534 lines
16 KiB
C++
534 lines
16 KiB
C++
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <inttypes.h>
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#include <functional>
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#include <iomanip>
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#include <mutex>
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#include <string>
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#include <sstream>
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#include <unordered_map>
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#include <backtrace.h>
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#include <android-base/macros.h>
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#include "Allocator.h"
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#include "HeapWalker.h"
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#include "Leak.h"
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#include "LeakFolding.h"
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#include "LeakPipe.h"
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#include "ProcessMappings.h"
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#include "PtracerThread.h"
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#include "ScopedDisableMalloc.h"
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#include "Semaphore.h"
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#include "ThreadCapture.h"
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#include "memunreachable/memunreachable.h"
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#include "bionic.h"
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#include "log.h"
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const size_t Leak::contents_length;
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using namespace std::chrono_literals;
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class MemUnreachable {
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public:
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MemUnreachable(pid_t pid, Allocator<void> allocator) : pid_(pid), allocator_(allocator),
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heap_walker_(allocator_) {}
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bool CollectAllocations(const allocator::vector<ThreadInfo>& threads,
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const allocator::vector<Mapping>& mappings);
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bool GetUnreachableMemory(allocator::vector<Leak>& leaks, size_t limit,
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size_t* num_leaks, size_t* leak_bytes);
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size_t Allocations() { return heap_walker_.Allocations(); }
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size_t AllocationBytes() { return heap_walker_.AllocationBytes(); }
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private:
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bool ClassifyMappings(const allocator::vector<Mapping>& mappings,
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allocator::vector<Mapping>& heap_mappings,
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allocator::vector<Mapping>& anon_mappings,
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allocator::vector<Mapping>& globals_mappings,
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allocator::vector<Mapping>& stack_mappings);
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DISALLOW_COPY_AND_ASSIGN(MemUnreachable);
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pid_t pid_;
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Allocator<void> allocator_;
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HeapWalker heap_walker_;
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};
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static void HeapIterate(const Mapping& heap_mapping,
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const std::function<void(uintptr_t, size_t)>& func) {
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malloc_iterate(heap_mapping.begin, heap_mapping.end - heap_mapping.begin,
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[](uintptr_t base, size_t size, void* arg) {
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auto f = reinterpret_cast<const std::function<void(uintptr_t, size_t)>*>(arg);
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(*f)(base, size);
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}, const_cast<void*>(reinterpret_cast<const void*>(&func)));
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}
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bool MemUnreachable::CollectAllocations(const allocator::vector<ThreadInfo>& threads,
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const allocator::vector<Mapping>& mappings) {
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ALOGI("searching process %d for allocations", pid_);
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allocator::vector<Mapping> heap_mappings{mappings};
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allocator::vector<Mapping> anon_mappings{mappings};
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allocator::vector<Mapping> globals_mappings{mappings};
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allocator::vector<Mapping> stack_mappings{mappings};
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if (!ClassifyMappings(mappings, heap_mappings, anon_mappings,
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globals_mappings, stack_mappings)) {
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return false;
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}
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for (auto it = heap_mappings.begin(); it != heap_mappings.end(); it++) {
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ALOGV("Heap mapping %" PRIxPTR "-%" PRIxPTR " %s", it->begin, it->end, it->name);
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HeapIterate(*it, [&](uintptr_t base, size_t size) {
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heap_walker_.Allocation(base, base + size);
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});
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}
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for (auto it = anon_mappings.begin(); it != anon_mappings.end(); it++) {
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ALOGV("Anon mapping %" PRIxPTR "-%" PRIxPTR " %s", it->begin, it->end, it->name);
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heap_walker_.Allocation(it->begin, it->end);
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}
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for (auto it = globals_mappings.begin(); it != globals_mappings.end(); it++) {
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ALOGV("Globals mapping %" PRIxPTR "-%" PRIxPTR " %s", it->begin, it->end, it->name);
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heap_walker_.Root(it->begin, it->end);
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}
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for (auto thread_it = threads.begin(); thread_it != threads.end(); thread_it++) {
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for (auto it = stack_mappings.begin(); it != stack_mappings.end(); it++) {
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if (thread_it->stack.first >= it->begin && thread_it->stack.first <= it->end) {
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ALOGV("Stack %" PRIxPTR "-%" PRIxPTR " %s", thread_it->stack.first, it->end, it->name);
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heap_walker_.Root(thread_it->stack.first, it->end);
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}
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}
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heap_walker_.Root(thread_it->regs);
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}
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ALOGI("searching done");
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return true;
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}
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bool MemUnreachable::GetUnreachableMemory(allocator::vector<Leak>& leaks,
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size_t limit, size_t* num_leaks, size_t* leak_bytes) {
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ALOGI("sweeping process %d for unreachable memory", pid_);
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leaks.clear();
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if (!heap_walker_.DetectLeaks()) {
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return false;
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}
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allocator::vector<Range> leaked1{allocator_};
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heap_walker_.Leaked(leaked1, 0, num_leaks, leak_bytes);
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ALOGI("sweeping done");
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ALOGI("folding related leaks");
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LeakFolding folding(allocator_, heap_walker_);
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if (!folding.FoldLeaks()) {
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return false;
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}
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allocator::vector<LeakFolding::Leak> leaked{allocator_};
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if (!folding.Leaked(leaked, num_leaks, leak_bytes)) {
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return false;
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}
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allocator::unordered_map<Leak::Backtrace, Leak*> backtrace_map{allocator_};
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// Prevent reallocations of backing memory so we can store pointers into it
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// in backtrace_map.
