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mach_o/Image.cpp dyld-1340 dyld-1162
--- dyld/dyld-1340/mach_o/Image.cpp
+++ dyld/dyld-1162/mach_o/Image.cpp
@@ -39,12 +39,11 @@
 #include "Image.h"
 #include "Misc.h"
 #include "CompactUnwind.h"
-#include "TargetPolicy.h"
 
 namespace mach_o {
 
 Image::Image(const void* buffer, size_t bufferSize, MappingKind kind)
-    : _buffer((Header*)buffer), _bufferSize(bufferSize), _mappingKind(kind), _hasZerofillExpansion(false)
+    : _buffer((Header*)buffer), _bufferSize(bufferSize), _hasZerofillExpansion(false)
 {
     // figure out location of LINKEDIT
     switch ( kind ) {
@@ -53,8 +52,7 @@
             break;
         case MappingKind::dyldLoadedPreFixups:
         case MappingKind::dyldLoadedPostFixups:
-            // this is a loaded image with segments mapped at their respective VM addresses
-            _hasZerofillExpansion = true;
+            _hasZerofillExpansion = _buffer->hasZerofillExpansion();
             break;
         case MappingKind::unknown:
             _hasZerofillExpansion = inferIfZerofillExpanded();
@@ -77,18 +75,12 @@
     makeFunctionStarts();
     makeCompactUnwind();
     makeSplitSegInfo();
-    makeFunctionVariants();
-    makeFunctionVariantFixups();
-}
-
-// for dyld loaded images only
-Image::Image(const mach_header* mh)
-: _buffer((Header*)mh), _bufferSize(0), _mappingKind(MappingKind::dyldLoadedPostFixups)
-{
-    // this is a loaded image with segments mapped at their respective VM addresses
-    _hasZerofillExpansion = true;
-    _linkeditBias         = _buffer->computeLinkEditBias(_hasZerofillExpansion);
-
+}
+
+// need move constructor because object has pointers to within itself (e.g. _exportsTrie points to _exportsTrieSpace)
+Image::Image(const Image&& other)
+    : _buffer(other._buffer), _bufferSize(other._bufferSize), _linkeditBias(other._linkeditBias),  _hasZerofillExpansion(other._hasZerofillExpansion)
+{
     // build parts
     makeExportsTrie();
     makeSymbolTable();
@@ -100,29 +92,6 @@
     makeFunctionStarts();
     makeCompactUnwind();
     makeSplitSegInfo();
-    makeFunctionVariants();
-    makeFunctionVariantFixups();
-}
-
-
-// need move constructor because object has pointers to within itself (e.g. _exportsTrie points to _exportsTrieSpace)
-Image::Image(const Image&& other)
-    : _buffer(other._buffer), _bufferSize(other._bufferSize), _linkeditBias(other._linkeditBias),
-      _mappingKind(other._mappingKind), _hasZerofillExpansion(other._hasZerofillExpansion)
-{
-    // build parts
-    makeExportsTrie();
-    makeSymbolTable();
-    makeRebaseOpcodes();
-    makeBindOpcodes();
-    makeLazyBindOpcodes();
-    makeWeakBindOpcodes();
-    makeChainedFixups();
-    makeFunctionStarts();
-    makeCompactUnwind();
-    makeSplitSegInfo();
-    makeFunctionVariants();
-    makeFunctionVariantFixups();
 }
 
 
@@ -168,12 +137,6 @@
     // create Policy object for this binary
     Policy policy(_buffer->arch(), _buffer->platformAndVersions(), _buffer->mh.filetype, false);
 
-    // validate initializers
-    if ( gImageValidateInitializers ) {
-        if ( Error err = this->validInitializers(policy) )
-            return err;
-    }
-
     // validate LINKEDIT
     if ( Error err = this->validLinkedit(policy) )
         return err;
@@ -187,28 +150,25 @@
     if ( Error err = validStructureLinkedit(policy) )
         return err;
 
-    uint64_t maxVmOffset = 0x4000;
-    uint32_t segCount = this->segmentCount();
-    MappedSegment segs[std::max(segCount,(uint32_t)1)];
-    for (uint32_t i=0; i < segCount; ++i) {
-        segs[i] = this->segment(i);
-        if ( segs[i].segName != "__LINKEDIT" ) {
-            maxVmOffset = std::max(maxVmOffset, segs[i].runtimeOffset + segs[i].runtimeSize);
-        }
-    }
-    std::span<const MappedSegment> segSpan{segs, segCount};
-
     // if image has an exports trie, validate that
     if ( this->hasExportsTrie() ) {
-        if ( Error err = this->exportsTrie().valid(header()->preferredLoadAddress(), maxVmOffset) )
+        uint64_t max = 0x200000000; // FIXME
+        if ( Error err = this->exportsTrie().valid(max) )
             return err;
     }
 
