Some `MAP_` constants defined on macOS but not in `mmap`

[ronaldoussoren]

Feature or enhancement

Proposal:

The following MAP_* flags are defined on macOS, but are not exposed in the module mmap:

• MAP_NORESERVE
• MAP_NOEXTEND
• MAP_HASSEMAPHORE
• MAP_NOCACHE
• MAP_JIT
• MAP_RESILIENT_CODESIGN
• MAP_RESILIENT_MEDIA
• MAP_32BIT
• MAP_TRANSLATED_ALLOW_EXECUTE
• MAP_UNIX03
• MAP_TPRO

The system also defines MAP_COPY, MAP_RENAME, but those seem to be less useful. MAP_FILE and MAP_FIXED are generic flags that aren't useful for module mmap.

This is based on the macOS 14.2 SDK.

Two other things I noticed, but something for different issues:

• There's a comment about msync(2) flags in the implementation for mmap.mmap.flush()
• There is no way to change the memory protection (PROT_READ etc.) after creating the mapping, exposing such functionality could be useful for using mmap to write executable code in Python.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-113868: Add a number of MAP_* flags from macOS to module mmap #113869

[brandtbucher]

• There is no way to change the memory protection (PROT_READ etc.) after creating the mapping, exposing such functionality could be useful for using mmap to write executable code in Python.

Sorry I'm late, but +1 for exposing mprotect. I was prototyping JITs in pure-Python a while back, and it was unfortunate to have to hack around the edges with ctypes just to do something like this (which "feels like" it should be part of the mmap module).