xref: /external/valgrind/main/coregrind/m_demangle/demangle.c

/*--------------------------------------------------------------------*/
/*--- Demangling of C++ mangled names.                  demangle.c ---*/
/*--------------------------------------------------------------------*/

/*
   This file is part of Valgrind, a dynamic binary instrumentation
   framework.

   Copyright (C) 2000-2013 Julian Seward
      jseward@acm.org

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307, USA.

   The GNU General Public License is contained in the file COPYING.
*/

#include "pub_core_basics.h"
#include "pub_core_demangle.h"
#include "pub_core_libcassert.h"
#include "pub_core_libcbase.h"
#include "pub_core_libcprint.h"
#include "pub_core_mallocfree.h"
#include "pub_core_options.h"

#include "vg_libciface.h"
#include "demangle.h"

/* The demangler's job is to take a raw symbol name and turn it into
   something a Human Bean can understand.  There are two levels of
   mangling.

   1. First, C++ names are mangled by the compiler.  So we'll have to
      undo that.

   2. Optionally, in relatively rare cases, the resulting name is then
      itself encoded using Z-escaping (see pub_core_redir.h) so as to
      become part of a redirect-specification.

   Therefore, VG_(demangle) first tries to undo (2).  If successful,
   the soname part is discarded (humans don't want to see that).
   Then, it tries to undo (1) (using demangling code from GNU/FSF).

   Finally, change the name of all symbols which are known to be
   functions below main() to "(below main)".  This helps reduce
   variability of stack traces, something which has been a problem for
   the testsuite for a long time.

   --------
   If do_cxx_demangle == True, does all the above stages:
   - undo (2) [Z-encoding]
   - undo (1) [C++ mangling]
   - do the below-main hack

   If do_cxx_demangle == False, the middle stage is skipped:
   - undo (2) [Z-encoding]
   - do the below-main hack
*/

/* Note that the C++ demangler is from GNU libiberty and is almost
   completely unmodified.  We use vg_libciface.h as a way to
   impedance-match the libiberty code into our own framework.

   The current code is from libiberty in the gcc tree, gcc svn
   r181975, dated 12 Dec 2011 (when the gcc trunk was in Stage 3
   leading up to a gcc-4.7 release).  As of r141363, libiberty is LGPL
   2.1, which AFAICT is compatible with "GPL 2 or later" and so is OK
   for inclusion in Valgrind.

   To update to a newer libiberty, it might be simplest to svn diff
   the gcc tree libibery against r181975 and then apply those diffs
   here. */

/* This is the main, standard demangler entry point. */

void VG_(demangle) ( Bool do_cxx_demangling, Bool do_z_demangling,
                     HChar* orig, HChar* result, Int result_size )
{
#  define N_ZBUF 4096
   HChar* demangled = NULL;
   HChar z_demangled[N_ZBUF];

   /* Possibly undo (2) */
   /* Z-Demangling was requested.
      The fastest way to see if it's a Z-mangled name is just to attempt
      to Z-demangle it (with NULL for the soname buffer, since we're not
      interested in that). */
   if (do_z_demangling) {
      if (VG_(maybe_Z_demangle)( orig, NULL,0,/*soname*/
                                 z_demangled, N_ZBUF, NULL, NULL, NULL )) {
         orig = z_demangled;
      }
   }

   /* Possibly undo (1) */
   if (do_cxx_demangling && VG_(clo_demangle)) {
      demangled = ML_(cplus_demangle) ( orig, DMGL_ANSI | DMGL_PARAMS );
   } else {
      demangled = NULL;
   }
   if (demangled) {
      VG_(strncpy_safely)(result, demangled, result_size);
      VG_(arena_free) (VG_AR_DEMANGLE, demangled);
   } else {
      VG_(strncpy_safely)(result, orig, result_size);
   }

   // 13 Mar 2005: We used to check here that the demangler wasn't leaking
   // by calling the (now-removed) function VG_(is_empty_arena)().  But,
   // very rarely (ie. I've heard of it twice in 3 years), the demangler
   // does leak.  But, we can't do much about it, and it's not a disaster,
   // so we just let it slide without aborting or telling the user.
#  undef N_ZBUF
}


/*------------------------------------------------------------*/
/*--- DEMANGLE Z-ENCODED NAMES                             ---*/
/*------------------------------------------------------------*/

/* Demangle a Z-encoded name as described in pub_tool_redir.h.
   Z-encoded names are used by Valgrind for doing function
   interception/wrapping.

   Demangle 'sym' into its soname and fnname parts, putting them in
   the specified buffers.  Returns a Bool indicating whether the
   demangled failed or not.  A failure can occur because the prefix
   isn't recognised, the internal Z-escaping is wrong, or because one
   or the other (or both) of the output buffers becomes full.  Passing
   'so' as NULL is acceptable if the caller is only interested in the
   function name part. */

Bool VG_(maybe_Z_demangle) ( const HChar* sym,
                             /*OUT*/HChar* so, Int soLen,
                             /*OUT*/HChar* fn, Int fnLen,
                             /*OUT*/Bool* isWrap,
                             /*OUT*/Int*  eclassTag,
                             /*OUT*/Int*  eclassPrio )
{
#  define EMITSO(ch)                           \
      do {                                     \
         if (so) {                             \
            if (soi >= soLen) {                \
               so[soLen-1] = 0; oflow = True;  \
            } else {                           \
               so[soi++] = ch; so[soi] = 0;    \
            }                                  \
         }                                     \
      } while (0)
#  define EMITFN(ch)                           \
      do {                                     \
         if (fni >= fnLen) {                   \
            fn[fnLen-1] = 0; oflow = True;     \
         } else {                              \
            fn[fni++] = ch; fn[fni] = 0;       \
         }                                     \
      } while (0)

