How does the dynamic loader work?

How does the dynamic loader work?

Dynamic loading is a mechanism by which a computer program can, at run time, load a library (or other binary) into memory, retrieve the addresses of functions and variables contained in the library, execute those functions or access those variables, and unload the library from memory.

Is the address of a global variable in C static or dynamic?

Global variables are static, and there is only one copy for the entire program. Inside a function the variable is allocated on the stack.

What is the advantage of using dynamic loading?

The advantage of dynamic loading is that an unused routine is never loaded. Dynamic loading does not require special support from the OS. Operating systems may help the programmer, however, by providing library routines to implement dynamic loading.

How are global variables treated in a dynamic link library?

A Dynamic-Link Library (DLL) can contain global data or local data. Variables that are declared as global in a DLL source code file are treated as global variables by the compiler and linker, but each process that loads a given DLL gets its own copy of that DLL’s global variables.

Where is the global variable in a shared library?

This library does 1 simple thing, it says to the app (app dynamically links the library at runtime) by how many apps it is already linked. Apps should have access to link counter. My knowledge in C and Linux is somewhat limited in this aspect, but as I understand this information should be stored in a global variable inside the shared object.

What happens to static variables in a shared library?

The scope of static variables is limited to the block in which the static variables are declared. As a result, each process has its own instance of the DLL global and static variables by default. When dynamically linking modules, it can be unclear whether different libraries have their own instances of globals or whether the globals are shared.

How are global variables treated in a DLL?

Variables that are declared as global in a DLL source code file are treated as global variables by the compiler and linker, but each process that loads a given DLL gets its own copy of that DLL’s global variables. The scope of static variables is limited to the block in which the static variables are declared.