1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/tools/trace-malloc/lib/nsTypeInfo.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,278 @@
1.4 +/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
1.5 + *
1.6 + * This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +/*
1.11 + typeinfo.cpp
1.12 +
1.13 + Speculatively use RTTI on a random object. If it contains a pointer at offset 0
1.14 + that is in the current process' address space, and that so on, then attempt to
1.15 + use C++ RTTI's typeid operation to obtain the name of the type.
1.16 +
1.17 + by Patrick C. Beard.
1.18 + */
1.19 +
1.20 +#include <typeinfo>
1.21 +#include <ctype.h>
1.22 +
1.23 +#include "nsTypeInfo.h"
1.24 +
1.25 +extern "C" void NS_TraceMallocShutdown();
1.26 +
1.27 +struct TraceMallocShutdown {
1.28 + TraceMallocShutdown() {}
1.29 + ~TraceMallocShutdown() {
1.30 + NS_TraceMallocShutdown();
1.31 + }
1.32 +};
1.33 +
1.34 +extern "C" void RegisterTraceMallocShutdown() {
1.35 + // This instanciates the dummy class above, and will trigger the class
1.36 + // destructor when libxul is unloaded. This is equivalent to atexit(),
1.37 + // but gracefully handles dlclose().
1.38 + static TraceMallocShutdown t;
1.39 +}
1.40 +
1.41 +class IUnknown {
1.42 +public:
1.43 + virtual long QueryInterface() = 0;
1.44 + virtual long AddRef() = 0;
1.45 + virtual long Release() = 0;
1.46 +};
1.47 +
1.48 +#if defined(MACOS)
1.49 +
1.50 +#include <Processes.h>
1.51 +
1.52 +class AddressSpace {
1.53 +public:
1.54 + AddressSpace();
1.55 + Boolean contains(void* ptr);
1.56 +private:
1.57 + ProcessInfoRec mInfo;
1.58 +};
1.59 +
1.60 +AddressSpace::AddressSpace()
1.61 +{
1.62 + ProcessSerialNumber psn = { 0, kCurrentProcess };
1.63 + mInfo.processInfoLength = sizeof(mInfo);
1.64 + ::GetProcessInformation(&psn, &mInfo);
1.65 +}
1.66 +
1.67 +Boolean AddressSpace::contains(void* ptr)
1.68 +{
1.69 + UInt32 start = UInt32(mInfo.processLocation);
1.70 + return (UInt32(ptr) >= start && UInt32(ptr) < (start + mInfo.processSize));
1.71 +}
1.72 +
1.73 +const char* nsGetTypeName(void* ptr)
1.74 +{
1.75 + // construct only one of these per process.
1.76 + static AddressSpace space;
1.77 +
1.78 + // sanity check the vtable pointer, before trying to use RTTI on the object.
1.79 + void** vt = *(void***)ptr;
1.80 + if (vt && !(unsigned(vt) & 0x3) && space.contains(vt) && space.contains(*vt)) {
1.81 + IUnknown* u = static_cast<IUnknown*>(ptr);
1.82 + const char* type = typeid(*u).name();
1.83 + // make sure it looks like a C++ identifier.
1.84 + if (type && (isalnum(type[0]) || type[0] == '_'))
1.85 + return type;
1.86 + }
1.87 + return "void*";
1.88 +}
1.89 +
1.90 +#endif
1.91 +
1.92 +// New, more "portable" Linux code is below, but this might be a useful
1.93 +// model for other platforms, so keeping.
1.94 +//#if defined(linux)
1.95 +#if 0
1.96 +
1.97 +#include <signal.h>
1.98 +#include <setjmp.h>
1.99 +
1.100 +static jmp_buf context;
1.101 +
1.102 +static void handler(int signum)
1.103 +{
1.104 + longjmp(context, signum);
1.105 +}
1.106 +
1.107 +#define attempt() setjmp(context)
1.108 +
1.109 +class Signaller {
1.110 +public:
1.111 + Signaller(int signum);
1.112 + ~Signaller();
1.113 +
1.114 +private:
1.115 + typedef void (*handler_t) (int signum);
1.116 + int mSignal;
1.117 + handler_t mOldHandler;
1.118 +};
1.119 +
1.120 +Signaller::Signaller(int signum)
1.121 + : mSignal(signum), mOldHandler(signal(signum, &handler))
1.122 +{
1.123 +}
1.124 +
1.125 +Signaller::~Signaller()
1.126 +{
1.127 + signal(mSignal, mOldHandler);
1.128 +}
1.129 +
1.130 +// The following are pointers that bamboozle our otherwise feeble
1.131 +// attempts to "safely" collect type names.
1.132 +//
1.133 +// XXX this kind of sucks because it means that anyone trying to use
1.134 +// this without NSPR will get unresolved symbols when this library
1.135 +// loads. It's also not very extensible. Oh well: FIX ME!
1.136 +extern "C" {
1.137 + // from nsprpub/pr/src/io/priometh.c (libnspr4.so)
1.138 + extern void* _pr_faulty_methods;
1.139 +};
1.140 +
1.141 +static inline int
1.142 +sanity_check_vtable_i386(void** vt)
1.143 +{
1.144 + // Now that we're "safe" inside the signal handler, we can
1.145 + // start poking around. If we're really an object with
1.146 + // RTTI, then the second entry in the vtable should point
1.147 + // to a function.