     // if image has a symbol table, validate that
     if ( this->hasSymbolTable() ) {
-        if ( Error err = this->symbolTable().valid(maxVmOffset) )
+        uint64_t max = 0x200000000; // FIXME
+        if ( Error err = this->symbolTable().valid(max) )
             return err;
     }
+
+    uint32_t segCount = this->segmentCount();
+    MappedSegment segs[segCount];
+    for (uint32_t i=0; i < segCount; ++i)
+        segs[i] = this->segment(i);
+    std::span<const MappedSegment> segSpan{segs, segCount};
 
     // if image has rebase opcodes
     if ( this->hasRebaseOpcodes() ) {
@@ -218,25 +178,19 @@
 
     // if image has bind opcodes
     if ( this->hasBindOpcodes() ) {
-        if ( Error err = this->bindOpcodes().valid(segSpan, _buffer->linkedDylibCount(), _buffer->mayHaveTextFixups(), policy.enforceFixupsInWritableSegments()) )
+        if ( Error err = this->bindOpcodes().valid(segSpan, _buffer->dependentDylibCount(), _buffer->mayHaveTextFixups(), policy.enforceFixupsInWritableSegments()) )
             return err;
     }
 
     // if image has lazy bind opcodes
     if ( this->hasLazyBindOpcodes() ) {
-        if ( Error err = this->lazyBindOpcodes().valid(segSpan, _buffer->linkedDylibCount(), _buffer->mayHaveTextFixups(), policy.enforceFixupsInWritableSegments()) )
+        if ( Error err = this->lazyBindOpcodes().valid(segSpan, _buffer->dependentDylibCount(), _buffer->mayHaveTextFixups(), policy.enforceFixupsInWritableSegments()) )
             return err;
     }
 
     // if image has chained fixups
     if ( this->hasChainedFixups() ) {
-        if ( Error err = this->chainedFixups().valid(_buffer->preferredLoadAddress(), segSpan) )
-            return err;
-    }
-
-    // if image has functions variant table
-    if ( this->hasFunctionVariants() ) {
-        if ( Error err = this->functionVariants().valid() )
+        if ( Error err = this->chainedFixups().valid(segSpan) )
             return err;
     }
 
@@ -407,12 +361,14 @@
     }
     if ( hasDyldInfo && hasChainedFixups )
         return Error("malformed mach-o contains LC_DYLD_INFO and LC_DYLD_CHAINED_FIXUPS");
+    if ( !hasExternalRelocs && !hasLocalRelocs && !hasDyldInfo && !hasChainedFixups && (!_buffer->isMainExecutable() || _buffer->isPIE()) && !_buffer->isObjectFile() )
+        return Error("malformed mach-o missing relocations, LC_DYLD_INFO, or LC_DYLD_CHAINED_FIXUPS");
 
     // find range of LINKEDIT
     __block uint64_t linkeditFileOffsetStart = 0;
     __block uint64_t linkeditFileOffsetEnd   = 0;
-    if ( _buffer->isObjectFile() || _buffer->isPreload() ) {
-        // .o  and -preload files don't have LINKEDIT, but the LINKEDIT content is still at the end of the file after the last section content
+    if ( _buffer->isObjectFile() ) {
+        // .o file don't have LINKEDIT, but the LINKEDIT content is still at the end of the file after the last section content
         _buffer->forEachSection(^(const Header::SectionInfo& info, bool& stop) {
             uint8_t sectType = (info.flags & SECTION_TYPE);
             bool isZeroFill = ((sectType == S_ZEROFILL) || (sectType == S_THREAD_LOCAL_ZEROFILL));
@@ -459,8 +415,8 @@
     // sort blobs by file-offset and check for overlaps
     const unsigned long blobCount = bp - blobs;
     if ( blobCount == 0 ) {
-        // ok for .o files or MH_FILESET to have no content and no symbols
-        if ( _buffer->isObjectFile() || _buffer->isFileSet() )
+        // ok for .o files to have no content and no symbols
+        if ( _buffer->isObjectFile() )
             return Error::none();
         return Error("malformed mach-o has no LINKEDIT information");
     }
@@ -492,192 +448,6 @@
 
