/* XML target description support for GDB.

   Copyright (C) 2006, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.

   Contributed by CodeSourcery.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "target.h"
#include "target-descriptions.h"
#include "xml-support.h"
#include "xml-tdesc.h"
#include "osabi.h"

#include "filenames.h"

#include "gdb_assert.h"

#if !defined(HAVE_LIBEXPAT)

/* Parse DOCUMENT into a target description.  Or don't, since we don't have
   an XML parser.  */

static struct target_desc *
tdesc_parse_xml (const char *document, xml_fetch_another fetcher,
		 void *fetcher_baton)
{
  static int have_warned;

  if (!have_warned)
    {
      have_warned = 1;
      warning (_("Can not parse XML target description; XML support was "
		 "disabled at compile time"));
    }

  return NULL;
}

#else /* HAVE_LIBEXPAT */

/* A record of every XML description we have parsed.  We never discard
   old descriptions, because we never discard gdbarches.  As long as we
   have a gdbarch referencing this description, we want to have a copy
   of it here, so that if we parse the same XML document again we can
   return the same "struct target_desc *"; if they are not singletons,
   then we will create unnecessary duplicate gdbarches.  See
   gdbarch_list_lookup_by_info.  */

struct tdesc_xml_cache
{
  const char *xml_document;
  struct target_desc *tdesc;
};
typedef struct tdesc_xml_cache tdesc_xml_cache_s;
DEF_VEC_O(tdesc_xml_cache_s);

static VEC(tdesc_xml_cache_s) *xml_cache;

/* Callback data for target description parsing.  */

struct tdesc_parsing_data
{
  /* The target description we are building.  */
  struct target_desc *tdesc;

  /* The target feature we are currently parsing, or last parsed.  */
  struct tdesc_feature *current_feature;

  /* The register number to use for the next register we see, if
     it does not have its own.  This starts at zero.  */
  int next_regnum;

  /* The struct or union we are currently parsing, or last parsed.  */
  struct tdesc_type *current_type;

  /* The byte size of the current struct type, if specified.  Zero
     if not specified.  */
  int current_type_size;

  /* Whether the current type is a flags type.  */
  int current_type_is_flags;
};

/* Handle the end of an <architecture> element and its value.  */

static void
tdesc_end_arch (struct gdb_xml_parser *parser,
		const struct gdb_xml_element *element,
		void *user_data, const char *body_text)
{
  struct tdesc_parsing_data *data = user_data;
  const struct bfd_arch_info *arch;

  arch = bfd_scan_arch (body_text);
  if (arch == NULL)
    gdb_xml_error (parser, _("Target description specified unknown "
			     "architecture \"%s\""), body_text);
  set_tdesc_architecture (data->tdesc, arch);
}

/* Handle the end of an <osabi> element and its value.  */

static void
tdesc_end_osabi (struct gdb_xml_parser *parser,
		 const struct gdb_xml_element *element,
		 void *user_data, const char *body_text)
{
  struct tdesc_parsing_data *data = user_data;
  enum gdb_osabi osabi;

  osabi = osabi_from_tdesc_string (body_text);
  if (osabi == GDB_OSABI_UNKNOWN)
    warning (_("Target description specified unknown osabi \"%s\""),
	     body_text);
  else
    set_tdesc_osabi (data->tdesc, osabi);
}

/* Handle the end of a <compatible> element and its value.  */

static void
tdesc_end_compatible (struct gdb_xml_parser *parser,
		      const struct gdb_xml_element *element,
		      void *user_data, const char *body_text)
{
  struct tdesc_parsing_data *data = user_data;
  const struct bfd_arch_info *arch;

  arch = bfd_scan_arch (body_text);
  tdesc_add_compatible (data->tdesc, arch);
}

/* Handle the start of a <target> element.  */

static void
tdesc_start_target (struct gdb_xml_parser *parser,
		    const struct gdb_xml_element *element,
		    void *user_data, VEC(gdb_xml_value_s) *attributes)
{
  char *version = xml_find_attribute (attributes, "version")->value;

  if (strcmp (version, "1.0") != 0)
    gdb_xml_error (parser,
		   _("Target description has unsupported version \"%s\""),
		   version);
}

