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abseil-cpp/absl/debugging/internal/demangle.cc

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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// For reference check out:
// https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling
//
// Note that we only have partial C++11 support yet.
#include "absl/debugging/internal/demangle.h"
#include <cstdint>
#include <cstdio>
#include <limits>
namespace absl {
namespace debugging_internal {
typedef struct {
const char *abbrev;
const char *real_name;
// Number of arguments in <expression> context, or 0 if disallowed.
int arity;
} AbbrevPair;
// List of operators from Itanium C++ ABI.
static const AbbrevPair kOperatorList[] = {
// New has special syntax (not currently supported).
{"nw", "new", 0},
{"na", "new[]", 0},
// Works except that the 'gs' prefix is not supported.
{"dl", "delete", 1},
{"da", "delete[]", 1},
{"ps", "+", 1}, // "positive"
{"ng", "-", 1}, // "negative"
{"ad", "&", 1}, // "address-of"
{"de", "*", 1}, // "dereference"
{"co", "~", 1},
{"pl", "+", 2},
{"mi", "-", 2},
{"ml", "*", 2},
{"dv", "/", 2},
{"rm", "%", 2},
{"an", "&", 2},
{"or", "|", 2},
{"eo", "^", 2},
{"aS", "=", 2},
{"pL", "+=", 2},
{"mI", "-=", 2},
{"mL", "*=", 2},
{"dV", "/=", 2},
{"rM", "%=", 2},
{"aN", "&=", 2},
{"oR", "|=", 2},
{"eO", "^=", 2},
{"ls", "<<", 2},
{"rs", ">>", 2},
{"lS", "<<=", 2},
{"rS", ">>=", 2},
{"eq", "==", 2},
{"ne", "!=", 2},
{"lt", "<", 2},
{"gt", ">", 2},
{"le", "<=", 2},
{"ge", ">=", 2},
{"nt", "!", 1},
{"aa", "&&", 2},
{"oo", "||", 2},
{"pp", "++", 1},
{"mm", "--", 1},
{"cm", ",", 2},
{"pm", "->*", 2},
{"pt", "->", 0}, // Special syntax
{"cl", "()", 0}, // Special syntax
{"ix", "[]", 2},
{"qu", "?", 3},
{"st", "sizeof", 0}, // Special syntax
{"sz", "sizeof", 1}, // Not a real operator name, but used in expressions.
{nullptr, nullptr, 0},
};
// List of builtin types from Itanium C++ ABI.
static const AbbrevPair kBuiltinTypeList[] = {
{"v", "void", 0},
{"w", "wchar_t", 0},
{"b", "bool", 0},
{"c", "char", 0},
{"a", "signed char", 0},
{"h", "unsigned char", 0},
{"s", "short", 0},
{"t", "unsigned short", 0},
{"i", "int", 0},
{"j", "unsigned int", 0},
{"l", "long", 0},
{"m", "unsigned long", 0},
{"x", "long long", 0},
{"y", "unsigned long long", 0},
{"n", "__int128", 0},
{"o", "unsigned __int128", 0},
{"f", "float", 0},
{"d", "double", 0},
{"e", "long double", 0},
{"g", "__float128", 0},
{"z", "ellipsis", 0},
{nullptr, nullptr, 0},
};
// List of substitutions Itanium C++ ABI.
static const AbbrevPair kSubstitutionList[] = {
{"St", "", 0},
{"Sa", "allocator", 0},
{"Sb", "basic_string", 0},
// std::basic_string<char, std::char_traits<char>,std::allocator<char> >
{"Ss", "string", 0},
// std::basic_istream<char, std::char_traits<char> >
{"Si", "istream", 0},
// std::basic_ostream<char, std::char_traits<char> >
{"So", "ostream", 0},
// std::basic_iostream<char, std::char_traits<char> >
{"Sd", "iostream", 0},
{nullptr, nullptr, 0},
};
// State needed for demangling. This struct is copied in almost every stack
// frame, so every byte counts.
typedef struct {
int mangled_idx; // Cursor of mangled name.
int out_cur_idx; // Cursor of output std::string.
int prev_name_idx; // For constructors/destructors.
signed int prev_name_length : 16; // For constructors/destructors.
signed int nest_level : 15; // For nested names.
unsigned int append : 1; // Append flag.
// Note: for some reason MSVC can't pack "bool append : 1" into the same int
// with the above two fields, so we use an int instead. Amusingly it can pack
// "signed bool" as expected, but relying on that to continue to be a legal
// type seems ill-advised (as it's illegal in at least clang).
} ParseState;
static_assert(sizeof(ParseState) == 4 * sizeof(int),
"unexpected size of ParseState");
// One-off state for demangling that's not subject to backtracking -- either
// constant data, data that's intentionally immune to backtracking (steps), or
// data that would never be changed by backtracking anyway (recursion_depth).
//
// Only one copy of this exists for each call to Demangle, so the size of this
// struct is nearly inconsequential.
typedef struct {
const char *mangled_begin; // Beginning of input std::string.
char *out; // Beginning of output std::string.
int out_end_idx; // One past last allowed output character.
int recursion_depth; // For stack exhaustion prevention.
int steps; // Cap how much work we'll do, regardless of depth.
ParseState parse_state; // Backtrackable state copied for most frames.
} State;
namespace {
// Prevent deep recursion / stack exhaustion.
// Also prevent unbounded handling of complex inputs.
class ComplexityGuard {
public:
explicit ComplexityGuard(State *state) : state_(state) {
++state->recursion_depth;
++state->steps;
}
~ComplexityGuard() { --state_->recursion_depth; }
// 256 levels of recursion seems like a reasonable upper limit on depth.
// 128 is not enough to demagle synthetic tests from demangle_unittest.txt:
// "_ZaaZZZZ..." and "_ZaaZcvZcvZ..."
static constexpr int kRecursionDepthLimit = 256;
// We're trying to pick a charitable upper-limit on how many parse steps are
// necessary to handle something that a human could actually make use of.
// This is mostly in place as a bound on how much work we'll do if we are
// asked to demangle an mangled name from an untrusted source, so it should be
// much larger than the largest expected symbol, but much smaller than the
// amount of work we can do in, e.g., a second.
//
// Some real-world symbols from an arbitrary binary started failing between
// 2^12 and 2^13, so we multiply the latter by an extra factor of 16 to set
// the limit.