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leaks.reserve(leaked.size());
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for (auto& it: leaked) {
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leaks.emplace_back();
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Leak* leak = &leaks.back();
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ssize_t num_backtrace_frames = malloc_backtrace(reinterpret_cast<void*>(it.range.begin),
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leak->backtrace.frames, leak->backtrace.max_frames);
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if (num_backtrace_frames > 0) {
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leak->backtrace.num_frames = num_backtrace_frames;
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auto inserted = backtrace_map.emplace(leak->backtrace, leak);
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if (!inserted.second) {
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// Leak with same backtrace already exists, drop this one and
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// increment similar counts on the existing one.
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leaks.pop_back();
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Leak* similar_leak = inserted.first->second;
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similar_leak->similar_count++;
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similar_leak->similar_size += it.range.size();
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similar_leak->similar_referenced_count += it.referenced_count;
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similar_leak->similar_referenced_size += it.referenced_size;
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similar_leak->total_size += it.range.size();
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similar_leak->total_size += it.referenced_size;
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continue;
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}
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}
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leak->begin = it.range.begin;
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leak->size = it.range.size();
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leak->referenced_count = it.referenced_count;
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leak->referenced_size = it.referenced_size;
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leak->total_size = leak->size + leak->referenced_size;
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memcpy(leak->contents, reinterpret_cast<void*>(it.range.begin),
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std::min(leak->size, Leak::contents_length));
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}
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ALOGI("folding done");
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std::sort(leaks.begin(), leaks.end(), [](const Leak& a, const Leak& b) {
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return a.total_size > b.total_size;
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});
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if (leaks.size() > limit) {
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leaks.resize(limit);
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}
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return true;
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}
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static bool has_prefix(const allocator::string& s, const char* prefix) {
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int ret = s.compare(0, strlen(prefix), prefix);
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return ret == 0;
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}
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bool MemUnreachable::ClassifyMappings(const allocator::vector<Mapping>& mappings,
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allocator::vector<Mapping>& heap_mappings,
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allocator::vector<Mapping>& anon_mappings,
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allocator::vector<Mapping>& globals_mappings,
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allocator::vector<Mapping>& stack_mappings)
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{
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heap_mappings.clear();
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anon_mappings.clear();
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globals_mappings.clear();
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stack_mappings.clear();
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allocator::string current_lib{allocator_};
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for (auto it = mappings.begin(); it != mappings.end(); it++) {
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if (it->execute) {
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current_lib = it->name;
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continue;
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}
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if (!it->read) {
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continue;
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}
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const allocator::string mapping_name{it->name, allocator_};
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if (mapping_name == "[anon:.bss]") {
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// named .bss section
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globals_mappings.emplace_back(*it);
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} else if (mapping_name == current_lib) {
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// .rodata or .data section
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globals_mappings.emplace_back(*it);
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} else if (mapping_name == "[anon:libc_malloc]") {
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// named malloc mapping
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heap_mappings.emplace_back(*it);
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} else if (has_prefix(mapping_name, "/dev/ashmem/dalvik")) {
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// named dalvik heap mapping
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globals_mappings.emplace_back(*it);
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} else if (has_prefix(mapping_name, "[stack")) {
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// named stack mapping
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stack_mappings.emplace_back(*it);
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} else if (mapping_name.size() == 0) {
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globals_mappings.emplace_back(*it);
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} else if (has_prefix(mapping_name, "[anon:") && mapping_name != "[anon:leak_detector_malloc]") {
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// TODO(ccross): it would be nice to treat named anonymous mappings as
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// possible leaks, but naming something in a .bss or .data section makes
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// it impossible to distinguish them from mmaped and then named mappings.
