extern crate kernel32;
extern crate winapi;
use std::{io, mem, ptr};
use std::fs::File;
use std::os::raw::c_void;
use std::os::windows::io::{AsRawHandle, RawHandle};
pub struct MmapInner {
file: Option<File>,
ptr: *mut c_void,
len: usize,
copy: bool,
}
impl MmapInner {
pub fn new(
file: &File,
protect: winapi::DWORD,
access: winapi::DWORD,
offset: usize,
len: usize,
copy: bool,
) -> io::Result<MmapInner> {
let alignment = offset % allocation_granularity();
let aligned_offset = offset - alignment;
let aligned_len = len + alignment;
unsafe {
let handle = kernel32::CreateFileMappingW(
file.as_raw_handle(),
ptr::null_mut(),
protect,
0,
0,
ptr::null(),
);
if handle == ptr::null_mut() {
return Err(io::Error::last_os_error());
}
let ptr = kernel32::MapViewOfFile(
handle,
access,
(aligned_offset >> 16 >> 16) as winapi::DWORD,
(aligned_offset & 0xffffffff) as winapi::DWORD,
aligned_len as winapi::SIZE_T,
);
kernel32::CloseHandle(handle);
if ptr == ptr::null_mut() {
Err(io::Error::last_os_error())
} else {
Ok(MmapInner {
file: Some(file.try_clone()?),
ptr: ptr.offset(alignment as isize),
len: len as usize,
copy: copy,
})
}
}
}
pub fn map(len: usize, file: &File, offset: usize) -> io::Result<MmapInner> {
let write = protection_supported(file.as_raw_handle(), winapi::PAGE_READWRITE);
let exec = protection_supported(file.as_raw_handle(), winapi::PAGE_EXECUTE_READ);
let mut access = winapi::FILE_MAP_READ;
let protection = match (write, exec) {
(true, true) => {
access |= winapi::FILE_MAP_WRITE | winapi::FILE_MAP_EXECUTE;
winapi::PAGE_EXECUTE_READWRITE
}
(true, false) => {
access |= winapi::FILE_MAP_WRITE;
winapi::PAGE_READWRITE
}
(false, true) => {
access |= winapi::FILE_MAP_EXECUTE;
winapi::PAGE_EXECUTE_READ
}
(false, false) => winapi::PAGE_READONLY,
};
let mut inner = MmapInner::new(file, protection, access, offset, len, false)?;
if write || exec {
inner.make_read_only()?;
}
Ok(inner)
}
pub fn map_exec(len: usize, file: &File, offset: usize) -> io::Result<MmapInner> {
let write = protection_supported(file.as_raw_handle(), winapi::PAGE_READWRITE);
let mut access = winapi::FILE_MAP_READ | winapi::FILE_MAP_EXECUTE;
let protection = if write {
access |= winapi::FILE_MAP_WRITE;
winapi::PAGE_EXECUTE_READWRITE
} else {
winapi::PAGE_EXECUTE_READ
};
let mut inner = MmapInner::new(file, protection, access, offset, len, false)?;
if write {
inner.make_exec()?;
}
Ok(inner)
}
pub fn map_mut(len: usize, file: &File, offset: usize) -> io::Result<MmapInner> {
let exec = protection_supported(file.as_raw_handle(), winapi::PAGE_EXECUTE_READ);
let mut access = winapi::FILE_MAP_READ | winapi::FILE_MAP_WRITE;
let protection = if exec {
access |= winapi::FILE_MAP_EXECUTE;
winapi::PAGE_EXECUTE_READWRITE
} else {
winapi::PAGE_READWRITE
};
let mut inner = MmapInner::new(file, protection, access, offset, len, false)?;
if exec {
inner.make_mut()?;
}
Ok(inner)
}
pub fn map_copy(len: usize, file: &File, offset: usize) -> io::Result<MmapInner> {
let exec = protection_supported(file.as_raw_handle(), winapi::PAGE_EXECUTE_READWRITE);
let mut access = winapi::FILE_MAP_COPY;
let protection = if exec {
access |= winapi::FILE_MAP_EXECUTE;
winapi::PAGE_EXECUTE_WRITECOPY
} else {
winapi::PAGE_WRITECOPY
};
