gdb/xml-support.h

   1 /* Helper routines for parsing XML using Expat.
   2
   3    Copyright (C) 2006-2024 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 "gdbsupport/gdb_obstack.h"
  25 #include "gdbsupport/xml-utils.h"
  26 #include "gdbsupport/byte-vector.h"
  27 #include <optional>
  28 #include "gdbsupport/function-view.h"
  29
  30 struct gdb_xml_parser;
  31 struct gdb_xml_element;
  32 struct gdb_xml_attribute;
  33
  34 /* Return an XML document which was compiled into GDB, from
  35    the given FILENAME, or NULL if the file was not compiled in.  */
  36
  37 const char *fetch_xml_builtin (const char *filename);
  38
  39 /* A to_xfer_partial helper function which reads XML files which were
  40    compiled into GDB.  The target may call this function from its own
  41    to_xfer_partial handler, after converting object and annex to the
  42    appropriate filename.  */
  43
  44 LONGEST xml_builtin_xfer_partial (const char *filename,
  45                                   gdb_byte *readbuf, const gdb_byte *writebuf,
  46                                   ULONGEST offset, LONGEST len);
  47
  48 /* Support for XInclude.  */
  49
  50 /* Callback to fetch a new XML file, based on the provided HREF.  */
  51
  52 using xml_fetch_another = gdb::function_view<std::optional<gdb::char_vector>
  53                                              (const char * /* href */)>;
  54
  55 /* Append the expansion of TEXT after processing <xi:include> tags in
  56    RESULT.  FETCHER will be called to retrieve any new files.  DEPTH
  57    should be zero on the initial call.
  58
  59    On failure, this function uses NAME in a warning and returns false.
  60    It may throw an exception, but does not for XML parsing
  61    problems.  */
  62
  63 bool xml_process_xincludes (std::string &result,
  64                             const char *name, const char *text,
  65                             xml_fetch_another fetcher, int depth);
  66
  67 /* Simplified XML parser infrastructure.  */
  68
  69 /* A name and value pair, used to record parsed attributes.  */
  70
  71 struct gdb_xml_value
  72 {
  73   gdb_xml_value (const char *name_, void *value_)
  74   : name (name_), value (value_)
  75   {}
  76
  77   const char *name;
  78   gdb::unique_xmalloc_ptr<void> value;
  79 };
  80
  81 /* The type of an attribute handler.
  82
  83    PARSER is the current XML parser, which should be used to issue any
  84    debugging or error messages.  The second argument is the
  85    corresponding attribute description, so that a single handler can
  86    be used for multiple attributes; the attribute name is available
  87    for error messages and the handler data is available for additional
  88    customization (see gdb_xml_parse_attr_enum).  VALUE is the string
  89    value of the attribute.
  90
  91    The returned value should be freeable with xfree, and will be freed
  92    after the start handler is called.  Errors should be reported by
  93    calling gdb_xml_error.  */
  94
  95 typedef void *(gdb_xml_attribute_handler) (struct gdb_xml_parser *parser,
  96                                            const struct gdb_xml_attribute *,
  97                                            const char *value);
  98
  99 /* Flags for attributes.  If no flags are specified, the attribute is
 100    required.  */
 101
 102 enum gdb_xml_attribute_flag
 103 {
 104   GDB_XML_AF_NONE,
 105   GDB_XML_AF_OPTIONAL = 1 << 0,  /* The attribute is optional.  */
 106 };
 107
 108 /* An expected attribute and the handler to call when it is
 109    encountered.  Arrays of struct gdb_xml_attribute are terminated
 110    by an entry with NAME == NULL.  */
 111
 112 struct gdb_xml_attribute
 113 {
 114   const char *name;
 115   int flags;
 116   gdb_xml_attribute_handler *handler;
 117   const void *handler_data;
 118 };
 119
 120 /* Flags for elements.  If no flags are specified, the element is
 121    required exactly once.  */
 122
 123 enum gdb_xml_element_flag
 124 {
 125   GDB_XML_EF_NONE,
 126   GDB_XML_EF_OPTIONAL = 1 << 0,  /* The element is optional.  */
 127   GDB_XML_EF_REPEATABLE = 1 << 1,  /* The element is repeatable.  */
 128 };
 129
 130 /* A handler called at the beginning of an element.
 131
 132    PARSER is the current XML parser, which should be used to issue any
 133    debugging or error messages.  ELEMENT is the current element.
