WingNews logo WingNews
top | item 47211202

(no title)

ajross | 6 hours ago

I think this is sort of missing the point, though. Yes, mmap() is in POSIX[1] in the sense of "where is it specified".

But mmap() was implemented in C because C is the natural language for exposing Unix system calls and mmap() is a syscall provided by the OS. And this is true up and down the stack. Best language for integrating with low level kernel networking (sockopts, routing, etc...)? C. Best language for async I/O primitives? C. Best language for SIMD integration? C. And it goes on and on.

Obviously you can do this stuff (including mmap()) in all sorts of runtimes. But it always appears first in C and gets ported elsewhere. Because no matter how much you think your language is better, if you have to go into the kernel to plumb out hooks for your new feature, you're going to integrated and test it using a C rig before you get the other ports.

[1] Given that the pedantry bottle was opened already, it's worth pointing out that you'd have gotten more points by noting that it appeared in 4.2BSD.

discuss

order

nickelpro|5 hours ago

If we're going to be pedantic, mmap is a syscall. It happens that the C version is standardized by POSIX.

The underlying syscall doesn't use the C ABI, you need to wrap it to use it from C in the same way you need to wrap it to use it from any language, which is exactly what glibc and friends do.

Moral of the story is mmap belongs to the platform, not the language.

a-dub|5 hours ago

it also appears in operating systems that aren't written in c. i see it as an operating system feature, categorically.