gdb/xml-tdesc.c

   1 /* XML target description support for GDB.
   2
   3    Copyright (C) 2006-2014 Free Software Foundation, Inc.
   4
   5    Contributed by CodeSourcery.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "target.h"
  24 #include "target-descriptions.h"
  25 #include "xml-support.h"
  26 #include "xml-tdesc.h"
  27 #include "osabi.h"
  28
  29 #include "filenames.h"
  30
  31 #if !defined(HAVE_LIBEXPAT)
  32
  33 /* Parse DOCUMENT into a target description.  Or don't, since we don't have
  34    an XML parser.  */
  35
  36 static struct target_desc *
  37 tdesc_parse_xml (const char *document, xml_fetch_another fetcher,
  38                  void *fetcher_baton)
  39 {
  40   static int have_warned;
  41
  42   if (!have_warned)
  43     {
  44       have_warned = 1;
  45       warning (_("Can not parse XML target description; XML support was "
  46                  "disabled at compile time"));
  47     }
  48
  49   return NULL;
  50 }
  51
  52 #else /* HAVE_LIBEXPAT */
  53
  54 /* A record of every XML description we have parsed.  We never discard
  55    old descriptions, because we never discard gdbarches.  As long as we
  56    have a gdbarch referencing this description, we want to have a copy
  57    of it here, so that if we parse the same XML document again we can
  58    return the same "struct target_desc *"; if they are not singletons,
  59    then we will create unnecessary duplicate gdbarches.  See
  60    gdbarch_list_lookup_by_info.  */
  61
  62 struct tdesc_xml_cache
  63 {
  64   const char *xml_document;
  65   struct target_desc *tdesc;
  66 };
  67 typedef struct tdesc_xml_cache tdesc_xml_cache_s;
  68 DEF_VEC_O(tdesc_xml_cache_s);
  69
  70 static VEC(tdesc_xml_cache_s) *xml_cache;
  71
  72 /* Callback data for target description parsing.  */
  73
  74 struct tdesc_parsing_data
  75 {
  76   /* The target description we are building.  */
  77   struct target_desc *tdesc;
  78
  79   /* The target feature we are currently parsing, or last parsed.  */
  80   struct tdesc_feature *current_feature;
  81
  82   /* The register number to use for the next register we see, if
  83      it does not have its own.  This starts at zero.  */
  84   int next_regnum;
  85
  86   /* The struct or union we are currently parsing, or last parsed.  */
  87   struct tdesc_type *current_type;
  88
  89   /* The byte size of the current struct type, if specified.  Zero
  90      if not specified.  */
  91   int current_type_size;
  92
  93   /* Whether the current type is a flags type.  */
  94   int current_type_is_flags;
  95 };
  96
  97 /* Handle the end of an <architecture> element and its value.  */
  98
  99 static void
 100 tdesc_end_arch (struct gdb_xml_parser *parser,
 101                 const struct gdb_xml_element *element,
 102                 void *user_data, const char *body_text)
 103 {
 104   struct tdesc_parsing_data *data = user_data;
 105   const struct bfd_arch_info *arch;
 106
 107   arch = bfd_scan_arch (body_text);
 108   if (arch == NULL)
 109     gdb_xml_error (parser, _("Target description specified unknown "
 110                              "architecture \"%s\""), body_text);
 111   set_tdesc_architecture (data->tdesc, arch);
 112 }
 113
 114 /* Handle the end of an <osabi> element and its value.  */
 115
 116 static void
 117 tdesc_end_osabi (struct gdb_xml_parser *parser,
 118                  const struct gdb_xml_element *element,
 119                  void *user_data, const char *body_text)
 120 {
 121   struct tdesc_parsing_data *data = user_data;
 122   enum gdb_osabi osabi;
 123
 124   osabi = osabi_from_tdesc_string (body_text);
 125   if (osabi == GDB_OSABI_UNKNOWN)
 126     warning (_("Target description specified unknown osabi \"%s\""),
 127              body_text);
 128   else
