Merge "Add caching of build id in MapInfo object."
diff --git a/libunwindstack/Android.bp b/libunwindstack/Android.bp
index 73dc921..d1b8271 100644
--- a/libunwindstack/Android.bp
+++ b/libunwindstack/Android.bp
@@ -191,6 +191,7 @@
"tests/LocalUnwinderTest.cpp",
"tests/LogFake.cpp",
"tests/MapInfoCreateMemoryTest.cpp",
+ "tests/MapInfoGetBuildIDTest.cpp",
"tests/MapInfoGetElfTest.cpp",
"tests/MapInfoGetLoadBiasTest.cpp",
"tests/MapInfoTest.cpp",
@@ -343,6 +344,7 @@
],
shared_libs: [
+ "libbase",
"libunwindstack",
],
}
diff --git a/libunwindstack/Elf.cpp b/libunwindstack/Elf.cpp
index 5b586a2..2f5eed9 100644
--- a/libunwindstack/Elf.cpp
+++ b/libunwindstack/Elf.cpp
@@ -140,8 +140,11 @@
return true;
}
-bool Elf::GetBuildID(std::string* build_id) {
- return valid_ && interface_->GetBuildID(build_id);
+std::string Elf::GetBuildID() {
+ if (!valid_) {
+ return "";
+ }
+ return interface_->GetBuildID();
}
void Elf::GetLastError(ErrorData* data) {
@@ -384,4 +387,22 @@
return false;
}
+std::string Elf::GetBuildID(Memory* memory) {
+ if (!IsValidElf(memory)) {
+ return "";
+ }
+
+ uint8_t class_type;
+ if (!memory->Read(EI_CLASS, &class_type, 1)) {
+ return "";
+ }
+
+ if (class_type == ELFCLASS32) {
+ return ElfInterface::ReadBuildIDFromMemory<Elf32_Ehdr, Elf32_Shdr, Elf32_Nhdr>(memory);
+ } else if (class_type == ELFCLASS64) {
+ return ElfInterface::ReadBuildIDFromMemory<Elf64_Ehdr, Elf64_Shdr, Elf64_Nhdr>(memory);
+ }
+ return "";
+}
+
} // namespace unwindstack
diff --git a/libunwindstack/ElfInterface.cpp b/libunwindstack/ElfInterface.cpp
index 709e6c9..c1b98d9 100644
--- a/libunwindstack/ElfInterface.cpp
+++ b/libunwindstack/ElfInterface.cpp
@@ -238,31 +238,31 @@
}
template <typename NhdrType>
-bool ElfInterface::ReadBuildID(std::string* build_id) {
+std::string ElfInterface::ReadBuildID() {
// Ensure there is no overflow in any of the calulations below.
uint64_t tmp;
if (__builtin_add_overflow(gnu_build_id_offset_, gnu_build_id_size_, &tmp)) {
- return false;
+ return "";
}
uint64_t offset = 0;
while (offset < gnu_build_id_size_) {
if (gnu_build_id_size_ - offset < sizeof(NhdrType)) {
- return false;
+ return "";
}
NhdrType hdr;
if (!memory_->ReadFully(gnu_build_id_offset_ + offset, &hdr, sizeof(hdr))) {
- return false;
+ return "";
}
offset += sizeof(hdr);
if (gnu_build_id_size_ - offset < hdr.n_namesz) {
- return false;
+ return "";
}
if (hdr.n_namesz > 0) {
std::string name(hdr.n_namesz, '\0');
if (!memory_->ReadFully(gnu_build_id_offset_ + offset, &(name[0]), hdr.n_namesz)) {
- return false;
+ return "";
}
// Trim trailing \0 as GNU is stored as a C string in the ELF file.