/* Handle the start of a <feature> element.  */

static void
tdesc_start_feature (struct gdb_xml_parser *parser,
		     const struct gdb_xml_element *element,
		     void *user_data, VEC(gdb_xml_value_s) *attributes)
{
  struct tdesc_parsing_data *data = user_data;
  char *name = xml_find_attribute (attributes, "name")->value;

  data->current_feature = tdesc_create_feature (data->tdesc, name);
}

/* Handle the start of a <reg> element.  Fill in the optional
   attributes and attach it to the containing feature.  */

static void
tdesc_start_reg (struct gdb_xml_parser *parser,
		 const struct gdb_xml_element *element,
		 void *user_data, VEC(gdb_xml_value_s) *attributes)
{
  struct tdesc_parsing_data *data = user_data;
  struct gdb_xml_value *attrs = VEC_address (gdb_xml_value_s, attributes);
  int ix = 0, length;
  char *name, *group, *type;
  int bitsize, regnum, save_restore;

  length = VEC_length (gdb_xml_value_s, attributes);

  name = attrs[ix++].value;
  bitsize = * (ULONGEST *) attrs[ix++].value;

  if (ix < length && strcmp (attrs[ix].name, "regnum") == 0)
    regnum = * (ULONGEST *) attrs[ix++].value;
  else
    regnum = data->next_regnum;

  if (ix < length && strcmp (attrs[ix].name, "type") == 0)
    type = attrs[ix++].value;
  else
    type = "int";

  if (ix < length && strcmp (attrs[ix].name, "group") == 0)
    group = attrs[ix++].value;
  else
    group = NULL;

  if (ix < length && strcmp (attrs[ix].name, "save-restore") == 0)
    save_restore = * (ULONGEST *) attrs[ix++].value;
  else
    save_restore = 1;

  if (strcmp (type, "int") != 0
      && strcmp (type, "float") != 0
      && tdesc_named_type (data->current_feature, type) == NULL)
    gdb_xml_error (parser, _("Register \"%s\" has unknown type \"%s\""),
		   name, type);

  tdesc_create_reg (data->current_feature, name, regnum, save_restore, group,
		    bitsize, type);

  data->next_regnum = regnum + 1;
}

/* Handle the start of a <union> element.  Initialize the type and
   record it with the current feature.  */

static void
tdesc_start_union (struct gdb_xml_parser *parser,
		   const struct gdb_xml_element *element,
		   void *user_data, VEC(gdb_xml_value_s) *attributes)
{
  struct tdesc_parsing_data *data = user_data;
  char *id = xml_find_attribute (attributes, "id")->value;

  data->current_type = tdesc_create_union (data->current_feature, id);
  data->current_type_size = 0;
  data->current_type_is_flags = 0;
}

/* Handle the start of a <struct> element.  Initialize the type and
   record it with the current feature.  */

static void
tdesc_start_struct (struct gdb_xml_parser *parser,
		   const struct gdb_xml_element *element,
		   void *user_data, VEC(gdb_xml_value_s) *attributes)
{
  struct tdesc_parsing_data *data = user_data;
  char *id = xml_find_attribute (attributes, "id")->value;
  struct tdesc_type *type;
  struct gdb_xml_value *attr;

  type = tdesc_create_struct (data->current_feature, id);
  data->current_type = type;
  data->current_type_size = 0;
  data->current_type_is_flags = 0;

  attr = xml_find_attribute (attributes, "size");
  if (attr != NULL)
    {
      int size = (int) * (ULONGEST *) attr->value;

      tdesc_set_struct_size (type, size);
      data->current_type_size = size;
    }
}

static void
tdesc_start_flags (struct gdb_xml_parser *parser,
		   const struct gdb_xml_element *element,
		   void *user_data, VEC(gdb_xml_value_s) *attributes)
{
  struct tdesc_parsing_data *data = user_data;
  char *id = xml_find_attribute (attributes, "id")->value;
  int length = (int) * (ULONGEST *)
    xml_find_attribute (attributes, "size")->value;
  struct tdesc_type *type;

  type = tdesc_create_flags (data->current_feature, id, length);

  data->current_type = type;
  data->current_type_size = 0;
  data->current_type_is_flags = 1;
}

