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Diffstat (limited to 'vendor/memmap2/src/lib.rs')
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diff --git a/vendor/memmap2/src/lib.rs b/vendor/memmap2/src/lib.rs new file mode 100644 index 000000000..b90d1bcf6 --- /dev/null +++ b/vendor/memmap2/src/lib.rs @@ -0,0 +1,1560 @@ +//! A cross-platform Rust API for memory mapped buffers. +//! +//! The core functionality is provided by either [`Mmap`] or [`MmapMut`], +//! which correspond to mapping a [`File`] to a [`&[u8]`](https://doc.rust-lang.org/std/primitive.slice.html) +//! or [`&mut [u8]`](https://doc.rust-lang.org/std/primitive.slice.html) +//! respectively. Both function by dereferencing to a slice, allowing the +//! [`Mmap`]/[`MmapMut`] to be used in the same way you would the equivelant slice +//! types. +//! +//! [`File`]: std::fs::File +//! +//! # Examples +//! +//! For simple cases [`Mmap`] can be used directly: +//! +//! ``` +//! use std::fs::File; +//! use std::io::Read; +//! +//! use memmap2::Mmap; +//! +//! # fn main() -> std::io::Result<()> { +//! let mut file = File::open("LICENSE-APACHE")?; +//! +//! let mut contents = Vec::new(); +//! file.read_to_end(&mut contents)?; +//! +//! let mmap = unsafe { Mmap::map(&file)? }; +//! +//! assert_eq!(&contents[..], &mmap[..]); +//! # Ok(()) +//! # } +//! ``` +//! +//! However for cases which require configuration of the mapping, then +//! you can use [`MmapOptions`] in order to further configure a mapping +//! before you create it. + +#[cfg_attr(unix, path = "unix.rs")] +#[cfg_attr(windows, path = "windows.rs")] +#[cfg_attr(not(any(unix, windows)), path = "stub.rs")] +mod os; +use crate::os::{file_len, MmapInner}; + +#[cfg(unix)] +mod advice; +#[cfg(unix)] +pub use crate::advice::Advice; + +use std::fmt; +#[cfg(not(any(unix, windows)))] +use std::fs::File; +use std::io::{Error, ErrorKind, Result}; +use std::ops::{Deref, DerefMut}; +#[cfg(unix)] +use std::os::unix::io::{AsRawFd, RawFd}; +#[cfg(windows)] +use std::os::windows::io::{AsRawHandle, RawHandle}; +use std::slice; +use std::usize; + +#[cfg(not(any(unix, windows)))] +pub struct MmapRawDescriptor<'a>(&'a File); + +#[cfg(unix)] +pub struct MmapRawDescriptor(RawFd); + +#[cfg(windows)] +pub struct MmapRawDescriptor(RawHandle); + +pub trait MmapAsRawDesc { + fn as_raw_desc(&self) -> MmapRawDescriptor; +} + +#[cfg(not(any(unix, windows)))] +impl MmapAsRawDesc for &File { + fn as_raw_desc(&self) -> MmapRawDescriptor { + MmapRawDescriptor(self) + } +} + +#[cfg(unix)] +impl MmapAsRawDesc for RawFd { + fn as_raw_desc(&self) -> MmapRawDescriptor { + MmapRawDescriptor(*self) + } +} + +#[cfg(unix)] +impl<'a, T> MmapAsRawDesc for &'a T +where + T: AsRawFd, +{ + fn as_raw_desc(&self) -> MmapRawDescriptor { + MmapRawDescriptor(self.as_raw_fd()) + } +} + +#[cfg(windows)] +impl MmapAsRawDesc for RawHandle { + fn as_raw_desc(&self) -> MmapRawDescriptor { + MmapRawDescriptor(*self) + } +} + +#[cfg(windows)] +impl<'a, T> MmapAsRawDesc for &'a T +where + T: AsRawHandle, +{ + fn as_raw_desc(&self) -> MmapRawDescriptor { + MmapRawDescriptor(self.as_raw_handle()) + } +} + +/// A memory map builder, providing advanced options and flags for specifying memory map behavior. +/// +/// `MmapOptions` can be used to create an anonymous memory map using [`map_anon()`], or a +/// file-backed memory map using one of [`map()`], [`map_mut()`], [`map_exec()`], +/// [`map_copy()`], or [`map_copy_read_only()`]. +/// +/// ## Safety +/// +/// All file-backed memory map constructors are marked `unsafe` because of the potential for +/// *Undefined Behavior* (UB) using the map if the underlying file is subsequently modified, in or +/// out of process. Applications must consider the risk and take appropriate precautions when +/// using file-backed maps. Solutions such as file permissions, locks or process-private (e.g. +/// unlinked) files