compiler-rt/lib/sanitizer_common/sanitizer_procmaps_mac.cpp - llvm-project - Git at Google

 //===-- sanitizer_procmaps_mac.cpp ----------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // Information about the process mappings (Mac-specific parts).
 //===----------------------------------------------------------------------===//

 #include "sanitizer_platform.h"
 #if SANITIZER_MAC
 #include "sanitizer_common.h"
 #include "sanitizer_placement_new.h"
 #include "sanitizer_procmaps.h"

 #include <mach-o/dyld.h>
 #include <mach-o/loader.h>
 #include <mach/mach.h>

 // These are not available in older macOS SDKs.
 #ifndef CPU_SUBTYPE_X86_64_H
 #define CPU_SUBTYPE_X86_64_H  ((cpu_subtype_t)8)   /* Haswell */
 #endif
 #ifndef CPU_SUBTYPE_ARM_V7S
 #define CPU_SUBTYPE_ARM_V7S   ((cpu_subtype_t)11)  /* Swift */
 #endif
 #ifndef CPU_SUBTYPE_ARM_V7K
 #define CPU_SUBTYPE_ARM_V7K   ((cpu_subtype_t)12)
 #endif
 #ifndef CPU_TYPE_ARM64
 #define CPU_TYPE_ARM64        (CPU_TYPE_ARM | CPU_ARCH_ABI64)
 #endif

 namespace __sanitizer {

 // Contains information used to iterate through sections.
 struct MemoryMappedSegmentData {
   char name[kMaxSegName];
   uptr nsects;
   const char *current_load_cmd_addr;
   u32 lc_type;
   uptr base_virt_addr;
   uptr addr_mask;
 };

 template <typename Section>
 static void NextSectionLoad(LoadedModule *module, MemoryMappedSegmentData *data,
                             bool isWritable) {
   const Section *sc = (const Section *)data->current_load_cmd_addr;
   data->current_load_cmd_addr += sizeof(Section);

   uptr sec_start = (sc->addr & data->addr_mask) + data->base_virt_addr;
   uptr sec_end = sec_start + sc->size;
   module->addAddressRange(sec_start, sec_end, /*executable=*/false, isWritable,
                           sc->sectname);
 }

 void MemoryMappedSegment::AddAddressRanges(LoadedModule *module) {
   // Don't iterate over sections when the caller hasn't set up the
   // data pointer, when there are no sections, or when the segment
   // is executable. Avoid iterating over executable sections because
   // it will confuse libignore, and because the extra granularity
   // of information is not needed by any sanitizers.
   if (!data_ || !data_->nsects || IsExecutable()) {
     module->addAddressRange(start, end, IsExecutable(), IsWritable(),
                             data_ ? data_->name : nullptr);
     return;
   }

   do {
     if (data_->lc_type == LC_SEGMENT) {
       NextSectionLoad<struct section>(module, data_, IsWritable());
 #ifdef MH_MAGIC_64
     } else if (data_->lc_type == LC_SEGMENT_64) {
       NextSectionLoad<struct section_64>(module, data_, IsWritable());
 #endif
     }
   } while (--data_->nsects);
 }

 MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
   Reset();
 }

 MemoryMappingLayout::~MemoryMappingLayout() {
 }

 bool MemoryMappingLayout::Error() const {
   return false;
 }

 // More information about Mach-O headers can be found in mach-o/loader.h
 // Each Mach-O image has a header (mach_header or mach_header_64) starting with
 // a magic number, and a list of linker load commands directly following the
 // header.
 // A load command is at least two 32-bit words: the command type and the
 // command size in bytes. We're interested only in segment load commands
 // (LC_SEGMENT and LC_SEGMENT_64), which tell that a part of the file is mapped
 // into the task's address space.
 // The |vmaddr|, |vmsize| and |fileoff| fields of segment_command or
 // segment_command_64 correspond to the memory address, memory size and the
 // file offset of the current memory segment.
 // Because these fields are taken from the images as is, one needs to add
 // _dyld_get_image_vmaddr_slide() to get the actual addresses at runtime.