//
// Spending one second on 2^17 parse steps would require each step to take
// 7.6us, or ~30000 clock cycles, so it's safe to say this can be done in
// under a second.
static constexpr int kParseStepsLimit = 1 << 17;
bool IsTooComplex() const {
return state_->recursion_depth > kRecursionDepthLimit ||
state_->steps > kParseStepsLimit;
}
private:
State *state_;
};
} // namespace
// We don't use strlen() in libc since it's not guaranteed to be async
// signal safe.
static size_t StrLen(const char *str) {
size_t len = 0;
while (*str != '\0') {
++str;
++len;
}
return len;
}
// Returns true if "str" has at least "n" characters remaining.
static bool AtLeastNumCharsRemaining(const char *str, int n) {
for (int i = 0; i < n; ++i) {
if (str[i] == '\0') {
return false;
}
}
return true;
}
// Returns true if "str" has "prefix" as a prefix.
static bool StrPrefix(const char *str, const char *prefix) {
size_t i = 0;
while (str[i] != '\0' && prefix[i] != '\0' && str[i] == prefix[i]) {
++i;
}
return prefix[i] == '\0'; // Consumed everything in "prefix".
}
static void InitState(State *state, const char *mangled, char *out,
int out_size) {
state->mangled_begin = mangled;
state->out = out;
state->out_end_idx = out_size;
state->recursion_depth = 0;
state->steps = 0;
state->parse_state.mangled_idx = 0;
state->parse_state.out_cur_idx = 0;
state->parse_state.prev_name_idx = 0;
state->parse_state.prev_name_length = -1;
state->parse_state.nest_level = -1;
state->parse_state.append = true;
}
static inline const char *RemainingInput(State *state) {
return &state->mangled_begin[state->parse_state.mangled_idx];
}
// Returns true and advances "mangled_idx" if we find "one_char_token"
// at "mangled_idx" position. It is assumed that "one_char_token" does
// not contain '\0'.
static bool ParseOneCharToken(State *state, const char one_char_token) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (RemainingInput(state)[0] == one_char_token) {
++state->parse_state.mangled_idx;
return true;
}
return false;
}
// Returns true and advances "mangled_cur" if we find "two_char_token"
// at "mangled_cur" position. It is assumed that "two_char_token" does
// not contain '\0'.
static bool ParseTwoCharToken(State *state, const char *two_char_token) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (RemainingInput(state)[0] == two_char_token[0] &&
RemainingInput(state)[1] == two_char_token[1]) {
state->parse_state.mangled_idx += 2;
return true;
}
return false;
}
// Returns true and advances "mangled_cur" if we find any character in
// "char_class" at "mangled_cur" position.
static bool ParseCharClass(State *state, const char *char_class) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (RemainingInput(state)[0] == '\0') {
return false;
}
const char *p = char_class;
for (; *p != '\0'; ++p) {
if (RemainingInput(state)[0] == *p) {
++state->parse_state.mangled_idx;
return true;
}
}
return false;
}
static bool ParseDigit(State *state, int *digit) {
char c = RemainingInput(state)[0];
if (ParseCharClass(state, "0123456789")) {
if (digit != nullptr) {
*digit = c - '0';
}
return true;
}
return false;
}
// This function is used for handling an optional non-terminal.
static bool Optional(bool /*status*/) { return true; }
// This function is used for handling <non-terminal>+ syntax.
typedef bool (*ParseFunc)(State *);
static bool OneOrMore(ParseFunc parse_func, State *state) {
if (parse_func(state)) {
while (parse_func(state)) {
}
return true;
}
return false;
}
// This function is used for handling <non-terminal>* syntax. The function
// always returns true and must be followed by a termination token or a
// terminating sequence not handled by parse_func (e.g.
// ParseOneCharToken(state, 'E')).
static bool ZeroOrMore(ParseFunc parse_func, State *state) {
while (parse_func(state)) {
}
return true;
}
// Append "str" at "out_cur_idx". If there is an overflow, out_cur_idx is
// set to out_end_idx+1. The output string is ensured to
// always terminate with '\0' as long as there is no overflow.
static void Append(State *state, const char *const str, const int length) {
for (int i = 0; i < length; ++i) {
if (state->parse_state.out_cur_idx + 1 <
state->out_end_idx) { // +1 for '\0'
state->out[state->parse_state.out_cur_idx++] = str[i];
} else {
// signal overflow
state->parse_state.out_cur_idx = state->out_end_idx + 1;
break;
}
}
if (state->parse_state.out_cur_idx < state->out_end_idx) {
state->out[state->parse_state.out_cur_idx] =
'\0'; // Terminate it with '\0'
}
}
// We don't use equivalents in libc to avoid locale issues.
static bool IsLower(char c) { return c >= 'a' && c <= 'z'; }
static bool IsAlpha(char c) {
return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}
static bool IsDigit(char c) { return c >= '0' && c <= '9'; }
// Returns true if "str" is a function clone suffix. These suffixes are used
// by GCC 4.5.x and later versions (and our locally-modified version of GCC
// 4.4.x) to indicate functions which have been cloned during optimization.
// We treat any sequence (.<alpha>+.<digit>+)+ as a function clone suffix.
static bool IsFunctionCloneSuffix(const char *str) {
size_t i = 0;
while (str[i] != '\0') {
// Consume a single .<alpha>+.<digit>+ sequence.
if (str[i] != '.' || !IsAlpha(str[i + 1])) {
return false;
}
i += 2;
while (IsAlpha(str[i])) {
++i;
}
if (str[i] != '.' || !IsDigit(str[i + 1])) {
return false;
}
i += 2;
while (IsDigit(str[i])) {
++i;
}
}
return true; // Consumed everything in "str".
}
static bool EndsWith(State *state, const char chr) {
return state->parse_state.out_cur_idx > 0 &&
chr == state->out[state->parse_state.out_cur_idx - 1];
}
// Append "str" with some tweaks, iff "append" state is true.
static void MaybeAppendWithLength(State *state, const char *const str,
const int length) {
if (state->parse_state.append && length > 0) {
// Append a space if the output buffer ends with '<' and "str"
// starts with '<' to avoid <<<.
if (str[0] == '<' && EndsWith(state, '<')) {
Append(state, " ", 1);
}
// Remember the last identifier name for ctors/dtors.
if (IsAlpha(str[0]) || str[0] == '_') {
state->parse_state.prev_name_idx = state->parse_state.out_cur_idx;
state->parse_state.prev_name_length = length;
}
Append(state, str, length);
}
}
// Appends a positive decimal number to the output if appending is enabled.
static bool MaybeAppendDecimal(State *state, unsigned int val) {
// Max {32-64}-bit unsigned int is 20 digits.
constexpr size_t kMaxLength = 20;
char buf[kMaxLength];
// We can't use itoa or sprintf as neither is specified to be
// async-signal-safe.
if (state->parse_state.append) {
// We can't have a one-before-the-beginning pointer, so instead start with
// one-past-the-end and manipulate one character before the pointer.
char *p = &buf[kMaxLength];
do { // val=0 is the only input that should write a leading zero digit.