     return Error::none();
 }
-
-struct VIS_HIDDEN SegmentRanges
-{
-    struct SegmentRange {
-        uint64_t vmAddrStart;
-        uint64_t vmAddrEnd;
-        uint32_t fileSize;
-    };
-
-    bool contains(uint64_t vmAddr) const {
-        for (const SegmentRange& range : segments) {
-            if ( (range.vmAddrStart <= vmAddr) && (vmAddr < range.vmAddrEnd) )
-                return true;
-        }
-        return false;
-    }
-
-private:
-    SegmentRange localAlloc[8];
-
-public:
-    dyld3::Array<SegmentRange> segments { localAlloc, sizeof(localAlloc) / sizeof(localAlloc[0]) };
-};
-
-
-Error Image::validInitializers(const Policy& policy) const
-{
-    // rdar://127245061 (ld-prime initializer verification fails on Go object files)
-    // Go creates object files with segment protections set to 0, while normally
-    // they're set to all. Object files consist of a single segment though, so
-    // we can skip the checks entirely.
-    if ( header()->isObjectFile() )
-        return Error::none();
-
-    uint64_t        prefLoadAddress = header()->preferredLoadAddress();
-    uint64_t        slide           = header()->getSlide();
-    __block Error   anErr;
-
-    __block SegmentRanges executableSegments;
-    header()->forEachSegment(^(const Header::SegmentInfo& info, bool& stop) {
-        if ( (info.initProt & VM_PROT_EXECUTE) != 0 ) {
-            executableSegments.segments.push_back({ info.vmaddr, info.vmaddr + info.vmsize, (uint32_t)info.fileSize });
-        }
-    });
-    if (executableSegments.segments.empty()) {
-        return Error("no executable segments");
-    }
-
-    // validate LC_ROUTINES initializer
-    header()->forEachLoadCommandSafe(^(const load_command* cmd, bool& stop) {
-        if ( cmd->cmd == LC_ROUTINES ) {
-            const routines_command* routines = (routines_command*)cmd;
-            uint64_t dashInitAddr = routines->init_address;
-            if ( !executableSegments.contains(dashInitAddr) ) {
-                anErr = Error("LC_ROUTINES initializer 0x%08llX is not an offset to an executable segment", dashInitAddr);
-                stop = true;
-            }
-        }
-        else if ( cmd->cmd == LC_ROUTINES_64 ) {
-            const routines_command_64* routines = (routines_command_64*)cmd;
-            uint64_t dashInitAddr = routines->init_address;
-            if ( !executableSegments.contains(dashInitAddr) ) {
-                anErr = Error("LC_ROUTINES _64 initializer 0x%08llX is not an offset to an executable segment", dashInitAddr);
-                stop = true;
-            }
-        }
-    });
-
-    // validate any function pointers in __DATA,__mod_init_func section
-    header()->forEachSection(^(const Header::SectionInfo& sectInfo, bool& stop) {
-        uint8_t sectType = (sectInfo.flags & SECTION_TYPE);
-        if ( (sectType == S_MOD_INIT_FUNC_POINTERS) || (sectType == S_MOD_TERM_FUNC_POINTERS)  ) {
-            if ( (sectInfo.size % header()->pointerSize()) != 0 ) {
-                anErr = Error("section %.*s/%.*s size (%llu) is not a multiple of pointer-size",
-                              (int)sectInfo.segmentName.size(), sectInfo.segmentName.data(),
-                              (int)sectInfo.sectionName.size(), sectInfo.sectionName.data(),
-                              sectInfo.size);
-                stop = true;
-                return;
-            }
-            if ( (sectInfo.address % header()->pointerSize()) != 0 ) {
-                anErr = Error("section %.*s/%.*s address (0x%llX) is not pointer aligned",
-                              (int)sectInfo.segmentName.size(), sectInfo.segmentName.data(),
-                              (int)sectInfo.sectionName.size(), sectInfo.sectionName.data(),
-                              sectInfo.address);
-                stop = true;
-                return;
-            }
-            const uint8_t* sectionContent = (uint8_t*)header() + sectInfo.fileOffset;
-            if ( header()->inDyldCache() )
-                sectionContent = (uint8_t*)(sectInfo.address + header()->getSlide());
-
-            if ( gImageAssumeContentRebased ) {
-                // in dyld, when this is called, the image is already rebased, so we can use pointers in section
-                const uintptr_t* initsStart = (uintptr_t*)sectionContent;
-                const uintptr_t* initsEnd   = (uintptr_t*)((uint8_t*)sectionContent + sectInfo.size);
-                for (const uintptr_t* p=initsStart; p < initsEnd; ++p) {
-                    if ( !executableSegments.contains(*p) ) {
-                        anErr = Error("initializer 0x%08lX is not in an executable segment", *p);