 void MemoryMappingLayout::Reset() {
   // Count down from the top.
   // TODO(glider): as per man 3 dyld, iterating over the headers with
   // _dyld_image_count is thread-unsafe. We need to register callbacks for
   // adding and removing images which will invalidate the MemoryMappingLayout
   // state.
   data_.current_image = _dyld_image_count();
   data_.current_load_cmd_count = -1;
   data_.current_load_cmd_addr = 0;
   data_.current_magic = 0;
   data_.current_filetype = 0;
   data_.current_arch = kModuleArchUnknown;
   internal_memset(data_.current_uuid, 0, kModuleUUIDSize);
 }

 // The dyld load address should be unchanged throughout process execution,
 // and it is expensive to compute once many libraries have been loaded,
 // so cache it here and do not reset.
 static mach_header *dyld_hdr = 0;
 static const char kDyldPath[] = "/usr/lib/dyld";
 static const int kDyldImageIdx = -1;

 // static
 void MemoryMappingLayout::CacheMemoryMappings() {
   // No-op on Mac for now.
 }

 void MemoryMappingLayout::LoadFromCache() {
   // No-op on Mac for now.
 }

 // _dyld_get_image_header() and related APIs don't report dyld itself.
 // We work around this by manually recursing through the memory map
 // until we hit a Mach header matching dyld instead. These recurse
 // calls are expensive, but the first memory map generation occurs
 // early in the process, when dyld is one of the only images loaded,
 // so it will be hit after only a few iterations.
 static mach_header *get_dyld_image_header() {
   unsigned depth = 1;
   vm_size_t size = 0;
   vm_address_t address = 0;
   kern_return_t err = KERN_SUCCESS;
   mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;

   while (true) {
     struct vm_region_submap_info_64 info;
     err = vm_region_recurse_64(mach_task_self(), &address, &size, &depth,
                                (vm_region_info_t)&info, &count);
     if (err != KERN_SUCCESS) return nullptr;

     if (size >= sizeof(mach_header) && info.protection & kProtectionRead) {
       mach_header *hdr = (mach_header *)address;
       if ((hdr->magic == MH_MAGIC || hdr->magic == MH_MAGIC_64) &&
           hdr->filetype == MH_DYLINKER) {
         return hdr;
       }
     }
     address += size;
   }
 }

 const mach_header *get_dyld_hdr() {
   if (!dyld_hdr) dyld_hdr = get_dyld_image_header();

   return dyld_hdr;
 }

 // Next and NextSegmentLoad were inspired by base/sysinfo.cc in
 // Google Perftools, https://github.com/gperftools/gperftools.

 // NextSegmentLoad scans the current image for the next segment load command
 // and returns the start and end addresses and file offset of the corresponding
 // segment.
 // Note that the segment addresses are not necessarily sorted.
 template <u32 kLCSegment, typename SegmentCommand>
 static bool NextSegmentLoad(MemoryMappedSegment *segment,
                             MemoryMappedSegmentData *seg_data,
                             MemoryMappingLayoutData *layout_data) {
   const char *lc = layout_data->current_load_cmd_addr;
   layout_data->current_load_cmd_addr += ((const load_command *)lc)->cmdsize;
   if (((const load_command *)lc)->cmd == kLCSegment) {
     const SegmentCommand* sc = (const SegmentCommand *)lc;
     uptr base_virt_addr, addr_mask;
     if (layout_data->current_image == kDyldImageIdx) {
       base_virt_addr = (uptr)get_dyld_hdr();
       // vmaddr is masked with 0xfffff because on macOS versions < 10.12,
       // it contains an absolute address rather than an offset for dyld.
       // To make matters even more complicated, this absolute address
       // isn't actually the absolute segment address, but the offset portion
       // of the address is accurate when combined with the dyld base address,
       // and the mask will give just this offset.
       addr_mask = 0xfffff;
     } else {
       base_virt_addr =
           (uptr)_dyld_get_image_vmaddr_slide(layout_data->current_image);
       addr_mask = ~0;
     }

     segment->start = (sc->vmaddr & addr_mask) + base_virt_addr;
     segment->end = segment->start + sc->vmsize;
     // Most callers don't need section information, so only fill this struct
     // when required.
     if (seg_data) {
       seg_data->nsects = sc->nsects;
       seg_data->current_load_cmd_addr =
           (const char *)lc + sizeof(SegmentCommand);
       seg_data->lc_type = kLCSegment;
       seg_data->base_virt_addr = base_virt_addr;
       seg_data->addr_mask = addr_mask;
       internal_strncpy(seg_data->name, sc->segname,
                        ARRAY_SIZE(seg_data->name));
     }