@@ -273,18 +273,20 @@
offset += (hdr.n_namesz + 3) & ~3;
if (name == "GNU" && hdr.n_type == NT_GNU_BUILD_ID) {
- if (gnu_build_id_size_ - offset < hdr.n_descsz) {
- return false;
+ if (gnu_build_id_size_ - offset < hdr.n_descsz || hdr.n_descsz == 0) {
+ return "";
}
- build_id->resize(hdr.n_descsz);
- return memory_->ReadFully(gnu_build_id_offset_ + offset, &(*build_id)[0],
- hdr.n_descsz);
+ std::string build_id(hdr.n_descsz - 1, '\0');
+ if (memory_->ReadFully(gnu_build_id_offset_ + offset, &build_id[0], hdr.n_descsz)) {
+ return build_id;
+ }
+ return "";
}
}
// Align hdr.n_descsz to next power multiple of 4. See man 5 elf.
offset += (hdr.n_descsz + 3) & ~3;
}
- return false;
+ return "";
}
template <typename EhdrType, typename ShdrType>
@@ -536,6 +538,103 @@
*size = ehdr.e_shoff + ehdr.e_shentsize * ehdr.e_shnum;
}
+template <typename EhdrType, typename ShdrType>
+bool GetBuildIDInfo(Memory* memory, uint64_t* build_id_offset, uint64_t* build_id_size) {
+ EhdrType ehdr;
+ if (!memory->ReadFully(0, &ehdr, sizeof(ehdr))) {
+ return false;
+ }
+
+ uint64_t offset = ehdr.e_shoff;
+ uint64_t sec_offset;
+ uint64_t sec_size;
+ ShdrType shdr;
+ if (ehdr.e_shstrndx >= ehdr.e_shnum) {
+ return false;
+ }
+
+ uint64_t sh_offset = offset + ehdr.e_shstrndx * ehdr.e_shentsize;
+ if (!memory->ReadFully(sh_offset, &shdr, sizeof(shdr))) {
+ return false;
+ }
+ sec_offset = shdr.sh_offset;
+ sec_size = shdr.sh_size;
+
+ // Skip the first header, it's always going to be NULL.
+ offset += ehdr.e_shentsize;
+ for (size_t i = 1; i < ehdr.e_shnum; i++, offset += ehdr.e_shentsize) {
+ if (!memory->ReadFully(offset, &shdr, sizeof(shdr))) {
+ return false;
+ }
+ std::string name;
+ if (shdr.sh_type == SHT_NOTE && shdr.sh_name < sec_size &&
+ memory->ReadString(sec_offset + shdr.sh_name, &name) && name == ".note.gnu.build-id") {
+ *build_id_offset = shdr.sh_offset;
+ *build_id_size = shdr.sh_size;
+ return true;
+ }
+ }
+
+ return false;
+}
+
+template <typename EhdrType, typename ShdrType, typename NhdrType>
+std::string ElfInterface::ReadBuildIDFromMemory(Memory* memory) {
+ uint64_t note_offset;
+ uint64_t note_size;
+ if (!GetBuildIDInfo<EhdrType, ShdrType>(memory, ¬e_offset, ¬e_size)) {
+ return "";
+ }
+
+ // Ensure there is no overflow in any of the calculations below.
+ uint64_t tmp;
+ if (__builtin_add_overflow(note_offset, note_size, &tmp)) {
+ return "";
+ }
+
+ uint64_t offset = 0;
+ while (offset < note_size) {
+ if (note_size - offset < sizeof(NhdrType)) {
+ return "";
+ }
+ NhdrType hdr;
+ if (!memory->ReadFully(note_offset + offset, &hdr, sizeof(hdr))) {
+ return "";
+ }
+ offset += sizeof(hdr);
+
+ if (note_size - offset < hdr.n_namesz) {
+ return "";
+ }
+ if (hdr.n_namesz > 0) {
+ std::string name(hdr.n_namesz, '\0');
+ if (!memory->ReadFully(note_offset + offset, &(name[0]), hdr.n_namesz)) {
+ return "";
+ }
+
+ // Trim trailing \0 as GNU is stored as a C string in the ELF file.
+ if (name.back() == '\0') name.resize(name.size() - 1);
+
+ // Align hdr.n_namesz to next power multiple of 4. See man 5 elf.
+ offset += (hdr.n_namesz + 3) & ~3;
+
+ if (name == "GNU" && hdr.n_type == NT_GNU_BUILD_ID) {
+ if (note_size - offset < hdr.n_descsz || hdr.n_descsz == 0) {
+ return "";
+ }
+ std::string build_id(hdr.n_descsz - 1, '\0');
+ if (memory->ReadFully(note_offset + offset, &build_id[0], hdr.n_descsz)) {
+ return build_id;
+ }
+ return "";
+ }
+ }
+ // Align hdr.n_descsz to next power multiple of 4. See man 5 elf.
