2aa020f49b
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
109 lines
3.9 KiB
C++
109 lines
3.9 KiB
C++
//===-- ObjectContainerUniversalMachO.h -------------------------*- C++ -*-===//
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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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#ifndef LLDB_SOURCE_PLUGINS_OBJECTCONTAINER_UNIVERSAL_MACH_O_OBJECTCONTAINERUNIVERSALMACHO_H
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#define LLDB_SOURCE_PLUGINS_OBJECTCONTAINER_UNIVERSAL_MACH_O_OBJECTCONTAINERUNIVERSALMACHO_H
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#include "lldb/Host/SafeMachO.h"
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#include "lldb/Symbol/ObjectContainer.h"
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#include "lldb/Utility/FileSpec.h"
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class ObjectContainerUniversalMachO : public lldb_private::ObjectContainer {
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public:
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ObjectContainerUniversalMachO(const lldb::ModuleSP &module_sp,
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lldb::DataBufferSP &data_sp,
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lldb::offset_t data_offset,
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const lldb_private::FileSpec *file,
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lldb::offset_t offset, lldb::offset_t length);
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~ObjectContainerUniversalMachO() override;
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// Static Functions
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static void Initialize();
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static void Terminate();
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static llvm::StringRef GetPluginNameStatic() { return "mach-o"; }
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static llvm::StringRef GetPluginDescriptionStatic() {
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return "Universal mach-o object container reader.";
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}
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static lldb_private::ObjectContainer *
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CreateInstance(const lldb::ModuleSP &module_sp, lldb::DataBufferSP &data_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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static size_t GetModuleSpecifications(const lldb_private::FileSpec &file,
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lldb::DataExtractorSP &extractor_sp,
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lldb::offset_t data_offset,
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lldb::offset_t file_offset,
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lldb::offset_t length,
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lldb_private::ModuleSpecList &specs);
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static bool MagicBytesMatch(const lldb_private::DataExtractor &data);
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// Member Functions
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bool ParseHeader() override;
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size_t GetNumArchitectures() const override;
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bool GetArchitectureAtIndex(uint32_t cpu_idx,
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lldb_private::ArchSpec &arch) const override;
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lldb::ObjectFileSP GetObjectFile(const lldb_private::FileSpec *file) override;
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// PluginInterface protocol
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llvm::StringRef GetPluginName() override { return GetPluginNameStatic(); }
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protected:
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llvm::MachO::fat_header m_header;
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struct FatArch {
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FatArch(llvm::MachO::fat_arch arch) : m_arch(arch), m_is_fat64(false) {}
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FatArch(llvm::MachO::fat_arch_64 arch) : m_arch(arch), m_is_fat64(true) {}
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uint32_t GetCPUType() const {
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return m_is_fat64 ? m_arch.fat_arch_64.cputype : m_arch.fat_arch.cputype;
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}
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uint32_t GetCPUSubType() const {
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return m_is_fat64 ? m_arch.fat_arch_64.cpusubtype
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: m_arch.fat_arch.cpusubtype;
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}
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uint64_t GetOffset() const {
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return m_is_fat64 ? m_arch.fat_arch_64.offset : m_arch.fat_arch.offset;
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}
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uint64_t GetSize() const {
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return m_is_fat64 ? m_arch.fat_arch_64.size : m_arch.fat_arch.size;
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}
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uint32_t GetAlign() const {
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return m_is_fat64 ? m_arch.fat_arch_64.align : m_arch.fat_arch.align;
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}
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private:
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const union Arch {
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Arch(llvm::MachO::fat_arch arch) : fat_arch(arch) {}
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Arch(llvm::MachO::fat_arch_64 arch) : fat_arch_64(arch) {}
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llvm::MachO::fat_arch fat_arch;
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llvm::MachO::fat_arch_64 fat_arch_64;
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} m_arch;
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const bool m_is_fat64;
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};
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std::vector<FatArch> m_fat_archs;
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static bool ParseHeader(lldb_private::DataExtractor &data,
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llvm::MachO::fat_header &header,
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std::vector<FatArch> &fat_archs);
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};
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#endif // LLDB_SOURCE_PLUGINS_OBJECTCONTAINER_UNIVERSAL_MACH_O_OBJECTCONTAINERUNIVERSALMACHO_H
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