     // Return the initial protection.
     segment->protection = sc->initprot;
     segment->offset = (layout_data->current_filetype ==
                        /*MH_EXECUTE*/ 0x2)
                           ? sc->vmaddr
                           : sc->fileoff;
     if (segment->filename) {
       const char *src = (layout_data->current_image == kDyldImageIdx)
                             ? kDyldPath
                             : _dyld_get_image_name(layout_data->current_image);
       internal_strncpy(segment->filename, src, segment->filename_size);
     }
     segment->arch = layout_data->current_arch;
     internal_memcpy(segment->uuid, layout_data->current_uuid, kModuleUUIDSize);
     return true;
   }
   return false;
 }

 ModuleArch ModuleArchFromCpuType(cpu_type_t cputype, cpu_subtype_t cpusubtype) {
   cpusubtype = cpusubtype & ~CPU_SUBTYPE_MASK;
   switch (cputype) {
     case CPU_TYPE_I386:
       return kModuleArchI386;
     case CPU_TYPE_X86_64:
       if (cpusubtype == CPU_SUBTYPE_X86_64_ALL) return kModuleArchX86_64;
       if (cpusubtype == CPU_SUBTYPE_X86_64_H) return kModuleArchX86_64H;
       CHECK(0 && "Invalid subtype of x86_64");
       return kModuleArchUnknown;
     case CPU_TYPE_ARM:
       if (cpusubtype == CPU_SUBTYPE_ARM_V6) return kModuleArchARMV6;
       if (cpusubtype == CPU_SUBTYPE_ARM_V7) return kModuleArchARMV7;
       if (cpusubtype == CPU_SUBTYPE_ARM_V7S) return kModuleArchARMV7S;
       if (cpusubtype == CPU_SUBTYPE_ARM_V7K) return kModuleArchARMV7K;
       CHECK(0 && "Invalid subtype of ARM");
       return kModuleArchUnknown;
     case CPU_TYPE_ARM64:
       return kModuleArchARM64;
     default:
       CHECK(0 && "Invalid CPU type");
       return kModuleArchUnknown;
   }
 }

 static const load_command *NextCommand(const load_command *lc) {
   return (const load_command *)((const char *)lc + lc->cmdsize);
 }

 static void FindUUID(const load_command *first_lc, u8 *uuid_output) {
   for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
     if (lc->cmd != LC_UUID) continue;

     const uuid_command *uuid_lc = (const uuid_command *)lc;
     const uint8_t *uuid = &uuid_lc->uuid[0];
     internal_memcpy(uuid_output, uuid, kModuleUUIDSize);
     return;
   }
 }

 static bool IsModuleInstrumented(const load_command *first_lc) {
   for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
     if (lc->cmd != LC_LOAD_DYLIB) continue;

     const dylib_command *dylib_lc = (const dylib_command *)lc;
     uint32_t dylib_name_offset = dylib_lc->dylib.name.offset;
     const char *dylib_name = ((const char *)dylib_lc) + dylib_name_offset;
     dylib_name = StripModuleName(dylib_name);
     if (dylib_name != 0 && (internal_strstr(dylib_name, "libclang_rt."))) {
       return true;
     }
   }
   return false;
 }

 bool MemoryMappingLayout::Next(MemoryMappedSegment *segment) {
   for (; data_.current_image >= kDyldImageIdx; data_.current_image--) {
     const mach_header *hdr = (data_.current_image == kDyldImageIdx)
                                  ? get_dyld_hdr()
                                  : _dyld_get_image_header(data_.current_image);
     if (!hdr) continue;
     if (data_.current_load_cmd_count < 0) {
       // Set up for this image;
       data_.current_load_cmd_count = hdr->ncmds;
       data_.current_magic = hdr->magic;
       data_.current_filetype = hdr->filetype;
       data_.current_arch = ModuleArchFromCpuType(hdr->cputype, hdr->cpusubtype);
       switch (data_.current_magic) {
 #ifdef MH_MAGIC_64
         case MH_MAGIC_64: {
           data_.current_load_cmd_addr =
               (const char *)hdr + sizeof(mach_header_64);
           break;
         }
 #endif
         case MH_MAGIC: {
           data_.current_load_cmd_addr = (const char *)hdr + sizeof(mach_header);
           break;
         }
         default: {
           continue;
         }
       }
       FindUUID((const load_command *)data_.current_load_cmd_addr,
                data_.current_uuid);
       data_.current_instrumented = IsModuleInstrumented(
           (const load_command *)data_.current_load_cmd_addr);
     }

