 778     /* do not return an incomplete filter */
 779     set_filter_error (res, error);
 780     g_object_unref (f);
 781     f = NULL;
 782   }
 783
 784 out:
 785   xmlFreeTextReader (reader);
 786
 787   return f;
 788 }
 789
 790 /**
 791  * mm_hit_collection_unserialize:
 792  * @s: a serialized #MMHitCollection, obtained with
 793  * #mm_hit_collection_serialize.
 794  * @error: a #GError.
 795  *
 796  * Builds a #MMHitCollection object from a serialized XML string.
 797  *
 798  * Return value: a #MMHitCollection object. Unref it when done.
 799  */
 800
 801 MMHitCollection *
 802 mm_hit_collection_unserialize (const char *s, GError **error)
 803 {
 804   MMHitCollection *hc = NULL;
 805   MMHit *hit;
 806   xmlTextReaderPtr reader;
 807   int res;
 808   const xmlChar *node_name;
 809
 810   reader = xmlReaderForMemory (s, strlen (s), NULL, NULL, 0);
 811
 812   /* cut all the elements before <hit-collection> */
 813   do {
 814     res = xmlTextReaderRead (reader);
 815     node_name = xmlTextReaderConstName (reader);
 816   } while (xmlStrcmp (node_name, BAD_CAST ("hit-collection")) != 0);
 817
 818   /* check for errors before <hit-collection> all at once, and not
 819    * in every iteration of the cycle.
 820    */
 821   if (res <= 0) {
 822     set_hit_collection_error (res, error);
 823     goto out;
 824   }
 825
 826   hc = mm_hit_collection_new ();
 827   res = xmlTextReaderRead (reader);
 828   node_name = xmlTextReaderConstName (reader);
 829
 830   /* we're either on the first <hit> or on </hit-collection> if the
 831    * object is empty. cycle until we're at the end of file.
 832    */
 833   while (!((xmlTextReaderNodeType (reader) == XML_READER_TYPE_END_ELEMENT) &&
 834            xmlStrcmp (node_name, BAD_CAST ("hit-collection")) == 0) && res > 0) {
 835     hit = unserialize_hit (reader, error);
 836     if (*error) {
 837       /* do not return an incomplete HitCollection */
 838       g_object_unref (hc);
 839       hc = NULL;
 840       goto out;
 841     }
 842     mm_hit_collection_add_hit (hc, hit);
 843     g_object_unref (hit);
 844     res = xmlTextReaderRead (reader);
 845     node_name = xmlTextReaderConstName (reader);
 846   }
 847
 848   if (res <= 0) {
 849     /* do not return an incomplete HitCollection */
 850     set_hit_collection_error (res, error);
 851     g_object_unref (hc);
 852     hc = NULL;
 853     goto out;
 854   }
 855
 856 out:
 857   xmlFreeTextReader (reader);
 858
 859   return hc;
 860 }
 861
 862 /**
 863  * mm_gvalue_to_string:
 864  * @v: a #GValue
 865  *
 866  * Builds a serialized XML version of a #GValue.
 867  *
 868  * Return value: a newly allocated string buffer containing the serialized
 869  * #GValue.
