[Mach-O] Refactor fix-up chain parsing #7506
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The parsing of fix-up chains is moved out of `MachoView` and into its own class. It deals purely in terms of offsets into the Mach-O slice. `MachoView` translates those offsets to mapped addresses when needed. This is primarily aimed at fixing incorrect handling of pointer formats that use offsets where in some cases the relocations would be applied at incorrect addresses due to confusion between file offsets, Mach-O slice offsets, and VM offsets. Additionally, it fixes addends from bind operations not being respected. These show up most frequently in C++ RTTI information.
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The parsing of fix-up chains is moved out of
MachoViewand into its own class. It deals purely in terms of offsets into the Mach-O slice.MachoViewtranslates those offsets to mapped addresses when needed.This is primarily aimed at fixing incorrect handling of pointer formats that use offsets where in some cases the relocations would be applied at incorrect addresses due to confusion between file offsets, Mach-O slice offsets, and VM offsets.
It incidentally fixes addends from bind operations not being respected. These show up most frequently in C++ RTTI information.
The chained fix-up parser contains a
#defineto enable it to produce debug output in the same format asdyld_info -fixup_chain_detailsto make it easy to cross-check parsing against Apple's implementation.Fixes #7421.