     for (; data_.current_load_cmd_count >= 0; data_.current_load_cmd_count--) {
       switch (data_.current_magic) {
         // data_.current_magic may be only one of MH_MAGIC, MH_MAGIC_64.
 #ifdef MH_MAGIC_64
         case MH_MAGIC_64: {
           if (NextSegmentLoad<LC_SEGMENT_64, struct segment_command_64>(
                   segment, segment->data_, &data_))
             return true;
           break;
         }
 #endif
         case MH_MAGIC: {
           if (NextSegmentLoad<LC_SEGMENT, struct segment_command>(
                   segment, segment->data_, &data_))
             return true;
           break;
         }
       }
     }
     // If we get here, no more load_cmd's in this image talk about
     // segments.  Go on to the next image.
   }
   return false;
 }

 void MemoryMappingLayout::DumpListOfModules(
     InternalMmapVectorNoCtor<LoadedModule> *modules) {
   Reset();
   InternalMmapVector<char> module_name(kMaxPathLength);
   MemoryMappedSegment segment(module_name.data(), module_name.size());
   MemoryMappedSegmentData data;
   segment.data_ = &data;
   while (Next(&segment)) {
     if (segment.filename[0] == '\0') continue;
     LoadedModule *cur_module = nullptr;
     if (!modules->empty() &&
         0 == internal_strcmp(segment.filename, modules->back().full_name())) {
       cur_module = &modules->back();
     } else {
       modules->push_back(LoadedModule());
       cur_module = &modules->back();
       cur_module->set(segment.filename, segment.start, segment.arch,
                       segment.uuid, data_.current_instrumented);
     }
     segment.AddAddressRanges(cur_module);
   }
 }

 }  // namespace __sanitizer

 #endif  // SANITIZER_MAC
	//===-- sanitizer_procmaps_mac.cpp ----------------------------------------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//
	//
	// Information about the process mappings (Mac-specific parts).
	//===----------------------------------------------------------------------===//

	#include "sanitizer_platform.h"
	#if SANITIZER_MAC
	#include "sanitizer_common.h"
	#include "sanitizer_placement_new.h"
	#include "sanitizer_procmaps.h"

	#include <mach-o/dyld.h>
	#include <mach-o/loader.h>
	#include <mach/mach.h>

	// These are not available in older macOS SDKs.
	#ifndef CPU_SUBTYPE_X86_64_H
	#define CPU_SUBTYPE_X86_64_H ((cpu_subtype_t)8) /* Haswell */
	#endif
	#ifndef CPU_SUBTYPE_ARM_V7S
	#define CPU_SUBTYPE_ARM_V7S ((cpu_subtype_t)11) /* Swift */
	#endif
	#ifndef CPU_SUBTYPE_ARM_V7K
	#define CPU_SUBTYPE_ARM_V7K ((cpu_subtype_t)12)
	#endif
	#ifndef CPU_TYPE_ARM64
	#define CPU_TYPE_ARM64 (CPU_TYPE_ARM \| CPU_ARCH_ABI64)
	#endif

	namespace __sanitizer {

	// Contains information used to iterate through sections.
	struct MemoryMappedSegmentData {
	char name[kMaxSegName];
	uptr nsects;
	const char *current_load_cmd_addr;
	u32 lc_type;
	uptr base_virt_addr;
	uptr addr_mask;
	};

	template <typename Section>
	static void NextSectionLoad(LoadedModule module, MemoryMappedSegmentData data,
	bool isWritable) {
	const Section sc = (const Section )data->current_load_cmd_addr;
	data->current_load_cmd_addr += sizeof(Section);

	uptr sec_start = (sc->addr & data->addr_mask) + data->base_virt_addr;
	uptr sec_end = sec_start + sc->size;
	module->addAddressRange(sec_start, sec_end, /executable=/false, isWritable,
	sc->sectname);
	}