*--p = (val % 10) + '0';
val /= 10;
} while (p > buf && val != 0);
// 'p' landed on the last character we set. How convenient.
Append(state, p, kMaxLength - (p - buf));
}
return true;
}
// A convenient wrapper around MaybeAppendWithLength().
// Returns true so that it can be placed in "if" conditions.
static bool MaybeAppend(State *state, const char *const str) {
if (state->parse_state.append) {
int length = StrLen(str);
MaybeAppendWithLength(state, str, length);
}
return true;
}
// This function is used for handling nested names.
static bool EnterNestedName(State *state) {
state->parse_state.nest_level = 0;
return true;
}
// This function is used for handling nested names.
static bool LeaveNestedName(State *state, int16_t prev_value) {
state->parse_state.nest_level = prev_value;
return true;
}
// Disable the append mode not to print function parameters, etc.
static bool DisableAppend(State *state) {
state->parse_state.append = false;
return true;
}
// Restore the append mode to the previous state.
static bool RestoreAppend(State *state, bool prev_value) {
state->parse_state.append = prev_value;
return true;
}
// Increase the nest level for nested names.
static void MaybeIncreaseNestLevel(State *state) {
if (state->parse_state.nest_level > -1) {
++state->parse_state.nest_level;
}
}
// Appends :: for nested names if necessary.
static void MaybeAppendSeparator(State *state) {
if (state->parse_state.nest_level >= 1) {
MaybeAppend(state, "::");
}
}
// Cancel the last separator if necessary.
static void MaybeCancelLastSeparator(State *state) {
if (state->parse_state.nest_level >= 1 && state->parse_state.append &&
state->parse_state.out_cur_idx >= 2) {
state->parse_state.out_cur_idx -= 2;
state->out[state->parse_state.out_cur_idx] = '\0';
}
}
// Returns true if the identifier of the given length pointed to by
// "mangled_cur" is anonymous namespace.
static bool IdentifierIsAnonymousNamespace(State *state, int length) {
// Returns true if "anon_prefix" is a proper prefix of "mangled_cur".
static const char anon_prefix[] = "_GLOBAL__N_";
return (length > static_cast<int>(sizeof(anon_prefix) - 1) &&
StrPrefix(RemainingInput(state), anon_prefix));
}
// Forward declarations of our parsing functions.
static bool ParseMangledName(State *state);
static bool ParseEncoding(State *state);
static bool ParseName(State *state);
static bool ParseUnscopedName(State *state);
static bool ParseNestedName(State *state);
static bool ParsePrefix(State *state);
static bool ParseUnqualifiedName(State *state);
static bool ParseSourceName(State *state);
static bool ParseLocalSourceName(State *state);
static bool ParseUnnamedTypeName(State *state);
static bool ParseNumber(State *state, int *number_out);
static bool ParseFloatNumber(State *state);
static bool ParseSeqId(State *state);
static bool ParseIdentifier(State *state, int length);
static bool ParseOperatorName(State *state, int *arity);
static bool ParseSpecialName(State *state);
static bool ParseCallOffset(State *state);
static bool ParseNVOffset(State *state);
static bool ParseVOffset(State *state);
static bool ParseCtorDtorName(State *state);
static bool ParseDecltype(State *state);
static bool ParseType(State *state);
static bool ParseCVQualifiers(State *state);
static bool ParseBuiltinType(State *state);
static bool ParseFunctionType(State *state);
static bool ParseBareFunctionType(State *state);
static bool ParseClassEnumType(State *state);
static bool ParseArrayType(State *state);
static bool ParsePointerToMemberType(State *state);
static bool ParseTemplateParam(State *state);
static bool ParseTemplateTemplateParam(State *state);
static bool ParseTemplateArgs(State *state);
static bool ParseTemplateArg(State *state);
static bool ParseBaseUnresolvedName(State *state);
static bool ParseUnresolvedName(State *state);
static bool ParseExpression(State *state);
static bool ParseExprPrimary(State *state);
static bool ParseExprCastValue(State *state);
static bool ParseLocalName(State *state);
static bool ParseLocalNameSuffix(State *state);
static bool ParseDiscriminator(State *state);
static bool ParseSubstitution(State *state, bool accept_std);
// Implementation note: the following code is a straightforward
// translation of the Itanium C++ ABI defined in BNF with a couple of
// exceptions.
//
// - Support GNU extensions not defined in the Itanium C++ ABI
// - <prefix> and <template-prefix> are combined to avoid infinite loop
// - Reorder patterns to shorten the code
// - Reorder patterns to give greedier functions precedence
// We'll mark "Less greedy than" for these cases in the code
//
// Each parsing function changes the parse state and returns true on
// success, or returns false and doesn't change the parse state (note:
// the parse-steps counter increases regardless of success or failure).
// To ensure that the parse state isn't changed in the latter case, we
// save the original state before we call multiple parsing functions
// consecutively with &&, and restore it if unsuccessful. See
// ParseEncoding() as an example of this convention. We follow the
// convention throughout the code.
//
// Originally we tried to do demangling without following the full ABI
// syntax but it turned out we needed to follow the full syntax to
// parse complicated cases like nested template arguments. Note that
// implementing a full-fledged demangler isn't trivial (libiberty's
// cp-demangle.c has +4300 lines).
//
// Note that (foo) in <(foo) ...> is a modifier to be ignored.
//
// Reference:
// - Itanium C++ ABI
// <https://mentorembedded.github.io/cxx-abi/abi.html#mangling>
// <mangled-name> ::= _Z <encoding>
static bool ParseMangledName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
return ParseTwoCharToken(state, "_Z") && ParseEncoding(state);
}
// <encoding> ::= <(function) name> <bare-function-type>
// ::= <(data) name>
// ::= <special-name>
static bool ParseEncoding(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
// Implementing the first two productions together as <name>
// [<bare-function-type>] avoids exponential blowup of backtracking.
//
// Since Optional(...) can't fail, there's no need to copy the state for
// backtracking.
if (ParseName(state) && Optional(ParseBareFunctionType(state))) {
return true;
}
if (ParseSpecialName(state)) {
return true;
}
return false;
}
// <name> ::= <nested-name>
// ::= <unscoped-template-name> <template-args>
// ::= <unscoped-name>
// ::= <local-name>
static bool ParseName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseNestedName(state) || ParseLocalName(state)) {
return true;
}
// We reorganize the productions to avoid re-parsing unscoped names.
