What is linker and loader in computer?

What is linker and loader in computer?

Linker and loader are crucial components in the process of transforming source code into an executable program. While they may seem similar, they serve distinct roles in the compilation process.

The **linker** is a program that combines multiple object files, which are generated by compiling the source code, into a single executable file. It resolves external symbols, performs memory allocation, and arranges the layout of the executable.

On the other hand, the **loader** is responsible for loading the executable program into memory and preparing it for execution. It performs memory allocation, resolves any remaining external references, and sets up the program’s initial execution environment.

Both the linker and loader play vital roles in the compilation process, ensuring that the source code is transformed into a functioning executable program.

How does the linker work?

The linker takes the object files generated by the compiler and combines them into a single executable file. It resolves external references by matching symbols in one object file to their definitions in another, ensuring that all references are properly linked.

What is symbol resolution?

Symbol resolution is the process of finding the memory address corresponding to a symbol or variable referenced in the code. The linker ensures that the references to symbols are correctly resolved to their definitions.

What is memory allocation?

Memory allocation refers to the process of assigning memory space to different variables, functions, and data structures in an executable program. The linker determines the size and location of each segment in memory.

How does the linker arrange the layout of the executable?

The linker organizes the sections of the executable in a specific order, such as code, data, and resources. It ensures that the different parts of the program are placed in the correct memory locations.

What are external references?

External references are symbols or functions defined in one object file and referenced in another. The linker resolves these references by connecting them to their corresponding definitions, either in other object files or in libraries.

What is a loader’s role in program execution?

The loader is responsible for loading the executable program into memory, setting up the necessary data structures and environment, and starting the execution of the program.

What is dynamic linking?

Dynamic linking is a mechanism where the linking process is deferred until runtime. The loader performs dynamic linking by connecting the program’s external references with their definitions in shared libraries when the program is loaded into memory.

How does the loader perform memory allocation?

The loader allocates memory for the program by reserving the required space for the code, data, stack, and heap segments. It ensures that there are no conflicts with other programs or system resources.

What is relocation?

Relocation is the process of modifying the object code to adjust memory addresses to match the actual loading address in memory. The loader performs relocation to adapt the program to the specific memory layout.

What happens if the linker fails?

If the linker fails, it means it is unable to combine the object files into a complete executable. This could occur due to unresolved symbols or incompatible object files, resulting in build errors.

What are shared libraries?

Shared libraries are collections of reusable code that can be shared by multiple programs. They are loaded dynamically into memory when required, and the loader resolves external references to symbols in these libraries.

Can a program execute without a loader?

No, a program cannot execute without a loader. The loader is responsible for the crucial task of loading the program into memory and preparing it for execution, ensuring a proper runtime environment. Without the loader, the program would not be able to execute.

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