let mut inner = MmapInner::new(file, protection, access, offset, len, true)?;
if exec {
inner.make_mut()?;
}
Ok(inner)
}
pub fn map_anon(len: usize, _stack: bool) -> io::Result<MmapInner> {
unsafe {
let handle = kernel32::CreateFileMappingW(
winapi::INVALID_HANDLE_VALUE,
ptr::null_mut(),
winapi::PAGE_EXECUTE_READWRITE,
(len >> 16 >> 16) as winapi::DWORD,
(len & 0xffffffff) as winapi::DWORD,
ptr::null(),
);
if handle == ptr::null_mut() {
return Err(io::Error::last_os_error());
}
let access = winapi::FILE_MAP_ALL_ACCESS | winapi::FILE_MAP_EXECUTE;
let ptr = kernel32::MapViewOfFile(handle, access, 0, 0, len as winapi::SIZE_T);
kernel32::CloseHandle(handle);
if ptr == ptr::null_mut() {
return Err(io::Error::last_os_error());
}
let mut old = 0;
let result = kernel32::VirtualProtect(
ptr,
len as winapi::SIZE_T,
winapi::PAGE_READWRITE,
&mut old,
);
if result != 0 {
Ok(MmapInner {
file: None,
ptr: ptr,
len: len as usize,
copy: false,
})
} else {
Err(io::Error::last_os_error())
}
}
}
pub fn flush(&self, offset: usize, len: usize) -> io::Result<()> {
self.flush_async(offset, len)?;
if let Some(ref file) = self.file {
file.sync_data()?;
}
Ok(())
}
pub fn flush_async(&self, offset: usize, len: usize) -> io::Result<()> {
let result = unsafe {
kernel32::FlushViewOfFile(self.ptr.offset(offset as isize), len as winapi::SIZE_T)
};
if result != 0 {
Ok(())
} else {
Err(io::Error::last_os_error())
}
}
fn virtual_protect(&mut self, protect: winapi::DWORD) -> io::Result<()> {
unsafe {
let alignment = self.ptr as usize % allocation_granularity();
let ptr = self.ptr.offset(-(alignment as isize));
let aligned_len = self.len as winapi::SIZE_T + alignment as winapi::SIZE_T;
let mut old = 0;
let result = kernel32::VirtualProtect(ptr, aligned_len, protect, &mut old);
if result != 0 {
Ok(())
} else {
Err(io::Error::last_os_error())
}
}
}
pub fn make_read_only(&mut self) -> io::Result<()> {
self.virtual_protect(winapi::PAGE_READONLY)
}
pub fn make_exec(&mut self) -> io::Result<()> {
if self.copy {
self.virtual_protect(winapi::PAGE_EXECUTE_WRITECOPY)
} else {
self.virtual_protect(winapi::PAGE_EXECUTE_READ)
}
}
pub fn make_mut(&mut self) -> io::Result<()> {
if self.copy {
self.virtual_protect(winapi::PAGE_WRITECOPY)
} else {
self.virtual_protect(winapi::PAGE_READWRITE)
}
}
#[inline]
pub fn ptr(&self) -> *const u8 {
self.ptr as *const u8
}
#[inline]
pub fn mut_ptr(&mut self) -> *mut u8 {
self.ptr as *mut u8
}
#[inline]
pub fn len(&self) -> usize {
self.len
}
}
impl Drop for MmapInner {
fn drop(&mut self) {
let alignment = self.ptr as usize % allocation_granularity();
unsafe {
let ptr = self.ptr.offset(-(alignment as isize));
assert!(
kernel32::UnmapViewOfFile(ptr) != 0,
"unable to unmap mmap: {}",
io::Error::last_os_error()
);
}
}
}
unsafe impl Sync for MmapInner {}
unsafe impl Send for MmapInner {}
fn protection_supported(handle: RawHandle, protection: winapi::DWORD) -> bool {
unsafe {
let handle =
kernel32::CreateFileMappingW(handle, ptr::null_mut(), protection, 0, 0, ptr::null());
if handle == ptr::null_mut() {
return false;
}
kernel32::CloseHandle(handle);
true
}
}
fn allocation_granularity() -> usize {
unsafe {
let mut info = mem::zeroed();
kernel32::GetSystemInfo(&mut info);
return info.dwAllocationGranularity as usize;
}
}