-                        break;
-                    }
-                }
-            } else {
-                if ( header()->is64() ) {
-                    const uint64_t* initsStart = (uint64_t*)sectionContent;
-                    const uint64_t* initsEnd   = (uint64_t*)((uint8_t*)sectionContent + sectInfo.size);
-                    for (const uint64_t* p=initsStart; p < initsEnd; ++p) {
-                        uint64_t anInit = *p;
-                        anInit -= prefLoadAddress;
-                        // FIXME: as a quick hack, the low 32-bits with either rebase opcodes or chained fixups is offset in image
-                        uint32_t low32 = (uint32_t)anInit;
-                        if ( !executableSegments.contains(prefLoadAddress+low32) ) {
-                            anErr = Error("initializer %lu/%llu is not in an executable segment", p-initsStart, sectInfo.size/8);
-                            break;
-                        }
-                    }
-                }
-                else {
-                    const uint32_t* initsStart = (uint32_t*)sectionContent;
-                    const uint32_t* initsEnd   = (uint32_t*)((uint8_t*)sectionContent + sectInfo.size);
-                    for (const uint32_t* p=initsStart; p < initsEnd; ++p) {
-                        uint32_t anInit = *p;
-                        anInit -= (uint32_t)prefLoadAddress;
-                        // FIXME: as a quick hack, the low 26-bits with either rebase opcodes or chained fixups is offset in image
-                        uint32_t low26 = anInit & 0x03FFFFFF;
-                        if ( !executableSegments.contains(prefLoadAddress+low26) ) {
-                            anErr = Error("initializer %lu/%llu is not in an executable segment", p-initsStart, sectInfo.size/84);
-                            break;
-                        }
-                    }
-                }
-            }
-            if ( sectType == S_MOD_TERM_FUNC_POINTERS ) {
-                if ( header()->isDyldManaged() && header()->isArch("arm6e") )
-                    anErr = Error("terminators section %.*s/%.*s not supported for arm64e",
-                                  (int)sectInfo.segmentName.size(), sectInfo.segmentName.data(),
-                                  (int)sectInfo.sectionName.size(), sectInfo.sectionName.data());
-            }
-        }
-    });
-    if ( anErr.hasError() )
-        return std::move(anErr);
-
-    // validate offsets in __TEXT,__init_offsets
-    header()->forEachSection(^(const Header::SectionInfo& sectInfo, bool& stop) {
-        if ( (sectInfo.flags & SECTION_TYPE) == S_INIT_FUNC_OFFSETS ) {
-            const uint8_t* content = (uint8_t*)(sectInfo.address + slide);
-            if ( sectInfo.segInitProt & VM_PROT_WRITE ) {
-                anErr = Error("initializer offsets section %.*s/%.*s must be in read-only segment",
-                              (int)sectInfo.segmentName.size(), sectInfo.segmentName.data(),
-                              (int)sectInfo.sectionName.size(), sectInfo.sectionName.data());
-                stop = true;
-                return;
-            }
-            if ( (sectInfo.size % 4) != 0 ) {
-                anErr = Error("initializer offsets section %.*s/%.*s has bad size",
-                              (int)sectInfo.segmentName.size(), sectInfo.segmentName.data(),
-                              (int)sectInfo.sectionName.size(), sectInfo.sectionName.data());
-                stop = true;
-                return;
-            }
-            if ( (sectInfo.address % 4) != 0 ) {
-                anErr = Error("initializer offsets section %.*s/%.*s is not 4-byte aligned",
-                              (int)sectInfo.segmentName.size(), sectInfo.segmentName.data(),
-                              (int)sectInfo.sectionName.size(), sectInfo.sectionName.data());
-                stop = true;
-                return;
-            }
-            const uint32_t* initsStart = (uint32_t*)content;
-            const uint32_t* initsEnd   = (uint32_t*)((uint8_t*)content + sectInfo.size);
-            for (const uint32_t* p=initsStart; p < initsEnd; ++p) {
-                uint32_t anInitOffset = *p;
-                if ( !executableSegments.contains(prefLoadAddress + anInitOffset) ) {
-                    anErr = Error("initializer 0x%08X is not an offset to an executable segment", anInitOffset);
-                    stop = true;
-                    break;
-                }
-            }
-        }
-    });
-    if ( anErr.hasError() )
-        return std::move(anErr);
-
-    return Error::none();
-}
-#endif // !TARGET_OS_EXCLAVEKIT
 
