[lldb] Support Universal Mach-O binaries with a fat64 header

[JDevlieghere]

Summary

Support universal Mach-O binaries with a fat64 header. After D146879, dsymutil can now generate such binaries when the offsets would otherwise overflow the 32-bit offsets in the regular fat header.

rdar://107289570

[aprantl]

lldb/source/Plugins/ObjectContainer/Universal-Mach-O/ObjectContainerUniversalMachO.cpp

205

Should this use AddOverflow?
https://llvm.org/doxygen/MathExtras_8h.html

lldb/test/API/macosx/universal64/TestUniversal64.py

22

would it be easy to verify in the test or the makefile that the dsym indeed has a fat header?

[JDevlieghere]

lldb/source/Plugins/ObjectContainer/Universal-Mach-O/ObjectContainerUniversalMachO.cpp

205

Yes, but nothing in ObjectContainerUniversalMachO is currently overflow aware. I'll fix up the whole file in a follow-up.

lldb/test/API/macosx/universal64/TestUniversal64.py

22

llvm-objdump can dump the universal headers but that's currently not a dependency of the test suite and I didn't think it was worth adding just for a sanity check.

[JDevlieghere]

lldb/source/Plugins/ObjectContainer/Universal-Mach-O/ObjectContainerUniversalMachO.cpp

205

Actually, it looks like AddOverflow only checks for signed overflow (std::enable_if_t< std::is_signed< T >::value, T >). I assumed it was going through APInt under the hood. I think that's probably overkill here.

[aprantl]

Thanks for checking!

lldb/packages/Python/lldbsuite/test/make/Makefile.rules

 #----------------------------------------------------------------------
 ARCHFLAG ?= -arch
 
 #----------------------------------------------------------------------
 # Change any build/tool options needed
 #----------------------------------------------------------------------
 ifeq "$(OS)" "Darwin"
   DS := $(DSYMUTIL)
-  DSFLAGS =
+  DSFLAGS := $(DSFLAGS_EXTRAS)
   DSYM = $(EXE).dSYM
   AR := $(CROSS_COMPILE)libtool
   ARFLAGS := -static -o
 else
   AR := $(CROSS_COMPILE)ar
   # On non-Apple platforms, -arch becomes -m
   ARCHFLAG := -m
 

lldb/source/Plugins/ObjectContainer/Universal-Mach-O/ObjectContainerUniversalMachO.h

public:
 
   lldb::ObjectFileSP GetObjectFile(const lldb_private::FileSpec *file) override;
 
   // PluginInterface protocol
   llvm::StringRef GetPluginName() override { return GetPluginNameStatic(); }
 
 protected:
   llvm::MachO::fat_header m_header;
-  std::vector<llvm::MachO::fat_arch> m_fat_archs;
+
+  struct FatArch {
+    FatArch(llvm::MachO::fat_arch arch) : m_arch(arch), m_is_fat64(false) {}
+    FatArch(llvm::MachO::fat_arch_64 arch) : m_arch(arch), m_is_fat64(true) {}
+
+    uint32_t GetCPUType() const {
+      return m_is_fat64 ? m_arch.fat_arch_64.cputype : m_arch.fat_arch.cputype;
+    }
+
+    uint32_t GetCPUSubType() const {
+      return m_is_fat64 ? m_arch.fat_arch_64.cpusubtype
+                        : m_arch.fat_arch.cpusubtype;
+    }
+
+    uint64_t GetOffset() const {
+      return m_is_fat64 ? m_arch.fat_arch_64.offset : m_arch.fat_arch.offset;
+    }
+
+    uint64_t GetSize() const {
+      return m_is_fat64 ? m_arch.fat_arch_64.size : m_arch.fat_arch.size;
+    }
+
+    uint32_t GetAlign() const {
+      return m_is_fat64 ? m_arch.fat_arch_64.align : m_arch.fat_arch.align;
+    }
+
+  private:
+    const union Arch {
+      Arch(llvm::MachO::fat_arch arch) : fat_arch(arch) {}
+      Arch(llvm::MachO::fat_arch_64 arch) : fat_arch_64(arch) {}
+      llvm::MachO::fat_arch fat_arch;
+      llvm::MachO::fat_arch_64 fat_arch_64;
+    } m_arch;
+    const bool m_is_fat64;
+  };
+  std::vector<FatArch> m_fat_archs;
 
   static bool ParseHeader(lldb_private::DataExtractor &data,
                           llvm::MachO::fat_header &header,
-                          std::vector<llvm::MachO::fat_arch> &fat_archs);
+                          std::vector<FatArch> &fat_archs);
 };
 