 129     set_tdesc_osabi (data->tdesc, osabi);
 130 }
 131
 132 /* Handle the end of a <compatible> element and its value.  */
 133
 134 static void
 135 tdesc_end_compatible (struct gdb_xml_parser *parser,
 136                       const struct gdb_xml_element *element,
 137                       void *user_data, const char *body_text)
 138 {
 139   struct tdesc_parsing_data *data = user_data;
 140   const struct bfd_arch_info *arch;
 141
 142   arch = bfd_scan_arch (body_text);
 143   tdesc_add_compatible (data->tdesc, arch);
 144 }
 145
 146 /* Handle the start of a <target> element.  */
 147
 148 static void
 149 tdesc_start_target (struct gdb_xml_parser *parser,
 150                     const struct gdb_xml_element *element,
 151                     void *user_data, VEC(gdb_xml_value_s) *attributes)
 152 {
 153   char *version = xml_find_attribute (attributes, "version")->value;
 154
 155   if (strcmp (version, "1.0") != 0)
 156     gdb_xml_error (parser,
 157                    _("Target description has unsupported version \"%s\""),
 158                    version);
 159 }
 160
 161 /* Handle the start of a <feature> element.  */
 162
 163 static void
 164 tdesc_start_feature (struct gdb_xml_parser *parser,
 165                      const struct gdb_xml_element *element,
 166                      void *user_data, VEC(gdb_xml_value_s) *attributes)
 167 {
 168   struct tdesc_parsing_data *data = user_data;
 169   char *name = xml_find_attribute (attributes, "name")->value;
 170
 171   data->current_feature = tdesc_create_feature (data->tdesc, name);
 172 }
 173
 174 /* Handle the start of a <reg> element.  Fill in the optional
 175    attributes and attach it to the containing feature.  */
 176
 177 static void
 178 tdesc_start_reg (struct gdb_xml_parser *parser,
 179                  const struct gdb_xml_element *element,
 180                  void *user_data, VEC(gdb_xml_value_s) *attributes)
 181 {
 182   struct tdesc_parsing_data *data = user_data;
 183   struct gdb_xml_value *attrs = VEC_address (gdb_xml_value_s, attributes);
 184   int ix = 0, length;
 185   char *name, *group, *type;
 186   int bitsize, regnum, save_restore;
 187
 188   length = VEC_length (gdb_xml_value_s, attributes);
 189
 190   name = attrs[ix++].value;
 191   bitsize = * (ULONGEST *) attrs[ix++].value;
 192
 193   if (ix < length && strcmp (attrs[ix].name, "regnum") == 0)
 194     regnum = * (ULONGEST *) attrs[ix++].value;
 195   else
 196     regnum = data->next_regnum;
 197
 198   if (ix < length && strcmp (attrs[ix].name, "type") == 0)
 199     type = attrs[ix++].value;
 200   else
 201     type = "int";
 202
 203   if (ix < length && strcmp (attrs[ix].name, "group") == 0)
 204     group = attrs[ix++].value;
 205   else
 206     group = NULL;
 207
 208   if (ix < length && strcmp (attrs[ix].name, "save-restore") == 0)
 209     save_restore = * (ULONGEST *) attrs[ix++].value;
 210   else
 211     save_restore = 1;
 212
 213   if (strcmp (type, "int") != 0
 214       && strcmp (type, "float") != 0
 215       && tdesc_named_type (data->current_feature, type) == NULL)
 216     gdb_xml_error (parser, _("Register \"%s\" has unknown type \"%s\""),
 217                    name, type);
 218
 219   tdesc_create_reg (data->current_feature, name, regnum, save_restore, group,
 220                     bitsize, type);
 221
 222   data->next_regnum = regnum + 1;
 223 }
 224
 225 /* Handle the start of a <union> element.  Initialize the type and
 226    record it with the current feature.  */
 227
 228 static void
 229 tdesc_start_union (struct gdb_xml_parser *parser,
 230                    const struct gdb_xml_element *element,
 231                    void *user_data, VEC(gdb_xml_value_s) *attributes)
 232 {
 233   struct tdesc_parsing_data *data = user_data;