/* Handle the start of a <field> element.  Attach the field to the
   current struct or union.  */

static void
tdesc_start_field (struct gdb_xml_parser *parser,
		   const struct gdb_xml_element *element,
		   void *user_data, VEC(gdb_xml_value_s) *attributes)
{
  struct tdesc_parsing_data *data = user_data;
  struct gdb_xml_value *attr;
  struct tdesc_type *field_type;
  char *field_name, *field_type_id;
  int start, end;

  field_name = xml_find_attribute (attributes, "name")->value;

  attr = xml_find_attribute (attributes, "type");
  if (attr != NULL)
    field_type_id = attr->value;
  else
    field_type_id = NULL;

  attr = xml_find_attribute (attributes, "start");
  if (attr != NULL)
    start = * (ULONGEST *) attr->value;
  else
    start = -1;

  attr = xml_find_attribute (attributes, "end");
  if (attr != NULL)
    end = * (ULONGEST *) attr->value;
  else
    end = -1;

  if (field_type_id != NULL)
    {
      if (data->current_type_is_flags)
	gdb_xml_error (parser, _("Cannot add typed field \"%s\" to flags"), 
		       field_name);
      if (data->current_type_size != 0)
	gdb_xml_error (parser,
		       _("Explicitly sized type can not "
			 "contain non-bitfield \"%s\""), 
		       field_name);

      field_type = tdesc_named_type (data->current_feature, field_type_id);
      if (field_type == NULL)
	gdb_xml_error (parser, _("Field \"%s\" references undefined "
				 "type \"%s\""),
		       field_name, field_type_id);

      tdesc_add_field (data->current_type, field_name, field_type);
    }
  else if (start != -1 && end != -1)
    {
      struct tdesc_type *t = data->current_type;

      if (data->current_type_is_flags)
	tdesc_add_flag (t, start, field_name);
      else
	{
	  if (data->current_type_size == 0)
	    gdb_xml_error (parser,
			   _("Implicitly sized type can "
			     "not contain bitfield \"%s\""), 
			   field_name);

	  if (end >= 64)
	    gdb_xml_error (parser,
			   _("Bitfield \"%s\" goes past "
			     "64 bits (unsupported)"),
			   field_name);

	  /* Assume that the bit numbering in XML is "lsb-zero".  Most
	     architectures other than PowerPC use this ordering.  In
	     the future, we can add an XML tag to indicate "msb-zero"
	     numbering.  */
	  if (start > end)
	    gdb_xml_error (parser, _("Bitfield \"%s\" has start after end"),
			   field_name);

	  if (end >= data->current_type_size * TARGET_CHAR_BIT)
	    gdb_xml_error (parser,
			   _("Bitfield \"%s\" does not fit in struct"));

	  tdesc_add_bitfield (t, field_name, start, end);
	}
    }
  else
    gdb_xml_error (parser, _("Field \"%s\" has neither type nor bit position"),
		   field_name);
}

/* Handle the start of a <vector> element.  Initialize the type and
   record it with the current feature.  */

static void
tdesc_start_vector (struct gdb_xml_parser *parser,
		    const struct gdb_xml_element *element,
		    void *user_data, VEC(gdb_xml_value_s) *attributes)
{
  struct tdesc_parsing_data *data = user_data;
  struct gdb_xml_value *attrs = VEC_address (gdb_xml_value_s, attributes);
  struct tdesc_type *field_type;
  char *id, *field_type_id;
  int count;

  id = attrs[0].value;
  field_type_id = attrs[1].value;
  count = * (ULONGEST *) attrs[2].value;