 #endif // LLDB_SOURCE_PLUGINS_OBJECTCONTAINER_UNIVERSAL_MACH_O_OBJECTCONTAINERUNIVERSALMACHO_H

lldb/source/Plugins/ObjectContainer/Universal-Mach-O/ObjectContainerUniversalMachO.cpp

if (data_sp) {
     }
   }
   return nullptr;
 }
 
 bool ObjectContainerUniversalMachO::MagicBytesMatch(const DataExtractor &data) {
   lldb::offset_t offset = 0;
   uint32_t magic = data.GetU32(&offset);
-  return magic == FAT_MAGIC || magic == FAT_CIGAM;
+  return magic == FAT_MAGIC || magic == FAT_CIGAM || magic == FAT_MAGIC_64 ||
+         magic == FAT_CIGAM_64;
 }
 
 ObjectContainerUniversalMachO::ObjectContainerUniversalMachO(
     const lldb::ModuleSP &module_sp, DataBufferSP &data_sp,
     lldb::offset_t data_offset, const FileSpec *file,
     lldb::offset_t file_offset, lldb::offset_t length)
     : ObjectContainer(module_sp, file, file_offset, length, data_sp,
                       data_offset),
       m_header(), m_fat_archs() {
   memset(&m_header, 0, sizeof(m_header));
 }
 
 ObjectContainerUniversalMachO::~ObjectContainerUniversalMachO() = default;
 
 bool ObjectContainerUniversalMachO::ParseHeader() {
   bool success = ParseHeader(m_data, m_header, m_fat_archs);
   // We no longer need any data, we parsed all we needed to parse and cached it
   // in m_header and m_fat_archs
   m_data.Clear();
   return success;
 }
 
 bool ObjectContainerUniversalMachO::ParseHeader(
     lldb_private::DataExtractor &data, llvm::MachO::fat_header &header,
-    std::vector<llvm::MachO::fat_arch> &fat_archs) {
-  bool success = false;
+    std::vector<FatArch> &fat_archs) {
   // Store the file offset for this universal file as we could have a universal
   // .o file in a BSD archive, or be contained in another kind of object.
-  // Universal mach-o files always have their headers in big endian.
   lldb::offset_t offset = 0;
   data.SetByteOrder(eByteOrderBig);
   header.magic = data.GetU32(&offset);
   fat_archs.clear();
 
-  if (header.magic == FAT_MAGIC) {
-
-    data.SetAddressByteSize(4);
+  // Universal mach-o files always have their headers in big endian.
+  if (header.magic == FAT_MAGIC || header.magic == FAT_MAGIC_64) {
+    const bool is_fat64 = header.magic == FAT_MAGIC_64;
+    data.SetAddressByteSize(is_fat64 ? 8 : 4);
 
     header.nfat_arch = data.GetU32(&offset);
 
     // Now we should have enough data for all of the fat headers, so lets index
     // them so we know how many architectures that this universal binary
     // contains.
-    uint32_t arch_idx = 0;
-    for (arch_idx = 0; arch_idx < header.nfat_arch; ++arch_idx) {
+    for (uint32_t arch_idx = 0; arch_idx < header.nfat_arch; ++arch_idx) {
       if (data.ValidOffsetForDataOfSize(offset, sizeof(fat_arch))) {
+        if (is_fat64) {
+          fat_arch_64 arch;
+          arch.cputype = data.GetU32(&offset);
+          arch.cpusubtype = data.GetU32(&offset);
+          arch.offset = data.GetU64(&offset);
+          arch.size = data.GetU64(&offset);
+          arch.align = data.GetU32(&offset);
+          arch.reserved = data.GetU32(&offset);
+          fat_archs.emplace_back(arch);
+        } else {
           fat_arch arch;
-        if (data.GetU32(&offset, &arch, sizeof(fat_arch) / sizeof(uint32_t)))
-          fat_archs.push_back(arch);
+          arch.cputype = data.GetU32(&offset);
+          arch.cpusubtype = data.GetU32(&offset);
+          arch.offset = data.GetU32(&offset);
+          arch.size = data.GetU32(&offset);
+          arch.align = data.GetU32(&offset);
+          fat_archs.emplace_back(arch);
         }
       }
-    success = true;
-  } else {
-    memset(&header, 0, sizeof(header));
     }
-  return success;
+    return true;
+  }
+
+  memset(&header, 0, sizeof(header));
+  return true;
 }
 
 size_t ObjectContainerUniversalMachO::GetNumArchitectures() const {
   return m_header.nfat_arch;
 }
 
 bool ObjectContainerUniversalMachO::GetArchitectureAtIndex(
     uint32_t idx, ArchSpec &arch) const {
   if (idx < m_header.nfat_arch) {
-    arch.SetArchitecture(eArchTypeMachO, m_fat_archs[idx].cputype,
-                         m_fat_archs[idx].cpusubtype);
+    arch.SetArchitecture(eArchTypeMachO, m_fat_archs[idx].GetCPUType(),
+                         m_fat_archs[idx].GetCPUSubType());
     return true;
   }
   return false;
 }
 