 234   char *id = xml_find_attribute (attributes, "id")->value;
 235
 236   data->current_type = tdesc_create_union (data->current_feature, id);
 237   data->current_type_size = 0;
 238   data->current_type_is_flags = 0;
 239 }
 240
 241 /* Handle the start of a <struct> element.  Initialize the type and
 242    record it with the current feature.  */
 243
 244 static void
 245 tdesc_start_struct (struct gdb_xml_parser *parser,
 246                    const struct gdb_xml_element *element,
 247                    void *user_data, VEC(gdb_xml_value_s) *attributes)
 248 {
 249   struct tdesc_parsing_data *data = user_data;
 250   char *id = xml_find_attribute (attributes, "id")->value;
 251   struct tdesc_type *type;
 252   struct gdb_xml_value *attr;
 253
 254   type = tdesc_create_struct (data->current_feature, id);
 255   data->current_type = type;
 256   data->current_type_size = 0;
 257   data->current_type_is_flags = 0;
 258
 259   attr = xml_find_attribute (attributes, "size");
 260   if (attr != NULL)
 261     {
 262       int size = (int) * (ULONGEST *) attr->value;
 263
 264       tdesc_set_struct_size (type, size);
 265       data->current_type_size = size;
 266     }
 267 }
 268
 269 static void
 270 tdesc_start_flags (struct gdb_xml_parser *parser,
 271                    const struct gdb_xml_element *element,
 272                    void *user_data, VEC(gdb_xml_value_s) *attributes)
 273 {
 274   struct tdesc_parsing_data *data = user_data;
 275   char *id = xml_find_attribute (attributes, "id")->value;
 276   int length = (int) * (ULONGEST *)
 277     xml_find_attribute (attributes, "size")->value;
 278   struct tdesc_type *type;
 279
 280   type = tdesc_create_flags (data->current_feature, id, length);
 281
 282   data->current_type = type;
 283   data->current_type_size = 0;
 284   data->current_type_is_flags = 1;
 285 }
 286
 287 /* Handle the start of a <field> element.  Attach the field to the
 288    current struct or union.  */
 289
 290 static void
 291 tdesc_start_field (struct gdb_xml_parser *parser,
 292                    const struct gdb_xml_element *element,
 293                    void *user_data, VEC(gdb_xml_value_s) *attributes)
 294 {
 295   struct tdesc_parsing_data *data = user_data;
 296   struct gdb_xml_value *attr;
 297   struct tdesc_type *field_type;
 298   char *field_name, *field_type_id;
 299   int start, end;
 300
 301   field_name = xml_find_attribute (attributes, "name")->value;
 302
 303   attr = xml_find_attribute (attributes, "type");
 304   if (attr != NULL)
 305     field_type_id = attr->value;
 306   else
 307     field_type_id = NULL;
 308
 309   attr = xml_find_attribute (attributes, "start");
 310   if (attr != NULL)
 311     start = * (ULONGEST *) attr->value;
 312   else
 313     start = -1;
 314
 315   attr = xml_find_attribute (attributes, "end");
 316   if (attr != NULL)
 317     end = * (ULONGEST *) attr->value;
 318   else
 319     end = -1;
 320
 321   if (field_type_id != NULL)
 322     {
 323       if (data->current_type_is_flags)
 324         gdb_xml_error (parser, _("Cannot add typed field \"%s\" to flags"),
 325                        field_name);
 326       if (data->current_type_size != 0)
 327         gdb_xml_error (parser,
 328                        _("Explicitly sized type can not "
 329                          "contain non-bitfield \"%s\""),
 330                        field_name);
 331
 332       field_type = tdesc_named_type (data->current_feature, field_type_id);
 333       if (field_type == NULL)
 334         gdb_xml_error (parser, _("Field \"%s\" references undefined "
 335                                  "type \"%s\""),
 336                        field_name, field_type_id);
 337
 338       tdesc_add_field (data->current_type, field_name, field_type);
 339     }
