In a PR last month I changed the ObjectFile CreateInstance etc methods to accept an optional DataExtractorSP instead of a DataBufferSP, and retain the extractor in a shared pointer internally in all of the ObjectFile subclasses. This is laying the groundwork for using a VirtualDataExtractor for some Mach-O binaries on macOS, where the segments of the binary are out-of-order in actual memory, and we add a lookup table to make it appear that the TEXT segment is at offset 0 in the Extractor, etc. Working on the actual implementation, I realized we were still using DataBufferSP's in ModuleSpec and Module, as well as in ObjectFile::GetModuleSpecifications. I originally was making a much larger NFC change where I had all ObjectFile subclasses operating on DataExtractors throughout their implementation, as well as in the DWARF parser. It was a very large patchset. Many subclasses start with their DataExtractor, then create smaller DataExtractors for parts of the binary image - the string table, the symbol table, etc., for processing. After consideration and discussion with Jonas, we agreed that a segment/section of a binary will never require a lookup table to access the bytes within it, so I changed VirtualDataExtractor::GetSubsetExtractorSP to (1) require that the Subset be contained within a single lookup table entry, and (2) return a simple DataExtractor bounded on that byte range. By doing this, I was able to remove all of my very-invasive changes to the ObjectFile subclass internals; it's only when they are operating on the entire binary image that care is needed. One pattern that subclasses like ObjectFileBreakpad use is to take an ArrayRef of the DataBuffer for a binary, then create a StringRef of that, then look for strings in it. With a VirtualDataExtractor and out-of-order binary segments, with gaps between them, this allows us to search the entire buffer looking for a string, and segfault when it gets to an unmapped region of the buffer. I added a VirtualDataExtractor::GetSubsetExtractorSP(0) which gets the largest contiguous memory region starting at offset 0 for this use case, and I added a comment about what was being done there because I know it is not obvious, and people not working on macOS wouldn't be familiar with the requirement. (when we have a ModuleSpec with a DataExtractor, any of the ObjectFile subclasses get a shot at Creating, so they all have to be able to iterate on these) rdar://148939795
156 lines
4.6 KiB
C++
156 lines
4.6 KiB
C++
//===-- ObjectFileMinidump.cpp --------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "ObjectFileMinidump.h"
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#include "MinidumpFileBuilder.h"
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#include "lldb/Core/ModuleSpec.h"
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#include "lldb/Core/PluginManager.h"
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#include "lldb/Core/Section.h"
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#include "lldb/Target/Process.h"
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#include "lldb/Utility/LLDBLog.h"
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#include "lldb/Utility/Log.h"
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#include "llvm/Support/FileSystem.h"
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using namespace lldb;
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using namespace lldb_private;
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LLDB_PLUGIN_DEFINE(ObjectFileMinidump)
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void ObjectFileMinidump::Initialize() {
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PluginManager::RegisterPlugin(
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GetPluginNameStatic(), GetPluginDescriptionStatic(), CreateInstance,
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CreateMemoryInstance, GetModuleSpecifications, SaveCore);
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}
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void ObjectFileMinidump::Terminate() {
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PluginManager::UnregisterPlugin(CreateInstance);
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}
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ObjectFile *ObjectFileMinidump::CreateInstance(
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const lldb::ModuleSP &module_sp, lldb::DataExtractorSP extractor_sp,
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lldb::offset_t data_offset, const lldb_private::FileSpec *file,
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lldb::offset_t offset, lldb::offset_t length) {
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return nullptr;
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}
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ObjectFile *ObjectFileMinidump::CreateMemoryInstance(
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const lldb::ModuleSP &module_sp, WritableDataBufferSP data_sp,
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const ProcessSP &process_sp, lldb::addr_t header_addr) {
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return nullptr;
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}
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size_t ObjectFileMinidump::GetModuleSpecifications(
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const lldb_private::FileSpec &file, lldb::DataExtractorSP &extractor_sp,
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lldb::offset_t data_offset, lldb::offset_t file_offset,
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lldb::offset_t length, lldb_private::ModuleSpecList &specs) {
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specs.Clear();
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return 0;
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}
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struct DumpFailRemoveHolder {
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DumpFailRemoveHolder(MinidumpFileBuilder &builder) : m_builder(builder) {}
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~DumpFailRemoveHolder() {
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if (!m_success)
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m_builder.DeleteFile();
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}
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void SetSuccess() { m_success = true; }
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private:
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MinidumpFileBuilder &m_builder;
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bool m_success = false;
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};
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bool ObjectFileMinidump::SaveCore(const lldb::ProcessSP &process_sp,
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lldb_private::SaveCoreOptions &options,
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lldb_private::Status &error) {
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// Output file and process_sp are both checked in PluginManager::SaveCore.
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assert(options.GetOutputFile().has_value());
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assert(process_sp);
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// Minidump defaults to stacks only.
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if (options.GetStyle() == SaveCoreStyle::eSaveCoreUnspecified)
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options.SetStyle(SaveCoreStyle::eSaveCoreStackOnly);
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llvm::Expected<lldb::FileUP> maybe_core_file = FileSystem::Instance().Open(
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options.GetOutputFile().value(),
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File::eOpenOptionWriteOnly | File::eOpenOptionCanCreate);
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if (!maybe_core_file) {
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error = Status::FromError(maybe_core_file.takeError());
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return false;
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}
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MinidumpFileBuilder builder(std::move(maybe_core_file.get()), process_sp,
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options);
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DumpFailRemoveHolder request(builder);
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Log *log = GetLog(LLDBLog::Object);
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error = builder.AddHeaderAndCalculateDirectories();
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if (error.Fail()) {
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LLDB_LOGF(log, "AddHeaderAndCalculateDirectories failed: %s",
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error.AsCString());
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return false;
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};
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error = builder.AddSystemInfo();
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if (error.Fail()) {
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LLDB_LOGF(log, "AddSystemInfo failed: %s", error.AsCString());
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return false;
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}
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error = builder.AddModuleList();
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if (error.Fail()) {
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LLDB_LOGF(log, "AddModuleList failed: %s", error.AsCString());
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return false;
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}
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error = builder.AddMiscInfo();
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if (error.Fail()) {
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LLDB_LOGF(log, "AddMiscInfo failed: %s", error.AsCString());
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return false;
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}
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error = builder.AddThreadList();
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if (error.Fail()) {
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LLDB_LOGF(log, "AddThreadList failed: %s", error.AsCString());
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return false;
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}
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error = builder.AddLinuxFileStreams();
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if (error.Fail()) {
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LLDB_LOGF(log, "AddLinuxFileStreams failed: %s", error.AsCString());
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return false;
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}
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// Add any exceptions but only if there are any in any threads.
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error = builder.AddExceptions();
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if (error.Fail()) {
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LLDB_LOGF(log, "AddExceptions failed: %s", error.AsCString());
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return false;
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}
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// Note: add memory HAS to be the last thing we do. It can overflow into 64b
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// land and many RVA's only support 32b
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error = builder.AddMemoryList();
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if (error.Fail()) {
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LLDB_LOGF(log, "AddMemoryList failed: %s", error.AsCString());
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return false;
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}
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error = builder.DumpFile();
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if (error.Fail()) {
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LLDB_LOGF(log, "DumpFile failed: %s", error.AsCString());
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return false;
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}
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request.SetSuccess();
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return true;
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}
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