gdb/xml-support.h

   1 /* Helper routines for parsing XML using Expat.
   2
   3    Copyright (C) 2006-2019 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20
  21 #ifndef XML_SUPPORT_H
  22 #define XML_SUPPORT_H
  23
  24 #include "gdb_obstack.h"
  25 #include "gdbsupport/vec.h"
  26 #include "gdbsupport/xml-utils.h"
  27 #include "gdbsupport/byte-vector.h"
  28
  29 struct gdb_xml_parser;
  30 struct gdb_xml_element;
  31 struct gdb_xml_attribute;
  32
  33 /* Return an XML document which was compiled into GDB, from
  34    the given FILENAME, or NULL if the file was not compiled in.  */
  35
  36 const char *fetch_xml_builtin (const char *filename);
  37
  38 /* A to_xfer_partial helper function which reads XML files which were
  39    compiled into GDB.  The target may call this function from its own
  40    to_xfer_partial handler, after converting object and annex to the
  41    appropriate filename.  */
  42
  43 LONGEST xml_builtin_xfer_partial (const char *filename,
  44                                   gdb_byte *readbuf, const gdb_byte *writebuf,
  45                                   ULONGEST offset, LONGEST len);
  46
  47 /* The text of compiled-in XML documents, from xml-builtin.c
  48    (generated).  */
  49
  50 extern const char *xml_builtin[][2];
  51
  52 /* Support for XInclude.  */
  53
  54 /* Callback to fetch a new XML file, based on the provided HREF.  */
  55
  56 typedef gdb::optional<gdb::char_vector> (*xml_fetch_another) (const char *href,
  57                                                               void *baton);
  58
  59 /* Append the expansion of TEXT after processing <xi:include> tags in
  60    RESULT.  FETCHER will be called (with FETCHER_BATON) to retrieve
  61    any new files.  DEPTH should be zero on the initial call.
  62
  63    On failure, this function uses NAME in a warning and returns false.
  64    It may throw an exception, but does not for XML parsing
  65    problems.  */
  66
  67 bool xml_process_xincludes (std::string &result,
  68                             const char *name, const char *text,
  69                             xml_fetch_another fetcher, void *fetcher_baton,
  70                             int depth);
  71
  72 /* Simplified XML parser infrastructure.  */
  73
  74 /* A name and value pair, used to record parsed attributes.  */
  75
  76 struct gdb_xml_value
  77 {
  78   gdb_xml_value (const char *name_, void *value_)
  79   : name (name_), value (value_)
  80   {}
  81
  82   const char *name;
  83   gdb::unique_xmalloc_ptr<void> value;
  84 };
  85
  86 /* The type of an attribute handler.
  87
  88    PARSER is the current XML parser, which should be used to issue any
  89    debugging or error messages.  The second argument is the
  90    corresponding attribute description, so that a single handler can
  91    be used for multiple attributes; the attribute name is available
  92    for error messages and the handler data is available for additional
  93    customization (see gdb_xml_parse_attr_enum).  VALUE is the string
  94    value of the attribute.
  95
  96    The returned value should be freeable with xfree, and will be freed
  97    after the start handler is called.  Errors should be reported by
  98    calling gdb_xml_error.  */
  99
 100 typedef void *(gdb_xml_attribute_handler) (struct gdb_xml_parser *parser,
 101                                            const struct gdb_xml_attribute *,
 102                                            const char *value);
 103
 104 /* Flags for attributes.  If no flags are specified, the attribute is
 105    required.  */
 106
 107 enum gdb_xml_attribute_flag
 108 {
 109   GDB_XML_AF_NONE,
 110   GDB_XML_AF_OPTIONAL = 1 << 0,  /* The attribute is optional.  */
 111 };
 112
 113 /* An expected attribute and the handler to call when it is
 114    encountered.  Arrays of struct gdb_xml_attribute are terminated
 115    by an entry with NAME == NULL.  */
 116
 117 struct gdb_xml_attribute
 118 {
 119   const char *name;
 120   int flags;
 121   gdb_xml_attribute_handler *handler;
 122   const void *handler_data;
 123 };
 124
 125 /* Flags for elements.  If no flags are specified, the element is
 126    required exactly once.  */
 127
 128 enum gdb_xml_element_flag
 129 {
 130   GDB_XML_EF_NONE,
 131   GDB_XML_EF_OPTIONAL = 1 << 0,  /* The element is optional.  */
 132   GDB_XML_EF_REPEATABLE = 1 << 1,  /* The element is repeatable.  */
 133 };
 134
 135 /* A handler called at the beginning of an element.