 340   else if (start != -1 && end != -1)
 341     {
 342       struct tdesc_type *t = data->current_type;
 343
 344       if (data->current_type_is_flags)
 345         tdesc_add_flag (t, start, field_name);
 346       else
 347         {
 348           if (data->current_type_size == 0)
 349             gdb_xml_error (parser,
 350                            _("Implicitly sized type can "
 351                              "not contain bitfield \"%s\""),
 352                            field_name);
 353
 354           if (end >= 64)
 355             gdb_xml_error (parser,
 356                            _("Bitfield \"%s\" goes past "
 357                              "64 bits (unsupported)"),
 358                            field_name);
 359
 360           /* Assume that the bit numbering in XML is "lsb-zero".  Most
 361              architectures other than PowerPC use this ordering.  In
 362              the future, we can add an XML tag to indicate "msb-zero"
 363              numbering.  */
 364           if (start > end)
 365             gdb_xml_error (parser, _("Bitfield \"%s\" has start after end"),
 366                            field_name);
 367
 368           if (end >= data->current_type_size * TARGET_CHAR_BIT)
 369             gdb_xml_error (parser,
 370                            _("Bitfield \"%s\" does not fit in struct"));
 371
 372           tdesc_add_bitfield (t, field_name, start, end);
 373         }
 374     }
 375   else
 376     gdb_xml_error (parser, _("Field \"%s\" has neither type nor bit position"),
 377                    field_name);
 378 }
 379
 380 /* Handle the start of a <vector> element.  Initialize the type and
 381    record it with the current feature.  */
 382
 383 static void
 384 tdesc_start_vector (struct gdb_xml_parser *parser,
 385                     const struct gdb_xml_element *element,
 386                     void *user_data, VEC(gdb_xml_value_s) *attributes)
 387 {
 388   struct tdesc_parsing_data *data = user_data;
 389   struct gdb_xml_value *attrs = VEC_address (gdb_xml_value_s, attributes);
 390   struct tdesc_type *field_type;
 391   char *id, *field_type_id;
 392   int count;
 393
 394   id = attrs[0].value;
 395   field_type_id = attrs[1].value;
 396   count = * (ULONGEST *) attrs[2].value;
 397
 398   field_type = tdesc_named_type (data->current_feature, field_type_id);
 399   if (field_type == NULL)
 400     gdb_xml_error (parser, _("Vector \"%s\" references undefined type \"%s\""),
 401                    id, field_type_id);
 402
 403   tdesc_create_vector (data->current_feature, id, field_type, count);
 404 }
 405
 406 /* The elements and attributes of an XML target description.  */
 407
 408 static const struct gdb_xml_attribute field_attributes[] = {
 409   { "name", GDB_XML_AF_NONE, NULL, NULL },
 410   { "type", GDB_XML_AF_OPTIONAL, NULL, NULL },
 411   { "start", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
 412   { "end", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
 413   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 414 };
 415
 416 static const struct gdb_xml_element struct_union_children[] = {
 417   { "field", field_attributes, NULL, GDB_XML_EF_REPEATABLE,
 418     tdesc_start_field, NULL },
 419   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
 420 };
 421
 422 static const struct gdb_xml_attribute reg_attributes[] = {
 423   { "name", GDB_XML_AF_NONE, NULL, NULL },
 424   { "bitsize", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
 425   { "regnum", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
 426   { "type", GDB_XML_AF_OPTIONAL, NULL, NULL },
 427   { "group", GDB_XML_AF_OPTIONAL, NULL, NULL },
 428   { "save-restore", GDB_XML_AF_OPTIONAL,
 429     gdb_xml_parse_attr_enum, gdb_xml_enums_boolean },
 430   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 431 };
