gdb/gdb-demangle.c

   1 /* Basic C++ demangling support for GDB.
   2
   3    Copyright (C) 1991-2020 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 bool demangle = true;
  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 bool asm_demangle = false;
  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 demangling 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 bool
 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         report_unrecognized_option_error ("demangle", arg_start);
 184
 185       arg_start = skip_spaces (p);
 186     }
 187
 188   name = arg_start;
 189
 190   if (*name == '\0')
 191     error (_("Usage: demangle [-l LANGUAGE] [--] NAME"));
 192
 193   if (!lang_name.empty ())
 194     {
 195       enum language lang_enum;
 196
 197       lang_enum = language_enum (lang_name.c_str ());
 198       if (lang_enum == language_unknown)
 199         error (_("Unknown language \"%s\""), lang_name.c_str ());
 200       lang = language_def (lang_enum);
 201     }
 202   else
 203     lang = current_language;
 204
 205   demangled = language_demangle (lang, name, DMGL_ANSI | DMGL_PARAMS);
 206   if (demangled != NULL)
 207     {
 208       printf_filtered ("%s\n", demangled);
 209       xfree (demangled);
 210     }
 211   else
 212     error (_("Can't demangle \"%s\""), name);
 213 }
 214
 215 void _initialize_gdb_demangle ();
 216 void
 217 _initialize_gdb_demangle ()
 218 {
 219   int i, ndems;
 220
 221   /* Fill the demangling_style_names[] array, and set the default
 222      demangling style chosen at compilation time.  */
 223   for (ndems = 0;
 224        libiberty_demanglers[ndems].demangling_style != unknown_demangling;
 225        ndems++)
 226     ;
 227   demangling_style_names = XCNEWVEC (const char *, ndems + 1);
 228   for (i = 0;
 229        libiberty_demanglers[i].demangling_style != unknown_demangling;
 230        i++)
 231     {
 232       demangling_style_names[i]
 233         = xstrdup (libiberty_demanglers[i].demangling_style_name);
 234
 235       if (current_demangling_style_string == NULL
 236           && strcmp (DEFAULT_DEMANGLING_STYLE, demangling_style_names[i]) == 0)
 237         current_demangling_style_string = demangling_style_names[i];
 238     }
 239
 240   add_setshow_boolean_cmd ("demangle", class_support, &demangle, _("\
 241 Set demangling of encoded C++/ObjC names when displaying symbols."), _("\
 242 Show demangling of encoded C++/ObjC names when displaying symbols."), NULL,
 243                            NULL,
 244                            show_demangle,
 245                            &setprintlist, &showprintlist);
 246
 247   add_setshow_boolean_cmd ("asm-demangle", class_support, &asm_demangle, _("\
 248 Set demangling of C++/ObjC names in disassembly listings."), _("\
 249 Show demangling of C++/ObjC names in disassembly listings."), NULL,
 250                            NULL,
 251                            show_asm_demangle,
 252                            &setprintlist, &showprintlist);
 253
 254   add_setshow_enum_cmd ("demangle-style", class_support,
 255                         demangling_style_names,
 256                         &current_demangling_style_string, _("\
 257 Set the current C++ demangling style."), _("\
 258 Show the current C++ demangling style."), _("\
 259 Use `set demangle-style' without arguments for a list of demangling styles."),
 260                         set_demangling_command,
 261                         show_demangling_style_names,
 262                         &setlist, &showlist);
 263
 264   add_cmd ("demangle", class_support, demangle_command, _("\
 265 Demangle a mangled name.\n\
 266 Usage: demangle [-l LANGUAGE] [--] NAME\n\
 267 If LANGUAGE is not specified, NAME is demangled in the current language."),
 268            &cmdlist);
 269 }