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// Copyright 2018 The Abseil Authors.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// 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("", 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.
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(),
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(),
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(),
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(),
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) {
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_";
} // namespace
} // namespace debugging_internal
} // namespace absl