malloc-replica

A small implementation of malloc, free, calloc, and realloc in C.
This project recreates core heap-management behavior by maintaining metadata blocks in a linked list and requesting memory from the operating system using sbrk().

The allocator supports multiple fit strategies, handles alignment, and tracks heap statistics to help visualize allocator behavior over time.

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Features / Requirements Modeled

Heap management

• Grows the heap on demand using sbrk()
• Maintains a linked list of heap blocks containing metadata:
  • block size
  • free/allocated status
  • pointer to the next block

Allocation behavior

• 4-byte alignment for all requested allocations
• Locates a usable free block using a selectable fit strategy
• Splits free blocks when there is enough leftover space to form a valid new block
• Reuses freed blocks instead of always growing the heap

Freeing and coalescing

• Marks blocks as free when free() is called
• Coalesces adjacent free blocks to reduce fragmentation

Supported allocation strategies (compile-time)

• First Fit
• Best Fit
• Worst Fit
• Next Fit

Statistics and reporting

Automatically prints heap statistics at program exit (registered with atexit()), including:

• number of mallocs
• number of frees
• number of reuses
• number of heap grows
• number of block splits
• number of coalesces
• number of blocks tracked
• total requested bytes
• maximum heap size reached