memory-allocator in C

Test

Run the following command to test:

./bin/test

If changes are made to mem_alloc.c, compile for testing using:

gcc -o ./bin/test test.c mem_alloc.c -pthread

Introduction

Implemented malloc(), calloc(), realloc() and free().
Implemented locking mechanism such that no 2 threads can concurrently access memory.
Made use of linked lists to handle non contiguous memory.

Virtual Address Space

Text section: Holds the binary code that the processor executes.
Data section: Stores static data that is initialized with non-zero values.
BSS (Block Started by Symbol): Contains static data that is initialized to zero. Any uninitialized static data in the program is set to zero and placed here.
Heap: Used for storing dynamically allocated data.
Stack: Contains automatic variables, function arguments, and a copy of the base pointer.

System Call - `sbrk()`

sbrk() is a function used to manage a program's memory dynamically. brk or program break points to the end of the heap.

sbrk(0): returns current address of program break.
sbrk(x): allocates memory and increments increments brk by x bytes.
sbrk(-x): releases memory and decrements brk by x bytes.
failure: sbrk() returns (void*) -1.

Mutex used for locking

pthread_mutex_t is used to ensure thread-safe memory allocation.
This mutex is used to lock critical sections in the memory allocation functions so no 2 threads can concurrently access memory.