  field_type = tdesc_named_type (data->current_feature, field_type_id);
  if (field_type == NULL)
    gdb_xml_error (parser, _("Vector \"%s\" references undefined type \"%s\""),
		   id, field_type_id);

  tdesc_create_vector (data->current_feature, id, field_type, count);
}

/* The elements and attributes of an XML target description.  */

static const struct gdb_xml_attribute field_attributes[] = {
  { "name", GDB_XML_AF_NONE, NULL, NULL },
  { "type", GDB_XML_AF_OPTIONAL, NULL, NULL },
  { "start", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
  { "end", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
  { NULL, GDB_XML_AF_NONE, NULL, NULL }
};

static const struct gdb_xml_element struct_union_children[] = {
  { "field", field_attributes, NULL, GDB_XML_EF_REPEATABLE,
    tdesc_start_field, NULL },
  { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
};

static const struct gdb_xml_attribute reg_attributes[] = {
  { "name", GDB_XML_AF_NONE, NULL, NULL },
  { "bitsize", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
  { "regnum", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
  { "type", GDB_XML_AF_OPTIONAL, NULL, NULL },
  { "group", GDB_XML_AF_OPTIONAL, NULL, NULL },
  { "save-restore", GDB_XML_AF_OPTIONAL,
    gdb_xml_parse_attr_enum, gdb_xml_enums_boolean },
  { NULL, GDB_XML_AF_NONE, NULL, NULL }
};

static const struct gdb_xml_attribute struct_union_attributes[] = {
  { "id", GDB_XML_AF_NONE, NULL, NULL },
  { "size", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL},
  { NULL, GDB_XML_AF_NONE, NULL, NULL }
};

static const struct gdb_xml_attribute flags_attributes[] = {
  { "id", GDB_XML_AF_NONE, NULL, NULL },
  { "size", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL},
  { NULL, GDB_XML_AF_NONE, NULL, NULL }
};

static const struct gdb_xml_attribute vector_attributes[] = {
  { "id", GDB_XML_AF_NONE, NULL, NULL },
  { "type", GDB_XML_AF_NONE, NULL, NULL },
  { "count", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
  { NULL, GDB_XML_AF_NONE, NULL, NULL }
};

static const struct gdb_xml_attribute feature_attributes[] = {
  { "name", GDB_XML_AF_NONE, NULL, NULL },
  { NULL, GDB_XML_AF_NONE, NULL, NULL }
};

static const struct gdb_xml_element feature_children[] = {
  { "reg", reg_attributes, NULL,
    GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
    tdesc_start_reg, NULL },
  { "struct", struct_union_attributes, struct_union_children,
    GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
    tdesc_start_struct, NULL },
  { "union", struct_union_attributes, struct_union_children,
    GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
    tdesc_start_union, NULL },
  { "flags", flags_attributes, struct_union_children,
    GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
    tdesc_start_flags, NULL },    
  { "vector", vector_attributes, NULL,
    GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
    tdesc_start_vector, NULL },
  { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
};

static const struct gdb_xml_attribute target_attributes[] = {
  { "version", GDB_XML_AF_NONE, NULL, NULL },
  { NULL, GDB_XML_AF_NONE, NULL, NULL }
};

static const struct gdb_xml_element target_children[] = {
  { "architecture", NULL, NULL, GDB_XML_EF_OPTIONAL,
    NULL, tdesc_end_arch },
  { "osabi", NULL, NULL, GDB_XML_EF_OPTIONAL,
    NULL, tdesc_end_osabi },
  { "compatible", NULL, NULL, GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
    NULL, tdesc_end_compatible },
  { "feature", feature_attributes, feature_children,
    GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
    tdesc_start_feature, NULL },
  { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
};

static const struct gdb_xml_element tdesc_elements[] = {
  { "target", target_attributes, target_children, GDB_XML_EF_NONE,
    tdesc_start_target, NULL },
  { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
};

