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extern crate libc;
use std::fs::File;
use std::os::unix::io::{AsRawFd, RawFd};
use std::{io, ptr};
#[cfg(any(
all(target_os = "linux", not(target_arch = "mips")),
target_os = "freebsd",
target_os = "android"
))]
const MAP_STACK: libc::c_int = libc::MAP_STACK;
#[cfg(not(any(
all(target_os = "linux", not(target_arch = "mips")),
target_os = "freebsd",
target_os = "android"
)))]
const MAP_STACK: libc::c_int = 0;
#[cfg(any(target_os = "linux", target_os = "android"))]
const MAP_POPULATE: libc::c_int = libc::MAP_POPULATE;
#[cfg(not(any(target_os = "linux", target_os = "android")))]
const MAP_POPULATE: libc::c_int = 0;
pub struct MmapInner {
ptr: *mut libc::c_void,
len: usize,
}
impl MmapInner {
/// Creates a new `MmapInner`.
///
/// This is a thin wrapper around the `mmap` sytem call.
fn new(
len: usize,
prot: libc::c_int,
flags: libc::c_int,
file: RawFd,
offset: u64,
) -> io::Result<MmapInner> {
let alignment = offset % page_size() as u64;
let aligned_offset = offset - alignment;
let aligned_len = len + alignment as usize;
if aligned_len == 0 {
// Normally the OS would catch this, but it segfaults under QEMU.
return Err(io::Error::new(
io::ErrorKind::InvalidInput,
"memory map must have a non-zero length",
));
}
unsafe {
let ptr = libc::mmap(
ptr::null_mut(),
aligned_len as libc::size_t,
prot,
flags,
file,
aligned_offset as libc::off_t,
);
if ptr == libc::MAP_FAILED {
Err(io::Error::last_os_error())
} else {
Ok(MmapInner {
ptr: ptr.offset(alignment as isize),
len,
})
}
}
}
pub fn map(len: usize, file: &File, offset: u64, populate: bool) -> io::Result<MmapInner> {
let populate = if populate { MAP_POPULATE } else { 0 };
MmapInner::new(
len,
libc::PROT_READ,
libc::MAP_SHARED | populate,
file.as_raw_fd(),
offset,
)
}
pub fn map_exec(len: usize, file: &File, offset: u64, populate: bool) -> io::Result<MmapInner> {
let populate = if populate { MAP_POPULATE } else { 0 };
MmapInner::new(
len,
libc::PROT_READ | libc::PROT_EXEC,
libc::MAP_SHARED | populate,
file.as_raw_fd(),
offset,
)
}
pub fn map_mut(len: usize, file: &File, offset: u64, populate: bool) -> io::Result<MmapInner> {
let populate = if populate { MAP_POPULATE } else { 0 };
MmapInner::new(
len,
libc::PROT_READ | libc::PROT_WRITE,
libc::MAP_SHARED | populate,
file.as_raw_fd(),
offset,
)
}
pub fn map_copy(len: usize, file: &File, offset: u64, populate: bool) -> io::Result<MmapInner> {
let populate = if populate { MAP_POPULATE } else { 0 };
MmapInner::new(
len,
libc::PROT_READ | libc::PROT_WRITE,
libc::MAP_PRIVATE | populate,
file.as_raw_fd(),
offset,
)
}
pub fn map_copy_read_only(
len: usize,
file: &File,
offset: u64,
populate: bool,
) -> io::Result<MmapInner> {
let populate = if populate { MAP_POPULATE } else { 0 };
MmapInner::new(
len,
libc::PROT_READ,
libc::MAP_PRIVATE | populate,
file.as_raw_fd(),
offset,
)
}
/// Open an anonymous memory map.
pub fn map_anon(len: usize, stack: bool) -> io::Result<MmapInner> {
let stack = if stack { MAP_STACK } else { 0 };
MmapInner::new(
len,
libc::PROT_READ | libc::PROT_WRITE,
libc::MAP_PRIVATE | libc::MAP_ANON | stack,
-1,
0,
)
}
pub fn flush(&self, offset: usize, len: usize) -> io::Result<()> {
let alignment = (self.ptr as usize + offset) % page_size();
let offset = offset as isize - alignment as isize;
let len = len + alignment;
let result =
unsafe { libc::msync(self.ptr.offset(offset), len as libc::size_t, libc::MS_SYNC) };
if result == 0 {
Ok(())
} else {
Err(io::Error::last_os_error())
}
}
pub fn flush_async(&self, offset: usize, len: usize) -> io::Result<()> {
let alignment = (self.ptr as usize + offset) % page_size();
let offset = offset as isize - alignment as isize;
let len = len + alignment;
let result =
unsafe { libc::msync(self.ptr.offset(offset), len as libc::size_t, libc::MS_ASYNC) };
if result == 0 {
Ok(())
} else {
Err(io::Error::last_os_error())
}
}
fn mprotect(&mut self, prot: libc::c_int) -> io::Result<()> {
unsafe {
let alignment = self.ptr as usize % page_size();
let ptr = self.ptr.offset(-(alignment as isize));
let len = self.len + alignment;
if libc::mprotect(ptr, len, prot) == 0 {
Ok(())
} else {
Err(io::Error::last_os_error())
}
}
}
pub fn make_read_only(&mut self) -> io::Result<()> {
self.mprotect(libc::PROT_READ)
}
pub fn make_exec(&mut self) -> io::Result<()> {
self.mprotect(libc::PROT_READ | libc::PROT_EXEC)
}
pub fn make_mut(&mut self) -> io::Result<()> {
self.mprotect(libc::PROT_READ | libc::PROT_WRITE)
}
#[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 % page_size();
unsafe {
assert!(
libc::munmap(
self.ptr.offset(-(alignment as isize)),
(self.len + alignment) as libc::size_t
) == 0,
"unable to unmap mmap: {}",
io::Error::last_os_error()
);
}
}
}
unsafe impl Sync for MmapInner {}
unsafe impl Send for MmapInner {}
fn page_size() -> usize {
unsafe { libc::sysconf(libc::_SC_PAGESIZE) as usize }
}
|
