Current implementation - syscall abstractions
I refactored my approach to test my malloc by just mocking syscalls under testing conditions to get rid of dynamic linking altogether.
This is the landing page for deeper study of my dynamic linking adventure while testing my malloc , an educational glibc inspired memory allocator with extensive instrumentation, determinism concerns, and cross-platform linking behavior.
The series are concerned with:
- how allocator logic is developed, tested, and kept deterministic
- how allocator interposition works across Linux (ELF) and macOS (Mach-O)
📌 Dynamic Linking Overview, a high-level explanation of why dynamic linking and allocator interposition matter, and how platform differences affect allocator behavior.
The current mainline implementation does not globally interpose on the system allocator. Instead, it prioritizes determinism and testability by abstracting system calls behind a mockable interface.
📌 Current Implementation & Syscall Abstraction, explains how the allocator is developed and tested today.
We touch on:
- Linux ELF: GOT, PLT, lazy binding, symbol resolution
- macOS Mach-O: two-level namespaces and dyld interposition
- Return address tracing and callsite classification
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Cross-platform allocator correctness constraints
- Return Address Tracing – How callsites were identified and classified
- GDB malloc Call Tracing – Step-by-step debugger walkthroughs
- ELF: GOT, PLT & Lazy Binding – How symbol resolution works on Linux
- Mach-O & dyld Interposition – Why macOS behaves differently and how to fix it
- Cross-Platform Implications – Design conclusions for the allocator
