NSGod / dsce

*uncaches your dyld*

dsce

Incomplete macOS 12+ dyld cache extractor. Used by OCLP to support some legacy GPUs and Wi-Fi hardware. Produces working binaries in many cases, but outputs should be treated with extreme suspicion...

credits

• Apple: dyld, objc4 (prerequisites)
• Hopper Disassembler: Mach-O inspection, Objective-C struct definitions
• Mach-O Explorer, MachOView: Mach-O inspection
• Wikipedia: LEB128
• Moraea: guidance, testing, encouragement

status

• copy header and load commands
  • allocate space for additional commands
• copy segments/sections, fixing offsets and alignment
  • optionally pad to keep addresses contiguous (produces 2+ GB images)
• generate rebase opcodes
  • by applying cache rebase chain
• generate bind opcodes
  • by scanning rebases for external pointers
    • matching imported dylib exports
    • recursing re-exported dylibs/symbols
  • by restoring uniqued __got section (Ventura)
  • using C++ addend hack
  • from weak/lazy bind info
• generate exports trie
  • regular
  • re-export
  • stub and resolver
• copy legacy symbols, indirect symbols, and string table
• fix Objective-C structures
  • revert selector uniquing
  • revert protocol uniquing
  • fix class, category, and protocol method lists
  • create fake __objc_imageinfo (work around Ventura crash)
• update UUIDs to D5CE<version>-... for visibility in logs (formerly 416D7900-...)
• produce fully compliant images
  • satisfy install_name_tool -id test
  • satisfy codesign -fs -
  • satisfy dyld_info -objc
  • satisfy Stubber (nm, Objective-C runtime, linker)
  • satisfy lldb (unlikely outside pad mode...)
• produce working images
  • 12.0 DP6 - GeForceAIRPlugin, GeForceMTLDriver
  • 12.0 DP6 - GeForceGLDriver
  • 12.6 - AppKit, QuartzCore, CoreGraphics, Carbon, RenderBox, VectorKit, Metal, MetalPerformanceShaders, MTLCompiler, GPUCompiler, AppleGVA, AppleGVACore
  • 12.6 - AMDMTLBronzeDriver, AMDShared, AMDRadeonVADriver, AMDRadeonVADriver2
  • 13.2.1 - AppKit, QuartzCore, CoreGraphics, Carbon, RenderBox, VectorKit, Metal, MetalPerformanceShaders, MTLCompiler, GPUCompiler
  • 13.2.1 - libSystem, Foundation, Combine, ContactsFoundation, FamilyCircle
• support Big Sur
• support Monterey
• support Ventura
• support arm64 (unlikely...)
• use sane amounts of RAM and CPU (getting closer...)
• write automated tests to detect regressions