// - Inline <unscoped-template-name> productions:
// <name> ::= <substitution> <template-args>
// ::= <unscoped-name> <template-args>
// ::= <unscoped-name>
// - Merge the two productions that start with unscoped-name:
// <name> ::= <unscoped-name> [<template-args>]
ParseState copy = state->parse_state;
// "std<...>" isn't a valid name.
if (ParseSubstitution(state, /*accept_std=*/false) &&
ParseTemplateArgs(state)) {
return true;
}
state->parse_state = copy;
// Note there's no need to restore state after this since only the first
// subparser can fail.
return ParseUnscopedName(state) && Optional(ParseTemplateArgs(state));
}
// <unscoped-name> ::= <unqualified-name>
// ::= St <unqualified-name>
static bool ParseUnscopedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseUnqualifiedName(state)) {
return true;
}
ParseState copy = state->parse_state;
if (ParseTwoCharToken(state, "St") && MaybeAppend(state, "std::") &&
ParseUnqualifiedName(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <ref-qualifer> ::= R // lvalue method reference qualifier
// ::= O // rvalue method reference qualifier
static inline bool ParseRefQualifier(State *state) {
return ParseCharClass(state, "OR");
}
// <nested-name> ::= N [<CV-qualifiers>] [<ref-qualifier>] <prefix>
// <unqualified-name> E
// ::= N [<CV-qualifiers>] [<ref-qualifier>] <template-prefix>
// <template-args> E
static bool ParseNestedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'N') && EnterNestedName(state) &&
Optional(ParseCVQualifiers(state)) &&
Optional(ParseRefQualifier(state)) && ParsePrefix(state) &&
LeaveNestedName(state, copy.nest_level) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// This part is tricky. If we literally translate them to code, we'll
// end up infinite loop. Hence we merge them to avoid the case.
//
// <prefix> ::= <prefix> <unqualified-name>
// ::= <template-prefix> <template-args>
// ::= <template-param>
// ::= <substitution>
// ::= # empty
// <template-prefix> ::= <prefix> <(template) unqualified-name>
// ::= <template-param>
// ::= <substitution>
static bool ParsePrefix(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
bool has_something = false;
while (true) {
MaybeAppendSeparator(state);
if (ParseTemplateParam(state) ||
ParseSubstitution(state, /*accept_std=*/true) ||
ParseUnscopedName(state) ||
(ParseOneCharToken(state, 'M') && ParseUnnamedTypeName(state))) {
has_something = true;
MaybeIncreaseNestLevel(state);
continue;
}
MaybeCancelLastSeparator(state);
if (has_something && ParseTemplateArgs(state)) {
return ParsePrefix(state);
} else {
break;
}
}
return true;
}
// <unqualified-name> ::= <operator-name>
// ::= <ctor-dtor-name>
// ::= <source-name>
// ::= <local-source-name> // GCC extension; see below.
// ::= <unnamed-type-name>
static bool ParseUnqualifiedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
return (ParseOperatorName(state, nullptr) || ParseCtorDtorName(state) ||
ParseSourceName(state) || ParseLocalSourceName(state) ||
ParseUnnamedTypeName(state));
}
// <source-name> ::= <positive length number> <identifier>
static bool ParseSourceName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
int length = -1;
if (ParseNumber(state, &length) && ParseIdentifier(state, length)) {
return true;
}
state->parse_state = copy;
return false;
}
// <local-source-name> ::= L <source-name> [<discriminator>]
//
// References:
// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31775
// https://gcc.gnu.org/viewcvs?view=rev&revision=124467
static bool ParseLocalSourceName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'L') && ParseSourceName(state) &&
Optional(ParseDiscriminator(state))) {
return true;
}
state->parse_state = copy;
return false;
}
// <unnamed-type-name> ::= Ut [<(nonnegative) number>] _
// ::= <closure-type-name>
// <closure-type-name> ::= Ul <lambda-sig> E [<(nonnegative) number>] _
// <lambda-sig> ::= <(parameter) type>+
static bool ParseUnnamedTypeName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
// Type's 1-based index n is encoded as { "", n == 1; itoa(n-2), otherwise }.
// Optionally parse the encoded value into 'which' and add 2 to get the index.
int which = -1;
// Unnamed type local to function or class.
if (ParseTwoCharToken(state, "Ut") && Optional(ParseNumber(state, &which)) &&
which <= std::numeric_limits<int>::max() - 2 && // Don't overflow.
ParseOneCharToken(state, '_')) {
MaybeAppend(state, "{unnamed type#");
MaybeAppendDecimal(state, 2 + which);
MaybeAppend(state, "}");
return true;
}
state->parse_state = copy;
// Closure type.
which = -1;
if (ParseTwoCharToken(state, "Ul") && DisableAppend(state) &&
OneOrMore(ParseType, state) && RestoreAppend(state, copy.append) &&
ParseOneCharToken(state, 'E') && Optional(ParseNumber(state, &which)) &&
which <= std::numeric_limits<int>::max() - 2 && // Don't overflow.
ParseOneCharToken(state, '_')) {
MaybeAppend(state, "{lambda()#");
MaybeAppendDecimal(state, 2 + which);
MaybeAppend(state, "}");
return true;
}
state->parse_state = copy;
return false;
}
// <number> ::= [n] <non-negative decimal integer>
// If "number_out" is non-null, then *number_out is set to the value of the
// parsed number on success.
static bool ParseNumber(State *state, int *number_out) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
bool negative = false;
if (ParseOneCharToken(state, 'n')) {
negative = true;
}
const char *p = RemainingInput(state);
uint64_t number = 0;
for (; *p != '\0'; ++p) {
if (IsDigit(*p)) {
number = number * 10 + (*p - '0');
} else {
break;
}
}
// Apply the sign with uint64_t arithmetic so overflows aren't UB. Gives
// "incorrect" results for out-of-range inputs, but negative values only
// appear for literals, which aren't printed.
if (negative) {
number = ~number + 1;
}
if (p != RemainingInput(state)) { // Conversion succeeded.
state->parse_state.mangled_idx += p - RemainingInput(state);
if (number_out != nullptr) {
// Note: possibly truncate "number".