+ offset += (hdr.n_descsz + 3) & ~3;
+ }
+ return "";
+}
+
// Instantiate all of the needed template functions.
template void ElfInterface::InitHeadersWithTemplate<uint32_t>(uint64_t);
template void ElfInterface::InitHeadersWithTemplate<uint64_t>(uint64_t);
@@ -551,8 +650,8 @@
template void ElfInterface::ReadSectionHeaders<Elf32_Ehdr, Elf32_Shdr>(const Elf32_Ehdr&);
template void ElfInterface::ReadSectionHeaders<Elf64_Ehdr, Elf64_Shdr>(const Elf64_Ehdr&);
-template bool ElfInterface::ReadBuildID<Elf32_Nhdr>(std::string*);
-template bool ElfInterface::ReadBuildID<Elf64_Nhdr>(std::string*);
+template std::string ElfInterface::ReadBuildID<Elf32_Nhdr>();
+template std::string ElfInterface::ReadBuildID<Elf64_Nhdr>();
template bool ElfInterface::GetSonameWithTemplate<Elf32_Dyn>(std::string*);
template bool ElfInterface::GetSonameWithTemplate<Elf64_Dyn>(std::string*);
@@ -571,4 +670,9 @@
template uint64_t ElfInterface::GetLoadBias<Elf32_Ehdr, Elf32_Phdr>(Memory*);
template uint64_t ElfInterface::GetLoadBias<Elf64_Ehdr, Elf64_Phdr>(Memory*);
+template std::string ElfInterface::ReadBuildIDFromMemory<Elf32_Ehdr, Elf32_Shdr, Elf32_Nhdr>(
+ Memory*);
+template std::string ElfInterface::ReadBuildIDFromMemory<Elf64_Ehdr, Elf64_Shdr, Elf64_Nhdr>(
+ Memory*);
+
} // namespace unwindstack
diff --git a/libunwindstack/MapInfo.cpp b/libunwindstack/MapInfo.cpp
index b9d8b3d..f319971 100644
--- a/libunwindstack/MapInfo.cpp
+++ b/libunwindstack/MapInfo.cpp
@@ -146,6 +146,10 @@
}
}
+ if (process_memory == nullptr) {
+ return nullptr;
+ }
+
// Need to verify that this elf is valid. It's possible that
// only part of the elf file to be mapped into memory is in the executable
// map. In this case, there will be another read-only map that includes the
@@ -263,4 +267,48 @@
return cur_load_bias;
}
+MapInfo::~MapInfo() {
+ uintptr_t id = build_id.load();
+ if (id != 0) {
+ delete reinterpret_cast<std::string*>(id);
+ }
+}
+
+std::string MapInfo::GetBuildID() {
+ uintptr_t id = build_id.load();
+ if (build_id != 0) {
+ return *reinterpret_cast<std::string*>(id);
+ }
+
+ // No need to lock, at worst if multiple threads do this at the same
+ // time it should be detected and only one thread should win and
+ // save the data.
+ std::unique_ptr<std::string> cur_build_id(new std::string);
+
+ // Now need to see if the elf object exists.
+ // Make sure no other thread is trying to add the elf to this map.
+ mutex_.lock();
+ Elf* elf_obj = elf.get();
+ mutex_.unlock();
+ if (elf_obj != nullptr) {
+ *cur_build_id = elf_obj->GetBuildID();
+ } else {
+ // This will only work if we can get the file associated with this memory.
+ // If this is only available in memory, then the section name information
+ // is not present and we will not be able to find the build id info.
+ std::unique_ptr<Memory> memory(GetFileMemory());
+ if (memory != nullptr) {
+ *cur_build_id = Elf::GetBuildID(memory.get());
+ }
+ }
+
+ id = reinterpret_cast<uintptr_t>(cur_build_id.get());
+ uintptr_t expected_id = 0;
+ if (build_id.compare_exchange_weak(expected_id, id)) {
+ // Value saved, so make sure the memory is not freed.