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globals_mappings.emplace_back(*it);
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}
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}
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return true;
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}
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template<typename T>
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static inline const char* plural(T val) {
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return (val == 1) ? "" : "s";
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}
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bool GetUnreachableMemory(UnreachableMemoryInfo& info, size_t limit) {
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int parent_pid = getpid();
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int parent_tid = gettid();
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Heap heap;
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Semaphore continue_parent_sem;
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LeakPipe pipe;
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PtracerThread thread{[&]() -> int {
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/////////////////////////////////////////////
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// Collection thread
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/////////////////////////////////////////////
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ALOGI("collecting thread info for process %d...", parent_pid);
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ThreadCapture thread_capture(parent_pid, heap);
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allocator::vector<ThreadInfo> thread_info(heap);
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allocator::vector<Mapping> mappings(heap);
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// ptrace all the threads
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if (!thread_capture.CaptureThreads()) {
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continue_parent_sem.Post();
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return 1;
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}
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// collect register contents and stacks
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if (!thread_capture.CapturedThreadInfo(thread_info)) {
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continue_parent_sem.Post();
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return 1;
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}
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// snapshot /proc/pid/maps
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if (!ProcessMappings(parent_pid, mappings)) {
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continue_parent_sem.Post();
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return 1;
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}
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// malloc must be enabled to call fork, at_fork handlers take the same
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// locks as ScopedDisableMalloc. All threads are paused in ptrace, so
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// memory state is still consistent. Unfreeze the original thread so it
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// can drop the malloc locks, it will block until the collection thread
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// exits.
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thread_capture.ReleaseThread(parent_tid);
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continue_parent_sem.Post();
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// fork a process to do the heap walking
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int ret = fork();
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if (ret < 0) {
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return 1;
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} else if (ret == 0) {
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/////////////////////////////////////////////
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// Heap walker process
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/////////////////////////////////////////////
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// Examine memory state in the child using the data collected above and
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// the CoW snapshot of the process memory contents.
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if (!pipe.OpenSender()) {
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_exit(1);
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}
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MemUnreachable unreachable{parent_pid, heap};
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if (!unreachable.CollectAllocations(thread_info, mappings)) {
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_exit(2);
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}
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size_t num_allocations = unreachable.Allocations();
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size_t allocation_bytes = unreachable.AllocationBytes();
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allocator::vector<Leak> leaks{heap};
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size_t num_leaks = 0;
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size_t leak_bytes = 0;
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bool ok = unreachable.GetUnreachableMemory(leaks, limit, &num_leaks, &leak_bytes);
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ok = ok && pipe.Sender().Send(num_allocations);
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ok = ok && pipe.Sender().Send(allocation_bytes);
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ok = ok && pipe.Sender().Send(num_leaks);
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ok = ok && pipe.Sender().Send(leak_bytes);
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ok = ok && pipe.Sender().SendVector(leaks);
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if (!ok) {
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_exit(3);
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}
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_exit(0);
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} else {
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// Nothing left to do in the collection thread, return immediately,
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// releasing all the captured threads.
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ALOGI("collection thread done");
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return 0;
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}
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}};
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/////////////////////////////////////////////
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// Original thread
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/////////////////////////////////////////////
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{
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// Disable malloc to get a consistent view of memory
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ScopedDisableMalloc disable_malloc;
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// Start the collection thread
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thread.Start();
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// Wait for the collection thread to signal that it is ready to fork the
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// heap walker process.
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continue_parent_sem.Wait(30s);
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// Re-enable malloc so the collection thread can fork.
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}
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// Wait for the collection thread to exit
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int ret = thread.Join();
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if (ret != 0) {
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return false;
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}
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// Get a pipe from the heap walker process. Transferring a new pipe fd
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// ensures no other forked processes can have it open, so when the heap
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// walker process dies the remote side of the pipe will close.