*number_out = number;
}
return true;
}
return false;
}
// Floating-point literals are encoded using a fixed-length lowercase
// hexadecimal string.
static bool ParseFloatNumber(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
const char *p = RemainingInput(state);
for (; *p != '\0'; ++p) {
if (!IsDigit(*p) && !(*p >= 'a' && *p <= 'f')) {
break;
}
}
if (p != RemainingInput(state)) { // Conversion succeeded.
state->parse_state.mangled_idx += p - RemainingInput(state);
return true;
}
return false;
}
// The <seq-id> is a sequence number in base 36,
// using digits and upper case letters
static bool ParseSeqId(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
const char *p = RemainingInput(state);
for (; *p != '\0'; ++p) {
if (!IsDigit(*p) && !(*p >= 'A' && *p <= 'Z')) {
break;
}
}
if (p != RemainingInput(state)) { // Conversion succeeded.
state->parse_state.mangled_idx += p - RemainingInput(state);
return true;
}
return false;
}
// <identifier> ::= <unqualified source code identifier> (of given length)
static bool ParseIdentifier(State *state, int length) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (length < 0 || !AtLeastNumCharsRemaining(RemainingInput(state), length)) {
return false;
}
if (IdentifierIsAnonymousNamespace(state, length)) {
MaybeAppend(state, "(anonymous namespace)");
} else {
MaybeAppendWithLength(state, RemainingInput(state), length);
}
state->parse_state.mangled_idx += length;
return true;
}
// <operator-name> ::= nw, and other two letters cases
// ::= cv <type> # (cast)
// ::= v <digit> <source-name> # vendor extended operator
static bool ParseOperatorName(State *state, int *arity) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (!AtLeastNumCharsRemaining(RemainingInput(state), 2)) {
return false;
}
// First check with "cv" (cast) case.
ParseState copy = state->parse_state;
if (ParseTwoCharToken(state, "cv") && MaybeAppend(state, "operator ") &&
EnterNestedName(state) && ParseType(state) &&
LeaveNestedName(state, copy.nest_level)) {
if (arity != nullptr) {
*arity = 1;
}
return true;
}
state->parse_state = copy;
// Then vendor extended operators.
if (ParseOneCharToken(state, 'v') && ParseDigit(state, arity) &&
ParseSourceName(state)) {
return true;
}
state->parse_state = copy;
// Other operator names should start with a lower alphabet followed
// by a lower/upper alphabet.
if (!(IsLower(RemainingInput(state)[0]) &&
IsAlpha(RemainingInput(state)[1]))) {
return false;
}
// We may want to perform a binary search if we really need speed.
const AbbrevPair *p;
for (p = kOperatorList; p->abbrev != nullptr; ++p) {
if (RemainingInput(state)[0] == p->abbrev[0] &&
RemainingInput(state)[1] == p->abbrev[1]) {
if (arity != nullptr) {
*arity = p->arity;
}
MaybeAppend(state, "operator");
if (IsLower(*p->real_name)) { // new, delete, etc.
MaybeAppend(state, " ");
}
MaybeAppend(state, p->real_name);
state->parse_state.mangled_idx += 2;
return true;
}
}
return false;
}
// <special-name> ::= TV <type>
// ::= TT <type>
// ::= TI <type>
// ::= TS <type>
// ::= Tc <call-offset> <call-offset> <(base) encoding>
// ::= GV <(object) name>
// ::= T <call-offset> <(base) encoding>
// G++ extensions:
// ::= TC <type> <(offset) number> _ <(base) type>
// ::= TF <type>
// ::= TJ <type>
// ::= GR <name>
// ::= GA <encoding>
// ::= Th <call-offset> <(base) encoding>
// ::= Tv <call-offset> <(base) encoding>
//
// Note: we don't care much about them since they don't appear in
// stack traces. The are special data.
static bool ParseSpecialName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "VTIS") &&
ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "Tc") && ParseCallOffset(state) &&
ParseCallOffset(state) && ParseEncoding(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "GV") && ParseName(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'T') && ParseCallOffset(state) &&
ParseEncoding(state)) {
return true;
}
state->parse_state = copy;
// G++ extensions
if (ParseTwoCharToken(state, "TC") && ParseType(state) &&
ParseNumber(state, nullptr) && ParseOneCharToken(state, '_') &&
DisableAppend(state) && ParseType(state)) {
RestoreAppend(state, copy.append);
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "FJ") &&
ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "GR") && ParseName(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "GA") && ParseEncoding(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "hv") &&
ParseCallOffset(state) && ParseEncoding(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <call-offset> ::= h <nv-offset> _
// ::= v <v-offset> _
static bool ParseCallOffset(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'h') && ParseNVOffset(state) &&
ParseOneCharToken(state, '_')) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'v') && ParseVOffset(state) &&
ParseOneCharToken(state, '_')) {
return true;
}
state->parse_state = copy;
return false;
}
// <nv-offset> ::= <(offset) number>
static bool ParseNVOffset(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
return ParseNumber(state, nullptr);
}
// <v-offset> ::= <(offset) number> _ <(virtual offset) number>
static bool ParseVOffset(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseNumber(state, nullptr) && ParseOneCharToken(state, '_') &&
ParseNumber(state, nullptr)) {
return true;
}
state->parse_state = copy;
return false;
}
// <ctor-dtor-name> ::= C1 | C2 | C3
// ::= D0 | D1 | D2
// # GCC extensions: "unified" constructor/destructor. See
// # https://github.com/gcc-mirror/gcc/blob/7ad17b583c3643bd4557f29b8391ca7ef08391f5/gcc/cp/mangle.c#L1847
// ::= C4 | D4
static bool ParseCtorDtorName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'C') && ParseCharClass(state, "1234")) {
const char *const prev_name = state->out + state->parse_state.prev_name_idx;
MaybeAppendWithLength(state, prev_name,
state->parse_state.prev_name_length);
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'D') && ParseCharClass(state, "0124")) {
const char *const prev_name = state->out + state->parse_state.prev_name_idx;
MaybeAppend(state, "~");
MaybeAppendWithLength(state, prev_name,
state->parse_state.prev_name_length);
return true;
}
state->parse_state = copy;
return false;
}
// <decltype> ::= Dt <expression> E # decltype of an id-expression or class
// # member access (C++0x)
// ::= DT <expression> E # decltype of an expression (C++0x)
static bool ParseDecltype(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'D') && ParseCharClass(state, "tT") &&
ParseExpression(state) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <type> ::= <CV-qualifiers> <type>
// ::= P <type> # pointer-to
// ::= R <type> # reference-to
// ::= O <type> # rvalue reference-to (C++0x)
// ::= C <type> # complex pair (C 2000)
// ::= G <type> # imaginary (C 2000)
// ::= U <source-name> <type> # vendor extended type qualifier
// ::= <builtin-type>
// ::= <function-type>
// ::= <class-enum-type> # note: just an alias for <name>
// ::= <array-type>
// ::= <pointer-to-member-type>
// ::= <template-template-param> <template-args>
// ::= <template-param>
// ::= <decltype>
// ::= <substitution>
// ::= Dp <type> # pack expansion of (C++0x)
//
static bool ParseType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
// We should check CV-qualifers, and PRGC things first.
//
// CV-qualifiers overlap with some operator names, but an operator name is not
// valid as a type. To avoid an ambiguity that can lead to exponential time
// complexity, refuse to backtrack the CV-qualifiers.