   Bool error, oflow, valid, fn_is_encoded, is_VG_Z_prefixed;
   Int  soi, fni, i;

   vg_assert(soLen > 0 || (soLen == 0 && so == NULL));
   vg_assert(fnLen > 0);
   error = False;
   oflow = False;
   soi = 0;
   fni = 0;

   valid =     sym[0] == '_'
           &&  sym[1] == 'v'
           &&  sym[2] == 'g'
           && (sym[3] == 'r' || sym[3] == 'w')
           &&  VG_(isdigit)(sym[4])
           &&  VG_(isdigit)(sym[5])
           &&  VG_(isdigit)(sym[6])
           &&  VG_(isdigit)(sym[7])
           &&  VG_(isdigit)(sym[8])
           &&  sym[9] == 'Z'
           && (sym[10] == 'Z' || sym[10] == 'U')
           &&  sym[11] == '_';

   if (valid
       && sym[4] == '0' && sym[5] == '0' && sym[6] == '0' && sym[7] == '0'
       && sym[8] != '0') {
      /* If the eclass tag is 0000 (meaning "no eclass"), the priority
         must be 0 too. */
      valid = False;
   }

   if (!valid)
      return False;

   fn_is_encoded = sym[10] == 'Z';

   if (isWrap)
      *isWrap = sym[3] == 'w';

   if (eclassTag) {
      *eclassTag =    1000 * ((Int)sym[4] - '0')
                   +  100 * ((Int)sym[5] - '0')
                   +  10 * ((Int)sym[6] - '0')
                   +  1 * ((Int)sym[7] - '0');
      vg_assert(*eclassTag >= 0 && *eclassTag <= 9999);
   }

   if (eclassPrio) {
      *eclassPrio = ((Int)sym[8]) - '0';
      vg_assert(*eclassPrio >= 0 && *eclassPrio <= 9);
   }

   /* Now check the soname prefix isn't "VG_Z_", as described in
      pub_tool_redir.h. */
   is_VG_Z_prefixed =
      sym[12] == 'V' &&
      sym[13] == 'G' &&
      sym[14] == '_' &&
      sym[15] == 'Z' &&
      sym[16] == '_';
   if (is_VG_Z_prefixed) {
      vg_assert2(0, "symbol with a 'VG_Z_' prefix: %s.\n"
                    "see pub_tool_redir.h for an explanation.", sym);
   }

   /* Now scan the Z-encoded soname. */
   i = 12;
   while (True) {

      if (sym[i] == '_')
      /* Found the delimiter.  Move on to the fnname loop. */
         break;

      if (sym[i] == 0) {
         error = True;
         goto out;
      }

      if (sym[i] != 'Z') {
         EMITSO(sym[i]);
         i++;
         continue;
      }

      /* We've got a Z-escape. */
      i++;
      switch (sym[i]) {
         case 'a': EMITSO('*'); break;
         case 'c': EMITSO(':'); break;
         case 'd': EMITSO('.'); break;
         case 'h': EMITSO('-'); break;
         case 'p': EMITSO('+'); break;
         case 's': EMITSO(' '); break;
         case 'u': EMITSO('_'); break;
         case 'A': EMITSO('@'); break;
         case 'D': EMITSO('$'); break;
         case 'L': EMITSO('('); break;
         case 'R': EMITSO(')'); break;
         case 'Z': EMITSO('Z'); break;
         default: error = True; goto out;
      }
      i++;
   }

   vg_assert(sym[i] == '_');
   i++;

   /* Now deal with the function name part. */
   if (!fn_is_encoded) {

      /* simple; just copy. */
      while (True) {
         if (sym[i] == 0)
            break;
         EMITFN(sym[i]);
         i++;
      }
      goto out;

   }

   /* else use a Z-decoding loop like with soname */
   while (True) {

      if (sym[i] == 0)
         break;

      if (sym[i] != 'Z') {
         EMITFN(sym[i]);
         i++;
         continue;
      }

      /* We've got a Z-escape. */
      i++;
      switch (sym[i]) {
         case 'a': EMITFN('*'); break;
         case 'c': EMITFN(':'); break;
         case 'd': EMITFN('.'); break;
         case 'h': EMITFN('-'); break;
         case 'p': EMITFN('+'); break;
         case 's': EMITFN(' '); break;
         case 'u': EMITFN('_'); break;
         case 'A': EMITFN('@'); break;
         case 'D': EMITFN('$'); break;
         case 'L': EMITFN('('); break;
         case 'R': EMITFN(')'); break;
         case 'Z': EMITFN('Z'); break;
         default: error = True; goto out;
      }
      i++;
   }

  out:
   EMITSO(0);
   EMITFN(0);

   if (error) {
      /* Something's wrong.  Give up. */
      VG_(message)(Vg_UserMsg,
                   "m_demangle: error Z-demangling: %s\n", sym);
      return False;
   }
   if (oflow) {
      /* It didn't fit.  Give up. */
      VG_(message)(Vg_UserMsg,
                   "m_demangle: oflow Z-demangling: %s\n", sym);
      return False;
   }

   return True;
}


/*--------------------------------------------------------------------*/
/*--- end                                                          ---*/
/*--------------------------------------------------------------------*/