/* Parse DOCUMENT into a target description and return it.  */

static struct target_desc *
tdesc_parse_xml (const char *document, xml_fetch_another fetcher,
		 void *fetcher_baton)
{
  struct cleanup *back_to, *result_cleanup;
  struct tdesc_parsing_data data;
  struct tdesc_xml_cache *cache;
  char *expanded_text;
  int ix;

  /* Expand all XInclude directives.  */
  expanded_text = xml_process_xincludes (_("target description"),
					 document, fetcher, fetcher_baton, 0);
  if (expanded_text == NULL)
    {
      warning (_("Could not load XML target description; ignoring"));
      return NULL;
    }

  /* Check for an exact match in the list of descriptions we have
     previously parsed.  strcmp is a slightly inefficient way to
     do this; an SHA-1 checksum would work as well.  */
  for (ix = 0; VEC_iterate (tdesc_xml_cache_s, xml_cache, ix, cache); ix++)
    if (strcmp (cache->xml_document, expanded_text) == 0)
      {
       xfree (expanded_text);
       return cache->tdesc;
      }

  back_to = make_cleanup (null_cleanup, NULL);

  memset (&data, 0, sizeof (struct tdesc_parsing_data));
  data.tdesc = allocate_target_description ();
  result_cleanup = make_cleanup_free_target_description (data.tdesc);
  make_cleanup (xfree, expanded_text);

  if (gdb_xml_parse_quick (_("target description"), "gdb-target.dtd",
			   tdesc_elements, expanded_text, &data) == 0)
    {
      /* Parsed successfully.  */
      struct tdesc_xml_cache new_cache;

      new_cache.xml_document = expanded_text;
      new_cache.tdesc = data.tdesc;
      VEC_safe_push (tdesc_xml_cache_s, xml_cache, &new_cache);
      discard_cleanups (result_cleanup);
      do_cleanups (back_to);
      return data.tdesc;
    }
  else
    {
      warning (_("Could not load XML target description; ignoring"));
      do_cleanups (back_to);
      return NULL;
    }
}
#endif /* HAVE_LIBEXPAT */


/* Read an XML target description from FILENAME.  Parse it, and return
   the parsed description.  */

const struct target_desc *
file_read_description_xml (const char *filename)
{
  struct target_desc *tdesc;
  char *tdesc_str;
  struct cleanup *back_to;
  char *dirname;

  tdesc_str = xml_fetch_content_from_file (filename, NULL);
  if (tdesc_str == NULL)
    {
      warning (_("Could not open \"%s\""), filename);
      return NULL;
    }

  back_to = make_cleanup (xfree, tdesc_str);

  dirname = ldirname (filename);
  if (dirname != NULL)
    make_cleanup (xfree, dirname);

  tdesc = tdesc_parse_xml (tdesc_str, xml_fetch_content_from_file, dirname);
  do_cleanups (back_to);

  return tdesc;
}

/* Read a string representation of available features from the target,
   using TARGET_OBJECT_AVAILABLE_FEATURES.  The returned string is
   malloc allocated and NUL-terminated.  NAME should be a non-NULL
   string identifying the XML document we want; the top level document
   is "target.xml".  Other calls may be performed for the DTD or
   for <xi:include>.  */

static char *
fetch_available_features_from_target (const char *name, void *baton_)
{
  struct target_ops *ops = baton_;

  /* Read this object as a string.  This ensures that a NUL
     terminator is added.  */
  return target_read_stralloc (ops,
			       TARGET_OBJECT_AVAILABLE_FEATURES,
			       name);
}


/* Read an XML target description using OPS.  Parse it, and return the
   parsed description.  */

const struct target_desc *
target_read_description_xml (struct target_ops *ops)
{
  struct target_desc *tdesc;
  char *tdesc_str;
  struct cleanup *back_to;

  tdesc_str = fetch_available_features_from_target ("target.xml", ops);
  if (tdesc_str == NULL)
    return NULL;

  back_to = make_cleanup (xfree, tdesc_str);
  tdesc = tdesc_parse_xml (tdesc_str,
			   fetch_available_features_from_target,
			   ops);
  do_cleanups (back_to);

  return tdesc;
}