	void MemoryMappedSegment::AddAddressRanges(LoadedModule *module) {
	// Don't iterate over sections when the caller hasn't set up the
	// data pointer, when there are no sections, or when the segment
	// is executable. Avoid iterating over executable sections because
	// it will confuse libignore, and because the extra granularity
	// of information is not needed by any sanitizers.
	if (!data_ \|\| !data_->nsects \|\| IsExecutable()) {
	module->addAddressRange(start, end, IsExecutable(), IsWritable(),
	data_ ? data_->name : nullptr);
	return;
	}

	do {
	if (data_->lc_type == LC_SEGMENT) {
	NextSectionLoad<struct section>(module, data_, IsWritable());
	#ifdef MH_MAGIC_64
	} else if (data_->lc_type == LC_SEGMENT_64) {
	NextSectionLoad<struct section_64>(module, data_, IsWritable());
	#endif
	}
	} while (--data_->nsects);
	}

	MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
	Reset();
	}

	MemoryMappingLayout::~MemoryMappingLayout() {
	}

	bool MemoryMappingLayout::Error() const {
	return false;
	}

	// More information about Mach-O headers can be found in mach-o/loader.h
	// Each Mach-O image has a header (mach_header or mach_header_64) starting with
	// a magic number, and a list of linker load commands directly following the
	// header.
	// A load command is at least two 32-bit words: the command type and the
	// command size in bytes. We're interested only in segment load commands
	// (LC_SEGMENT and LC_SEGMENT_64), which tell that a part of the file is mapped
	// into the task's address space.
	// The \|vmaddr\|, \|vmsize\| and \|fileoff\| fields of segment_command or
	// segment_command_64 correspond to the memory address, memory size and the
	// file offset of the current memory segment.
	// Because these fields are taken from the images as is, one needs to add
	// _dyld_get_image_vmaddr_slide() to get the actual addresses at runtime.

	void MemoryMappingLayout::Reset() {
	// Count down from the top.
	// TODO(glider): as per man 3 dyld, iterating over the headers with
	// _dyld_image_count is thread-unsafe. We need to register callbacks for
	// adding and removing images which will invalidate the MemoryMappingLayout
	// state.
	data_.current_image = _dyld_image_count();
	data_.current_load_cmd_count = -1;
	data_.current_load_cmd_addr = 0;
	data_.current_magic = 0;
	data_.current_filetype = 0;
	data_.current_arch = kModuleArchUnknown;
	internal_memset(data_.current_uuid, 0, kModuleUUIDSize);
	}

	// The dyld load address should be unchanged throughout process execution,
	// and it is expensive to compute once many libraries have been loaded,
	// so cache it here and do not reset.
	static mach_header *dyld_hdr = 0;
	static const char kDyldPath[] = "/usr/lib/dyld";
	static const int kDyldImageIdx = -1;

	// static
	void MemoryMappingLayout::CacheMemoryMappings() {
	// No-op on Mac for now.
	}

	void MemoryMappingLayout::LoadFromCache() {
	// No-op on Mac for now.
	}

	// _dyld_get_image_header() and related APIs don't report dyld itself.
	// We work around this by manually recursing through the memory map
	// until we hit a Mach header matching dyld instead. These recurse
	// calls are expensive, but the first memory map generation occurs
	// early in the process, when dyld is one of the only images loaded,
	// so it will be hit after only a few iterations.
	static mach_header *get_dyld_image_header() {
	unsigned depth = 1;
	vm_size_t size = 0;
	vm_address_t address = 0;
	kern_return_t err = KERN_SUCCESS;
	mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;

	while (true) {
	struct vm_region_submap_info_64 info;
	err = vm_region_recurse_64(mach_task_self(), &address, &size, &depth,
	(vm_region_info_t)&info, &count);
	if (err != KERN_SUCCESS) return nullptr;

	if (size >= sizeof(mach_header) && info.protection & kProtectionRead) {
	mach_header hdr = (mach_header )address;
	if ((hdr->magic == MH_MAGIC \|\| hdr->magic == MH_MAGIC_64) &&
	hdr->filetype == MH_DYLINKER) {
	return hdr;
	}
	}
	address += size;
	}
	}

	const mach_header *get_dyld_hdr() {
	if (!dyld_hdr) dyld_hdr = get_dyld_image_header();

	return dyld_hdr;
	}

	// Next and NextSegmentLoad were inspired by base/sysinfo.cc in
	// Google Perftools, https://github.com/gperftools/gperftools.

