gdb/demangle.c

   1 /* Basic C++ demangling support for GDB.
   2
   3    Copyright (C) 1991-2017 Free Software Foundation, Inc.
   4
   5    Written by Fred Fish at Cygnus Support.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22
  23 /*  This file contains support code for C++ demangling that is common
  24    to a styles of demangling, and GDB specific.  */
  25
  26 #include "defs.h"
  27 #include "cli/cli-utils.h" /* for skip_to_space */
  28 #include "command.h"
  29 #include "gdbcmd.h"
  30 #include "demangle.h"
  31 #include "gdb-demangle.h"
  32 #include "language.h"
  33
  34 /* Select the default C++ demangling style to use.  The default is "auto",
  35    which allows gdb to attempt to pick an appropriate demangling style for
  36    the executable it has loaded.  It can be set to a specific style ("gnu",
  37    "lucid", "arm", "hp", etc.) in which case gdb will never attempt to do auto
  38    selection of the style unless you do an explicit "set demangle auto".
  39    To select one of these as the default, set DEFAULT_DEMANGLING_STYLE in
  40    the appropriate target configuration file.  */
  41
  42 #ifndef DEFAULT_DEMANGLING_STYLE
  43 #define DEFAULT_DEMANGLING_STYLE AUTO_DEMANGLING_STYLE_STRING
  44 #endif
  45
  46 /* See documentation in gdb-demangle.h.  */
  47 int demangle = 1;
  48
  49 static void
  50 show_demangle (struct ui_file *file, int from_tty,
  51                struct cmd_list_element *c, const char *value)
  52 {
  53   fprintf_filtered (file,
  54                     _("Demangling of encoded C++/ObjC names "
  55                       "when displaying symbols is %s.\n"),
  56                     value);
  57 }
  58
  59 /* See documentation in gdb-demangle.h.  */
  60 int asm_demangle = 0;
  61
  62 static void
  63 show_asm_demangle (struct ui_file *file, int from_tty,
  64                    struct cmd_list_element *c, const char *value)
  65 {
  66   fprintf_filtered (file,
  67                     _("Demangling of C++/ObjC names in "
  68                       "disassembly listings is %s.\n"),
  69                     value);
  70 }
  71
  72 /* String name for the current demangling style.  Set by the
  73    "set demangle-style" command, printed as part of the output by the
  74    "show demangle-style" command.  */
  75
  76 static const char *current_demangling_style_string;
  77
  78 /* The array of names of the known demanglyng styles.  Generated by
  79    _initialize_demangler from libiberty_demanglers[] array.  */
  80
  81 static const char **demangling_style_names;
  82 static void
  83 show_demangling_style_names(struct ui_file *file, int from_tty,
  84                             struct cmd_list_element *c, const char *value)
  85 {
  86   fprintf_filtered (file, _("The current C++ demangling style is \"%s\".\n"),
  87                     value);
  88 }
  89
  90 /* Set current demangling style.  Called by the "set demangle-style"
  91    command after it has updated the current_demangling_style_string to
  92    match what the user has entered.
  93
  94    If the user has entered a string that matches a known demangling style
  95    name in the demanglers[] array then just leave the string alone and update
  96    the current_demangling_style enum value to match.
  97
  98    If the user has entered a string that doesn't match, including an empty
  99    string, then print a list of the currently known styles and restore
 100    the current_demangling_style_string to match the current_demangling_style
 101    enum value.
 102
 103    Note:  Assumes that current_demangling_style_string always points to
 104    a malloc'd string, even if it is a null-string.  */
 105
 106 static void
 107 set_demangling_command (const char *ignore,
 108                         int from_tty, struct cmd_list_element *c)
 109 {
 110   const struct demangler_engine *dem;
 111   int i;
 112
 113   /*  First just try to match whatever style name the user supplied with
 114      one of the known ones.  Don't bother special casing for an empty
 115      name, we just treat it as any other style name that doesn't match.