+ cur_build_id.release();
+ }
+ return *reinterpret_cast<std::string*>(id);
+}
+
} // namespace unwindstack
diff --git a/libunwindstack/benchmarks/unwind_benchmarks.cpp b/libunwindstack/benchmarks/unwind_benchmarks.cpp
index db0fb54..8caecc7 100644
--- a/libunwindstack/benchmarks/unwind_benchmarks.cpp
+++ b/libunwindstack/benchmarks/unwind_benchmarks.cpp
@@ -20,6 +20,9 @@
#include <benchmark/benchmark.h>
+#include <android-base/strings.h>
+
+#include <unwindstack/Elf.h>
#include <unwindstack/Maps.h>
#include <unwindstack/Memory.h>
#include <unwindstack/Regs.h>
@@ -80,4 +83,63 @@
}
BENCHMARK(BM_cached_unwind);
+static void Initialize(benchmark::State& state, unwindstack::Maps& maps,
+ unwindstack::MapInfo** build_id_map_info) {
+ if (!maps.Parse()) {
+ state.SkipWithError("Failed to parse local maps.");
+ return;
+ }
+
+ // Find the libc.so share library and use that for benchmark purposes.
+ *build_id_map_info = nullptr;
+ for (unwindstack::MapInfo* map_info : maps) {
+ if (map_info->offset == 0 && map_info->GetBuildID() != "") {
+ *build_id_map_info = map_info;
+ break;
+ }
+ }
+
+ if (*build_id_map_info == nullptr) {
+ state.SkipWithError("Failed to find a map with a BuildID.");
+ }
+}
+
+static void BM_get_build_id_from_elf(benchmark::State& state) {
+ unwindstack::LocalMaps maps;
+ unwindstack::MapInfo* build_id_map_info;
+ Initialize(state, maps, &build_id_map_info);
+
+ unwindstack::Elf* elf = build_id_map_info->GetElf(std::shared_ptr<unwindstack::Memory>(),
+ unwindstack::Regs::CurrentArch());
+ if (!elf->valid()) {
+ state.SkipWithError("Cannot get valid elf from map.");
+ }
+
+ for (auto _ : state) {
+ uintptr_t id = build_id_map_info->build_id;
+ if (id != 0) {
+ delete reinterpret_cast<std::string*>(id);
+ build_id_map_info->build_id = 0;
+ }
+ benchmark::DoNotOptimize(build_id_map_info->GetBuildID());
+ }
+}
+BENCHMARK(BM_get_build_id_from_elf);
+
+static void BM_get_build_id_from_file(benchmark::State& state) {
+ unwindstack::LocalMaps maps;
+ unwindstack::MapInfo* build_id_map_info;
+ Initialize(state, maps, &build_id_map_info);
+
+ for (auto _ : state) {
+ uintptr_t id = build_id_map_info->build_id;
+ if (id != 0) {
+ delete reinterpret_cast<std::string*>(id);
+ build_id_map_info->build_id = 0;
+ }
+ benchmark::DoNotOptimize(build_id_map_info->GetBuildID());
+ }
+}
+BENCHMARK(BM_get_build_id_from_file);
+
BENCHMARK_MAIN();
diff --git a/libunwindstack/include/unwindstack/Elf.h b/libunwindstack/include/unwindstack/Elf.h
index 27f7201..00a249f 100644
--- a/libunwindstack/include/unwindstack/Elf.h
+++ b/libunwindstack/include/unwindstack/Elf.h
@@ -65,8 +65,6 @@
bool GetGlobalVariable(const std::string& name, uint64_t* memory_address);
- bool GetBuildID(std::string* build_id);
-
uint64_t GetRelPc(uint64_t pc, const MapInfo* map_info);
bool Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, Regs* regs, Memory* process_memory,
@@ -74,6 +72,8 @@
ElfInterface* CreateInterfaceFromMemory(Memory* memory);
+ std::string GetBuildID();
+
uint64_t GetLoadBias() { return load_bias_; }
bool IsValidPc(uint64_t pc);
@@ -102,6 +102,8 @@
static uint64_t GetLoadBias(Memory* memory);
+ static std::string GetBuildID(Memory* memory);