 870  */
 871
 872 char *
 873 mm_gvalue_to_string (GValue *v)
 874 {
 875   char *ret = NULL;
 876   GType type = G_VALUE_TYPE (v);
 877
 878   /* guess the most used cases and handle those first */
 879   if (type == G_TYPE_STRING) {
 880     ret = g_strdup (g_value_get_string (v));
 881   } else if (type == G_TYPE_BOOLEAN) {
 882     ret = g_strdup_printf ("%d", g_value_get_boolean (v));
 883   } else if (type == G_TYPE_INT) {
 884     ret = g_strdup_printf ("%d", g_value_get_int (v));
 885   } else if (type == G_TYPE_FLOAT) {
 886     ret = g_strdup_printf ("%f", g_value_get_float (v));
 887   } else if (type == G_TYPE_DOUBLE) {
 888     char double_buff[G_ASCII_DTOSTR_BUF_SIZE];
 889     ret = g_ascii_dtostr (double_buff, sizeof (double_buff),
 890                           g_value_get_double (v));
 891   } else if (type == G_TYPE_LONG) {
 892     ret = g_strdup_printf ("%ld", g_value_get_long (v));
 893   } else if (type == G_TYPE_INT64) {
 894     ret = g_strdup_printf ("%lld", g_value_get_int64 (v));
 895   } else if (type == G_TYPE_UINT) {
 896     ret = g_strdup_printf ("%u", g_value_get_uint (v));
 897   } else if (type == G_TYPE_ULONG) {
 898     ret = g_strdup_printf ("%lu", g_value_get_ulong (v));
 899   } else if (type == G_TYPE_UINT64) {
 900     ret = g_strdup_printf ("%llu", g_value_get_uint64 (v));
 901   } else if (G_VALUE_HOLDS_CHAR (v)) {
 902     ret = g_strdup_printf ("%c", g_value_get_char (v));
 903   } else if (G_VALUE_HOLDS_UCHAR (v)) {
 904     ret = g_strdup_printf ("%c", g_value_get_uchar (v));
 905   } else {
 906     g_warning ("Can't convert the value to string: unhandled type");
 907   }
 908
 909   return ret;
 910 }
 911
 912 /**
 913  * mm_gvalue_from_string:
 914  * @val_string: a string description of a #GValue. You can use
 915  * #mm_gvalue_to_string to have one.
 916  * @type: the type of the #GValue.
 917  * @v: a zero-filled uninitialized #GValue.
 918  *
 919  * Fills @v with the #GValue contained in the XML description @val_string.
 920  *
 921  * Return value: %TRUE in case of success, %FALSE in case of failure.
 922  */
 923
 924 gboolean
 925 mm_gvalue_from_string (const char *val_string, GType type, GValue *v)
 926 {
 927   gboolean retval = TRUE;
 928
 929   g_value_init (v, type);
 930
 931   if (type == G_TYPE_STRING) {
 932     g_value_set_string (v, val_string);
 933   } else if (type == G_TYPE_BOOLEAN) {
 934     gboolean bval;
 935     sscanf (val_string, "%d", &bval);
 936     g_value_set_boolean (v, bval);
 937   } else if (type == G_TYPE_INT) {
 938     gint ival;
 939     sscanf (val_string, "%d", &ival);
 940     g_value_set_int (v, ival);
 941   } else if (type == G_TYPE_FLOAT) {
 942     gfloat fval;
 943     sscanf (val_string, "%f", &fval);
 944     g_value_set_float (v, fval);
 945   } else if (type == G_TYPE_DOUBLE) {
 946     gdouble dval;
 947     dval = g_ascii_strtod (val_string, NULL);
 948     g_value_set_double (v, dval);
 949   } else if (type == G_TYPE_LONG) {
 950     glong lval;
 951     sscanf (val_string, "%ld", &lval);
 952     g_value_set_long (v, lval);
 953   } else if (type == G_TYPE_INT64) {
 954     g_value_set_int64 (v, g_ascii_strtoll (val_string, NULL, 0));
 955   } else if (type == G_TYPE_UINT) {
 956     guint uval;
 957     sscanf (val_string, "%u", &uval);
 958     g_value_set_uint (v, uval);
 959   } else if (type == G_TYPE_ULONG) {
 960     gulong ulval;
 961     sscanf (val_string, "%lu", &ulval);
 962     g_value_set_ulong (v, ulval);
 963   } else if (type == G_TYPE_UINT64) {
 964     g_value_set_uint64 (v, g_ascii_strtoull (val_string, NULL, 0));
 965   } else if (G_VALUE_HOLDS_CHAR (v)) {
 966     gchar cval;
 967     sscanf (val_string, "%c", &cval);
 968     g_value_set_char (v, cval);
 969   } else if (G_VALUE_HOLDS_UCHAR (v)) {
 970     guchar ucval;
 971     sscanf (val_string, "%c", &ucval);
 972     g_value_set_uchar (v, ucval);
 973   } else {
 974     retval = FALSE;
 975   }
 976
 977   return retval;
 978 }