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 static void demangle_command (char *, int);
  47
  48 /* See documentation in gdb-demangle.h.  */
  49 int demangle = 1;
  50
  51 static void
  52 show_demangle (struct ui_file *file, int from_tty,
  53                struct cmd_list_element *c, const char *value)
  54 {
  55   fprintf_filtered (file,
  56                     _("Demangling of encoded C++/ObjC names "
  57                       "when displaying symbols is %s.\n"),
  58                     value);
  59 }
  60
  61 /* See documentation in gdb-demangle.h.  */
  62 int asm_demangle = 0;
  63
  64 static void
  65 show_asm_demangle (struct ui_file *file, int from_tty,
  66                    struct cmd_list_element *c, const char *value)
  67 {
  68   fprintf_filtered (file,
  69                     _("Demangling of C++/ObjC names in "
  70                       "disassembly listings is %s.\n"),
  71                     value);
  72 }
  73
  74 /* String name for the current demangling style.  Set by the
  75    "set demangle-style" command, printed as part of the output by the
  76    "show demangle-style" command.  */
  77
  78 static const char *current_demangling_style_string;
  79
  80 /* The array of names of the known demanglyng styles.  Generated by
  81    _initialize_demangler from libiberty_demanglers[] array.  */
  82
  83 static const char **demangling_style_names;
  84 static void
  85 show_demangling_style_names(struct ui_file *file, int from_tty,
  86                             struct cmd_list_element *c, const char *value)
  87 {
  88   fprintf_filtered (file, _("The current C++ demangling style is \"%s\".\n"),
  89                     value);
  90 }
  91
  92 /* Set current demangling style.  Called by the "set demangle-style"
  93    command after it has updated the current_demangling_style_string to
  94    match what the user has entered.
  95
  96    If the user has entered a string that matches a known demangling style
  97    name in the demanglers[] array then just leave the string alone and update
  98    the current_demangling_style enum value to match.
  99
 100    If the user has entered a string that doesn't match, including an empty
 101    string, then print a list of the currently known styles and restore
 102    the current_demangling_style_string to match the current_demangling_style
 103    enum value.
 104
 105    Note:  Assumes that current_demangling_style_string always points to
 106    a malloc'd string, even if it is a null-string.  */
 107
 108 static void
 109 set_demangling_command (char *ignore, int from_tty, struct cmd_list_element *c)
 110 {
 111   const struct demangler_engine *dem;
 112   int i;
 113
 114   /*  First just try to match whatever style name the user supplied with
 115      one of the known ones.  Don't bother special casing for an empty
 116      name, we just treat it as any other style name that doesn't match.
 117      If we match, update the current demangling style enum.  */
 118
 119   for (dem = libiberty_demanglers, i = 0;
 120        dem->demangling_style != unknown_demangling;
 121        dem++)
 122     {
 123       if (strcmp (current_demangling_style_string,
 124                   dem->demangling_style_name) == 0)
 125         {
 126           current_demangling_style = dem->demangling_style;
 127           current_demangling_style_string = demangling_style_names[i];
 128           break;
 129         }
 130       i++;
 131     }
 132
 133   /* We should have found a match, given we only add known styles to
 134      the enumeration list.  */
 135   gdb_assert (dem->demangling_style != unknown_demangling);
 136 }
 137
 138 /* G++ uses a special character to indicate certain internal names.  Which
 139    character it is depends on the platform:
 140    - Usually '$' on systems where the assembler will accept that
 141    - Usually '.' otherwise (this includes most sysv4-like systems and most
 142      ELF targets)
 143    - Occasionally '_' if neither of the above is usable
 144
 145    We check '$' first because it is the safest, and '.' often has another
 146    meaning.  We don't currently try to handle '_' because the precise forms
 147    of the names are different on those targets.  */
 148
 149 static char cplus_markers[] = {'$', '.', '\0'};
 150
 151 /* See documentation in gdb-demangle.h.  */
 152
 153 int
 154 is_cplus_marker (int c)