+
static void SetCachingEnabled(bool enable);
static bool CachingEnabled() { return cache_enabled_; }
diff --git a/libunwindstack/include/unwindstack/ElfInterface.h b/libunwindstack/include/unwindstack/ElfInterface.h
index 52992d9..d41bb13 100644
--- a/libunwindstack/include/unwindstack/ElfInterface.h
+++ b/libunwindstack/include/unwindstack/ElfInterface.h
@@ -62,7 +62,7 @@
virtual bool GetGlobalVariable(const std::string& name, uint64_t* memory_address) = 0;
- virtual bool GetBuildID(std::string* build_id) = 0;
+ virtual std::string GetBuildID() = 0;
virtual bool Step(uint64_t rel_pc, Regs* regs, Memory* process_memory, bool* finished);
@@ -100,6 +100,9 @@
template <typename EhdrType, typename PhdrType>
static uint64_t GetLoadBias(Memory* memory);
+ template <typename EhdrType, typename ShdrType, typename NhdrType>
+ static std::string ReadBuildIDFromMemory(Memory* memory);
+
protected:
template <typename AddressType>
void InitHeadersWithTemplate(uint64_t load_bias);
@@ -128,7 +131,7 @@
static void GetMaxSizeWithTemplate(Memory* memory, uint64_t* size);
template <typename NhdrType>
- bool ReadBuildID(std::string* build_id);
+ std::string ReadBuildID();
Memory* memory_;
std::unordered_map<uint64_t, LoadInfo> pt_loads_;
@@ -192,9 +195,7 @@
return ElfInterface::GetGlobalVariableWithTemplate<Elf32_Sym>(name, memory_address);
}
- bool GetBuildID(std::string* build_id) {
- return ElfInterface::ReadBuildID<Elf32_Nhdr>(build_id);
- }
+ std::string GetBuildID() override { return ElfInterface::ReadBuildID<Elf32_Nhdr>(); }
static void GetMaxSize(Memory* memory, uint64_t* size) {
GetMaxSizeWithTemplate<Elf32_Ehdr>(memory, size);
@@ -226,9 +227,7 @@
return ElfInterface::GetGlobalVariableWithTemplate<Elf64_Sym>(name, memory_address);
}
- bool GetBuildID(std::string* build_id) {
- return ElfInterface::ReadBuildID<Elf64_Nhdr>(build_id);
- }
+ std::string GetBuildID() override { return ElfInterface::ReadBuildID<Elf64_Nhdr>(); }
static void GetMaxSize(Memory* memory, uint64_t* size) {
GetMaxSizeWithTemplate<Elf64_Ehdr>(memory, size);
diff --git a/libunwindstack/include/unwindstack/MapInfo.h b/libunwindstack/include/unwindstack/MapInfo.h
index a9febd1..5143ff1 100644
--- a/libunwindstack/include/unwindstack/MapInfo.h
+++ b/libunwindstack/include/unwindstack/MapInfo.h
@@ -38,7 +38,8 @@
flags(flags),
name(name),
prev_map(map_info),
- load_bias(static_cast<uint64_t>(-1)) {}
+ load_bias(static_cast<uint64_t>(-1)),
+ build_id(0) {}
MapInfo(MapInfo* map_info, uint64_t start, uint64_t end, uint64_t offset, uint64_t flags,
const std::string& name)
: start(start),
@@ -47,8 +48,9 @@
flags(flags),
name(name),
prev_map(map_info),
- load_bias(static_cast<uint64_t>(-1)) {}
- ~MapInfo() = default;
+ load_bias(static_cast<uint64_t>(-1)),
+ build_id(0) {}
+ ~MapInfo();
uint64_t start = 0;
uint64_t end = 0;
@@ -68,6 +70,11 @@
std::atomic_uint64_t load_bias;
+ // This is a pointer to a new'd std::string.
+ // Using an atomic value means that we don't need to lock and will
+ // make it easier to move to a fine grained lock in the future.
+ std::atomic_uintptr_t build_id;
+
// This function guarantees it will never return nullptr.
