Building and Using Shared Libraries on Linux course outline

1. Course Introduction
2. Fundamentals of Shared Libraries
   • Background
   • The static linker and the dynamic linker
   • Static vs shared libraries
   • Basics of shared library creation and use
   • Position-independent code (PIC)
   • The shared library soname
   • In pictures: library creation, linking, and loading
3. Versioning and Installation
   • Shared library versioning
   • Shared library real names, sonames, and linker names
   • Installing shared libraries
   • ldconfig
4. ELF (Executable and Linkable Format)
   • ELF file layout
   • The program header table (PHT)
   • The section header table (SHT)
   • Program header table vs section header table
   • ELF sections
   • Useful commands: readelf and objdump
5. The Dynamic Linker
   • Rpath: specifying library search paths in an object
   • Dynamic string tokens
   • Finding shared libraries at run time
   • How programs get run
6. Symbol Interposition and Library Load Order
   • Symbol resolution and symbol interposition
   • Symbol resolution and library load order
   • Link-map lists (namespaces)
   • The global look-up scope
   • LD_DEBUG: tracing the dynamic linker
7. Dynamically Loaded Libraries (dlopen)
   • Opening a shared library: dlopen()
   • Obtaining the address of a symbol: dlsym()
   • The dlopen API: example
   • The dlopen API: further details
8. Shared Libraries and the Static Linker
   • Recording dynamic dependencies
   • How the static linker finds library dependencies
   • Handling secondary dependencies at link time
9. Symbol Visibility
   • Controlling symbol visibility
   • Controlling symbol visibility: –Bsymbolic
   • Symbol attributes: binding and visibility
   • Controlling visibility on a per-symbol bases
   • Using version scripts to control symbol visibility
   • Summary of techniques for build-time visibility control
   • Run-time visibility control: dlopen()-ed libraries
10. Look-up Scopes
    • Look-up scopes
    • LD_DEBUG=scopes
11. Preloading
    • Preloading shared libraries
    • Preloading example
    • Use cases for preloading
12. Weak Symbols (*)
    • Weak symbols
    • Linker rules for strong and weak symbols
    • Use cases for weak symbols
13. Symbol Versioning
    • Creating a symbol-versioned library
    • An aside: version "dependencies"
    • Summary: assigning a version to a symbol
    • ELF and symbol versioning
    • Symbol versioning and symbol resolution
    • Advantages of symbol versioning
    • Referencing a nondefault symbol version
    • Removing a public versioned symbol
    • The library base version
    • Appendix: version node syntax
    • Appendix: the .symver assembler directive
14. Symbol Versioning: Further Topics (*)
    • Symbol versioning design approaches
    • Transitioning an existing library to symbol versioning
    • Further details on symbol versioning
    • Symbol-version matching rules
    • Addendum: a few C++ details
15. Lazy Binding (*)
    • Lazy binding
    • Immediate binding
    • Lazy binding versus immediate binding
16. GOT and PLT (*)
    • The GOT and PLT
    • Relocation and the PLT: in pictures
    • Relocation and the PLT: code
    • Observing the effect of lazy binding on the GOT
    • Performance considerations

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