What is DLL in memory?

What is DLL in memory?

A dynamic link library (DLL) is a collection of small programs that can be loaded when needed by larger programs and used at the same time. The advantage of DLL files is space is saved in random access memory (RAM) because the files don’t get loaded into RAM together with the main program.

How is DLL loaded in memory?

DLLs and Memory Management

1. The threads of the process that called the DLL can use handles opened by a DLL function.
2. The DLL uses the stack of the calling thread and the virtual address space of the calling process.
3. The DLL allocates memory from the virtual address space of the calling process.

What is the entry point for a shared object or a DLL?

The function DllMain is the entry point of the DLL.

When to use the entry point function in a DLL?

The system calls the entry-point function in the context of the process or thread that caused the function to be called. This allows a DLL to use its entry-point function for allocating memory in the virtual address space of the calling process or to open handles accessible to the process.

How to load a DLL from memory programming?

Open the given file and check the DOS and PE headers. Try to allocate a memory block of PEHeader.OptionalHeader.SizeOfImage bytes at position PEHeader.OptionalHeader.ImageBase. Parse section headers and copy sections to their addresses.

How does DLL allocate memory in virtual address space?

This allows a DLL to use its entry-point function for allocating memory in the virtual address space of the calling process or to open handles accessible to the process. The entry-point function can also allocate memory that is private to a new thread by using thread local storage (TLS).

How to disable the entry point function in Win32?

When a process unloads the DLL, the entry-point function is called only once for the entire process, rather than once for each existing thread of the process. You can use DisableThreadLibraryCalls to disable notification when threads are terminated. Only one thread at a time can call the entry-point function.