gdb/python/lib/gdb/types.py

   1 # Type utilities.
   2 # Copyright (C) 2010-2021 Free Software Foundation, Inc.
   3
   4 # This program is free software; you can redistribute it and/or modify
   5 # it under the terms of the GNU General Public License as published by
   6 # the Free Software Foundation; either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 """Utilities for working with gdb.Types."""
  18
  19 import gdb
  20
  21
  22 def get_basic_type(type_):
  23     """Return the "basic" type of a type.
  24
  25     Arguments:
  26         type_: The type to reduce to its basic type.
  27
  28     Returns:
  29         type_ with const/volatile is stripped away,
  30         and typedefs/references converted to the underlying type.
  31     """
  32
  33     while (type_.code == gdb.TYPE_CODE_REF or
  34            type_.code == gdb.TYPE_CODE_RVALUE_REF or
  35            type_.code == gdb.TYPE_CODE_TYPEDEF):
  36         if (type_.code == gdb.TYPE_CODE_REF or
  37             type_.code == gdb.TYPE_CODE_RVALUE_REF):
  38             type_ = type_.target()
  39         else:
  40             type_ = type_.strip_typedefs()
  41     return type_.unqualified()
  42
  43
  44 def has_field(type_, field):
  45     """Return True if a type has the specified field.
  46
  47     Arguments:
  48         type_: The type to examine.
  49             It must be one of gdb.TYPE_CODE_STRUCT, gdb.TYPE_CODE_UNION.
  50         field: The name of the field to look up.
  51
  52     Returns:
  53         True if the field is present either in type_ or any baseclass.
  54
  55     Raises:
  56         TypeError: The type is not a struct or union.
  57     """
  58
  59     type_ = get_basic_type(type_)
  60     if (type_.code != gdb.TYPE_CODE_STRUCT and
  61         type_.code != gdb.TYPE_CODE_UNION):
  62         raise TypeError("not a struct or union")
  63     for f in type_.fields():
  64         if f.is_base_class:
  65             if has_field(f.type, field):
  66                 return True
  67         else:
  68             # NOTE: f.name could be None
  69             if f.name == field:
  70                 return True
  71     return False
  72
  73
  74 def make_enum_dict(enum_type):
  75     """Return a dictionary from a program's enum type.
  76
  77     Arguments:
  78         enum_type: The enum to compute the dictionary for.
  79
  80     Returns:
  81         The dictionary of the enum.
  82
  83     Raises:
  84         TypeError: The type is not an enum.
  85     """
  86
  87     if enum_type.code != gdb.TYPE_CODE_ENUM:
  88         raise TypeError("not an enum type")
  89     enum_dict = {}
  90     for field in enum_type.fields():
  91         # The enum's value is stored in "enumval".
  92         enum_dict[field.name] = field.enumval
  93     return enum_dict
  94
  95
  96 def deep_items (type_):
  97     """Return an iterator that recursively traverses anonymous fields.
  98
  99     Arguments:
 100         type_: The type to traverse.  It should be one of
 101         gdb.TYPE_CODE_STRUCT or gdb.TYPE_CODE_UNION.
 102
 103     Returns:
 104         an iterator similar to gdb.Type.iteritems(), i.e., it returns
 105         pairs of key, value, but for any anonymous struct or union
 106         field that field is traversed recursively, depth-first.
 107     """
 108     for k, v in type_.iteritems ():
 109         if k:
 110             yield k, v
 111         else:
 112             for i in deep_items (v.type):
 113                 yield i
 114
 115 class TypePrinter(object):
 116     """The base class for type printers.
 117
 118     Instances of this type can be used to substitute type names during
 119     'ptype'.
 120
 121     A type printer must have at least 'name' and 'enabled' attributes,
 122     and supply an 'instantiate' method.
 123
 124     The 'instantiate' method must either return None, or return an
 125     object which has a 'recognize' method.  This method must accept a
 126     gdb.Type argument and either return None, meaning that the type
 127     was not recognized, or a string naming the type.
 128     """
 129
 130     def __init__(self, name):
 131         self.name = name
 132         self.enabled = True
 133
 134     def instantiate(self):
 135         return None
 136
 137 # Helper function for computing the list of type recognizers.
 138 def _get_some_type_recognizers(result, plist):
 139     for printer in plist:
 140         if printer.enabled:
 141             inst = printer.instantiate()
 142             if inst is not None:
 143                 result.append(inst)
 144     return None
 145
 146 def get_type_recognizers():
 147     "Return a list of the enabled type recognizers for the current context."
 148     result = []
 149
 150     # First try the objfiles.
 151     for objfile in gdb.objfiles():
 152         _get_some_type_recognizers(result, objfile.type_printers)
 153     # Now try the program space.
 154     _get_some_type_recognizers(result, gdb.current_progspace().type_printers)
 155     # Finally, globals.
 156     _get_some_type_recognizers(result, gdb.type_printers)
 157
 158     return result
 159
 160 def apply_type_recognizers(recognizers, type_obj):
 161     """Apply the given list of type recognizers to the type TYPE_OBJ.
 162     If any recognizer in the list recognizes TYPE_OBJ, returns the name
 163     given by the recognizer.  Otherwise, this returns None."""
 164     for r in recognizers:
 165         result = r.recognize(type_obj)
 166         if result is not None:
 167             return result
 168     return None
 169
 170 def register_type_printer(locus, printer):
 171     """Register a type printer.
 172     PRINTER is the type printer instance.
 173     LOCUS is either an objfile, a program space, or None, indicating
 174     global registration."""
 175
 176     if locus is None:
 177         locus = gdb
 178     locus.type_printers.insert(0, printer)