diff options
Diffstat (limited to 'absl/debugging/internal')
| -rw-r--r-- | absl/debugging/internal/demangle.cc | 1862 | ||||
| -rw-r--r-- | absl/debugging/internal/demangle.h | 67 | ||||
| -rw-r--r-- | absl/debugging/internal/demangle_test.cc | 191 |
3 files changed, 2120 insertions, 0 deletions
diff --git a/absl/debugging/internal/demangle.cc b/absl/debugging/internal/demangle.cc new file mode 100644 index 00000000..c9ca2f3b --- /dev/null +++ b/absl/debugging/internal/demangle.cc @@ -0,0 +1,1862 @@ +// 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 +// +// http://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 std::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: +// http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31775 +// http://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 std::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; + + // 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 diff --git a/absl/debugging/internal/demangle.h b/absl/debugging/internal/demangle.h new file mode 100644 index 00000000..2e75564e --- /dev/null +++ b/absl/debugging/internal/demangle.h @@ -0,0 +1,67 @@ +// 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 +// +// http://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. + +// An async-signal-safe and thread-safe demangler for Itanium C++ ABI +// (aka G++ V3 ABI). +// +// The demangler is implemented to be used in async signal handlers to +// symbolize stack traces. We cannot use libstdc++'s +// abi::__cxa_demangle() in such signal handlers since it's not async +// signal safe (it uses malloc() internally). +// +// Note that this demangler doesn't support full demangling. More +// specifically, it doesn't print types of function parameters and +// types of template arguments. It just skips them. However, it's +// still very useful to extract basic information such as class, +// function, constructor, destructor, and operator names. +// +// See the implementation note in demangle.cc if you are interested. +// +// Example: +// +// | Mangled Name | The Demangler | abi::__cxa_demangle() +// |---------------|---------------|----------------------- +// | _Z1fv | f() | f() +// | _Z1fi | f() | f(int) +// | _Z3foo3bar | foo() | foo(bar) +// | _Z1fIiEvi | f<>() | void f<int>(int) +// | _ZN1N1fE | N::f | N::f +// | _ZN3Foo3BarEv | Foo::Bar() | Foo::Bar() +// | _Zrm1XS_" | operator%() | operator%(X, X) +// | _ZN3FooC1Ev | Foo::Foo() | Foo::Foo() +// | _Z1fSs | f() | f(std::basic_string<char, +// | | | std::char_traits<char>, +// | | | std::allocator<char> >) +// +// See the unit test for more examples. +// +// Note: we might want to write demanglers for ABIs other than Itanium +// C++ ABI in the future. +// + +#ifndef ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_ +#define ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_ + +namespace absl { +namespace debugging_internal { + +// Demangle `mangled`. On success, return true and write the +// demangled symbol name to `out`. Otherwise, return false. +// `out` is modified even if demangling is unsuccessful. +bool Demangle(const char *mangled, char *out, int out_size); + +} // namespace debugging_internal +} // namespace absl + +#endif // ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_ diff --git a/absl/debugging/internal/demangle_test.cc b/absl/debugging/internal/demangle_test.cc new file mode 100644 index 00000000..b9d9008f --- /dev/null +++ b/absl/debugging/internal/demangle_test.cc @@ -0,0 +1,191 @@ +// 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 +// +// http://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. + +#include "absl/debugging/internal/demangle.h" + +#include <cstdlib> +#include <string> + +#include "gtest/gtest.h" +#include "absl/base/internal/raw_logging.h" +#include "absl/debugging/internal/stack_consumption.h" +#include "absl/memory/memory.h" + +namespace absl { +namespace debugging_internal { +namespace { + +// A wrapper function for Demangle() to make the unit test simple. +static const char *DemangleIt(const char * const mangled) { + static char demangled[4096]; + if (Demangle(mangled, demangled, sizeof(demangled))) { + return demangled; + } else { + return mangled; + } +} + +// Test corner cases of bounary conditions. +TEST(Demangle, CornerCases) { + char tmp[10]; + EXPECT_TRUE(Demangle("_Z6foobarv", tmp, sizeof(tmp))); + // sizeof("foobar()") == 9 + EXPECT_STREQ("foobar()", tmp); + EXPECT_TRUE(Demangle("_Z6foobarv", tmp, 9)); + EXPECT_STREQ("foobar()", tmp); + EXPECT_FALSE(Demangle("_Z6foobarv", tmp, 8)); // Not enough. + EXPECT_FALSE(Demangle("_Z6foobarv", tmp, 1)); + EXPECT_FALSE(Demangle("_Z6foobarv", tmp, 0)); + EXPECT_FALSE(Demangle("_Z6foobarv", nullptr, 0)); // Should not cause SEGV. + EXPECT_FALSE(Demangle("_Z1000000", tmp, 9)); +} + +// Test handling of functions suffixed with .clone.N, which is used +// by GCC 4.5.x (and our locally-modified version of GCC 4.4.x), and +// .constprop.N and .isra.N, which are used by GCC 4.6.x. These +// suffixes are used to indicate functions which have been cloned +// during optimization. We