1.148 + //
1.149 + // Let's see if the second entry:
1.150 + //
1.151 + // 1) looks like a 4-byte aligned pointer
1.152 + //
1.153 + // 2) points to something that looks like the following
1.154 + // i386 instructions:
1.155 + //
1.156 + // 55 push %ebp
1.157 + // 89e5 mov %esp,%ebp
1.158 + // 53 push %ebx
1.159 + //
1.160 + // or
1.161 + //
1.162 + // 55 push %ebp
1.163 + // 89e5 mov %esp,%ebp
1.164 + // 56 push %esi
1.165 + //
1.166 + // (which is the standard function prologue generated
1.167 + // by egcs, plus a ``signature'' instruction that appears
1.168 + // in the typeid() function's implementation).
1.169 + unsigned char** fp1 = reinterpret_cast<unsigned char**>(vt) + 1;
1.170 +
1.171 + // Does it look like an address?
1.172 + unsigned char* ip = *fp1;
1.173 + if ((unsigned(ip) & 3) != 0)
1.174 + return 0;
1.175 +
1.176 + // Does it look like it refers to the standard prologue?
1.177 + static unsigned char prologue[] = { 0x55, 0x89, 0xE5 };
1.178 + for (unsigned i = 0; i < sizeof(prologue); ++i)
1.179 + if (*ip++ != prologue[i])
1.180 + return 0;
1.181 +
1.182 + // Is the next instruction a `push %ebx' or `push %esi'?
1.183 + if (*ip == 0x53 || *ip == 0x56) {
1.184 + return 1;
1.185 + }
1.186 +
1.187 + // Nope. There's another variant that has a `sub' instruction,
1.188 + // followed by a `cmpl' and a `jne'. Check for that.
1.189 + if (ip[0] == 0x83 && ip[1] == 0xec // sub
1.190 + && ip[3] == 0x83 && ip[4] == 0x3d // cmpl
1.191 + && ip[10] == 0x75 // jne
1.192 + ) {
1.193 + return 1;
1.194 + }
1.195 +
1.196 + return 0;
1.197 +}
1.198 +
1.199 +static inline int
1.200 +sanity_check_vtable_ppc(void** vt)
1.201 +{
1.202 + // XXX write me!
1.203 + return 1;
1.204 +}
1.205 +
1.206 +#if defined(__i386)
1.207 +# define SANITY_CHECK_VTABLE(vt) (sanity_check_vtable_i386(vt))
1.208 +#elif defined(PPC)
1.209 +# define SANITY_CHECK_VTABLE(vt) (sanity_check_vtable_ppc(vt))
1.210 +#else
1.211 +# define SANITY_CHECK_VTABLE(vt) (1)
1.212 +#endif
1.213 +
1.214 +const char* nsGetTypeName(void* ptr)
1.215 +{
1.216 + // sanity check the vtable pointer, before trying to use RTTI on the object.
1.217 + void** vt = *(void***)ptr;
1.218 + if (vt && !(unsigned(vt) & 3) && (vt != &_pr_faulty_methods)) {
1.219 + Signaller s1(SIGSEGV);
1.220 + if (attempt() == 0) {
1.221 + if (SANITY_CHECK_VTABLE(vt)) {
1.222 + // Looks like a function: what the hell, let's call it.
1.223 + IUnknown* u = static_cast<IUnknown*>(ptr);
1.224 + const char* type = typeid(*u).name();
1.225 + // EGCS seems to prefix a length string.
1.226 + while (isdigit(*type)) ++type;
1.227 + return type;
1.228 + }
1.229 + }
1.230 + }
1.231 + return "void*";
1.232 +}
1.233 +
1.234 +#endif
1.235 +
1.236 +#if defined(linux) || defined(XP_MACOSX)
1.237 +
1.238 +#define __USE_GNU
1.239 +#include <dlfcn.h>
1.240 +#include <ctype.h>
1.241 +#include <string.h>
1.242 +
1.243 +const char* nsGetTypeName(void* ptr)
1.244 +{
1.245 +#if defined(__GXX_ABI_VERSION) && __GXX_ABI_VERSION >= 100 /* G++ V3 ABI */
1.246 + const int expected_offset = 8;
1.247 + const char vtable_sym_start[] = "_ZTV";
1.248 + const int vtable_sym_start_length = sizeof(vtable_sym_start) - 1;
1.249 +#else
1.250 + const int expected_offset = 0;
1.251 + const char vtable_sym_start[] = "__vt_";
1.252 + const int vtable_sym_start_length = sizeof(vtable_sym_start) - 1;
1.253 +#endif
1.254 + void* vt = *(void**)ptr;
1.255 + Dl_info info;
1.256 + // If dladdr fails, if we're not at the expected offset in the vtable,
1.257 + // or if the symbol name isn't a vtable symbol name, return "void*".
1.258 + if ( !dladdr(vt, &info) ||
1.259 + ((char*)info.dli_saddr) + expected_offset != vt ||
1.260 + !info.dli_sname ||
1.261 + strncmp(info.dli_sname, vtable_sym_start, vtable_sym_start_length))
1.262 + return "void*";
1.263 +
1.264 + // skip the garbage at the beginning of things like
1.265 + // __vt_14nsRootBoxFrame (gcc 2.96) or _ZTV14nsRootBoxFrame (gcc 3.0)
1.266 + const char* rv = info.dli_sname + vtable_sym_start_length;
1.267 + while (*rv && isdigit(*rv))
1.268 + ++rv;
1.269 + return rv;
1.270 +}
1.271 +
1.272 +#endif
1.273 +
1.274 +#ifdef XP_WIN32
1.275 +const char* nsGetTypeName(void* ptr)
1.276 +{
1.277 + //TODO: COMPLETE THIS
1.278 + return "void*";
1.279 +}
1.280 +
1.281 +#endif //XP_WIN32