 155 {
 156   return c && strchr (cplus_markers, c) != NULL;
 157 }
 158
 159 /* Demangle the given string in the current language.  */
 160
 161 static void
 162 demangle_command (char *args, int from_tty)
 163 {
 164   char *demangled;
 165   const char *name;
 166   const char *arg_start;
 167   int processing_args = 1;
 168   const struct language_defn *lang;
 169
 170   std::string arg_buf = args != NULL ? args : "";
 171   arg_start = arg_buf.c_str ();
 172
 173   gdb::unique_xmalloc_ptr<char> lang_name;
 174   while (processing_args
 175          && *arg_start == '-')
 176     {
 177       const char *p = skip_to_space (arg_start);
 178
 179       if (strncmp (arg_start, "-l", p - arg_start) == 0)
 180         lang_name.reset (extract_arg (&p));
 181       else if (strncmp (arg_start, "--", p - arg_start) == 0)
 182         processing_args = 0;
 183       else
 184         {
 185           gdb::unique_xmalloc_ptr<char> option (extract_arg (&p));
 186           error (_("Unrecognized option '%s' to demangle command.  "
 187                    "Try \"help demangle\"."), option.get ());
 188         }
 189
 190       arg_start = skip_spaces (p);
 191     }
 192
 193   name = arg_start;
 194
 195   if (*name == '\0')
 196     error (_("Usage: demangle [-l language] [--] name"));
 197
 198   if (lang_name != NULL)
 199     {
 200       enum language lang_enum;
 201
 202       lang_enum = language_enum (lang_name.get ());
 203       if (lang_enum == language_unknown)
 204         error (_("Unknown language \"%s\""), lang_name.get ());
 205       lang = language_def (lang_enum);
 206     }
 207   else
 208     lang = current_language;
 209
 210   demangled = language_demangle (lang, name, DMGL_ANSI | DMGL_PARAMS);
 211   if (demangled != NULL)
 212     {
 213       printf_filtered ("%s\n", demangled);
 214       xfree (demangled);
 215     }
 216   else
 217     error (_("Can't demangle \"%s\""), name);
 218 }
 219
 220 void
 221 _initialize_demangler (void)
 222 {
 223   int i, ndems;
 224
 225   /* Fill the demangling_style_names[] array, and set the default
 226      demangling style chosen at compilation time.  */
 227   for (ndems = 0;
 228        libiberty_demanglers[ndems].demangling_style != unknown_demangling;
 229        ndems++)
 230     ;
 231   demangling_style_names = XCNEWVEC (const char *, ndems + 1);
 232   for (i = 0;
 233        libiberty_demanglers[i].demangling_style != unknown_demangling;
 234        i++)
 235     {
 236       demangling_style_names[i]
 237         = xstrdup (libiberty_demanglers[i].demangling_style_name);
 238
 239       if (current_demangling_style_string == NULL
 240           && strcmp (DEFAULT_DEMANGLING_STYLE, demangling_style_names[i]) == 0)
 241         current_demangling_style_string = demangling_style_names[i];
 242     }
 243
 244   add_setshow_boolean_cmd ("demangle", class_support, &demangle, _("\
 245 Set demangling of encoded C++/ObjC names when displaying symbols."), _("\
 246 Show demangling of encoded C++/ObjC names when displaying symbols."), NULL,
 247                            NULL,
 248                            show_demangle,
 249                            &setprintlist, &showprintlist);
 250
 251   add_setshow_boolean_cmd ("asm-demangle", class_support, &asm_demangle, _("\
 252 Set demangling of C++/ObjC names in disassembly listings."), _("\
 253 Show demangling of C++/ObjC names in disassembly listings."), NULL,
 254                            NULL,
 255                            show_asm_demangle,
 256                            &setprintlist, &showprintlist);
 257
 258   add_setshow_enum_cmd ("demangle-style", class_support,
 259                         demangling_style_names,
 260                         &current_demangling_style_string, _("\
 261 Set the current C++ demangling style."), _("\
 262 Show the current C++ demangling style."), _("\
 263 Use `set demangle-style' without arguments for a list of demangling styles."),
 264                         set_demangling_command,
 265                         show_demangling_style_names,
 266                         &setlist, &showlist);
 267
 268   add_cmd ("demangle", class_support, demangle_command, _("\
 269 Demangle a mangled name.\n\
 270 Usage: demangle [-l language] [--] name\n\
 271 If LANGUAGE is not specified, NAME is demangled in the current language."),
 272            &cmdlist);
 273 }