exist but are platform specific and limited. +/// +/// [`map_anon()`]: MmapOptions::map_anon() +/// [`map()`]: MmapOptions::map() +/// [`map_mut()`]: MmapOptions::map_mut() +/// [`map_exec()`]: MmapOptions::map_exec() +/// [`map_copy()`]: MmapOptions::map_copy() +/// [`map_copy_read_only()`]: MmapOptions::map_copy_read_only() +#[derive(Clone, Debug, Default)] +pub struct MmapOptions { + offset: u64, + len: Option<usize>, + stack: bool, + populate: bool, +} + +impl MmapOptions { + /// Creates a new set of options for configuring and creating a memory map. + /// + /// # Example + /// + /// ``` + /// use memmap2::{MmapMut, MmapOptions}; + /// # use std::io::Result; + /// + /// # fn main() -> Result<()> { + /// // Create a new memory map builder. + /// let mut mmap_options = MmapOptions::new(); + /// + /// // Configure the memory map builder using option setters, then create + /// // a memory map using one of `mmap_options.map_anon`, `mmap_options.map`, + /// // `mmap_options.map_mut`, `mmap_options.map_exec`, or `mmap_options.map_copy`: + /// let mut mmap: MmapMut = mmap_options.len(36).map_anon()?; + /// + /// // Use the memory map: + /// mmap.copy_from_slice(b"...data to copy to the memory map..."); + /// # Ok(()) + /// # } + /// ``` + pub fn new() -> MmapOptions { + MmapOptions::default() + } + + /// Configures the memory map to start at byte `offset` from the beginning of the file. + /// + /// This option has no effect on anonymous memory maps. + /// + /// By default, the offset is 0. + /// + /// # Example + /// + /// ``` + /// use memmap2::MmapOptions; + /// use std::fs::File; + /// + /// # fn main() -> std::io::Result<()> { + /// let mmap = unsafe { + /// MmapOptions::new() + /// .offset(30) + /// .map(&File::open("LICENSE-APACHE")?)? + /// }; + /// assert_eq!(&b"Apache License"[..], + /// &mmap[..14]); + /// # Ok(()) + /// # } + /// ``` + pub fn offset(&mut self, offset: u64) -> &mut Self { + self.offset = offset; + self + } + + /// Configures the created memory mapped buffer to be `len` bytes long. + /// + /// This option is mandatory for anonymous memory maps. + /// + /// For file-backed memory maps, the length will default to the file length. + /// + /// # Example + /// + /// ``` + /// use memmap2::MmapOptions; + /// use std::fs::File; + /// + /// # fn main() -> std::io::Result<()> { + /// let mmap = unsafe { + /// MmapOptions::new() + /// .len(9) + /// .map(&File::open("README.md")?)? + /// }; + /// assert_eq!(&b"# memmap2"[..], &mmap[..]); + /// # Ok(()) + /// # } + /// ``` + pub fn len(&mut self, len: usize) -> &mut Self { + self.len = Some(len); + self + } + + /// Returns the configured length, or the length of the provided file. + fn get_len<T: MmapAsRawDesc>(&self, file: &T) -> Result<usize> { + self.len.map(Ok).unwrap_or_else(|| { + let desc = file.as_raw_desc(); + let file_len = file_len(desc.0)?; + + if file_len < self.offset { + return Err(Error::new( + ErrorKind::InvalidData, + "memory map offset is larger than length", + )); + } + let len = file_len - self.offset; + + // This check it not relevant on 64bit targets, because usize == u64 + #[cfg(not(target_pointer_width = "64"))] + { + if len > (usize::MAX as u64) { + return Err(Error::new( + ErrorKind::InvalidData, + "memory map length overflows usize", + )); + } + } + + Ok(len as usize) + }) + } + + /// Configures the anonymous memory map to be suitable for a process or thread stack. + /// + /// This option corresponds to the `MAP_STACK` flag on Linux. It has no effect on Windows. + /// + /// This option has no effect on file-backed memory maps. + /// + /// # Example + /// + /// ``` + /// use memmap2::MmapOptions; + /// + /// # fn main() -> std::io::Result<()> { + /// let stack = MmapOptions::new().stack().len(4096).map_anon(); + /// # Ok(()) + /// # } + /// ``` + pub fn stack(&mut self) -> &mut Self { + self.stack = true; + self + } + + /// Populate (prefault) page tables for a mapping. + /// + /// For a file mapping, this causes read-ahead on the file. This will help to reduce blocking on page faults later. + /// + /// This option corresponds to the `MAP_POPULATE` flag on Linux. It has no effect on Windows. + /// + /// # Example + /// + /// ``` + /// use memmap2::MmapOptions; + /// use std::fs::File; + /// + /// # fn main() -> std::io::Result<()> { + /// let file = File::open("LICENSE-MIT")?; + /// + /// let mmap = unsafe { + /// MmapOptions::new().populate().map(&file)? + /// }; + /// + /// assert_eq!