 134    USER_DATA is the opaque pointer supplied when the parser was
 135    created.  ATTRIBUTES is a vector of the values of any attributes
 136    attached to this element.
 137
 138    The start handler will only be called if all the required
 139    attributes were present and parsed successfully, and elements of
 140    ATTRIBUTES are guaranteed to be in the same order used in
 141    ELEMENT->ATTRIBUTES (not the order from the XML file).  Accordingly
 142    fixed offsets can be used to find any non-optional attributes as
 143    long as no optional attributes precede them.  */
 144
 145 typedef void (gdb_xml_element_start_handler)
 146      (struct gdb_xml_parser *parser, const struct gdb_xml_element *element,
 147       void *user_data, std::vector<gdb_xml_value> &attributes);
 148
 149 /* A handler called at the end of an element.
 150
 151    PARSER, ELEMENT, and USER_DATA are as for the start handler.  BODY
 152    is any accumulated body text inside the element, with leading and
 153    trailing whitespace removed.  It will never be NULL.  */
 154
 155 typedef void (gdb_xml_element_end_handler)
 156      (struct gdb_xml_parser *, const struct gdb_xml_element *,
 157       void *user_data, const char *body_text);
 158
 159 /* An expected element and the handlers to call when it is
 160    encountered.  Arrays of struct gdb_xml_element are terminated
 161    by an entry with NAME == NULL.  */
 162
 163 struct gdb_xml_element
 164 {
 165   const char *name;
 166   const struct gdb_xml_attribute *attributes;
 167   const struct gdb_xml_element *children;
 168   int flags;
 169
 170   gdb_xml_element_start_handler *start_handler;
 171   gdb_xml_element_end_handler *end_handler;
 172 };
 173
 174 /* Parse a XML document.  DOCUMENT is the data to parse, which should
 175    be NUL-terminated. If non-NULL, use the compiled-in DTD named
 176    DTD_NAME to drive the parsing.
 177
 178    The return value is 0 for success or -1 for error.  It may throw,
 179    but only if something unexpected goes wrong during parsing; parse
 180    errors will be caught, warned about, and reported as failure.  */
 181
 182 int gdb_xml_parse_quick (const char *name, const char *dtd_name,
 183                          const struct gdb_xml_element *elements,
 184                          const char *document, void *user_data);
 185
 186 /* Issue a debugging message from one of PARSER's handlers.  */
 187
 188 void gdb_xml_debug (struct gdb_xml_parser *parser, const char *format, ...)
 189   ATTRIBUTE_PRINTF (2, 3);
 190
 191 /* Issue an error message from one of PARSER's handlers, and stop
 192    parsing.  */
 193
 194 [[noreturn]] void gdb_xml_error (struct gdb_xml_parser *parser,
 195                                  const char *format, ...)
 196   ATTRIBUTE_PRINTF (2, 3);
 197
 198 /* Find the attribute named NAME in the set of parsed attributes
 199    ATTRIBUTES.  Returns NULL if not found.  */
 200
 201 struct gdb_xml_value *xml_find_attribute
 202   (std::vector<gdb_xml_value> &attributes, const char *name);
 203
 204 /* Parse an integer attribute into a ULONGEST.  */
 205
 206 extern gdb_xml_attribute_handler gdb_xml_parse_attr_ulongest;
 207
 208 /* Map NAME to VALUE.  A struct gdb_xml_enum * should be saved as the
 209    value of handler_data when using gdb_xml_parse_attr_enum to parse a
 210    fixed list of possible strings.  The list is terminated by an entry
 211    with NAME == NULL.  */
 212
 213 struct gdb_xml_enum
 214 {
 215   const char *name;
 216   ULONGEST value;
 217 };
 218
 219 /* A handler_data for yes/no boolean values.  */
 220 extern const struct gdb_xml_enum gdb_xml_enums_boolean[];
 221
 222 extern gdb_xml_attribute_handler gdb_xml_parse_attr_enum;
 223
 224 /* Parse an integer string into a ULONGEST and return it, or call
 225    gdb_xml_error if it could not be parsed.  */
 226
 227 ULONGEST gdb_xml_parse_ulongest (struct gdb_xml_parser *parser,
 228                                  const char *value);
 229
 230 /* Open FILENAME, read all its text into memory, close it, and return
 231    the text.  If something goes wrong, return an uninstantiated optional
 232    and warn.  */
 233
 234 extern std::optional<gdb::char_vector> xml_fetch_content_from_file
 235     (const char *filename, const char *dirname);
 236
 237 #endif