Elf* GetElf(const std::shared_ptr<Memory>& process_memory, ArchEnum expected_arch);
@@ -77,6 +84,8 @@
bool GetFunctionName(uint64_t addr, std::string* name, uint64_t* func_offset);
+ std::string GetBuildID();
+
private:
MapInfo(const MapInfo&) = delete;
void operator=(const MapInfo&) = delete;
diff --git a/libunwindstack/tests/ElfFake.h b/libunwindstack/tests/ElfFake.h
index c2bd0f6..946bc3c 100644
--- a/libunwindstack/tests/ElfFake.h
+++ b/libunwindstack/tests/ElfFake.h
@@ -72,9 +72,7 @@
bool GetFunctionName(uint64_t, std::string*, uint64_t*) override;
bool GetGlobalVariable(const std::string&, uint64_t*) override;
- bool GetBuildID(std::string*) override {
- return false;
- }
+ std::string GetBuildID() override { return fake_build_id_; }
bool Step(uint64_t, Regs*, Memory*, bool*) override;
@@ -82,6 +80,9 @@
globals_[global] = offset;
}
+ void FakeSetBuildID(std::string& build_id) { fake_build_id_ = build_id; }
+ void FakeSetBuildID(const char* build_id) { fake_build_id_ = build_id; }
+
static void FakePushFunctionData(const FunctionData data) { functions_.push_back(data); }
static void FakePushStepData(const StepData data) { steps_.push_back(data); }
@@ -96,6 +97,7 @@
private:
std::unordered_map<std::string, uint64_t> globals_;
+ std::string fake_build_id_;
static std::deque<FunctionData> functions_;
static std::deque<StepData> steps_;
diff --git a/libunwindstack/tests/ElfInterfaceTest.cpp b/libunwindstack/tests/ElfInterfaceTest.cpp
index 6023dc4..7239749 100644
--- a/libunwindstack/tests/ElfInterfaceTest.cpp
+++ b/libunwindstack/tests/ElfInterfaceTest.cpp
@@ -1228,9 +1228,7 @@
uint64_t load_bias = 0;
ASSERT_TRUE(elf->Init(&load_bias));
- std::string build_id;
- ASSERT_TRUE(elf->GetBuildID(&build_id));
- EXPECT_STREQ(build_id.c_str(), "BUILDID");
+ ASSERT_EQ("BUILDID", elf->GetBuildID());
}
template <typename Ehdr, typename Shdr, typename Nhdr, typename ElfInterfaceType>
@@ -1292,9 +1290,7 @@
uint64_t load_bias = 0;
ASSERT_TRUE(elf->Init(&load_bias));
- std::string build_id;
- ASSERT_TRUE(elf->GetBuildID(&build_id));
- EXPECT_STREQ(build_id.c_str(), "BUILDID");
+ ASSERT_EQ("BUILDID", elf->GetBuildID());
}
template <typename Ehdr, typename Shdr, typename Nhdr, typename ElfInterfaceType>
@@ -1346,8 +1342,7 @@
uint64_t load_bias = 0;
ASSERT_TRUE(elf->Init(&load_bias));
- std::string build_id;
- ASSERT_FALSE(elf->GetBuildID(&build_id));
+ ASSERT_EQ("", elf->GetBuildID());
}
template <typename Ehdr, typename Shdr, typename Nhdr, typename ElfInterfaceType>
@@ -1399,8 +1394,7 @@
uint64_t load_bias = 0;
ASSERT_TRUE(elf->Init(&load_bias));
- std::string build_id;
- ASSERT_FALSE(elf->GetBuildID(&build_id));
+ ASSERT_EQ("", elf->GetBuildID());
}
template <typename Ehdr, typename Shdr, typename Nhdr, typename ElfInterfaceType>
@@ -1452,8 +1446,7 @@
uint64_t load_bias = 0;
ASSERT_TRUE(elf->Init(&load_bias));
- std::string build_id;
- ASSERT_FALSE(elf->GetBuildID(&build_id));
+ ASSERT_EQ("", elf->GetBuildID());
}
TEST_F(ElfInterfaceTest, build_id32) {
diff --git a/libunwindstack/tests/ElfTest.cpp b/libunwindstack/tests/ElfTest.cpp
index f7689ce..1ff2306 100644
--- a/libunwindstack/tests/ElfTest.cpp
+++ b/libunwindstack/tests/ElfTest.cpp
@@ -311,7 +311,7 @@
void InitHeaders(uint64_t) override {}
bool GetSoname(std::string*) override { return false; }
bool GetFunctionName(uint64_t, std::string*, uint64_t*) override { return false; }
- bool GetBuildID(std::string*) override { return false; }
+ std::string GetBuildID() override { return ""; }
MOCK_METHOD4(Step, bool(uint64_t, Regs*, Memory*, bool*));
MOCK_METHOD2(GetGlobalVariable, bool(const std::string&, uint64_t*));
diff --git a/libunwindstack/tests/MapInfoGetBuildIDTest.cpp b/libunwindstack/tests/MapInfoGetBuildIDTest.cpp
new file mode 100644
index 0000000..3b89c59
--- /dev/null
+++ b/libunwindstack/tests/MapInfoGetBuildIDTest.cpp
@@ -0,0 +1,183 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * 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 <elf.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include <atomic>