 116      If we match, update the current demangling style enum.  */
 117
 118   for (dem = libiberty_demanglers, i = 0;
 119        dem->demangling_style != unknown_demangling;
 120        dem++)
 121     {
 122       if (strcmp (current_demangling_style_string,
 123                   dem->demangling_style_name) == 0)
 124         {
 125           current_demangling_style = dem->demangling_style;
 126           current_demangling_style_string = demangling_style_names[i];
 127           break;
 128         }
 129       i++;
 130     }
 131
 132   /* We should have found a match, given we only add known styles to
 133      the enumeration list.  */
 134   gdb_assert (dem->demangling_style != unknown_demangling);
 135 }
 136
 137 /* G++ uses a special character to indicate certain internal names.  Which
 138    character it is depends on the platform:
 139    - Usually '$' on systems where the assembler will accept that
 140    - Usually '.' otherwise (this includes most sysv4-like systems and most
 141      ELF targets)
 142    - Occasionally '_' if neither of the above is usable
 143
 144    We check '$' first because it is the safest, and '.' often has another
 145    meaning.  We don't currently try to handle '_' because the precise forms
 146    of the names are different on those targets.  */
 147
 148 static char cplus_markers[] = {'$', '.', '\0'};
 149
 150 /* See documentation in gdb-demangle.h.  */
 151
 152 int
 153 is_cplus_marker (int c)
 154 {
 155   return c && strchr (cplus_markers, c) != NULL;
 156 }
 157
 158 /* Demangle the given string in the current language.  */
 159
 160 static void
 161 demangle_command (const char *args, int from_tty)
 162 {
 163   char *demangled;
 164   const char *name;
 165   const char *arg_start;
 166   int processing_args = 1;
 167   const struct language_defn *lang;
 168
 169   std::string arg_buf = args != NULL ? args : "";
 170   arg_start = arg_buf.c_str ();
 171
 172   std::string lang_name;
 173   while (processing_args
 174          && *arg_start == '-')
 175     {
 176       const char *p = skip_to_space (arg_start);
 177
 178       if (strncmp (arg_start, "-l", p - arg_start) == 0)
 179         lang_name = extract_arg (&p);
 180       else if (strncmp (arg_start, "--", p - arg_start) == 0)
 181         processing_args = 0;
 182       else
 183         {
 184           std::string option = extract_arg (&p);
 185           error (_("Unrecognized option '%s' to demangle command.  "
 186                    "Try \"help demangle\"."), option.c_str ());
 187         }
 188
 189       arg_start = skip_spaces (p);
 190     }
 191
 192   name = arg_start;
 193
 194   if (*name == '\0')
 195     error (_("Usage: demangle [-l language] [--] name"));
 196
 197   if (!lang_name.empty ())
 198     {
 199       enum language lang_enum;
 200
 201       lang_enum = language_enum (lang_name.c_str ());
 202       if (lang_enum == language_unknown)
 203         error (_("Unknown language \"%s\""), lang_name.c_str ());
 204       lang = language_def (lang_enum);
 205     }
 206   else
 207     lang = current_language;
 208
 209   demangled = language_demangle (lang, name, DMGL_ANSI | DMGL_PARAMS);
 210   if (demangled != NULL)
 211     {
 212       printf_filtered ("%s\n", demangled);
 213       xfree (demangled);
 214     }
 215   else
 216     error (_("Can't demangle \"%s\""), name);
 217 }
 218
 219 void
 220 _initialize_demangler (void)
 221 {
 222   int i, ndems;
 223
 224   /* Fill the demangling_style_names[] array, and set the default
 225      demangling style chosen at compilation time.  */
 226   for (ndems = 0;
 227        libiberty_demanglers[ndems].demangling_style != unknown_demangling;
 228        ndems++)
 229     ;
 230   demangling_style_names = XCNEWVEC (const char *, ndems + 1);
 231   for (i = 0;
 232        libiberty_demanglers[i].demangling_style != unknown_demangling;
 233        i++)
 234     {
 235       demangling_style_names[i]
 236         = xstrdup (libiberty_demanglers[i].demangling_style_name);
 237
 238       if (current_demangling_style_string == NULL
 239           && strcmp (DEFAULT_DEMANGLING_STYLE, demangling_style_names[i]) == 0)
 240         current_demangling_style_string = demangling_style_names[i];
 241     }
 242
 243   add_setshow_boolean_cmd ("demangle", class_support, &demangle, _("\
 244 Set demangling of encoded C++/ObjC names when displaying symbols."), _("\
 245 Show demangling of encoded C++/ObjC names when displaying symbols."), NULL,
 246                            NULL,
 247                            show_demangle,
 248                            &setprintlist, &showprintlist);
 249
 250   add_setshow_boolean_cmd ("asm-demangle", class_support, &asm_demangle, _("\
 251 Set demangling of C++/ObjC names in disassembly listings."), _("\
 252 Show demangling of C++/ObjC names in disassembly listings."), NULL,
 253                            NULL,
 254                            show_asm_demangle,
 255                            &setprintlist, &showprintlist);
 256
 257   add_setshow_enum_cmd ("demangle-style", class_support,
 258                         demangling_style_names,
 259                         &current_demangling_style_string, _("\
 260 Set the current C++ demangling style."), _("\
 261 Show the current C++ demangling style."), _("\
 262 Use `set demangle-style' without arguments for a list of demangling styles."),
 263                         set_demangling_command,
 264                         show_demangling_style_names,
 265                         &setlist, &showlist);
 266
 267   add_cmd ("demangle", class_support, demangle_command, _("\
 268 Demangle a mangled name.\n\
 269 Usage: demangle [-l language] [--] name\n\
 270 If LANGUAGE is not specified, NAME is demangled in the current language."),
 271            &cmdlist);
 272 }