 void Image::makeExportsTrie()
 {
@@ -793,22 +563,9 @@
             if ( chainedFixupsCmd->datasize != 0 ) {
                 const dyld_chained_fixups_header* fixupsHeader = (dyld_chained_fixups_header*)(_linkeditBias + chainedFixupsCmd->dataoff);
                 _chainedFixups = new (_chainedFixupsSpace) ChainedFixups(fixupsHeader, chainedFixupsCmd->datasize);
-                stop = true;
-            }
-        }
-    });
-
-    if ( !header()->isPreload() && !header()->isStaticExecutable() )
-        return;
-
-    if ( _chainedFixups == nullptr ) {
-        header()->forEachSection(^(const Header::SectionInfo& info, bool& stop) {
-            if ( (info.sectionName == "__chain_fixups") && (info.segmentName == "__TEXT") ) {
-                const dyld_chained_fixups_header* fixupsHeader = (dyld_chained_fixups_header*)((uint8_t*)header() + info.fileOffset);
-                _chainedFixups = new (_chainedFixupsSpace) ChainedFixups(fixupsHeader, (size_t)info.size);
-            }
-        });
-    }
+            }
+        }
+    });
 }
 
 void Image::makeFunctionStarts()
@@ -843,35 +600,11 @@
     (void)_buffer->forEachLoadCommand(^(const load_command* cmd, bool& stop) {
         if ( cmd->cmd == LC_SEGMENT_SPLIT_INFO ) {
             const linkedit_data_command* splitSegCmd = (linkedit_data_command*)cmd;
-            const uint8_t* startBytes = (uint8_t*)(_linkeditBias + splitSegCmd->dataoff);
-            _splitSegInfo = new (_splitSegSpace) SplitSegInfo(startBytes, splitSegCmd->datasize);
-            stop = true;
-        }
-    });
-}
-
-void Image::makeFunctionVariants()
-{
-    // if image has a LC_FUNCTION_VARIANTS load command, use placement new to build FunctionVariants object in _functionVariantsSpace
-    (void)_buffer->forEachLoadCommand(^(const load_command* cmd, bool& stop) {
-        if ( cmd->cmd == LC_FUNCTION_VARIANTS ) {
-            const linkedit_data_command* functionVariantsCmd = (linkedit_data_command*)cmd;
-            const uint8_t* startBytes = (uint8_t*)(_linkeditBias + functionVariantsCmd->dataoff);
-            _functionVariants = new (_functionVariantsSpace) FunctionVariants(std::span<const uint8_t>(startBytes, functionVariantsCmd->datasize));
-            stop = true;
-        }
-    });
-}
-
-void Image::makeFunctionVariantFixups()
-{
-    // if image has a LC_FUNCTION_VARIANT_FIXUPS load command, use placement new to build _functionVariantFixups object in _functionVariantFixupsSpace
-    (void)_buffer->forEachLoadCommand(^(const load_command* cmd, bool& stop) {
-        if ( cmd->cmd == LC_FUNCTION_VARIANT_FIXUPS ) {
-            const linkedit_data_command* functionVariantFixupsCmd = (linkedit_data_command*)cmd;
-            const uint8_t* startBytes = (uint8_t*)(_linkeditBias + functionVariantFixupsCmd->dataoff);
-            _functionVariantFixups = new (_functionVariantFixupsSpace) FunctionVariantFixups(std::span<const uint8_t>(startBytes, functionVariantFixupsCmd->datasize));
-            stop = true;
+            if ( splitSegCmd->datasize != 0 ) {
+                const uint8_t* startBytes = (uint8_t*)(_linkeditBias + splitSegCmd->dataoff);
+                _splitSegInfo = new (_splitSegSpace) SplitSegInfo(startBytes, splitSegCmd->datasize);
+                stop = true;
+            }
         }
     });
 }
@@ -903,7 +636,6 @@
                 else
                     result.content = (uint8_t*)_buffer + segCmd->fileoff;
                 result.runtimeSize  = segCmd->vmsize;
-                result.fileOffset   = segCmd->fileoff;
                 result.segName      = segCmd->segname;
                 result.readable     = ((segCmd->initprot & VM_PROT_READ)    != 0);
                 result.writable     = ((segCmd->initprot & VM_PROT_WRITE)   != 0);
@@ -923,7 +655,6 @@
                 else
                     result.content = (uint8_t*)_buffer + segCmd->fileoff;
                 result.runtimeSize  = segCmd->vmsize;
-                result.fileOffset   = segCmd->fileoff;
                 result.segName      = segCmd->segname;
                 result.readable     = ((segCmd->initprot & VM_PROT_READ)    != 0);
                 result.writable     = ((segCmd->initprot & VM_PROT_WRITE)   != 0);
@@ -935,6 +666,7 @@
     });
     return result;
 }
+#endif // !TARGET_OS_EXCLAVEKIT
 