+#include <memory>
+#include <string>
+#include <thread>
+#include <vector>
+
+#include <android-base/test_utils.h>
+
+#include <gtest/gtest.h>
+
+#include <unwindstack/Elf.h>
+#include <unwindstack/MapInfo.h>
+#include <unwindstack/Maps.h>
+#include <unwindstack/Memory.h>
+
+#include "ElfFake.h"
+#include "ElfTestUtils.h"
+#include "MemoryFake.h"
+
+namespace unwindstack {
+
+class MapInfoGetBuildIDTest : public ::testing::Test {
+ protected:
+ void SetUp() override {
+ tf_.reset(new TemporaryFile);
+
+ memory_ = new MemoryFake;
+ elf_ = new ElfFake(new MemoryFake);
+ elf_interface_ = new ElfInterfaceFake(memory_);
+ elf_->FakeSetInterface(elf_interface_);
+ elf_container_.reset(elf_);
+ map_info_.reset(new MapInfo(nullptr, 0x1000, 0x20000, 0, PROT_READ | PROT_WRITE, tf_->path));
+ }
+
+ void MultipleThreadTest(std::string expected_build_id);
+
+ MemoryFake* memory_;
+ ElfFake* elf_;
+ ElfInterfaceFake* elf_interface_;
+ std::unique_ptr<ElfFake> elf_container_;
+ std::unique_ptr<MapInfo> map_info_;
+ std::unique_ptr<TemporaryFile> tf_;
+};
+
+TEST_F(MapInfoGetBuildIDTest, no_elf_and_no_valid_elf_in_memory) {
+ MapInfo info(nullptr, 0x1000, 0x2000, 0, PROT_READ, "");
+
+ EXPECT_EQ("", info.GetBuildID());
+}
+
+TEST_F(MapInfoGetBuildIDTest, from_elf) {
+ map_info_->elf.reset(elf_container_.release());
+ elf_interface_->FakeSetBuildID("FAKE_BUILD_ID");
+
+ EXPECT_EQ("FAKE_BUILD_ID", map_info_->GetBuildID());
+}
+
+void MapInfoGetBuildIDTest::MultipleThreadTest(std::string expected_build_id) {
+ static constexpr size_t kNumConcurrentThreads = 100;
+
+ std::string build_id_values[kNumConcurrentThreads];
+ std::vector<std::thread*> threads;
+
+ std::atomic_bool wait;
+ wait = true;
+ // Create all of the threads and have them do the GetLoadBias at the same time
+ // to make it likely that a race will occur.
+ for (size_t i = 0; i < kNumConcurrentThreads; i++) {
+ std::thread* thread = new std::thread([i, this, &wait, &build_id_values]() {
+ while (wait)
+ ;
+ build_id_values[i] = map_info_->GetBuildID();
+ });
+ threads.push_back(thread);
+ }
+
+ // Set them all going and wait for the threads to finish.
+ wait = false;
+ for (auto thread : threads) {
+ thread->join();
+ delete thread;
+ }
+
+ // Now verify that all of the elf files are exactly the same and valid.
+ for (size_t i = 0; i < kNumConcurrentThreads; i++) {
+ EXPECT_EQ(expected_build_id, build_id_values[i]) << "Thread " << i << " mismatched.";
+ }
+}
+
+TEST_F(MapInfoGetBuildIDTest, multiple_thread_elf_exists) {
+ map_info_->elf.reset(elf_container_.release());
+ elf_interface_->FakeSetBuildID("FAKE_BUILD_ID");
+
+ MultipleThreadTest("FAKE_BUILD_ID");
+}
+
+static void InitElfData(int fd) {
+ Elf32_Ehdr ehdr;
+ TestInitEhdr(&ehdr, ELFCLASS32, EM_ARM);
+ ehdr.e_shoff = 0x2000;
+ ehdr.e_shnum = 3;
+ ehdr.e_shentsize = sizeof(Elf32_Shdr);
+ ehdr.e_shstrndx = 2;
+ off_t offset = 0;
+ ASSERT_EQ(offset, lseek(fd, offset, SEEK_SET));
+ ASSERT_EQ(static_cast<ssize_t>(sizeof(ehdr)), write(fd, &ehdr, sizeof(ehdr)));
+
+ char note_section[128];
+ Elf32_Nhdr note_header = {};
+ note_header.n_namesz = 4; // "GNU"
+ note_header.n_descsz = 12; // "ELF_BUILDID"
+ note_header.n_type = NT_GNU_BUILD_ID;
+ memcpy(¬e_section, ¬e_header, sizeof(note_header));
+ size_t note_offset = sizeof(note_header);
+ memcpy(¬e_section[note_offset], "GNU", sizeof("GNU"));
+ note_offset += sizeof("GNU");
+ memcpy(¬e_section[note_offset], "ELF_BUILDID", sizeof("ELF_BUILDID"));
+ note_offset += sizeof("ELF_BUILDID");
+
+ Elf32_Shdr shdr = {};
+ shdr.sh_type = SHT_NOTE;
+ shdr.sh_name = 0x500;
+ shdr.sh_offset = 0xb000;
+ shdr.sh_size = sizeof(note_section);
+ offset += ehdr.e_shoff + sizeof(shdr);
+ ASSERT_EQ(offset, lseek(fd, offset, SEEK_SET));
+ ASSERT_EQ(static_cast<ssize_t>(sizeof(shdr)), write(fd, &shdr, sizeof(shdr)));
+
+ // The string data for section header names.