 ObjectFileSP
 ObjectContainerUniversalMachO::GetObjectFile(const FileSpec *file) {
   uint32_t arch_idx = 0;
if (arch_idx >= m_header.nfat_arch) {
           break;
       }
     }
 
     if (arch_idx < m_header.nfat_arch) {
       DataBufferSP data_sp;
       lldb::offset_t data_offset = 0;
       return ObjectFile::FindPlugin(
-          module_sp, file, m_offset + m_fat_archs[arch_idx].offset,
-          m_fat_archs[arch_idx].size, data_sp, data_offset);
+          module_sp, file, m_offset + m_fat_archs[arch_idx].GetOffset(),
+          m_fat_archs[arch_idx].GetSize(), data_sp, data_offset);
     }
   }
   return ObjectFileSP();
 }
 
 size_t ObjectContainerUniversalMachO::GetModuleSpecifications(
     const lldb_private::FileSpec &file, lldb::DataBufferSP &data_sp,
     lldb::offset_t data_offset, lldb::offset_t file_offset,
     lldb::offset_t file_size, lldb_private::ModuleSpecList &specs) {
   const size_t initial_count = specs.GetSize();
 
   DataExtractor data;
   data.SetData(data_sp, data_offset, data_sp->GetByteSize());
 
   if (ObjectContainerUniversalMachO::MagicBytesMatch(data)) {
     llvm::MachO::fat_header header;
-    std::vector<llvm::MachO::fat_arch> fat_archs;
+    std::vector<FatArch> fat_archs;
     if (ParseHeader(data, header, fat_archs)) {
-      for (const llvm::MachO::fat_arch &fat_arch : fat_archs) {
-        const lldb::offset_t slice_file_offset = fat_arch.offset + file_offset;
-        if (fat_arch.offset < file_size && file_size > slice_file_offset) {
+      for (const FatArch &fat_arch : fat_archs) {
+        const lldb::offset_t slice_file_offset =
+            fat_arch.GetOffset() + file_offset;
+        if (fat_arch.GetOffset() < file_size && file_size > slice_file_offset) {
           ObjectFile::GetModuleSpecifications(
               file, slice_file_offset, file_size - slice_file_offset, specs);
         }
       }
     }
   }
   return specs.GetSize() - initial_count;
 }

lldb/test/API/macosx/universal64/Makefile

+EXE := fat.out
+
+ifdef FAT64_DSYM
+  DSFLAGS_EXTRAS=-fat64
+endif
+
+include Makefile.rules
+
+all: fat.out
+
+fat.out: fat.arm64.out fat.x86_64.out
+  lipo -fat64 -create -o $@ $^
+
+fat.x86_64.out: fat.x86_64.o
+  $(CC) -isysroot $(SDKROOT) -target x86_64-apple-macosx10.9 -o $@ $<
+
+fat.arm64.out: fat.arm64.o
+  $(CC) -isysroot $(SDKROOT) -target arm64-apple-macosx10.9 -o $@ $<
+
+fat.x86_64.o: main.c
+  $(CC) -isysroot $(SDKROOT) -g -O0 -target x86_64-apple-macosx11 -c -o $@ $<
+
+fat.arm64.o: main.c
+  $(CC) -isysroot $(SDKROOT) -g -O0 -target arm64-apple-macosx11 -c -o $@ $<

lldb/test/API/macosx/universal64/TestUniversal64.py

+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class Universal64TestCase(TestBase):
+    NO_DEBUG_INFO_TESTCASE = True
+
+    def do_test(self):
+        # Get the executable.
+        exe = self.getBuildArtifact("fat.out")
+
+        # Create a target.
+        self.target = self.dbg.CreateTarget(exe)
+
+        # Create a breakpoint on main.
+        main_bp = self.target.BreakpointCreateByName("main")
+        self.assertTrue(main_bp, VALID_BREAKPOINT)
+
+        # Make sure the binary and the dSYM are in the image list.
+        self.expect("image list ", patterns=['fat.out', 'fat.out.dSYM'])
+
+        # The dynamic loader doesn't support fat64 executables so we can't
+        # actually launch them here.
+
+    @skipUnlessDarwin
+    @skipIfDarwinEmbedded
+    def test_universal64_executable(self):
+        """Test fat64 universal executable"""
+        self.build(debug_info="dsym")
+        self.do_test()
+
+    @skipUnlessDarwin
+    @skipIfDarwinEmbedded
+    @skipIf(compiler="clang", compiler_version=['<', '7.0'])
+    def test_universal64_dsym(self):
+        """Test fat64 universal dSYM"""
+        self.build(debug_info="dsym", dictionary={'FAT64_DSYM': '1'})
+        self.do_test()

lldb/test/API/macosx/universal64/main.c

+#include <stdio.h>
+
+int foo() { return 0; }
+
+int main(int argc, char **argv) { return foo(); }