 void Image::withSegments(void (^callback)(std::span<const MappedSegment> segments)) const
 {
@@ -955,136 +687,31 @@
     else if ( this->hasBindOpcodes() ) {
         // FIXME: Do we want to pass up the strong binds?
         this->bindOpcodes().forEachBindTarget(callback, ^(const char* symbolName) { });
-
-        if ( hasLazyBindOpcodes() )
-            this->lazyBindOpcodes().forEachBindTarget(callback, ^(const char* symbolName) { });
-    }
-}
-
+        // FIXME: lazy binds
+    }
+}
+
+
+// This is a high level abstraction for mach-o files.  No matter the format, it iterates all fixups
 void Image::forEachFixup(void (^callback)(const Fixup& fixup, bool& stop)) const
 {
-    withSegments(^(std::span<const MappedSegment> segments) {
-        forEachFixup(segments, callback);
-    });
-}
-
-// This is a high level abstraction for mach-o files.  No matter the format, it iterates all fixups
-void Image::forEachFixup(std::span<const MappedSegment> segments, void (^callback)(const Fixup& fixup, bool& stop)) const
-{
-    const uint64_t     prefLoadAddr = this->header()->preferredLoadAddress();
-    uint16_t           fwPointerFormat;
-    uint32_t           fwStartsCount;
-    const uint32_t*    fwStarts;
-    if ( this->hasChainedFixups() ) {
-        const ChainedFixups& chainedFixups = this->chainedFixups();
-        // userland binary with LC_DYLD_CHAINED_FIXUPS or firmware with __chain_fixups section
-        std::vector<uint64_t> segOffsetTable;
-        if ( header()->isPreload() ) {
-            // build segOffsetTable from chained fixups header
-            for (int segIndex=0; ; ++segIndex) {
-                const dyld_chained_starts_in_segment* segInfo = chainedFixups.startsForSegment(segIndex);
-                if ( segInfo == nullptr )
-                    break;
-                segOffsetTable.push_back(segInfo->segment_offset);
-            }
-        }
-        chainedFixups.forEachFixupChainStartLocation(segments, ^(const void* chainStart, uint32_t segIndex, uint32_t pageIndex, uint32_t pageSize, const ChainedFixups::PointerFormat& pf, bool& stop) {
-            pf.forEachFixupLocationInChain(chainStart, prefLoadAddr, &segments[segIndex], segOffsetTable, pageIndex, pageSize, callback);
-        });
-    }
-    else if ( this->header()->hasFirmwareChainStarts(&fwPointerFormat, &fwStartsCount, &fwStarts) ) {
-        // firmware binary with __TEXT,__chain_starts section
-        // Note: for historical reasons firmware __chain_starts section use file-offsets from the start of __TEXT
-        // but that can be changed with -fixup_chains_section_vm linker option. But which option is used is not
-        // encoded in the binary, so we need a heuristic here.
-        bool startOffsetsAreFileOffsets = true;
-        if ( (fwStartsCount > 0) && (segments.back().fileOffset + segments.back().runtimeSize < fwStarts[fwStartsCount-1]) )
-            startOffsetsAreFileOffsets = false;
-
-        const ChainedFixups::PointerFormat& pf = ChainedFixups::PointerFormat::make(fwPointerFormat);
-        for (uint32_t i=0; i < fwStartsCount; ++i) {
-            const void*    chainStart = nullptr;
-            if ( startOffsetsAreFileOffsets ) {
-                chainStart = ((uint8_t*)this->header()) + segments[0].fileOffset + fwStarts[i];
-            }
-            else {
-                for (const MappedSegment& seg : segments) {
-                    uint32_t startOffset = fwStarts[i];
-                    if ( (seg.runtimeOffset <= startOffset) && (startOffset < seg.runtimeOffset+seg.runtimeSize) ) {
-                        uint64_t vmOffsetInSegment = startOffset - seg.runtimeOffset;
-                        chainStart = ((uint8_t*)this->header()) + seg.fileOffset + vmOffsetInSegment;
-                        break;
-                    }
-                }
-            }
-            pf.forEachFixupLocationInChain(chainStart, prefLoadAddr, nullptr, {}, 0, 0, ^(const Fixup& fixup, bool& stop) {
-                Fixup     fixupWithSeg = fixup;
-                uint64_t  chainOffset  = (uint8_t*)fixup.location - ((uint8_t*)this->header());