 136
 137    PARSER is the current XML parser, which should be used to issue any
 138    debugging or error messages.  ELEMENT is the current element.
 139    USER_DATA is the opaque pointer supplied when the parser was
 140    created.  ATTRIBUTES is a vector of the values of any attributes
 141    attached to this element.
 142
 143    The start handler will only be called if all the required
 144    attributes were present and parsed successfully, and elements of
 145    ATTRIBUTES are guaranteed to be in the same order used in
 146    ELEMENT->ATTRIBUTES (not the order from the XML file).  Accordingly
 147    fixed offsets can be used to find any non-optional attributes as
 148    long as no optional attributes precede them.  */
 149
 150 typedef void (gdb_xml_element_start_handler)
 151      (struct gdb_xml_parser *parser, const struct gdb_xml_element *element,
 152       void *user_data, std::vector<gdb_xml_value> &attributes);
 153
 154 /* A handler called at the end of an element.
 155
 156    PARSER, ELEMENT, and USER_DATA are as for the start handler.  BODY
 157    is any accumulated body text inside the element, with leading and
 158    trailing whitespace removed.  It will never be NULL.  */
 159
 160 typedef void (gdb_xml_element_end_handler)
 161      (struct gdb_xml_parser *, const struct gdb_xml_element *,
 162       void *user_data, const char *body_text);
 163
 164 /* An expected element and the handlers to call when it is
 165    encountered.  Arrays of struct gdb_xml_element are terminated
 166    by an entry with NAME == NULL.  */
 167
 168 struct gdb_xml_element
 169 {
 170   const char *name;
 171   const struct gdb_xml_attribute *attributes;
 172   const struct gdb_xml_element *children;
 173   int flags;
 174
 175   gdb_xml_element_start_handler *start_handler;
 176   gdb_xml_element_end_handler *end_handler;
 177 };
 178
 179 /* Parse a XML document.  DOCUMENT is the data to parse, which should
 180    be NUL-terminated. If non-NULL, use the compiled-in DTD named
 181    DTD_NAME to drive the parsing.
 182
 183    The return value is 0 for success or -1 for error.  It may throw,
 184    but only if something unexpected goes wrong during parsing; parse
 185    errors will be caught, warned about, and reported as failure.  */
 186
 187 int gdb_xml_parse_quick (const char *name, const char *dtd_name,
 188                          const struct gdb_xml_element *elements,
 189                          const char *document, void *user_data);
 190
 191 /* Issue a debugging message from one of PARSER's handlers.  */
 192
 193 void gdb_xml_debug (struct gdb_xml_parser *parser, const char *format, ...)
 194   ATTRIBUTE_PRINTF (2, 3);
 195
 196 /* Issue an error message from one of PARSER's handlers, and stop
 197    parsing.  */
 198
 199 void gdb_xml_error (struct gdb_xml_parser *parser, const char *format, ...)
 200   ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 201
 202 /* Find the attribute named NAME in the set of parsed attributes
 203    ATTRIBUTES.  Returns NULL if not found.  */
 204
 205 struct gdb_xml_value *xml_find_attribute
 206   (std::vector<gdb_xml_value> &attributes, const char *name);
 207
 208 /* Parse an integer attribute into a ULONGEST.  */
 209
 210 extern gdb_xml_attribute_handler gdb_xml_parse_attr_ulongest;
 211
 212 /* Map NAME to VALUE.  A struct gdb_xml_enum * should be saved as the
 213    value of handler_data when using gdb_xml_parse_attr_enum to parse a
 214    fixed list of possible strings.  The list is terminated by an entry
 215    with NAME == NULL.  */
 216
 217 struct gdb_xml_enum
 218 {
 219   const char *name;
 220   ULONGEST value;
 221 };
 222
 223 /* A handler_data for yes/no boolean values.  */
 224 extern const struct gdb_xml_enum gdb_xml_enums_boolean[];
 225
 226 extern gdb_xml_attribute_handler gdb_xml_parse_attr_enum;
 227
 228 /* Parse an integer string into a ULONGEST and return it, or call
 229    gdb_xml_error if it could not be parsed.  */
 230
 231 ULONGEST gdb_xml_parse_ulongest (struct gdb_xml_parser *parser,
 232                                  const char *value);
 233
 234 /* Open FILENAME, read all its text into memory, close it, and return
 235    the text.  If something goes wrong, return an uninstantiated optional
 236    and warn.  */
 237
 238 extern gdb::optional<gdb::char_vector> xml_fetch_content_from_file
 239     (const char *filename, void *baton);
 240
 241 #endif