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ftmemsim-valgrind/coregrind/m_demangle/demangle.c
Nicholas Nethercote 4831385c67 Fix Rust v0 demangling. 
It's currently broken due to a silly test that prevents the v0
demangling code from even running.

The commit also adds a test, to avoid such problems in the future.
2021-11-10 10:03:06 +11:00

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/*--------------------------------------------------------------------*/
/*--- Demangling of C++ mangled names. demangle.c ---*/
/*--------------------------------------------------------------------*/
/*
This file is part of Valgrind, a dynamic binary instrumentation
framework.
Copyright (C) 2000-2017 Julian Seward
jseward@acm.org
Rust demangler components are
Copyright (C) 2016-2016 David Tolnay
dtolnay@gmail.com
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, see <http://www.gnu.org/licenses/>.
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, it changes 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, it does all the above stages:
- undo (2) [Z-encoding]
- undo (1) [C++ mangling]
- do the below-main hack
If do_cxx_demangle == False, the C++ and Rust stags are 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 libiberty code included here was taken from the GCC repository
and is released under the LGPL 2.1 license, which AFAICT is compatible
with "GPL 2 or later" and so is OK for inclusion in Valgrind.
To update to a newer libiberty, use the "update-demangler" script
which is included in the valgrind repository. */
/* This is the main, standard demangler entry point. */
/* Upon return, *RESULT will point to the demangled name.
The memory buffer that holds the demangled name is allocated on the
heap and will be deallocated in the next invocation. Conceptually,
that buffer is owned by VG_(demangle). That means two things:
(1) Users of VG_(demangle) must not free that buffer.
(2) If the demangled name needs to be stashed away for later use,
the contents of the buffer need to be copied. It is not sufficient
to just store the pointer as it will point to deallocated memory
after the next VG_(demangle) invocation. */
void VG_(demangle) ( Bool do_cxx_demangling, Bool do_z_demangling,
/* IN */ const HChar *orig,
/* OUT */ const HChar **result )
{
/* 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) {
const HChar *z_demangled;
if (VG_(maybe_Z_demangle)( orig, NULL, /*soname*/
&z_demangled, NULL, NULL, NULL )) {
orig = z_demangled;
}
}
/* Possibly undo (1) */
// - C++ mangled symbols start with "_Z" (possibly with exceptions?)
// - Rust "legacy" mangled symbols start with "_Z".
// - Rust "v0" mangled symbols start with "_R".
// XXX: the Java/Rust/Ada demangling here probably doesn't work. See
// https://bugs.kde.org/show_bug.cgi?id=445235 for details.
if (do_cxx_demangling && VG_(clo_demangle)
&& orig != NULL && orig[0] == '_' && (orig[1] == 'Z' || orig[1] == 'R')) {
/* !!! vvv STATIC vvv !!! */
static HChar* demangled = NULL;
/* !!! ^^^ STATIC ^^^ !!! */
/* Free up previously demangled name */
if (demangled) {
VG_(arena_free) (VG_AR_DEMANGLE, demangled);
demangled = NULL;
}
demangled = ML_(cplus_demangle) ( orig, DMGL_ANSI | DMGL_PARAMS );
*result = (demangled == NULL) ? orig : demangled;
} else {
*result = orig;
}
// 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.
}
/*------------------------------------------------------------*/
/*--- 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*/const HChar** so,
/*OUT*/const HChar** fn,
/*OUT*/Bool* isWrap,
/*OUT*/Int* eclassTag,
/*OUT*/Int* eclassPrio )
{
static HChar *sobuf;
static HChar *fnbuf;
static SizeT buf_len = 0;
/* The length of the name after undoing Z-encoding is always smaller
than the mangled name. Making the soname and fnname buffers as large
as the demangled name is therefore always safe and overflow can never
occur. */
SizeT len = VG_(strlen)(sym) + 1;
if (buf_len < len) {
sobuf = VG_(arena_realloc)(VG_AR_DEMANGLE, "Z-demangle", sobuf, len);
fnbuf = VG_(arena_realloc)(VG_AR_DEMANGLE, "Z-demangle", fnbuf, len);
buf_len = len;
}
sobuf[0] = fnbuf[0] = '\0';
if (so)
*so = sobuf;
*fn = fnbuf;
# define EMITSO(ch) \
do { \
if (so) { \
sobuf[soi++] = ch; sobuf[soi] = 0; \
} \
} while (0)
# define EMITFN(ch) \
do { \
fnbuf[fni++] = ch; fnbuf[fni] = 0; \
} while (0)
Bool error, valid, fn_is_encoded, is_VG_Z_prefixed;
Int soi, fni, i;
error = 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('$'); break;
case 'L': EMITSO('('); break;
case 'P': EMITSO('%'); break;
case 'R': EMITSO(')'); break;
case 'S': EMITSO('/'); break;
case 'Z': EMITSO('Z'); break;
default: error = True; goto out;
}
i++;
}
vg_assert(sym[i] == '_');
i++;
/* Now deal with the function name part. */
if (!fn_is_encoded) {
/* simple; just copy. */
while (True) {
if (sym[i] == 0)
break;
EMITFN(sym[i]);
i++;
}
goto out;
}
/* else use a Z-decoding loop like with soname */
while (True) {
if (sym[i] == 0)
break;
if (sym[i] != 'Z') {
EMITFN(sym[i]);
i++;
continue;
}
/* We've got a Z-escape. */
i++;
switch (sym[i]) {
case 'a': EMITFN('*'); break;
case 'c': EMITFN(':'); break;
case 'd': EMITFN('.'); break;
case 'h': EMITFN('-'); break;
case 'p': EMITFN('+'); break;
case 's': EMITFN(' '); break;
case 'u': EMITFN('_'); break;
case 'A': EMITFN('@'); break;
case 'D': EMITFN('$'); break;
case 'L': EMITFN('('); break;
case 'P': EMITFN('%'); break;
case 'R': EMITFN(')'); break;
case 'S': 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;
}
return True;
}
/*--------------------------------------------------------------------*/
/*--- end ---*/
/*--------------------------------------------------------------------*/
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