	// NextSegmentLoad scans the current image for the next segment load command
	// and returns the start and end addresses and file offset of the corresponding
	// segment.
	// Note that the segment addresses are not necessarily sorted.
	template <u32 kLCSegment, typename SegmentCommand>
	static bool NextSegmentLoad(MemoryMappedSegment *segment,
	MemoryMappedSegmentData *seg_data,
	MemoryMappingLayoutData *layout_data) {
	const char *lc = layout_data->current_load_cmd_addr;
	layout_data->current_load_cmd_addr += ((const load_command *)lc)->cmdsize;
	if (((const load_command *)lc)->cmd == kLCSegment) {
	const SegmentCommand* sc = (const SegmentCommand *)lc;
	uptr base_virt_addr, addr_mask;
	if (layout_data->current_image == kDyldImageIdx) {
	base_virt_addr = (uptr)get_dyld_hdr();
	// vmaddr is masked with 0xfffff because on macOS versions < 10.12,
	// it contains an absolute address rather than an offset for dyld.
	// To make matters even more complicated, this absolute address
	// isn't actually the absolute segment address, but the offset portion
	// of the address is accurate when combined with the dyld base address,
	// and the mask will give just this offset.
	addr_mask = 0xfffff;
	} else {
	base_virt_addr =
	(uptr)_dyld_get_image_vmaddr_slide(layout_data->current_image);
	addr_mask = ~0;
	}

	segment->start = (sc->vmaddr & addr_mask) + base_virt_addr;
	segment->end = segment->start + sc->vmsize;
	// Most callers don't need section information, so only fill this struct
	// when required.
	if (seg_data) {
	seg_data->nsects = sc->nsects;
	seg_data->current_load_cmd_addr =
	(const char *)lc + sizeof(SegmentCommand);
	seg_data->lc_type = kLCSegment;
	seg_data->base_virt_addr = base_virt_addr;
	seg_data->addr_mask = addr_mask;
	internal_strncpy(seg_data->name, sc->segname,
	ARRAY_SIZE(seg_data->name));
	}

	// Return the initial protection.
	segment->protection = sc->initprot;
	segment->offset = (layout_data->current_filetype ==
	/MH_EXECUTE/ 0x2)
	? sc->vmaddr
	: sc->fileoff;
	if (segment->filename) {
	const char *src = (layout_data->current_image == kDyldImageIdx)
	? kDyldPath
	: _dyld_get_image_name(layout_data->current_image);
	internal_strncpy(segment->filename, src, segment->filename_size);
	}
	segment->arch = layout_data->current_arch;
	internal_memcpy(segment->uuid, layout_data->current_uuid, kModuleUUIDSize);
	return true;
	}
	return false;
	}

	ModuleArch ModuleArchFromCpuType(cpu_type_t cputype, cpu_subtype_t cpusubtype) {
	cpusubtype = cpusubtype & ~CPU_SUBTYPE_MASK;
	switch (cputype) {
	case CPU_TYPE_I386:
	return kModuleArchI386;
	case CPU_TYPE_X86_64:
	if (cpusubtype == CPU_SUBTYPE_X86_64_ALL) return kModuleArchX86_64;
	if (cpusubtype == CPU_SUBTYPE_X86_64_H) return kModuleArchX86_64H;
	CHECK(0 && "Invalid subtype of x86_64");
	return kModuleArchUnknown;
	case CPU_TYPE_ARM:
	if (cpusubtype == CPU_SUBTYPE_ARM_V6) return kModuleArchARMV6;
	if (cpusubtype == CPU_SUBTYPE_ARM_V7) return kModuleArchARMV7;
	if (cpusubtype == CPU_SUBTYPE_ARM_V7S) return kModuleArchARMV7S;
	if (cpusubtype == CPU_SUBTYPE_ARM_V7K) return kModuleArchARMV7K;
	CHECK(0 && "Invalid subtype of ARM");
	return kModuleArchUnknown;
	case CPU_TYPE_ARM64:
	return kModuleArchARM64;
	default:
	CHECK(0 && "Invalid CPU type");
	return kModuleArchUnknown;
	}
	}

