1 # Pretty-printer utilities. 2 # Copyright (C) 2010-2016 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 pretty-printers.""" 18 19 import gdb 20 import gdb.types 21 import re 22 import sys 23 24 if sys.version_info[0] > 2: 25 # Python 3 removed basestring and long 26 basestring = str 27 long = int 28 29 class PrettyPrinter(object): 30 """A basic pretty-printer. 31 32 Attributes: 33 name: A unique string among all printers for the context in which 34 it is defined (objfile, progspace, or global(gdb)), and should 35 meaningfully describe what can be pretty-printed. 36 E.g., "StringPiece" or "protobufs". 37 subprinters: An iterable object with each element having a `name' 38 attribute, and, potentially, "enabled" attribute. 39 Or this is None if there are no subprinters. 40 enabled: A boolean indicating if the printer is enabled. 41 42 Subprinters are for situations where "one" pretty-printer is actually a 43 collection of several printers. E.g., The libstdc++ pretty-printer has 44 a pretty-printer for each of several different types, based on regexps. 45 """ 46 47 # While one might want to push subprinters into the subclass, it's 48 # present here to formalize such support to simplify 49 # commands/pretty_printers.py. 50 51 def __init__(self, name, subprinters=None): 52 self.name = name 53 self.subprinters = subprinters 54 self.enabled = True 55 56 def __call__(self, val): 57 # The subclass must define this. 58 raise NotImplementedError("PrettyPrinter __call__") 59 60 61 class SubPrettyPrinter(object): 62 """Baseclass for sub-pretty-printers. 63 64 Sub-pretty-printers needn't use this, but it formalizes what's needed. 65 66 Attributes: 67 name: The name of the subprinter. 68 enabled: A boolean indicating if the subprinter is enabled. 69 """ 70 71 def __init__(self, name): 72 self.name = name 73 self.enabled = True 74 75 76 def register_pretty_printer(obj, printer, replace=False): 77 """Register pretty-printer PRINTER with OBJ. 78 79 The printer is added to the front of the search list, thus one can override 80 an existing printer if one needs to. Use a different name when overriding 81 an existing printer, otherwise an exception will be raised; multiple 82 printers with the same name are disallowed. 83 84 Arguments: 85 obj: Either an objfile, progspace, or None (in which case the printer 86 is registered globally). 87 printer: Either a function of one argument (old way) or any object 88 which has attributes: name, enabled, __call__. 89 replace: If True replace any existing copy of the printer. 90 Otherwise if the printer already exists raise an exception. 91 92 Returns: 93 Nothing. 94 95 Raises: 96 TypeError: A problem with the type of the printer. 97 ValueError: The printer's name contains a semicolon ";". 98 RuntimeError: A printer with the same name is already registered. 99 100 If the caller wants the printer to be listable and disableable, it must 101 follow the PrettyPrinter API. This applies to the old way (functions) too. 102 If printer is an object, __call__ is a method of two arguments: 103 self, and the value to be pretty-printed. See PrettyPrinter. 104 """ 105 106 # Watch for both __name__ and name. 107 # Functions get the former for free, but we don't want to use an 108 # attribute named __foo__ for pretty-printers-as-objects. 109 # If printer has both, we use `name'. 110 if not hasattr(printer, "__name__") and not hasattr(printer, "name"): 111 raise TypeError("printer missing attribute: name") 112 if hasattr(printer, "name") and not hasattr(printer, "enabled"): 113 raise TypeError("printer missing attribute: enabled") 114 if not hasattr(printer, "__call__"): 115 raise TypeError("printer missing attribute: __call__") 116 117 if hasattr(printer, "name"): 118 name = printer.name 119 else: 120 name = printer.__name__ 121 if obj is None or obj is gdb: 122 if gdb.parameter("verbose"): 123 gdb.write("Registering global %s pretty-printer ...\n" % name) 124 obj = gdb 125 else: 126 if gdb.parameter("verbose"): 127 gdb.write("Registering %s pretty-printer for %s ...\n" % ( 128 name, obj.filename)) 129 130 # Printers implemented as functions are old-style. In order to not risk 131 # breaking anything we do not check __name__ here. 132 if hasattr(printer, "name"): 133 if not isinstance(printer.name, basestring): 134 raise TypeError("printer name is not a string") 135 # If printer provides a name, make sure it doesn't contain ";". 136 # Semicolon is used by the info/enable/disable pretty-printer commands 137 # to delimit subprinters. 138 if printer.name.find(";") >= 0: 139 raise ValueError("semicolon ';' in printer name") 140 # Also make sure the name is unique. 141 # Alas, we can't do the same for functions and __name__, they could 142 # all have a canonical name like "lookup_function". 