ignore these suffixes. +TEST(Demangle, Clones) { + char tmp[20]; + EXPECT_TRUE(Demangle("_ZL3Foov", tmp, sizeof(tmp))); + EXPECT_STREQ("Foo()", tmp); + EXPECT_TRUE(Demangle("_ZL3Foov.clone.3", tmp, sizeof(tmp))); + EXPECT_STREQ("Foo()", tmp); + EXPECT_TRUE(Demangle("_ZL3Foov.constprop.80", tmp, sizeof(tmp))); + EXPECT_STREQ("Foo()", tmp); + EXPECT_TRUE(Demangle("_ZL3Foov.isra.18", tmp, sizeof(tmp))); + EXPECT_STREQ("Foo()", tmp); + EXPECT_TRUE(Demangle("_ZL3Foov.isra.2.constprop.18", tmp, sizeof(tmp))); + EXPECT_STREQ("Foo()", tmp); + // Invalid (truncated), should not demangle. + EXPECT_FALSE(Demangle("_ZL3Foov.clo", tmp, sizeof(tmp))); + // Invalid (.clone. not followed by number), should not demangle. + EXPECT_FALSE(Demangle("_ZL3Foov.clone.", tmp, sizeof(tmp))); + // Invalid (.clone. followed by non-number), should not demangle. + EXPECT_FALSE(Demangle("_ZL3Foov.clone.foo", tmp, sizeof(tmp))); + // Invalid (.constprop. not followed by number), should not demangle. + EXPECT_FALSE(Demangle("_ZL3Foov.isra.2.constprop.", tmp, sizeof(tmp))); +} + +// Tests that verify that Demangle footprint is within some limit. +// They are not to be run under sanitizers as the sanitizers increase +// stack consumption by about 4x. +#if defined(ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION) && \ + !ADDRESS_SANITIZER && !MEMORY_SANITIZER && !THREAD_SANITIZER + +static const char *g_mangled; +static char g_demangle_buffer[4096]; +static char *g_demangle_result; + +static void DemangleSignalHandler(int signo) { + if (Demangle(g_mangled, g_demangle_buffer, sizeof(g_demangle_buffer))) { + g_demangle_result = g_demangle_buffer; + } else { + g_demangle_result = nullptr; + } +} + +// Call Demangle and figure out the stack footprint of this call. +static const char *DemangleStackConsumption(const char *mangled, + int *stack_consumed) { + g_mangled = mangled; + *stack_consumed = GetSignalHandlerStackConsumption(DemangleSignalHandler); + ABSL_RAW_LOG(INFO, "Stack consumption of Demangle: %d", *stack_consumed); + return g_demangle_result; +} + +// Demangle stack consumption should be within 8kB for simple mangled names +// with some level of nesting. With alternate signal stack we have 64K, +// but some signal handlers run on thread stack, and could have arbitrarily +// little space left (so we don't want to make this number too large). +const int kStackConsumptionUpperLimit = 8192; + +// Returns a mangled name nested to the given depth. +static std::string NestedMangledName(int depth) { + std::string mangled_name = "_Z1a"; + if (depth > 0) { + mangled_name += "IXL"; + mangled_name += NestedMangledName(depth - 1); + mangled_name += "EEE"; + } + return mangled_name; +} + +TEST(Demangle, DemangleStackConsumption) { + // Measure stack consumption of Demangle for nested mangled names of varying + // depth. Since Demangle is implemented as a recursive descent parser, + // stack consumption will grow as the nesting depth increases. By measuring + // the stack consumption for increasing depths, we can see the growing + // impact of any stack-saving changes made to the code for Demangle. + int stack_consumed = 0; + + const char *demangled = + DemangleStackConsumption("_Z6foobarv", &stack_consumed); + EXPECT_STREQ("foobar()", demangled); + EXPECT_GT(stack_consumed, 0); + EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit); + + const std::string nested_mangled_name0 = NestedMangledName(0); + demangled = DemangleStackConsumption(nested_mangled_name0.c_str(), + &stack_consumed); + EXPECT_STREQ("a", demangled); + EXPECT_GT(stack_consumed, 0); + EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit); + + const std::string nested_mangled_name1 = NestedMangledName(1); + demangled = DemangleStackConsumption(nested_mangled_name1.c_str(), + &stack_consumed); + EXPECT_STREQ("a<>", demangled); + EXPECT_GT(stack_consumed, 0); + EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit); + + const std::string nested_mangled_name2 = NestedMangledName(2); + demangled = DemangleStackConsumption(nested_mangled_name2.c_str(), + &stack_consumed); + EXPECT_STREQ("a<>", demangled); + EXPECT_GT(stack_consumed, 0); + EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit); + + const std::string nested_mangled_name3 = NestedMangledName(3); + demangled = DemangleStackConsumption(nested_mangled_name3.c_str(), + &stack_consumed); + EXPECT_STREQ("a<>", demangled); + EXPECT_GT(stack_consumed, 0); + EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit); +} + +#endif // Stack consumption tests + +static void TestOnInput(const char* input) { + static const int kOutSize = 1048576; + auto out = absl::make_unique<char[]>(kOutSize); + Demangle(input, out.get(), kOutSize); +} + +TEST(DemangleRegression, NegativeLength) { + TestOnInput("_ZZn4"); +} +TEST(DemangleRegression, DeeplyNestedArrayType) { + const int depth = 100000; + std::string data = "_ZStI"; + data.reserve(data.size() + 3 * depth + 1); + for (int i = 0; i < depth; i++) { + data += "A1_"; + } + TestOnInput(data.c_str()); +} + +} // namespace +} // namespace debugging_internal +} // namespace absl |