	static const load_command NextCommand(const load_command lc) {
	return (const load_command )((const char )lc + lc->cmdsize);
	}

	static void FindUUID(const load_command first_lc, u8 uuid_output) {
	for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
	if (lc->cmd != LC_UUID) continue;

	const uuid_command uuid_lc = (const uuid_command )lc;
	const uint8_t *uuid = &uuid_lc->uuid[0];
	internal_memcpy(uuid_output, uuid, kModuleUUIDSize);
	return;
	}
	}

	static bool IsModuleInstrumented(const load_command *first_lc) {
	for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
	if (lc->cmd != LC_LOAD_DYLIB) continue;

	const dylib_command dylib_lc = (const dylib_command )lc;
	uint32_t dylib_name_offset = dylib_lc->dylib.name.offset;
	const char dylib_name = ((const char )dylib_lc) + dylib_name_offset;
	dylib_name = StripModuleName(dylib_name);
	if (dylib_name != 0 && (internal_strstr(dylib_name, "libclang_rt."))) {
	return true;
	}
	}
	return false;
	}

	bool MemoryMappingLayout::Next(MemoryMappedSegment *segment) {
	for (; data_.current_image >= kDyldImageIdx; data_.current_image--) {
	const mach_header *hdr = (data_.current_image == kDyldImageIdx)
	? get_dyld_hdr()
	: _dyld_get_image_header(data_.current_image);
	if (!hdr) continue;
	if (data_.current_load_cmd_count < 0) {
	// Set up for this image;
	data_.current_load_cmd_count = hdr->ncmds;
	data_.current_magic = hdr->magic;
	data_.current_filetype = hdr->filetype;
	data_.current_arch = ModuleArchFromCpuType(hdr->cputype, hdr->cpusubtype);
	switch (data_.current_magic) {
	#ifdef MH_MAGIC_64
	case MH_MAGIC_64: {
	data_.current_load_cmd_addr =
	(const char *)hdr + sizeof(mach_header_64);
	break;
	}
	#endif
	case MH_MAGIC: {
	data_.current_load_cmd_addr = (const char *)hdr + sizeof(mach_header);
	break;
	}
	default: {
	continue;
	}
	}
	FindUUID((const load_command *)data_.current_load_cmd_addr,
	data_.current_uuid);
	data_.current_instrumented = IsModuleInstrumented(
	(const load_command *)data_.current_load_cmd_addr);
	}

	for (; data_.current_load_cmd_count >= 0; data_.current_load_cmd_count--) {
	switch (data_.current_magic) {
	// data_.current_magic may be only one of MH_MAGIC, MH_MAGIC_64.
	#ifdef MH_MAGIC_64
	case MH_MAGIC_64: {
	if (NextSegmentLoad<LC_SEGMENT_64, struct segment_command_64>(
	segment, segment->data_, &data_))
	return true;
	break;
	}
	#endif
	case MH_MAGIC: {
	if (NextSegmentLoad<LC_SEGMENT, struct segment_command>(
	segment, segment->data_, &data_))
	return true;
	break;
	}
	}
	}
	// If we get here, no more load_cmd's in this image talk about
	// segments. Go on to the next image.
	}
	return false;
	}

	void MemoryMappingLayout::DumpListOfModules(
	InternalMmapVectorNoCtor<LoadedModule> *modules) {
	Reset();
	InternalMmapVector<char> module_name(kMaxPathLength);
	MemoryMappedSegment segment(module_name.data(), module_name.size());
	MemoryMappedSegmentData data;
	segment.data_ = &data;
	while (Next(&segment)) {
	if (segment.filename[0] == '\0') continue;
	LoadedModule *cur_module = nullptr;
	if (!modules->empty() &&
	0 == internal_strcmp(segment.filename, modules->back().full_name())) {
	cur_module = &modules->back();
	} else {
	modules->push_back(LoadedModule());
	cur_module = &modules->back();
	cur_module->set(segment.filename, segment.start, segment.arch,
	segment.uuid, data_.current_instrumented);
	}
	segment.AddAddressRanges(cur_module);
	}
	}

	} // namespace __sanitizer

	#endif // SANITIZER_MAC