Source code
Revision control
Copy as Markdown
Other Tools
// Copyright © 2017 Mozilla Foundation
//
// This program is made available under an ISC-style license. See the
// accompanying file LICENSE for details.
#![allow(clippy::missing_safety_doc)]
use crate::errors::*;
use crate::PlatformHandle;
use std::{convert::TryInto, ffi::c_void, slice};
#[cfg(unix)]
pub use unix::SharedMem;
#[cfg(windows)]
pub use windows::SharedMem;
#[derive(Copy, Clone)]
struct SharedMemView {
ptr: *mut c_void,
size: usize,
}
unsafe impl Send for SharedMemView {}
impl SharedMemView {
pub unsafe fn get_slice(&self, size: usize) -> Result<&[u8]> {
let map = slice::from_raw_parts(self.ptr as _, self.size);
if size <= self.size {
Ok(&map[..size])
} else {
bail!("mmap size");
}
}
pub unsafe fn get_mut_slice(&mut self, size: usize) -> Result<&mut [u8]> {
let map = slice::from_raw_parts_mut(self.ptr as _, self.size);
if size <= self.size {
Ok(&mut map[..size])
} else {
bail!("mmap size")
}
}
}
#[cfg(unix)]
mod unix {
use super::*;
use memmap2::{MmapMut, MmapOptions};
use std::fs::File;
use std::os::unix::io::{AsRawFd, FromRawFd};
#[cfg(target_os = "android")]
fn open_shm_file(_id: &str, size: usize) -> Result<File> {
unsafe {
let fd = ashmem::ASharedMemory_create(std::ptr::null(), size);
if fd >= 0 {
// Drop PROT_EXEC
let r = ashmem::ASharedMemory_setProt(fd, libc::PROT_READ | libc::PROT_WRITE);
assert_eq!(r, 0);
return Ok(File::from_raw_fd(fd.try_into().unwrap()));
}
Err(std::io::Error::last_os_error().into())
}
}
#[cfg(not(target_os = "android"))]
fn open_shm_file(id: &str, size: usize) -> Result<File> {
let file = open_shm_file_impl(id)?;
allocate_file(&file, size)?;
Ok(file)
}
#[cfg(not(target_os = "android"))]
fn open_shm_file_impl(id: &str) -> Result<File> {
use std::env::temp_dir;
use std::fs::{remove_file, OpenOptions};
let id_cstring = std::ffi::CString::new(id).unwrap();
#[cfg(target_os = "linux")]
{
unsafe {
let r = libc::syscall(libc::SYS_memfd_create, id_cstring.as_ptr(), 0);
if r >= 0 {
return Ok(File::from_raw_fd(r.try_into().unwrap()));
}
}
let mut path = std::path::PathBuf::from("/dev/shm");
path.push(id);
if let Ok(file) = OpenOptions::new()
.read(true)
.write(true)
.create_new(true)
.open(&path)
{
let _ = remove_file(&path);
return Ok(file);
}
}
unsafe {
let fd = libc::shm_open(
id_cstring.as_ptr(),
libc::O_RDWR | libc::O_CREAT | libc::O_EXCL,
0o600,
);
if fd >= 0 {
libc::shm_unlink(id_cstring.as_ptr());
return Ok(File::from_raw_fd(fd));
}
}
let mut path = temp_dir();
path.push(id);
let file = OpenOptions::new()
.read(true)
.write(true)
.create_new(true)
.open(&path)?;
let _ = remove_file(&path);
Ok(file)
}
#[cfg(not(target_os = "android"))]
fn handle_enospc(s: &str) -> Result<()> {
let err = std::io::Error::last_os_error();
let errno = err.raw_os_error().unwrap_or(0);
assert_ne!(errno, 0);
debug!("allocate_file: {} failed errno={}", s, errno);
if errno == libc::ENOSPC {
return Err(err.into());
}
Ok(())
}
#[cfg(not(target_os = "android"))]
fn allocate_file(file: &File, size: usize) -> Result<()> {
// First, set the file size. This may create a sparse file on
// many systems, which can fail with SIGBUS when accessed via a
// mapping and the lazy backing allocation fails due to low disk
// space. To avoid this, try to force the entire file to be
// preallocated before mapping using OS-specific approaches below.
file.set_len(size.try_into().unwrap())?;
let fd = file.as_raw_fd();
let size: libc::off_t = size.try_into().unwrap();
// Try Linux-specific fallocate.
#[cfg(target_os = "linux")]
{
if unsafe { libc::fallocate(fd, 0, 0, size) } == 0 {
return Ok(());
}
handle_enospc("fallocate()")?;
}
// Try macOS-specific fcntl.