 432
 433 static const struct gdb_xml_attribute struct_union_attributes[] = {
 434   { "id", GDB_XML_AF_NONE, NULL, NULL },
 435   { "size", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL},
 436   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 437 };
 438
 439 static const struct gdb_xml_attribute flags_attributes[] = {
 440   { "id", GDB_XML_AF_NONE, NULL, NULL },
 441   { "size", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL},
 442   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 443 };
 444
 445 static const struct gdb_xml_attribute vector_attributes[] = {
 446   { "id", GDB_XML_AF_NONE, NULL, NULL },
 447   { "type", GDB_XML_AF_NONE, NULL, NULL },
 448   { "count", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
 449   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 450 };
 451
 452 static const struct gdb_xml_attribute feature_attributes[] = {
 453   { "name", GDB_XML_AF_NONE, NULL, NULL },
 454   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 455 };
 456
 457 static const struct gdb_xml_element feature_children[] = {
 458   { "reg", reg_attributes, NULL,
 459     GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
 460     tdesc_start_reg, NULL },
 461   { "struct", struct_union_attributes, struct_union_children,
 462     GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
 463     tdesc_start_struct, NULL },
 464   { "union", struct_union_attributes, struct_union_children,
 465     GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
 466     tdesc_start_union, NULL },
 467   { "flags", flags_attributes, struct_union_children,
 468     GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
 469     tdesc_start_flags, NULL },
 470   { "vector", vector_attributes, NULL,
 471     GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
 472     tdesc_start_vector, NULL },
 473   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
 474 };
 475
 476 static const struct gdb_xml_attribute target_attributes[] = {
 477   { "version", GDB_XML_AF_NONE, NULL, NULL },
 478   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 479 };
 480
 481 static const struct gdb_xml_element target_children[] = {
 482   { "architecture", NULL, NULL, GDB_XML_EF_OPTIONAL,
 483     NULL, tdesc_end_arch },
 484   { "osabi", NULL, NULL, GDB_XML_EF_OPTIONAL,
 485     NULL, tdesc_end_osabi },
 486   { "compatible", NULL, NULL, GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
 487     NULL, tdesc_end_compatible },
 488   { "feature", feature_attributes, feature_children,
 489     GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
 490     tdesc_start_feature, NULL },
 491   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
 492 };
 493
 494 static const struct gdb_xml_element tdesc_elements[] = {
 495   { "target", target_attributes, target_children, GDB_XML_EF_NONE,
 496     tdesc_start_target, NULL },
 497   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
 498 };
 499
 500 /* Parse DOCUMENT into a target description and return it.  */
 501
 502 static struct target_desc *
 503 tdesc_parse_xml (const char *document, xml_fetch_another fetcher,
 504                  void *fetcher_baton)
 505 {
 506   struct cleanup *back_to, *result_cleanup;
 507   struct tdesc_parsing_data data;
 508   struct tdesc_xml_cache *cache;
 509   char *expanded_text;
 510   int ix;
 511
 512   /* Expand all XInclude directives.  */
 513   expanded_text = xml_process_xincludes (_("target description"),
 514                                          document, fetcher, fetcher_baton, 0);
 515   if (expanded_text == NULL)
 516     {
 517       warning (_("Could not load XML target description; ignoring"));
 518       return NULL;
 519     }
 520
 521   /* Check for an exact match in the list of descriptions we have
