Enable `mmap` stdlib module (memory-mapped file I/O)

[ppenna]

Summary

Enable the mmap C extension module, which provides memory-mapped file I/O support.

Current State

Commented out in Modules/Setup.stdlib:

#mmap mmapmodule.c

Why Enable It

• mmap enables efficient file I/O by mapping files directly into memory
• Used by multiprocessing.shared_memory for shared memory segments
• importlib can use mmap for faster module loading
• Many data processing libraries rely on mmap for large file handling
• ctypes may use mmap internally

Work Required

1. Uncomment in Modules/Setup.stdlib:

   mmap mmapmodule.c
   

2. Nanvix POSIX syscall requirements:
   • mmap(addr, length, prot, flags, fd, offset) — map files/memory
   • munmap(addr, length) — unmap memory
   • msync(addr, length, flags) — synchronize mapped memory
   • madvise(addr, length, advice) — memory advisory (optional)
   • mremap(old_addr, old_size, new_size, flags) — resize mapping (Linux-specific, optional)
3. Required headers: <sys/mman.h>
4. Protection flags needed: PROT_READ, PROT_WRITE, PROT_EXEC
5. Mapping flags needed: MAP_SHARED, MAP_PRIVATE, MAP_ANONYMOUS
6. Build and test: python -c "import mmap; print(mmap.PAGESIZE)"

POSIX API Dependencies

API	Purpose
mmap()	Create memory mapping
munmap()	Remove memory mapping
msync()	Flush changes to disk
madvise()	Memory usage hints (optional)
mprotect()	Change protection (optional)

Complexity

High — requires Nanvix to support virtual memory mapping syscalls. This is a fundamental OS capability.

Source Files

• Modules/mmapmodule.c