Method py_new

crates/stdlib/src/mmap.rs:445–544

(_cls: &Py<PyType>, args: Self::Args, vm: &VirtualMachine)

        #[cfg(unix)]
        fn py_new(_cls: &Py<PyType>, args: Self::Args, vm: &VirtualMachine) -> PyResult<Self> {
            use libc::{MAP_PRIVATE, MAP_SHARED, PROT_READ, PROT_WRITE};

            let mut map_size = args.validate_new_args(vm)?;
            let MmapNewArgs {
                fileno: fd,
                flags,
                prot,
                access,
                offset,
                ..
            } = args;

            if (access != AccessMode::Default)
                && ((flags != MAP_SHARED) || (prot != (PROT_WRITE | PROT_READ)))
            {
                return Err(vm.new_value_error("mmap can't specify both access and flags, prot."));
            }

            // TODO: memmap2 doesn't support mapping with prot and flags right now
            let (_flags, _prot, access) = match access {
                AccessMode::Read => (MAP_SHARED, PROT_READ, access),
                AccessMode::Write => (MAP_SHARED, PROT_READ | PROT_WRITE, access),
                AccessMode::Copy => (MAP_PRIVATE, PROT_READ | PROT_WRITE, access),
                AccessMode::Default => {
                    let access = if (prot & PROT_READ) != 0 && (prot & PROT_WRITE) != 0 {
                        access
                    } else if (prot & PROT_WRITE) != 0 {
                        AccessMode::Write
                    } else {
                        AccessMode::Read
                    };
                    (flags, prot, access)
                }
            };

            let fd = unsafe { crt_fd::Borrowed::try_borrow_raw(fd) };

            // macOS: Issue #11277: fsync(2) is not enough on OS X - a special, OS X specific
            // fcntl(2) is necessary to force DISKSYNC and get around mmap(2) bug
            #[cfg(target_os = "macos")]
            if let Ok(fd) = fd {
                use std::os::fd::AsRawFd;
                unsafe { libc::fcntl(fd.as_raw_fd(), libc::F_FULLFSYNC) };
            }

            if let Ok(fd) = fd {
                let metadata = fstat(fd)
                    .map_err(|err| io::Error::from_raw_os_error(err as i32).to_pyexception(vm))?;
                let file_len = metadata.st_size as i64;

                if map_size == 0 {
                    if file_len == 0 {
                        return Err(vm.new_value_error("cannot mmap an empty file"));
                    }

                    if offset > file_len {
                        return Err(vm.new_value_error("mmap offset is greater than file size"));