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if (!pipe.OpenReceiver()) {
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return false;
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}
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bool ok = true;
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ok = ok && pipe.Receiver().Receive(&info.num_allocations);
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ok = ok && pipe.Receiver().Receive(&info.allocation_bytes);
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ok = ok && pipe.Receiver().Receive(&info.num_leaks);
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ok = ok && pipe.Receiver().Receive(&info.leak_bytes);
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ok = ok && pipe.Receiver().ReceiveVector(info.leaks);
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if (!ok) {
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return false;
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}
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ALOGI("unreachable memory detection done");
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ALOGE("%zu bytes in %zu allocation%s unreachable out of %zu bytes in %zu allocation%s",
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info.leak_bytes, info.num_leaks, plural(info.num_leaks),
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info.allocation_bytes, info.num_allocations, plural(info.num_allocations));
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return true;
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}
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std::string Leak::ToString(bool log_contents) const {
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std::ostringstream oss;
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oss << " " << std::dec << size;
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oss << " bytes unreachable at ";
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oss << std::hex << begin;
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oss << std::endl;
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if (referenced_count > 0) {
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oss << std::dec;
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oss << " referencing " << referenced_size << " unreachable bytes";
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oss << " in " << referenced_count << " allocation" << plural(referenced_count);
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oss << std::endl;
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}
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if (similar_count > 0) {
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oss << std::dec;
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oss << " and " << similar_size << " similar unreachable bytes";
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oss << " in " << similar_count << " allocation" << plural(similar_count);
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oss << std::endl;
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if (similar_referenced_count > 0) {
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oss << " referencing " << similar_referenced_size << " unreachable bytes";
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oss << " in " << similar_referenced_count << " allocation" << plural(similar_referenced_count);
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oss << std::endl;
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}
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}
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if (log_contents) {
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const int bytes_per_line = 16;
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const size_t bytes = std::min(size, contents_length);
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if (bytes == size) {
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oss << " contents:" << std::endl;
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} else {
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oss << " first " << bytes << " bytes of contents:" << std::endl;
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}
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for (size_t i = 0; i < bytes; i += bytes_per_line) {
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oss << " " << std::hex << begin + i << ": ";
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size_t j;
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oss << std::setfill('0');
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for (j = i; j < bytes && j < i + bytes_per_line; j++) {
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oss << std::setw(2) << static_cast<int>(contents[j]) << " ";
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}
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oss << std::setfill(' ');
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for (; j < i + bytes_per_line; j++) {
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oss << " ";
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}
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for (j = i; j < bytes && j < i + bytes_per_line; j++) {
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char c = contents[j];
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if (c < ' ' || c >= 0x7f) {
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c = '.';
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}
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oss << c;
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}
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oss << std::endl;
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}
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}
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if (backtrace.num_frames > 0) {
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oss << backtrace_string(backtrace.frames, backtrace.num_frames);
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}
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return oss.str();
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}
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// Figure out the abi based on defined macros.
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#if defined(__arm__)
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#define ABI_STRING "arm"
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#elif defined(__aarch64__)
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#define ABI_STRING "arm64"
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#elif defined(__mips__) && !defined(__LP64__)
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#define ABI_STRING "mips"
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#elif defined(__mips__) && defined(__LP64__)
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#define ABI_STRING "mips64"
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#elif defined(__i386__)
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#define ABI_STRING "x86"
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#elif defined(__x86_64__)
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#define ABI_STRING "x86_64"
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#else
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#error "Unsupported ABI"
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#endif
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std::string UnreachableMemoryInfo::ToString(bool log_contents) const {
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std::ostringstream oss;
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oss << " " << leak_bytes << " bytes in ";
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oss << num_leaks << " unreachable allocation" << plural(num_leaks);
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oss << std::endl;
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oss << " ABI: '" ABI_STRING "'" << std::endl;
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oss << std::endl;
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for (auto it = leaks.begin(); it != leaks.end(); it++) {
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oss << it->ToString(log_contents);
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oss << std::endl;
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}
|
|
|
|
return oss.str();
|
|
}
|
|
|
|
std::string GetUnreachableMemoryString(bool log_contents, size_t limit) {
|
|
UnreachableMemoryInfo info;
|
|
if (!GetUnreachableMemory(info, limit)) {
|
|
return "Failed to get unreachable memory\n";
|
|
}
|
|
|
|
return info.ToString(log_contents);
|
|
}
|
|
|
|
bool LogUnreachableMemory(bool log_contents, size_t limit) {
|
|
UnreachableMemoryInfo info;
|
|
if (!GetUnreachableMemory(info, limit)) {
|
|
return false;
|
|
}
|
|
|
|
for (auto it = info.leaks.begin(); it != info.leaks.end(); it++) {
|
|
ALOGE("%s", it->ToString(log_contents).c_str());
|
|
}
|
|
return true;
|
|
}
|
|
|
|
|
|
bool NoLeaks() {
|
|
UnreachableMemoryInfo info;
|
|
if (!GetUnreachableMemory(info, 0)) {
|
|
return false;
|
|
}
|
|
|
|
return info.num_leaks == 0;
|
|
}
|