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authorGravatar Abseil Team <absl-team@google.com>2018-02-21 08:32:10 -0800
committerGravatar Derek Mauro <dmauro@google.com>2018-02-22 10:15:18 -0500
commitdca2eb50f9f5ee378395ee020953dc20a2a84c97 (patch)
tree31c1476614cb761bc3f9547d3a3d0d37cf948cca /absl/debugging
parent03c1513538584f4a04d666be5eb469e3979febba (diff)
Changes imported from Abseil "staging" branch:
- db061dd2b795837e6154be0991077ca5a03ec471 Release the async-signal safe demangler as an internal im... by Derek Mauro <dmauro@google.com> - 310440eb33d946df79d26bf1edf795f6a0b466b9 Use static_cast to constrain nanoseconds to int range, av... by Abseil Team <absl-team@google.com> GitOrigin-RevId: db061dd2b795837e6154be0991077ca5a03ec471 Change-Id: Ibc1bc1db355a48115451da5ce88d66a1f6e1a182
Diffstat (limited to 'absl/debugging')
-rw-r--r--absl/debugging/BUILD.bazel24
-rw-r--r--absl/debugging/CMakeLists.txt38
-rw-r--r--absl/debugging/internal/demangle.cc1862
-rw-r--r--absl/debugging/internal/demangle.h67
-rw-r--r--absl/debugging/internal/demangle_test.cc191
5 files changed, 2181 insertions, 1 deletions
diff --git a/absl/debugging/BUILD.bazel b/absl/debugging/BUILD.bazel
index d4cdf492..20b455b8 100644
--- a/absl/debugging/BUILD.bazel
+++ b/absl/debugging/BUILD.bazel
@@ -64,10 +64,34 @@ cc_library(
deps = [
"//absl/base",
"//absl/base:dynamic_annotations",
+ ],
+)
+
+cc_library(
+ name = "demangle_internal",
+ srcs = ["internal/demangle.cc"],
+ hdrs = ["internal/demangle.h"],
+ copts = ABSL_DEFAULT_COPTS,
+ deps = [
+ "//absl/base",
"//absl/base:core_headers",
],
)
+cc_test(
+ name = "demangle_test",
+ srcs = ["internal/demangle_test.cc"],
+ copts = ABSL_TEST_COPTS,
+ deps = [
+ ":demangle_internal",
+ ":stack_consumption",
+ "//absl/base",
+ "//absl/base:core_headers",
+ "//absl/memory",
+ "@com_google_googletest//:gtest_main",
+ ],
+)
+
cc_library(
name = "leak_check",
srcs = select({
diff --git a/absl/debugging/CMakeLists.txt b/absl/debugging/CMakeLists.txt
index 57efe80f..758c00fe 100644
--- a/absl/debugging/CMakeLists.txt
+++ b/absl/debugging/CMakeLists.txt
@@ -22,6 +22,7 @@ list(APPEND DEBUGGING_PUBLIC_HEADERS
list(APPEND DEBUGGING_INTERNAL_HEADERS
"internal/address_is_readable.h"
+ "internal/demangle.h"
"internal/elf_mem_image.h"
"internal/stacktrace_config.h"
"internal/vdso_support.h"
@@ -31,6 +32,7 @@ list(APPEND DEBUGGING_INTERNAL_HEADERS
list(APPEND STACKTRACE_SRC
"stacktrace.cc"
"internal/address_is_readable.cc"
+ "internal/demangle.cc"
"internal/elf_mem_image.cc"
"internal/vdso_support.cc"
${DEBUGGING_PUBLIC_HEADERS}
@@ -79,6 +81,41 @@ absl_header_library(
## TESTS
#
+list(APPEND DEBUGGING_INTERNAL_TEST_HEADERS
+ "internal/stack_consumption.h"
+)
+
+list(APPEND STACK_CONSUMPTION_SRC
+ "internal/stack_consumption.cc"
+ ${DEBUGGING_INTERNAL_TEST_HEADERS}
+)
+
+absl_library(
+ TARGET
+ absl_stack_consumption
+ SOURCES
+ ${STACK_CONSUMPTION_SRC}
+)
+
+absl_test(
+ TARGET
+ absl_stack_consumption_test
+ SOURCES
+ ${STACK_CONSUMPTION_SRC}
+)
+
+list(APPEND DEMANGLE_TEST_SRC "demangle_test.cc")
+
+absl_test(
+ TARGET
+ demangle_test
+ SOURCES
+ ${DEMANGLE_TEST_SRC}
+ PUBLIC_LIBRARIES
+ absl_stacktrace absl_stack_consumption
+)
+
+
# test leak_check_test
list(APPEND LEAK_CHECK_TEST_SRC "leak_check_test.cc")
@@ -90,4 +127,3 @@ absl_test(
PUBLIC_LIBRARIES
absl_leak_check
)
-
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