 522      previously parsed.  strcmp is a slightly inefficient way to
 523      do this; an SHA-1 checksum would work as well.  */
 524   for (ix = 0; VEC_iterate (tdesc_xml_cache_s, xml_cache, ix, cache); ix++)
 525     if (strcmp (cache->xml_document, expanded_text) == 0)
 526       {
 527        xfree (expanded_text);
 528        return cache->tdesc;
 529       }
 530
 531   back_to = make_cleanup (null_cleanup, NULL);
 532
 533   memset (&data, 0, sizeof (struct tdesc_parsing_data));
 534   data.tdesc = allocate_target_description ();
 535   result_cleanup = make_cleanup_free_target_description (data.tdesc);
 536   make_cleanup (xfree, expanded_text);
 537
 538   if (gdb_xml_parse_quick (_("target description"), "gdb-target.dtd",
 539                            tdesc_elements, expanded_text, &data) == 0)
 540     {
 541       /* Parsed successfully.  */
 542       struct tdesc_xml_cache new_cache;
 543
 544       new_cache.xml_document = expanded_text;
 545       new_cache.tdesc = data.tdesc;
 546       VEC_safe_push (tdesc_xml_cache_s, xml_cache, &new_cache);
 547       discard_cleanups (result_cleanup);
 548       do_cleanups (back_to);
 549       return data.tdesc;
 550     }
 551   else
 552     {
 553       warning (_("Could not load XML target description; ignoring"));
 554       do_cleanups (back_to);
 555       return NULL;
 556     }
 557 }
 558 #endif /* HAVE_LIBEXPAT */
 559 \f
 560
 561 /* Read an XML target description from FILENAME.  Parse it, and return
 562    the parsed description.  */
 563
 564 const struct target_desc *
 565 file_read_description_xml (const char *filename)
 566 {
 567   struct target_desc *tdesc;
 568   char *tdesc_str;
 569   struct cleanup *back_to;
 570   char *dirname;
 571
 572   tdesc_str = xml_fetch_content_from_file (filename, NULL);
 573   if (tdesc_str == NULL)
 574     {
 575       warning (_("Could not open \"%s\""), filename);
 576       return NULL;
 577     }
 578
 579   back_to = make_cleanup (xfree, tdesc_str);
 580
 581   dirname = ldirname (filename);
 582   if (dirname != NULL)
 583     make_cleanup (xfree, dirname);
 584
 585   tdesc = tdesc_parse_xml (tdesc_str, xml_fetch_content_from_file, dirname);
 586   do_cleanups (back_to);
 587
 588   return tdesc;
 589 }
 590
 591 /* Read a string representation of available features from the target,
 592    using TARGET_OBJECT_AVAILABLE_FEATURES.  The returned string is
 593    malloc allocated and NUL-terminated.  NAME should be a non-NULL
 594    string identifying the XML document we want; the top level document
 595    is "target.xml".  Other calls may be performed for the DTD or
 596    for <xi:include>.  */
 597
 598 static char *
 599 fetch_available_features_from_target (const char *name, void *baton_)
 600 {
 601   struct target_ops *ops = baton_;
 602
 603   /* Read this object as a string.  This ensures that a NUL
 604      terminator is added.  */
 605   return target_read_stralloc (ops,
 606                                TARGET_OBJECT_AVAILABLE_FEATURES,
 607                                name);
 608 }
 609 \f
 610
 611 /* Read an XML target description using OPS.  Parse it, and return the
 612    parsed description.  */
 613
 614 const struct target_desc *
 615 target_read_description_xml (struct target_ops *ops)
 616 {
 617   struct target_desc *tdesc;
 618   char *tdesc_str;
 619   struct cleanup *back_to;
 620
 621   tdesc_str = fetch_available_features_from_target ("target.xml", ops);
 622   if (tdesc_str == NULL)
 623     return NULL;
 624
 625   back_to = make_cleanup (xfree, tdesc_str);
 626   tdesc = tdesc_parse_xml (tdesc_str,
 627                            fetch_available_features_from_target,
 628                            ops);
 629   do_cleanups (back_to);
 630
 631   return tdesc;
 632 }