-                // Note: firmware chains can cross segments, so we cannot pre-compute 'seg'
-                for (size_t s=0; s < segments.size(); ++s) {
-                    if ( (segments[s].fileOffset <= chainOffset) && (chainOffset < segments[s].fileOffset+segments[s].runtimeSize) ) {
-                        fixupWithSeg.segment = &segments[s];
-                        break;
-                    }
-                }
-                callback(fixupWithSeg, stop);
+    const uint64_t prefLoadAddr = this->header()->preferredLoadAddress();
+    this->withSegments(^(std::span<const MappedSegment> segments) {
+        if ( this->hasChainedFixups() ) {
+            this->chainedFixups().forEachFixupChainStartLocation(segments, ^(const void* chainStart, uint32_t segIndex, const ChainedFixups::PointerFormat& pf, bool& stop) {
+                pf.forEachFixupLocationInChain(chainStart, prefLoadAddr, &segments[segIndex], callback);
             });
         }
-    }
-    else if ( this->header()->hasFirmwareRebaseRuns() ) {
-        // firmware binary with __TEXT,__rebase_info section
-        bool is64 = this->header()->is64();
-        this->header()->forEachFirmwareRebaseRuns(^(uint32_t address, bool& stop) {
-            // Note: __rebase_info addresses are vmaddrs
-            const MappedSegment* seg       = nullptr;
-            uint64_t             segOffset = 0;
-            for (size_t s=0; s < segments.size(); ++s) {
-                uint64_t segStartAddresss = prefLoadAddr+segments[s].runtimeOffset;
-                if ( (segStartAddresss <= address) && (address < segStartAddresss+segments[s].runtimeSize) ) {
-                    seg       = &segments[s];
-                    segOffset = address - segStartAddresss;
-                    break;
-                }
-            }
-            if ( seg != nullptr ) {
-                const void* loc          = (uint8_t*)seg->content + segOffset;
-                uint64_t    targetVmAddr = is64 ? (*(uint64_t*)loc) : (*(uint32_t*)loc);
-                Fixup fixup(loc, seg, targetVmAddr-prefLoadAddr);
-                callback(fixup, stop);
-            }
-        });
-    }
-    else if ( this->header()->hasOpcodeFixups() ) {
-        // userland binary with LC_DYLD_INFO
-        uint32_t bindOrdinal = 0;
-        if ( this->hasBindOpcodes() ) {
-            bindOrdinal = this->bindOpcodes().forEachBindLocation(segments, bindOrdinal, callback);
-        }
-        if ( this->hasLazyBindOpcodes() ) {
-            this->lazyBindOpcodes().forEachBindLocation(segments, bindOrdinal, callback);
-        }
-        if ( this->hasRebaseOpcodes() ) {
-            this->rebaseOpcodes().forEachRebaseLocation(segments, prefLoadAddr, callback);
-        }
-    }
-    else {
-        // unsupported format
-    }
-}
-
-void Image::forEachFilesetImage(void (^callback)(const Image& entryImage, std::string_view name, bool& stop)) const
-{
-    int64_t slide = header()->getSlide();
-    header()->forEachLoadCommandSafe(^(const load_command *cmd, bool &stop) {
-        if (cmd->cmd == LC_FILESET_ENTRY) {
-            const fileset_entry_command* app_cache_cmd = (const fileset_entry_command*)cmd;
-            const char* name = (char*)app_cache_cmd + app_cache_cmd->entry_id.offset;
-
-            void* entryStart = (void*)(app_cache_cmd->vmaddr + slide);
-            size_t entrySize = _bufferSize - (size_t)((uint64_t)entryStart - (uint64_t)header());
-            Image entryImage(entryStart, entrySize, MappingKind::wholeSliceMapped);
-            callback(entryImage, name, stop);
-            return;
+        else {
+            if ( this->hasBindOpcodes() ) {
+                this->bindOpcodes().forEachBindLocation(segments, callback);
+            }
+            if ( this->hasLazyBindOpcodes() ) {
+                this->lazyBindOpcodes().forEachBindLocation(segments, callback);
+            }
+            if ( this->hasRebaseOpcodes() ) {
+                this->rebaseOpcodes().forEachRebaseLocation(segments, prefLoadAddr, callback);
+            }
         }
     });
 }
@@ -1109,94 +736,5 @@
     return std::span<uint8_t>();
 }
 