143 # PERF: gdb records printers in a list, making this inefficient. 144 i = 0 145 for p in obj.pretty_printers: 146 if hasattr(p, "name") and p.name == printer.name: 147 if replace: 148 del obj.pretty_printers[i] 149 break 150 else: 151 raise RuntimeError("pretty-printer already registered: %s" % 152 printer.name) 153 i = i + 1 154 155 obj.pretty_printers.insert(0, printer) 156 157 158 class RegexpCollectionPrettyPrinter(PrettyPrinter): 159 """Class for implementing a collection of regular-expression based pretty-printers. 160 161 Intended usage: 162 163 pretty_printer = RegexpCollectionPrettyPrinter("my_library") 164 pretty_printer.add_printer("myclass1", "^myclass1$", MyClass1Printer) 165 ... 166 pretty_printer.add_printer("myclassN", "^myclassN$", MyClassNPrinter) 167 register_pretty_printer(obj, pretty_printer) 168 """ 169 170 class RegexpSubprinter(SubPrettyPrinter): 171 def __init__(self, name, regexp, gen_printer): 172 super(RegexpCollectionPrettyPrinter.RegexpSubprinter, self).__init__(name) 173 self.regexp = regexp 174 self.gen_printer = gen_printer 175 self.compiled_re = re.compile(regexp) 176 177 def __init__(self, name): 178 super(RegexpCollectionPrettyPrinter, self).__init__(name, []) 179 180 def add_printer(self, name, regexp, gen_printer): 181 """Add a printer to the list. 182 183 The printer is added to the end of the list. 184 185 Arguments: 186 name: The name of the subprinter. 187 regexp: The regular expression, as a string. 188 gen_printer: A function/method that given a value returns an 189 object to pretty-print it. 190 191 Returns: 192 Nothing. 193 """ 194 195 # NOTE: A previous version made the name of each printer the regexp. 196 # That makes it awkward to pass to the enable/disable commands (it's 197 # cumbersome to make a regexp of a regexp). So now the name is a 198 # separate parameter. 199 200 self.subprinters.append(self.RegexpSubprinter(name, regexp, 201 gen_printer)) 202 203 def __call__(self, val): 204 """Lookup the pretty-printer for the provided value.""" 205 206 # Get the type name. 207 typename = gdb.types.get_basic_type(val.type).tag 208 if not typename: 209 typename = val.type.name 210 if not typename: 211 return None 212 213 # Iterate over table of type regexps to determine 214 # if a printer is registered for that type. 215 # Return an instantiation of the printer if found. 216 for printer in self.subprinters: 217 if printer.enabled and printer.compiled_re.search(typename): 218 return printer.gen_printer(val) 219 220 # Cannot find a pretty printer. Return None. 221 return None 222 223 # A helper class for printing enum types. This class is instantiated 224 # with a list of enumerators to print a particular Value. 225 class _EnumInstance: 226 def __init__(self, enumerators, val): 227 self.enumerators = enumerators 228 self.val = val 229 230 def to_string(self): 231 flag_list = [] 232 v = long(self.val) 233 any_found = False 234 for (e_name, e_value) in self.enumerators: 235 if v & e_value != 0: 236 flag_list.append(e_name) 237 v = v & ~e_value 238 any_found = True 239 if not any_found or v != 0: 240 # Leftover value. 241 flag_list.append('<unknown: 0x%x>' % v) 242 return "0x%x [%s]" % (int(self.val), " | ".join(flag_list)) 243 244 class FlagEnumerationPrinter(PrettyPrinter): 245 """A pretty-printer which can be used to print a flag-style enumeration. 246 A flag-style enumeration is one where the enumerators are or'd 247 together to create values. The new printer will print these 248 symbolically using '|' notation. The printer must be registered 249 manually. This printer is most useful when an enum is flag-like, 250 but has some overlap. GDB's built-in printing will not handle 251 this case, but this printer will attempt to.""" 252 253 def __init__(self, enum_type): 254 super(FlagEnumerationPrinter, self).__init__(enum_type) 255 self.initialized = False 256 257 def __call__(self, val): 258 if not self.initialized: 259 self.initialized = True 260 flags = gdb.lookup_type(self.name) 261 self.enumerators = [] 262 for field in flags.fields(): 263 self.enumerators.append((field.name, field.enumval)) 264 # Sorting the enumerators by value usually does the right 265 # thing. 266 self.enumerators.sort(key = lambda x: x[1]) 267 268 if self.enabled: 269 return _EnumInstance(self.enumerators, val) 270 else: 271 return None 272 273 274 # Builtin pretty-printers. 275 # The set is defined as empty, and files in printing/*.py add their printers 276 # to this with add_builtin_pretty_printer. 277 278 _builtin_pretty_printers = RegexpCollectionPrettyPrinter("builtin") 279 280 register_pretty_printer(None, _builtin_pretty_printers) 281 282 # Add a builtin pretty-printer. 283 284 def add_builtin_pretty_printer(name, regexp, printer): 285 _builtin_pretty_printers.add_printer(name, regexp, printer) 286