//
// _Z4aoeuIrMvvE
// => _Z 4aoeuI rM v v E
// aoeu<operator%=, void, void>
// => _Z 4aoeuI r Mv v E
// aoeu<void void::* restrict>
//
// By consuming the CV-qualifiers first, the former parse is disabled.
if (ParseCVQualifiers(state)) {
const bool result = ParseType(state);
if (!result) state->parse_state = copy;
return result;
}
state->parse_state = copy;
// Similarly, these tag characters can overlap with other <name>s resulting in
// two different parse prefixes that land on <template-args> in the same
// place, such as "C3r1xI...". So, disable the "ctor-name = C3" parse by
// refusing to backtrack the tag characters.
if (ParseCharClass(state, "OPRCG")) {
const bool result = ParseType(state);
if (!result) state->parse_state = copy;
return result;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "Dp") && ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'U') && ParseSourceName(state) &&
ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseBuiltinType(state) || ParseFunctionType(state) ||
ParseClassEnumType(state) || ParseArrayType(state) ||
ParsePointerToMemberType(state) || ParseDecltype(state) ||
// "std" on its own isn't a type.
ParseSubstitution(state, /*accept_std=*/false)) {
return true;
}
if (ParseTemplateTemplateParam(state) && ParseTemplateArgs(state)) {
return true;
}
state->parse_state = copy;
// Less greedy than <template-template-param> <template-args>.
if (ParseTemplateParam(state)) {
return true;
}
return false;
}
// <CV-qualifiers> ::= [r] [V] [K]
// We don't allow empty <CV-qualifiers> to avoid infinite loop in
// ParseType().
static bool ParseCVQualifiers(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
int num_cv_qualifiers = 0;
num_cv_qualifiers += ParseOneCharToken(state, 'r');
num_cv_qualifiers += ParseOneCharToken(state, 'V');
num_cv_qualifiers += ParseOneCharToken(state, 'K');
return num_cv_qualifiers > 0;
}
// <builtin-type> ::= v, etc.
// ::= u <source-name>
static bool ParseBuiltinType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
const AbbrevPair *p;
for (p = kBuiltinTypeList; p->abbrev != nullptr; ++p) {
if (RemainingInput(state)[0] == p->abbrev[0]) {
MaybeAppend(state, p->real_name);
++state->parse_state.mangled_idx;
return true;
}
}
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'u') && ParseSourceName(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <function-type> ::= F [Y] <bare-function-type> E
static bool ParseFunctionType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'F') &&
Optional(ParseOneCharToken(state, 'Y')) && ParseBareFunctionType(state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <bare-function-type> ::= <(signature) type>+
static bool ParseBareFunctionType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
DisableAppend(state);
if (OneOrMore(ParseType, state)) {
RestoreAppend(state, copy.append);
MaybeAppend(state, "()");
return true;
}
state->parse_state = copy;
return false;
}
// <class-enum-type> ::= <name>
static bool ParseClassEnumType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
return ParseName(state);
}
// <array-type> ::= A <(positive dimension) number> _ <(element) type>
// ::= A [<(dimension) expression>] _ <(element) type>
static bool ParseArrayType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'A') && ParseNumber(state, nullptr) &&
ParseOneCharToken(state, '_') && ParseType(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'A') && Optional(ParseExpression(state)) &&
ParseOneCharToken(state, '_') && ParseType(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <pointer-to-member-type> ::= M <(class) type> <(member) type>
static bool ParsePointerToMemberType(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'M') && ParseType(state) && ParseType(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <template-param> ::= T_
// ::= T <parameter-2 non-negative number> _
static bool ParseTemplateParam(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseTwoCharToken(state, "T_")) {
MaybeAppend(state, "?"); // We don't support template substitutions.
return true;
}
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'T') && ParseNumber(state, nullptr) &&
ParseOneCharToken(state, '_')) {
MaybeAppend(state, "?"); // We don't support template substitutions.
return true;
}
state->parse_state = copy;
return false;
}
// <template-template-param> ::= <template-param>
// ::= <substitution>
static bool ParseTemplateTemplateParam(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
return (ParseTemplateParam(state) ||
// "std" on its own isn't a template.
ParseSubstitution(state, /*accept_std=*/false));
}
// <template-args> ::= I <template-arg>+ E
static bool ParseTemplateArgs(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
DisableAppend(state);
if (ParseOneCharToken(state, 'I') && OneOrMore(ParseTemplateArg, state) &&
ParseOneCharToken(state, 'E')) {
RestoreAppend(state, copy.append);
MaybeAppend(state, "<>");
return true;
}
state->parse_state = copy;
return false;
}
// <template-arg> ::= <type>
// ::= <expr-primary>
// ::= J <template-arg>* E # argument pack
// ::= X <expression> E
static bool ParseTemplateArg(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'J') && ZeroOrMore(ParseTemplateArg, state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
// There can be significant overlap between the following leading to
// exponential backtracking:
//
// <expr-primary> ::= L <type> <expr-cast-value> E
// e.g. L 2xxIvE 1 E
// <type> ==> <local-source-name> <template-args>
// e.g. L 2xx IvE
//
// This means parsing an entire <type> twice, and <type> can contain
// <template-arg>, so this can generate exponential backtracking. There is
// only overlap when the remaining input starts with "L <source-name>", so
// parse all cases that can start this way jointly to share the common prefix.
//
// We have:
//
// <template-arg> ::= <type>
// ::= <expr-primary>
//
// First, drop all the productions of <type> that must start with something
// other than 'L'. All that's left is <class-enum-type>; inline it.
//
// <type> ::= <nested-name> # starts with 'N'
// ::= <unscoped-name>
// ::= <unscoped-template-name> <template-args>
// ::= <local-name> # starts with 'Z'
//
// Drop and inline again:
//
// <type> ::= <unscoped-name>
// ::= <unscoped-name> <template-args>
// ::= <substitution> <template-args> # starts with 'S'
//
// Merge the first two, inline <unscoped-name>, drop last:
//
// <type> ::= <unqualified-name> [<template-args>]
// ::= St <unqualified-name> [<template-args>] # starts with 'S'
//
// Drop and inline:
//
// <type> ::= <operator-name> [<template-args>] # starts with lowercase
// ::= <ctor-dtor-name> [<template-args>] # starts with 'C' or 'D'
// ::= <source-name> [<template-args>] # starts with digit
// ::= <local-source-name> [<template-args>]
// ::= <unnamed-type-name> [<template-args>] # starts with 'U'
//
// One more time:
//
// <type> ::= L <source-name> [<template-args>]
//
// Likewise with <expr-primary>:
//
// <expr-primary> ::= L <type> <expr-cast-value> E
// ::= LZ <encoding> E # cannot overlap; drop
// ::= L <mangled_name> E # cannot overlap; drop
//
// By similar reasoning as shown above, the only <type>s starting with
// <source-name> are "<source-name> [<template-args>]". Inline this.
