Creating 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. The Dynamic Linker
   • Rpath: specifying library search paths in an object
   • Dynamic string tokens
   • Finding shared libraries at run time
   • Symbol resolution and symbol interposition
   • Link-map lists (namespaces)
   • The global look-up scope
   • LD_DEBUG: tracing the operation of the dynamic linker
5. Shared Libraries and the Static Linker
   • Recording dynamic dependencies
   • Handling secondary dependencies at link time
   • How the static linker finds library dependencies
6. ELF and Program Execution
   • 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
   • How programs get run
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. Symbol Visibility
   • Symbol attributes: binding and visibility
   • Controlling symbol visibility
   • Controlling visibility on a per-symbol bases
   • Controlling symbol visibility: dlopen()-ed libraries
   • Using version scripts to control symbol visibility
   • Look-up scopes
   • LD_DEBUG=scopes
9. Preloading
   • Preloading shared libraries
10. Weak Symbols (*)
    • Weak symbols
    • Use cases for weak symbols
11. Symbol Versioning
    • Creating a symbol-versioned library
    • ELF and symbol versioning
    • Advantages of symbol versioning
    • Further details on symbol versioning
    • The library base version
12. Symbol Versioning: Further Topics (*)
    • Transitioning an existing library to symbol versioning
    • Symbol versioning design approaches
    • Symbol-version matching rules
    • Addendum: a few C++ details
13. Lazy Binding (*)
    • Lazy binding
14. GOTand 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

Return to the course overview