(&b"Copyright"[..], &mmap[..9]); + /// # Ok(()) + /// # } + /// ``` + pub fn populate(&mut self) -> &mut Self { + self.populate = true; + self + } + + /// Creates a read-only memory map backed by a file. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with read permissions. + /// + /// # Example + /// + /// ``` + /// use memmap2::MmapOptions; + /// use std::fs::File; + /// use std::io::Read; + /// + /// # fn main() -> std::io::Result<()> { + /// let mut file = File::open("LICENSE-APACHE")?; + /// + /// let mut contents = Vec::new(); + /// file.read_to_end(&mut contents)?; + /// + /// let mmap = unsafe { + /// MmapOptions::new().map(&file)? + /// }; + /// + /// assert_eq!(&contents[..], &mmap[..]); + /// # Ok(()) + /// # } + /// ``` + pub unsafe fn map<T: MmapAsRawDesc>(&self, file: T) -> Result<Mmap> { + let desc = file.as_raw_desc(); + + MmapInner::map(self.get_len(&file)?, desc.0, self.offset, self.populate) + .map(|inner| Mmap { inner }) + } + + /// Creates a readable and executable memory map backed by a file. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with read permissions. + pub unsafe fn map_exec<T: MmapAsRawDesc>(&self, file: T) -> Result<Mmap> { + let desc = file.as_raw_desc(); + + MmapInner::map_exec(self.get_len(&file)?, desc.0, self.offset, self.populate) + .map(|inner| Mmap { inner }) + } + + /// Creates a writeable memory map backed by a file. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with read and write permissions. + /// + /// # Example + /// + /// ``` + /// # extern crate memmap2; + /// # extern crate tempfile; + /// # + /// use std::fs::OpenOptions; + /// use std::path::PathBuf; + /// + /// use memmap2::MmapOptions; + /// # + /// # fn main() -> std::io::Result<()> { + /// # let tempdir = tempfile::tempdir()?; + /// let path: PathBuf = /* path to file */ + /// # tempdir.path().join("map_mut"); + /// let file = OpenOptions::new().read(true).write(true).create(true).open(&path)?; + /// file.set_len(13)?; + /// + /// let mut mmap = unsafe { + /// MmapOptions::new().map_mut(&file)? + /// }; + /// + /// mmap.copy_from_slice(b"Hello, world!"); + /// # Ok(()) + /// # } + /// ``` + pub unsafe fn map_mut<T: MmapAsRawDesc>(&self, file: T) -> Result<MmapMut> { + let desc = file.as_raw_desc(); + + MmapInner::map_mut(self.get_len(&file)?, desc.0, self.offset, self.populate) + .map(|inner| MmapMut { inner }) + } + + /// Creates a copy-on-write memory map backed by a file. + /// + /// Data written to the memory map will not be visible by other processes, + /// and will not be carried through to the underlying file. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with writable permissions. + /// + /// # Example + /// + /// ``` + /// use memmap2::MmapOptions; + /// use std::fs::File; + /// use std::io::Write; + /// + /// # fn main() -> std::io::Result<()> { + /// let file = File::open("LICENSE-APACHE")?; + /// let mut mmap = unsafe { MmapOptions::new().map_copy(&file)? }; + /// (&mut mmap[..]).write_all(b"Hello, world!")?; + /// # Ok(()) + /// # } + /// ``` + pub unsafe fn map_copy<T: MmapAsRawDesc>(&self, file: T) -> Result<MmapMut> { + let desc = file.as_raw_desc(); + + MmapInner::map_copy(self.get_len(&file)?, desc.0, self.offset, self.populate) + .map(|inner| MmapMut { inner }) + } + + /// Creates a copy-on-write read-only memory map backed by a file. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with read permissions. + /// + /// # Example + /// + /// ``` + /// use memmap2::MmapOptions; + /// use std::fs::File; + /// use std::io::Read; + /// + /// # fn main() -> std::io::Result<()> { + /// let mut file = File::open("README.md")?; + /// + /// let mut contents = Vec::new(); + /// file.read_to_end(&mut contents)?; + /// + /// let mmap = unsafe { + /// MmapOptions::new().map_copy_read_only(&file)? + /// }; + /// + /// assert_eq!(&contents[..], &mmap[..]); + /// # Ok(()) + /// # } + /// ``` + pub unsafe fn map_copy_read_only<T: MmapAsRawDesc>(&self, file: T) -> Result<Mmap> { + let desc = file.as_raw_desc(); + + MmapInner::map_copy_read_only(self.get_len(&file)?, desc.0, self.offset, self.populate) + .map(|inner| Mmap { inner }) + } + + /// Creates an anonymous memory map. + /// + /// Note: the memory map length must be configured to be greater than 0 before creating an + /// anonymous memory map using `MmapOptions::len()`. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails. + pub fn map_anon(&self) -> Result<MmapMut> { + MmapInner::map_anon(self.len.unwrap_or(0), self.stack).map(|inner| MmapMut { inner }) + } + + /// Creates a raw memory map. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with read and write permissions. + pub fn map_raw<T: MmapAsRawDesc>(&self, file: T) -> Result<MmapRaw> { + let desc = file.as_raw_desc(); + + MmapInner::map_mut(self.get_len(&file)?, desc.0, self.offset, self.populate) + .map(|inner| MmapRaw { inner }) + } +} + +/// A handle to an immutable memory mapped buffer. +/// +/// A `Mmap` may be backed by a file, or it can be anonymous map, backed by volatile memory. Use +/// [`MmapOptions`] or [`map()`] to create a file-backed memory map. To create an immutable +/// anonymous memory map, first create a mutable anonymous memory map, and then make it immutable +/// with [`MmapMut::make_read_only()`]. +/// +/// A file backed `Mmap` is created by `&File` reference, and will remain valid even after the +/// `File` is dropped. In other words, the `Mmap` handle is completely independent of the `File` +/// used to create it. For consistency, on some platforms this is achieved by duplicating the +/// underlying file handle. The memory will be unmapped when the `Mmap` handle is dropped. +/// +/// Dereferencing and accessing the bytes of the buffer may result in page faults (e.g. swapping +/// the mapped pages into physical memory) though the details of this are platform specific. +/// +/// `Mmap` is [`Sync`](std::marker::Sync) and [`Send`](std::marker::Send). +/// +/// ## Safety +/// +/// All file-backed memory map constructors are marked `unsafe` because of the potential for +/// *Undefined Behavior* (UB) using the map if the underlying file is subsequently modified, in or +/// out of process. Applications must consider the risk and take appropriate precautions when using +/// file-backed maps. Solutions such as file permissions, locks or process-private (e.g. unlinked) +/// files exist but are platform specific and limited. +/// +/// ## Example +/// +/// ``` +/// use memmap2::MmapOptions; +/// use std::io::Write; +/// use std::fs::File; +/// +/// # fn main() -> std::io::Result<()> { +/// let file = File::open("README.md")?; +/// let mmap = unsafe { MmapOptions::new().map(&file)? }; +/// assert_eq!(b"# memmap2", &mmap[0..9]); +/// # Ok(()) +/// # } +/// ``` +/// +/// See [`MmapMut`] for the mutable version. +/// +/// [`map()`]: Mmap::map() +pub struct Mmap { + inner: MmapInner, +} + +impl Mmap { + /// Creates a read-only memory map backed by a file. + /// + /// This is equivalent to calling `MmapOptions::new().map(file)`. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with read permissions. + /// + /// # Example + /// + /// ``` + /// use std::fs::File; + /// use std::io::Read; + /// + /// use memmap2::Mmap; + /// + /// # fn main() -> std::io::Result<()> { + /// let mut file = File::open("LICENSE-APACHE")?; + /// + /// let mut contents = Vec::new(); + /// file.read_to_end(&mut contents)?; + /// + /// let mmap = unsafe { Mmap::map(&file)? }; + /// + /// assert_eq!(&contents[..], &mmap[..]); + /// # Ok(()) + /// # } + /// ``` + pub unsafe fn map<T: MmapAsRawDesc>(file: T) -> Result<Mmap> { + MmapOptions::new().map(file) + } + + /// Transition the memory map to be writable. + /// + /// If the memory map is file-backed, the file must have been opened with write permissions. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with writable permissions. + /// + /// # Example + /// + /// ``` + /// # extern crate memmap2; + /// # extern crate tempfile; + /// # + /// use memmap2::Mmap; + /// use std::ops::DerefMut; + /// use std::io::Write; + /// # use std::fs::OpenOptions; + /// + /// # fn main() -> std::io::Result<()> { + /// # let tempdir = tempfile::tempdir()?; + /// let file = /* file opened with write permissions */ + /// # OpenOptions::new() + /// # .read(true) + /// # .write(true) + /// # .create(true) + /// # .open(tempdir.path() + /// # .join("make_mut"))?; + /// # file.set_len(128)?; + /// let mmap = unsafe { Mmap::map(&file)? }; + /// // ... use the read-only memory map ... + /// let mut mut_mmap = mmap.make_mut()?; + /// mut_mmap.deref_mut().write_all(b"hello, world!")?; + /// # Ok(()) + /// # } + /// ``` + pub fn make_mut(mut self) -> Result<MmapMut> { + self.inner.make_mut()?; + Ok(MmapMut { inner: self.inner }) + } + + /// Advise OS how this memory map will be accessed. Only supported on Unix. + /// + /// See [madvise()](https://man7.org/linux/man-pages/man2/madvise.2.html) map page. + #[cfg(unix)] + pub fn advise(&self, advice: Advice) -> Result<()> { + self.inner.advise(advice) + } +} + +#[cfg(feature = "stable_deref_trait")] +unsafe impl stable_deref_trait::StableDeref for Mmap {} + +impl Deref for Mmap { + type Target = [u8]; + + #[inline] + fn deref(&self) -> &[u8] { + unsafe { slice::from_raw_parts(self.inner.ptr(), self.inner.len()) } + } +} + +impl AsRef<[u8]> for Mmap { + #[inline] + fn as_ref(&self) -> &[u8] { + self.deref() + } +} + +impl fmt::Debug for Mmap { + fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { + fmt.debug_struct("Mmap") + .field("ptr", &self.as_ptr()) + .field("len", &self.len()) + .finish() + } +} + +/// A handle to a raw memory mapped buffer. +/// +/// This struct never hands out references to its interior, only raw pointers. +/// This can be helpful when creating shared memory maps between untrusted processes. +pub struct MmapRaw { + inner: MmapInner, +} + +impl MmapRaw { + /// Creates a writeable memory map backed by a file. + /// + /// This is equivalent to calling `MmapOptions::new().map_raw(file)`. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with read and write permissions. + pub fn map_raw<T: MmapAsRawDesc>(file: T) -> Result<MmapRaw> { + MmapOptions::new().map_raw(file) + } + + /// Returns a raw pointer to the memory mapped file. + /// + /// Before dereferencing this pointer, you have to make sure that the file has not been + /// truncated since the memory map was created. + /// Avoiding this will not introduce memory safety issues in Rust terms, + /// but will cause SIGBUS (or equivalent) signal. + #[inline] + pub fn as_ptr(&self) -> *const u8 { + self.inner.ptr() + } + + /// Returns an unsafe mutable pointer to the memory mapped file. + /// + /// Before dereferencing this pointer, you have to make sure that the file has not been + /// truncated since the memory map was created. + /// Avoiding this will not introduce memory safety issues in Rust terms, + /// but will cause SIGBUS (or equivalent) signal. + #[inline] + pub fn as_mut_ptr(&self) -> *mut u8 { + self.inner.ptr() as _ + } + + /// Returns the length in bytes of the memory map. + /// + /// Note