//
// <expr-primary> ::= L <source-name> [<template-args>] <expr-cast-value> E
//
// Now inline both of these into <template-arg>:
//
// <template-arg> ::= L <source-name> [<template-args>]
// ::= L <source-name> [<template-args>] <expr-cast-value> E
//
// Merge them and we're done:
// <template-arg>
// ::= L <source-name> [<template-args>] [<expr-cast-value> E]
if (ParseLocalSourceName(state) && Optional(ParseTemplateArgs(state))) {
copy = state->parse_state;
if (ParseExprCastValue(state) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return true;
}
// Now that the overlapping cases can't reach this code, we can safely call
// both of these.
if (ParseType(state) || ParseExprPrimary(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'X') && ParseExpression(state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <unresolved-type> ::= <template-param> [<template-args>]
// ::= <decltype>
// ::= <substitution>
static inline bool ParseUnresolvedType(State *state) {
// No ComplexityGuard because we don't copy the state in this stack frame.
return (ParseTemplateParam(state) && Optional(ParseTemplateArgs(state))) ||
ParseDecltype(state) || ParseSubstitution(state, /*accept_std=*/false);
}
// <simple-id> ::= <source-name> [<template-args>]
static inline bool ParseSimpleId(State *state) {
// No ComplexityGuard because we don't copy the state in this stack frame.
// Note: <simple-id> cannot be followed by a parameter pack; see comment in
// ParseUnresolvedType.
return ParseSourceName(state) && Optional(ParseTemplateArgs(state));
}
// <base-unresolved-name> ::= <source-name> [<template-args>]
// ::= on <operator-name> [<template-args>]
// ::= dn <destructor-name>
static bool ParseBaseUnresolvedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseSimpleId(state)) {
return true;
}
ParseState copy = state->parse_state;
if (ParseTwoCharToken(state, "on") && ParseOperatorName(state, nullptr) &&
Optional(ParseTemplateArgs(state))) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "dn") &&
(ParseUnresolvedType(state) || ParseSimpleId(state))) {
return true;
}
state->parse_state = copy;
return false;
}
// <unresolved-name> ::= [gs] <base-unresolved-name>
// ::= sr <unresolved-type> <base-unresolved-name>
// ::= srN <unresolved-type> <unresolved-qualifier-level>+ E
// <base-unresolved-name>
// ::= [gs] sr <unresolved-qualifier-level>+ E
// <base-unresolved-name>
static bool ParseUnresolvedName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (Optional(ParseTwoCharToken(state, "gs")) &&
ParseBaseUnresolvedName(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "sr") && ParseUnresolvedType(state) &&
ParseBaseUnresolvedName(state)) {
return true;
}
state->parse_state = copy;
if (ParseTwoCharToken(state, "sr") && ParseOneCharToken(state, 'N') &&
ParseUnresolvedType(state) &&
OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
return true;
}
state->parse_state = copy;
if (Optional(ParseTwoCharToken(state, "gs")) &&
ParseTwoCharToken(state, "sr") &&
OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <expression> ::= <1-ary operator-name> <expression>
// ::= <2-ary operator-name> <expression> <expression>
// ::= <3-ary operator-name> <expression> <expression> <expression>
// ::= cl <expression>+ E
// ::= cv <type> <expression> # type (expression)
// ::= cv <type> _ <expression>* E # type (expr-list)
// ::= st <type>
// ::= <template-param>
// ::= <function-param>
// ::= <expr-primary>
// ::= dt <expression> <unresolved-name> # expr.name
// ::= pt <expression> <unresolved-name> # expr->name
// ::= sp <expression> # argument pack expansion
// ::= sr <type> <unqualified-name> <template-args>
// ::= sr <type> <unqualified-name>
// <function-param> ::= fp <(top-level) CV-qualifiers> _
// ::= fp <(top-level) CV-qualifiers> <number> _
// ::= fL <number> p <(top-level) CV-qualifiers> _
// ::= fL <number> p <(top-level) CV-qualifiers> <number> _
static bool ParseExpression(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseTemplateParam(state) || ParseExprPrimary(state)) {
return true;
}
// Object/function call expression.
ParseState copy = state->parse_state;
if (ParseTwoCharToken(state, "cl") && OneOrMore(ParseExpression, state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
// Function-param expression (level 0).
if (ParseTwoCharToken(state, "fp") && Optional(ParseCVQualifiers(state)) &&
Optional(ParseNumber(state, nullptr)) && ParseOneCharToken(state, '_')) {
return true;
}
state->parse_state = copy;
// Function-param expression (level 1+).
if (ParseTwoCharToken(state, "fL") && Optional(ParseNumber(state, nullptr)) &&
ParseOneCharToken(state, 'p') && Optional(ParseCVQualifiers(state)) &&
Optional(ParseNumber(state, nullptr)) && ParseOneCharToken(state, '_')) {
return true;
}
state->parse_state = copy;
// Parse the conversion expressions jointly to avoid re-parsing the <type> in
// their common prefix. Parsed as:
// <expression> ::= cv <type> <conversion-args>
// <conversion-args> ::= _ <expression>* E
// ::= <expression>
//
// Also don't try ParseOperatorName after seeing "cv", since ParseOperatorName
// also needs to accept "cv <type>" in other contexts.
if (ParseTwoCharToken(state, "cv")) {
if (ParseType(state)) {
ParseState copy2 = state->parse_state;
if (ParseOneCharToken(state, '_') && ZeroOrMore(ParseExpression, state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy2;
if (ParseExpression(state)) {
return true;
}
}
} else {
// Parse unary, binary, and ternary operator expressions jointly, taking
// care not to re-parse subexpressions repeatedly. Parse like:
// <expression> ::= <operator-name> <expression>
// [<one-to-two-expressions>]
// <one-to-two-expressions> ::= <expression> [<expression>]
int arity = -1;
if (ParseOperatorName(state, &arity) &&
arity > 0 && // 0 arity => disabled.