-static void forEachPointerInSection(const Header* hdr, uint8_t sectionType, uint64_t prefLoadAddress,
-                                    bool contentRebased, void (^callback)(uint32_t offset))
-{
-    hdr->forEachSection(^(const Header::SectionInfo& sectInfo, bool& stop) {
-        if ( (sectInfo.flags & SECTION_TYPE) == sectionType ) {
-            const uint8_t* sectionContent = (uint8_t*)hdr + sectInfo.fileOffset;
-            if ( hdr->inDyldCache() )
-                sectionContent = (uint8_t*)(sectInfo.address + hdr->getSlide());
-
-            if ( contentRebased ) {
-                // in dyld, when this is called, the image is already rebased, so we can use pointers in section
-                const uintptr_t* initsStart = (uintptr_t*)sectionContent;
-                const uintptr_t* initsEnd   = (uintptr_t*)((uint8_t*)sectionContent + sectInfo.size);
-                for (const uintptr_t* p=initsStart; p < initsEnd; ++p) {
-                    uintptr_t anInit       = *p;
-                    uint32_t  anInitOffset = (uint32_t)(anInit - prefLoadAddress);
-                    callback(anInitOffset);
-                }
-            } else {
-                if ( hdr->is64() ) {
-                    const uint64_t* initsStart = (uint64_t*)sectionContent;
-                    const uint64_t* initsEnd   = (uint64_t*)((uint8_t*)sectionContent + sectInfo.size);
-                    for (const uint64_t* p=initsStart; p < initsEnd; ++p) {
-                        uint64_t anInit = *p;
-                        // FIXME: as a quick hack, the low 32-bits with either rebase opcodes or chained fixups is offset in image
-                        callback((uint32_t)anInit);
-                    }
-                }
-                else {
-                    const uint32_t* initsStart = (uint32_t*)sectionContent;
-                    const uint32_t* initsEnd   = (uint32_t*)((uint8_t*)sectionContent + sectInfo.size);
-                    for (const uint32_t* p=initsStart; p < initsEnd; ++p) {
-                        uint32_t anInitOffset = *p;
-                        // FIXME: as a quick hack, the low 26-bits with either rebase opcodes or chained fixups is offset in image
-                        callback(anInitOffset & 0x03FFFFFF);
-                    }
-                }
-            }
-        }
-    });
-}
-
-void Image::forEachInitializer(bool contentRebased, void (^callback)(uint32_t offset)) const
-{
-    const Header*   hdr             = header();
-    uint64_t        prefLoadAddress = hdr->preferredLoadAddress();
-
-    // if dylib linked with -init linker option, that initializer is first
-    hdr->forEachLoadCommandSafe(^(const load_command* cmd, bool& stop) {
-        if ( cmd->cmd == LC_ROUTINES ) {
-            const routines_command* routines = (routines_command*)cmd;
-            uint64_t dashInit = routines->init_address;
-            callback((uint32_t)(dashInit - prefLoadAddress));
-        }
-        else if ( cmd->cmd == LC_ROUTINES_64 ) {
-            const routines_command_64* routines = (routines_command_64*)cmd;
-            uint64_t dashInit = routines->init_address;
-            callback((uint32_t)(dashInit - prefLoadAddress));
-        }
-    });
-
-    // next any function pointers in __DATA,__mod_init_func section
-    forEachPointerInSection(hdr, S_MOD_INIT_FUNC_POINTERS, prefLoadAddress, contentRebased, callback);
-
-    // next any function pointers in __TEXT,__init_offsets
-    hdr->forEachSection(^(const Header::SectionInfo& sectInfo, bool& stop) {
-        if ( (sectInfo.flags & SECTION_TYPE) == S_INIT_FUNC_OFFSETS ) {
-            const uint8_t* sectionContent = (uint8_t*)hdr + sectInfo.fileOffset;
-            if ( hdr->inDyldCache() )
-                sectionContent = (uint8_t*)(sectInfo.address + hdr->getSlide());
-            const uint32_t* initsStart = (uint32_t*)sectionContent;
-            const uint32_t* initsEnd   = (uint32_t*)((uint8_t*)sectionContent + sectInfo.size);
-            for (const uint32_t* p=initsStart; p < initsEnd; ++p) {
-                uint32_t anInitOffset = *p;
-                callback(anInitOffset);
-            }
-        }
-    });
-}
-
-void Image::forEachClassicTerminator(bool contentRebased, void (^callback)(uint32_t offset)) const
-{
-    uint64_t prefLoadAddress = header()->preferredLoadAddress();
-
-    // any function pointers in __DATA,__mod_term_func section
-    forEachPointerInSection(header(), S_MOD_TERM_FUNC_POINTERS, prefLoadAddress, contentRebased, callback);
-}
-
-
 
 } // namespace mach_o