that truncating the file can cause the length to change (and render this value unusable). + #[inline] + pub fn len(&self) -> usize { + self.inner.len() + } + + /// Flushes outstanding memory map modifications to disk. + /// + /// When this method returns with a non-error result, all outstanding changes to a file-backed + /// memory map are guaranteed to be durably stored. The file's metadata (including last + /// modification timestamp) may not be updated. + /// + /// # Example + /// + /// ``` + /// # extern crate memmap2; + /// # extern crate tempfile; + /// # + /// use std::fs::OpenOptions; + /// use std::io::Write; + /// use std::path::PathBuf; + /// use std::slice; + /// + /// use memmap2::MmapRaw; + /// + /// # fn main() -> std::io::Result<()> { + /// let tempdir = tempfile::tempdir()?; + /// let path: PathBuf = /* path to file */ + /// # tempdir.path().join("flush"); + /// let file = OpenOptions::new().read(true).write(true).create(true).open(&path)?; + /// file.set_len(128)?; + /// + /// let mut mmap = unsafe { MmapRaw::map_raw(&file)? }; + /// + /// let mut memory = unsafe { slice::from_raw_parts_mut(mmap.as_mut_ptr(), 128) }; + /// memory.write_all(b"Hello, world!")?; + /// mmap.flush()?; + /// # Ok(()) + /// # } + /// ``` + pub fn flush(&self) -> Result<()> { + let len = self.len(); + self.inner.flush(0, len) + } + + /// Asynchronously flushes outstanding memory map modifications to disk. + /// + /// This method initiates flushing modified pages to durable storage, but it will not wait for + /// the operation to complete before returning. The file's metadata (including last + /// modification timestamp) may not be updated. + pub fn flush_async(&self) -> Result<()> { + let len = self.len(); + self.inner.flush_async(0, len) + } + + /// Flushes outstanding memory map modifications in the range to disk. + /// + /// The offset and length must be in the bounds of the memory map. + /// + /// When this method returns with a non-error result, all outstanding changes to a file-backed + /// memory in the range are guaranteed to be durable stored. The file's metadata (including + /// last modification timestamp) may not be updated. It is not guaranteed the only the changes + /// in the specified range are flushed; other outstanding changes to the memory map may be + /// flushed as well. + pub fn flush_range(&self, offset: usize, len: usize) -> Result<()> { + self.inner.flush(offset, len) + } + + /// Asynchronously flushes outstanding memory map modifications in the range to disk. + /// + /// The offset and length must be in the bounds of the memory map. + /// + /// This method initiates flushing modified pages to durable storage, but it will not wait for + /// the operation to complete before returning. The file's metadata (including last + /// modification timestamp) may not be updated. It is not guaranteed that the only changes + /// flushed are those in the specified range; other outstanding changes to the memory map may + /// be flushed as well. + pub fn flush_async_range(&self, offset: usize, len: usize) -> Result<()> { + self.inner.flush_async(offset, len) + } +} + +impl fmt::Debug for MmapRaw { + fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { + fmt.debug_struct("MmapRaw") + .field("ptr", &self.as_ptr()) + .field("len", &self.len()) + .finish() + } +} + +/// A handle to a mutable memory mapped buffer. +/// +/// A file-backed `MmapMut` buffer may be used to read from or write to a file. An anonymous +/// `MmapMut` buffer may be used any place that an in-memory byte buffer is needed. Use +/// [`MmapMut::map_mut()`] and [`MmapMut::map_anon()`] to create a mutable memory map of the +/// respective types, or [`MmapOptions::map_mut()`] and [`MmapOptions::map_anon()`] if non-default +/// options are required. +/// +/// A file backed `MmapMut` is created by `&File` reference, and will remain valid even