+ memset(&shdr, 0, sizeof(shdr));
+ shdr.sh_type = SHT_STRTAB;
+ shdr.sh_name = 0x20000;
+ shdr.sh_offset = 0xf000;
+ shdr.sh_size = 0x1000;
+ offset += sizeof(shdr);
+ ASSERT_EQ(offset, lseek(fd, offset, SEEK_SET));
+ ASSERT_EQ(static_cast<ssize_t>(sizeof(shdr)), write(fd, &shdr, sizeof(shdr)));
+
+ offset = 0xf500;
+ ASSERT_EQ(offset, lseek(fd, offset, SEEK_SET));
+ ASSERT_EQ(static_cast<ssize_t>(sizeof(".note.gnu.build-id")),
+ write(fd, ".note.gnu.build-id", sizeof(".note.gnu.build-id")));
+
+ offset = 0xb000;
+ ASSERT_EQ(offset, lseek(fd, offset, SEEK_SET));
+ ASSERT_EQ(static_cast<ssize_t>(sizeof(note_section)),
+ write(fd, note_section, sizeof(note_section)));
+}
+
+TEST_F(MapInfoGetBuildIDTest, from_memory) {
+ InitElfData(tf_->fd);
+
+ EXPECT_EQ("ELF_BUILDID", map_info_->GetBuildID());
+}
+
+TEST_F(MapInfoGetBuildIDTest, multiple_thread_elf_exists_in_memory) {
+ InitElfData(tf_->fd);
+
+ MultipleThreadTest("ELF_BUILDID");
+}
+
+} // namespace unwindstack
diff --git a/libunwindstack/tests/MapInfoGetElfTest.cpp b/libunwindstack/tests/MapInfoGetElfTest.cpp
index 99f8fa3..d7b8485 100644
--- a/libunwindstack/tests/MapInfoGetElfTest.cpp
+++ b/libunwindstack/tests/MapInfoGetElfTest.cpp
@@ -88,6 +88,12 @@
ASSERT_TRUE(elf->valid());
EXPECT_EQ(static_cast<uint32_t>(EM_ARM), elf->machine_type());
EXPECT_EQ(ELFCLASS32, elf->class_type());
+
+ // Now verify that an empty process memory returns an invalid elf object.
+ info.elf.reset();
+ elf = info.GetElf(std::shared_ptr<Memory>(), ARCH_ARM);
+ ASSERT_TRUE(elf != nullptr);
+ ASSERT_FALSE(elf->valid());
}
TEST_F(MapInfoGetElfTest, valid64) {
diff --git a/libunwindstack/tools/unwind_info.cpp b/libunwindstack/tools/unwind_info.cpp
index 3f2dfb0..3f5b88b 100644
--- a/libunwindstack/tools/unwind_info.cpp
+++ b/libunwindstack/tools/unwind_info.cpp
@@ -123,8 +123,8 @@
printf("Soname: %s\n", soname.c_str());
}
- std::string build_id;
- if (elf.GetBuildID(&build_id)) {
+ std::string build_id = elf.GetBuildID();
+ if (!build_id.empty()) {
printf("Build ID: ");
for (size_t i = 0; i < build_id.size(); ++i) {
printf("%02hhx", build_id[i]);