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 (char *ignore, int from_tty, struct cmd_list_element *c)
 108 {
 109   const struct demangler_engine *dem;
 110   int i;
 111
 112   /*  First just try to match whatever style name the user supplied with
 113      one of the known ones.  Don't bother special casing for an empty
 114      name, we just treat it as any other style name that doesn't match.
 115      If we match, update the current demangling style enum.  */
 116
 117   for (dem = libiberty_demanglers, i = 0;
 118        dem->demangling_style != unknown_demangling;
 119        dem++)
 120     {
 121       if (strcmp (current_demangling_style_string,
 122                   dem->demangling_style_name) == 0)
 123         {
 124           current_demangling_style = dem->demangling_style;
 125           current_demangling_style_string = demangling_style_names[i];
 126           break;
 127         }
 128       i++;
 129     }
 130
 131   /* We should have found a match, given we only add known styles to
 132      the enumeration list.  */
 133   gdb_assert (dem->demangling_style != unknown_demangling);
 134 }
 135
 136 /* G++ uses a special character to indicate certain internal names.  Which
 137    character it is depends on the platform:
 138    - Usually '$' on systems where the assembler will accept that
 139    - Usually '.' otherwise (this includes most sysv4-like systems and most
 140      ELF targets)
 141    - Occasionally '_' if neither of the above is usable
 142
 143    We check '$' first because it is the safest, and '.' often has another
 144    meaning.  We don't currently try to handle '_' because the precise forms
 145    of the names are different on those targets.  */
 146
 147 static char cplus_markers[] = {'$', '.', '\0'};
 148
 149 /* See documentation in gdb-demangle.h.  */
 150
 151 int
 152 is_cplus_marker (int c)
 153 {
 154   return c && strchr (cplus_markers, c) != NULL;
 155 }
 156
 157 /* Demangle the given string in the current language.  */
 158
 159 static void
 160 demangle_command (const char *args, int from_tty)
 161 {
 162   char *demangled;
 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         {
 183           std::string option = extract_arg (&p);
 184           error (_("Unrecognized option '%s' to demangle command.  "
 185                    "Try \"help demangle\"."), option.c_str ());
 186         }
 187
 188       arg_start = skip_spaces (p);
 189     }
 190
 191   name = arg_start;
 192
 193   if (*name == '\0')
 194     error (_("Usage: demangle [-l language] [--] name"));
 195
 196   if (!lang_name.empty ())
 197     {
 198       enum language lang_enum;
 199
 200       lang_enum = language_enum (lang_name.c_str ());
 201       if (lang_enum == language_unknown)
 202         error (_("Unknown language \"%s\""), lang_name.c_str ());
 203       lang = language_def (lang_enum);
 204     }
 205   else
 206     lang = current_language;
 207
 208   demangled = language_demangle (lang, name, DMGL_ANSI | DMGL_PARAMS);
 209   if (demangled != NULL)
 210     {
 211       printf_filtered ("%s\n", demangled);
 212       xfree (demangled);
 213     }
 214   else
 215     error (_("Can't demangle \"%s\""), name);
 216 }
 217
 218 void
 219 _initialize_demangler (void)
 220 {
 221   int i, ndems;
 222
 223   /* Fill the demangling_style_names[] array, and set the default
 224      demangling style chosen at compilation time.  */
 225   for (ndems = 0;
 226        libiberty_demanglers[ndems].demangling_style != unknown_demangling;
 227        ndems++)
 228     ;
 229   demangling_style_names = XCNEWVEC (const char *, ndems + 1);
 230   for (i = 0;
 231        libiberty_demanglers[i].demangling_style != unknown_demangling;
 232        i++)
 233     {
 234       demangling_style_names[i]
 235         = xstrdup (libiberty_demanglers[i].demangling_style_name);
 236
 237       if (current_demangling_style_string == NULL
 238           && strcmp (DEFAULT_DEMANGLING_STYLE, demangling_style_names[i]) == 0)
 239         current_demangling_style_string = demangling_style_names[i];
 240     }
 241
 242   add_setshow_boolean_cmd ("demangle", class_support, &demangle, _("\
 243 Set demangling of encoded C++/ObjC names when displaying symbols."), _("\
 244 Show demangling of encoded C++/ObjC names when displaying symbols."), NULL,
 245                            NULL,
 246                            show_demangle,
 247                            &setprintlist, &showprintlist);
 248
 249   add_setshow_boolean_cmd ("asm-demangle", class_support, &asm_demangle, _("\
 250 Set demangling of C++/ObjC names in disassembly listings."), _("\
 251 Show demangling of C++/ObjC names in disassembly listings."), NULL,
 252                            NULL,
 253                            show_asm_demangle,
 254                            &setprintlist, &showprintlist);
 255
 256   add_setshow_enum_cmd ("demangle-style", class_support,
 257                         demangling_style_names,
 258                         &current_demangling_style_string, _("\
 259 Set the current C++ demangling style."), _("\
 260 Show the current C++ demangling style."), _("\
 261 Use `set demangle-style' without arguments for a list of demangling styles."),
 262                         set_demangling_command,
 263                         show_demangling_style_names,
 264                         &setlist, &showlist);
 265
 266   add_cmd ("demangle", class_support, demangle_command, _("\
 267 Demangle a mangled name.\n\
 268 Usage: demangle [-l language] [--] name\n\
 269 If LANGUAGE is not specified, NAME is demangled in the current language."),
 270            &cmdlist);
 271 }