#[cfg(target_os = "macos")]
{
let params = libc::fstore_t {
fst_flags: libc::F_ALLOCATEALL,
fst_posmode: libc::F_PEOFPOSMODE,
fst_offset: 0,
fst_length: size,
fst_bytesalloc: 0,
};
if unsafe { libc::fcntl(fd, libc::F_PREALLOCATE, ¶ms) } == 0 {
return Ok(());
}
handle_enospc("fcntl(F_PREALLOCATE)")?;
}
// Fall back to portable version, where available.
#[cfg(any(target_os = "linux", target_os = "freebsd", target_os = "dragonfly"))]
{
if unsafe { libc::posix_fallocate(fd, 0, size) } == 0 {
return Ok(());
}
handle_enospc("posix_fallocate()")?;
}
Ok(())
}
pub struct SharedMem {
file: File,
_mmap: MmapMut,
view: SharedMemView,
}
impl SharedMem {
pub fn new(id: &str, size: usize) -> Result<SharedMem> {
let file = open_shm_file(id, size)?;
let mut mmap = unsafe { MmapOptions::new().len(size).map_mut(&file)? };
assert_eq!(mmap.len(), size);
let view = SharedMemView {
ptr: mmap.as_mut_ptr() as _,
size,
};
Ok(SharedMem {
file,
_mmap: mmap,
view,
})
}
pub unsafe fn make_handle(&self) -> Result<PlatformHandle> {
PlatformHandle::duplicate(self.file.as_raw_fd()).map_err(|e| e.into())
}
pub unsafe fn from(handle: PlatformHandle, size: usize) -> Result<SharedMem> {
let file = File::from_raw_fd(handle.into_raw());
let mut mmap = MmapOptions::new().len(size).map_mut(&file)?;
assert_eq!(mmap.len(), size);
let view = SharedMemView {
ptr: mmap.as_mut_ptr() as _,
size,
};
Ok(SharedMem {
file,
_mmap: mmap,
view,
})
}
pub unsafe fn get_slice(&self, size: usize) -> Result<&[u8]> {
self.view.get_slice(size)
}
pub unsafe fn get_mut_slice(&mut self, size: usize) -> Result<&mut [u8]> {
self.view.get_mut_slice(size)
}
pub fn get_size(&self) -> usize {
self.view.size
}
}
}
#[cfg(windows)]
mod windows {
use std::ptr;
use windows_sys::Win32::{
Foundation::{CloseHandle, FALSE, HANDLE, INVALID_HANDLE_VALUE},
System::Memory::{
CreateFileMappingA, MapViewOfFile, UnmapViewOfFile, FILE_MAP_ALL_ACCESS,
MEMORY_MAPPED_VIEW_ADDRESS, PAGE_READWRITE,
},
};
use crate::valid_handle;
use super::*;
pub struct SharedMem {
handle: HANDLE,
view: SharedMemView,
}
unsafe impl Send for SharedMem {}
impl Drop for SharedMem {
fn drop(&mut self) {
unsafe {
let ok = UnmapViewOfFile(MEMORY_MAPPED_VIEW_ADDRESS {
Value: self.view.ptr,
});
assert_ne!(ok, FALSE);
let ok = CloseHandle(self.handle);
assert_ne!(ok, FALSE);
}
}
}
impl SharedMem {
pub fn new(_id: &str, size: usize) -> Result<SharedMem> {
unsafe {
let handle = CreateFileMappingA(
INVALID_HANDLE_VALUE,
ptr::null_mut(),
PAGE_READWRITE,
(size as u64 >> 32).try_into().unwrap(),
(size as u64 & (u32::MAX as u64)).try_into().unwrap(),
ptr::null(),
);
if !valid_handle(handle as _) {
return Err(std::io::Error::last_os_error().into());
}
let ptr = MapViewOfFile(handle, FILE_MAP_ALL_ACCESS, 0, 0, size);
if !valid_handle(ptr.Value) {
return Err(std::io::Error::last_os_error().into());
}
Ok(SharedMem {
handle,
view: SharedMemView {
ptr: ptr.Value,
size,
},
})
}
}
pub unsafe fn make_handle(&self) -> Result<PlatformHandle> {
PlatformHandle::duplicate(self.handle as _).map_err(|e| e.into())
}
pub unsafe fn from(handle: PlatformHandle, size: usize) -> Result<SharedMem> {
let handle = handle.into_raw();
let ptr = MapViewOfFile(handle as _, FILE_MAP_ALL_ACCESS, 0, 0, size);
if !valid_handle(ptr.Value) {
return Err(std::io::Error::last_os_error().into());
}
Ok(SharedMem {
handle: handle as _,
view: SharedMemView {
ptr: ptr.Value,
size,
},
})
}
pub unsafe fn get_slice(&self, size: usize) -> Result<&[u8]> {
self.view.get_slice(size)
}
pub unsafe fn get_mut_slice(&mut self, size: usize) -> Result<&mut [u8]> {
self.view.get_mut_slice(size)
}
pub fn get_size(&self) -> usize {
self.view.size
}
}
}