(arity < 3 || ParseExpression(state)) &&
(arity < 2 || ParseExpression(state)) &&
(arity < 1 || ParseExpression(state))) {
return true;
}
}
state->parse_state = copy;
// sizeof type
if (ParseTwoCharToken(state, "st") && ParseType(state)) {
return true;
}
state->parse_state = copy;
// Object and pointer member access expressions.
if ((ParseTwoCharToken(state, "dt") || ParseTwoCharToken(state, "pt")) &&
ParseExpression(state) && ParseType(state)) {
return true;
}
state->parse_state = copy;
// Pointer-to-member access expressions. This parses the same as a binary
// operator, but it's implemented separately because "ds" shouldn't be
// accepted in other contexts that parse an operator name.
if (ParseTwoCharToken(state, "ds") && ParseExpression(state) &&
ParseExpression(state)) {
return true;
}
state->parse_state = copy;
// Parameter pack expansion
if (ParseTwoCharToken(state, "sp") && ParseExpression(state)) {
return true;
}
state->parse_state = copy;
return ParseUnresolvedName(state);
}
// <expr-primary> ::= L <type> <(value) number> E
// ::= L <type> <(value) float> E
// ::= L <mangled-name> E
// // A bug in g++'s C++ ABI version 2 (-fabi-version=2).
// ::= LZ <encoding> E
//
// Warning, subtle: the "bug" LZ production above is ambiguous with the first
// production where <type> starts with <local-name>, which can lead to
// exponential backtracking in two scenarios:
//
// - When whatever follows the E in the <local-name> in the first production is
// not a name, we backtrack the whole <encoding> and re-parse the whole thing.
//
// - When whatever follows the <local-name> in the first production is not a
// number and this <expr-primary> may be followed by a name, we backtrack the
// <name> and re-parse it.
//
// Moreover this ambiguity isn't always resolved -- for example, the following
// has two different parses:
//
// _ZaaILZ4aoeuE1x1EvE
// => operator&&<aoeu, x, E, void>
// => operator&&<(aoeu::x)(1), void>
//
// To resolve this, we just do what GCC's demangler does, and refuse to parse
// casts to <local-name> types.
static bool ParseExprPrimary(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
// The "LZ" special case: if we see LZ, we commit to accept "LZ <encoding> E"
// or fail, no backtracking.
if (ParseTwoCharToken(state, "LZ")) {
if (ParseEncoding(state) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// The merged cast production.
if (ParseOneCharToken(state, 'L') && ParseType(state) &&
ParseExprCastValue(state)) {
return true;
}
state->parse_state = copy;
if (ParseOneCharToken(state, 'L') && ParseMangledName(state) &&
ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <number> or <float>, followed by 'E', as described above ParseExprPrimary.
static bool ParseExprCastValue(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
// We have to be able to backtrack after accepting a number because we could
// have e.g. "7fffE", which will accept "7" as a number but then fail to find
// the 'E'.
ParseState copy = state->parse_state;
if (ParseNumber(state, nullptr) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
if (ParseFloatNumber(state) && ParseOneCharToken(state, 'E')) {
return true;
}
state->parse_state = copy;
return false;
}
// <local-name> ::= Z <(function) encoding> E <(entity) name> [<discriminator>]
// ::= Z <(function) encoding> E s [<discriminator>]
//
// Parsing a common prefix of these two productions together avoids an
// exponential blowup of backtracking. Parse like:
// <local-name> := Z <encoding> E <local-name-suffix>
// <local-name-suffix> ::= s [<discriminator>]
// ::= <name> [<discriminator>]
static bool ParseLocalNameSuffix(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (MaybeAppend(state, "::") && ParseName(state) &&
Optional(ParseDiscriminator(state))) {
return true;
}
// Since we're not going to overwrite the above "::" by re-parsing the
// <encoding> (whose trailing '\0' byte was in the byte now holding the
// first ':'), we have to rollback the "::" if the <name> parse failed.
if (state->parse_state.append) {
state->out[state->parse_state.out_cur_idx - 2] = '\0';
}
return ParseOneCharToken(state, 's') && Optional(ParseDiscriminator(state));
}
static bool ParseLocalName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'Z') && ParseEncoding(state) &&
ParseOneCharToken(state, 'E') && ParseLocalNameSuffix(state)) {
return true;
}
state->parse_state = copy;
return false;
}
// <discriminator> := _ <(non-negative) number>
static bool ParseDiscriminator(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, '_') && ParseNumber(state, nullptr)) {
return true;
}
state->parse_state = copy;
return false;
}
// <substitution> ::= S_
// ::= S <seq-id> _
// ::= St, etc.
//
// "St" is special in that it's not valid as a standalone name, and it *is*
// allowed to precede a name without being wrapped in "N...E". This means that
// if we accept it on its own, we can accept "St1a" and try to parse
// template-args, then fail and backtrack, accept "St" on its own, then "1a" as
// an unqualified name and re-parse the same template-args. To block this
// exponential backtracking, we disable it with 'accept_std=false' in
// problematic contexts.
static bool ParseSubstitution(State *state, bool accept_std) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseTwoCharToken(state, "S_")) {
MaybeAppend(state, "?"); // We don't support substitutions.
return true;
}
ParseState copy = state->parse_state;
if (ParseOneCharToken(state, 'S') && ParseSeqId(state) &&
ParseOneCharToken(state, '_')) {
MaybeAppend(state, "?"); // We don't support substitutions.
return true;
}
state->parse_state = copy;
// Expand abbreviations like "St" => "std".
if (ParseOneCharToken(state, 'S')) {
const AbbrevPair *p;
for (p = kSubstitutionList; p->abbrev != nullptr; ++p) {
if (RemainingInput(state)[0] == p->abbrev[1] &&
(accept_std || p->abbrev[1] != 't')) {
MaybeAppend(state, "std");
if (p->real_name[0] != '\0') {
MaybeAppend(state, "::");
MaybeAppend(state, p->real_name);
}
++state->parse_state.mangled_idx;
return true;
}
}
}
state->parse_state = copy;
return false;
}
// Parse <mangled-name>, optionally followed by either a function-clone suffix
// or version suffix. Returns true only if all of "mangled_cur" was consumed.
static bool ParseTopLevelMangledName(State *state) {
ComplexityGuard guard(state);
if (guard.IsTooComplex()) return false;
if (ParseMangledName(state)) {
if (RemainingInput(state)[0] != '\0') {
// Drop trailing function clone suffix, if any.
if (IsFunctionCloneSuffix(RemainingInput(state))) {
return true;
}
// Append trailing version suffix if any.
// ex. _Z3foo@@GLIBCXX_3.4
if (RemainingInput(state)[0] == '@') {
MaybeAppend(state, RemainingInput(state));
return true;
}
return false; // Unconsumed suffix.
}
return true;
}
return false;
}
static bool Overflowed(const State *state) {
return state->parse_state.out_cur_idx >= state->out_end_idx;
}
// The demangler entry point.
bool Demangle(const char *mangled, char *out, int out_size) {
State state;
InitState(&state, mangled, out, out_size);
return ParseTopLevelMangledName(&state) && !Overflowed(&state);
}
} // namespace debugging_internal
} // namespace absl