gdb/gdb-demangle.c

   1 /* Basic C++ demangling support for GDB.
   2
   3    Copyright (C) 1991-2022 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   gdb_printf (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   gdb_printf (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   gdb_printf (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   const char *name;
 164   const char *arg_start;
 165   int processing_args = 1;
 166   const struct language_defn *lang;
 167
 168   std::string arg_buf = args != NULL ? args : "";
 169   arg_start = arg_buf.c_str ();
 170
 171   std::string lang_name;
 172   while (processing_args
 173          && *arg_start == '-')
 174     {
 175       const char *p = skip_to_space (arg_start);
 176
 177       if (strncmp (arg_start, "-l", p - arg_start) == 0)
 178         lang_name = extract_arg (&p);
 179       else if (strncmp (arg_start, "--", p - arg_start) == 0)
 180         processing_args = 0;
 181       else
 182         report_unrecognized_option_error ("demangle", arg_start);
 183
 184       arg_start = skip_spaces (p);
 185     }
 186
 187   name = arg_start;
 188
 189   if (*name == '\0')
 190     error (_("Usage: demangle [-l LANGUAGE] [--] NAME"));
 191
 192   if (!lang_name.empty ())
 193     {
 194       enum language lang_enum;
 195
 196       lang_enum = language_enum (lang_name.c_str ());
 197       if (lang_enum == language_unknown)
 198         error (_("Unknown language \"%s\""), lang_name.c_str ());
 199       lang = language_def (lang_enum);
 200     }
 201   else
 202     lang = current_language;
 203
 204   gdb::unique_xmalloc_ptr<char> demangled
 205     = language_demangle (lang, name, DMGL_ANSI | DMGL_PARAMS);
 206   if (demangled != NULL)
 207     gdb_printf ("%s\n", demangled.get ());
 208   else
 209     error (_("Can't demangle \"%s\""), name);
 210 }
 211
 212 void _initialize_gdb_demangle ();
 213 void
 214 _initialize_gdb_demangle ()
 215 {
 216   int i, ndems;
 217
 218   /* Fill the demangling_style_names[] array, and set the default
 219      demangling style chosen at compilation time.  */
 220   for (ndems = 0;
 221        libiberty_demanglers[ndems].demangling_style != unknown_demangling;
 222        ndems++)
 223     ;
 224   demangling_style_names = XCNEWVEC (const char *, ndems + 1);
 225   for (i = 0;
 226        libiberty_demanglers[i].demangling_style != unknown_demangling;
 227        i++)
 228     {
 229       demangling_style_names[i]
 230         = xstrdup (libiberty_demanglers[i].demangling_style_name);
 231
 232       if (current_demangling_style_string == NULL
 233           && strcmp (DEFAULT_DEMANGLING_STYLE, demangling_style_names[i]) == 0)
 234         current_demangling_style_string = demangling_style_names[i];
 235     }
 236
 237   add_setshow_boolean_cmd ("demangle", class_support, &demangle, _("\
 238 Set demangling of encoded C++/ObjC names when displaying symbols."), _("\
 239 Show demangling of encoded C++/ObjC names when displaying symbols."), NULL,
 240                            NULL,
 241                            show_demangle,
 242                            &setprintlist, &showprintlist);
 243
 244   add_setshow_boolean_cmd ("asm-demangle", class_support, &asm_demangle, _("\
 245 Set demangling of C++/ObjC names in disassembly listings."), _("\
 246 Show demangling of C++/ObjC names in disassembly listings."), NULL,
 247                            NULL,
 248                            show_asm_demangle,
 249                            &setprintlist, &showprintlist);
 250
 251   add_setshow_enum_cmd ("demangle-style", class_support,
 252                         demangling_style_names,
 253                         &current_demangling_style_string, _("\
 254 Set the current C++ demangling style."), _("\
 255 Show the current C++ demangling style."), _("\
 256 Use `set demangle-style' without arguments for a list of demangling styles."),
 257                         set_demangling_command,
 258                         show_demangling_style_names,
 259                         &setlist, &showlist);
 260
 261   add_cmd ("demangle", class_support, demangle_command, _("\
 262 Demangle a mangled name.\n\
 263 Usage: demangle [-l LANGUAGE] [--] NAME\n\
 264 If LANGUAGE is not specified, NAME is demangled in the current language."),
 265            &cmdlist);
 266 }