after the +/// `File` is dropped. In other words, the `MmapMut` handle is completely independent of the `File` +/// used to create it. For consistency, on some platforms this is achieved by duplicating the +/// underlying file handle. The memory will be unmapped when the `MmapMut` handle is dropped. +/// +/// Dereferencing and accessing the bytes of the buffer may result in page faults (e.g. swapping +/// the mapped pages into physical memory) though the details of this are platform specific. +/// +/// `Mmap` is [`Sync`](std::marker::Sync) and [`Send`](std::marker::Send). +/// +/// See [`Mmap`] for the immutable version. +/// +/// ## Safety +/// +/// All file-backed memory map constructors are marked `unsafe` because of the potential for +/// *Undefined Behavior* (UB) using the map if the underlying file is subsequently modified, in or +/// out of process. Applications must consider the risk and take appropriate precautions when using +/// file-backed maps. Solutions such as file permissions, locks or process-private (e.g. unlinked) +/// files exist but are platform specific and limited. +pub struct MmapMut { + inner: MmapInner, +} + +impl MmapMut { + /// Creates a writeable memory map backed by a file. + /// + /// This is equivalent to calling `MmapOptions::new().map_mut(file)`. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file is not open with read and write permissions. + /// + /// # Example + /// + /// ``` + /// # extern crate memmap2; + /// # extern crate tempfile; + /// # + /// use std::fs::OpenOptions; + /// use std::path::PathBuf; + /// + /// use memmap2::MmapMut; + /// # + /// # fn main() -> std::io::Result<()> { + /// # let tempdir = tempfile::tempdir()?; + /// let path: PathBuf = /* path to file */ + /// # tempdir.path().join("map_mut"); + /// let file = OpenOptions::new() + /// .read(true) + /// .write(true) + /// .create(true) + /// .open(&path)?; + /// file.set_len(13)?; + /// + /// let mut mmap = unsafe { MmapMut::map_mut(&file)? }; + /// + /// mmap.copy_from_slice(b"Hello, world!"); + /// # Ok(()) + /// # } + /// ``` + pub unsafe fn map_mut<T: MmapAsRawDesc>(file: T) -> Result<MmapMut> { + MmapOptions::new().map_mut(file) + } + + /// Creates an anonymous memory map. + /// + /// This is equivalent to calling `MmapOptions::new().len(length).map_anon()`. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails. + pub fn map_anon(length: usize) -> Result<MmapMut> { + MmapOptions::new().len(length).map_anon() + } + + /// Flushes outstanding memory map modifications to disk. + /// + /// When this method returns with a non-error result, all outstanding changes to a file-backed + /// memory map are guaranteed to be durably stored. The file's metadata (including last + /// modification timestamp) may not be updated. + /// + /// # Example + /// + /// ``` + /// # extern crate memmap2; + /// # extern crate tempfile; + /// # + /// use std::fs::OpenOptions; + /// use std::io::Write; + /// use std::path::PathBuf; + /// + /// use memmap2::MmapMut; + /// + /// # fn main() -> std::io::Result<()> { + /// # let tempdir = tempfile::tempdir()?; + /// let path: PathBuf = /* path to file */ + /// # tempdir.path().join("flush"); + /// let file = OpenOptions::new().read(true).write(true).create(true).open(&path)?; + /// file.set_len(128)?; + /// + /// let mut mmap = unsafe { MmapMut::map_mut(&file)? }; + /// + /// (&mut mmap[..]).write_all(b"Hello, world!")?; + /// mmap.flush()?; + /// # Ok(()) + /// # } + /// ``` + pub fn flush(&self) -> Result<()> { + let len = self.len(); + self.inner.flush(0, len) + } + + /// Asynchronously flushes outstanding memory map modifications to disk. + /// + /// This method initiates flushing modified pages to durable storage, but it will not wait for + /// the operation to complete before returning. The file's metadata (including last + /// modification timestamp) may not be updated. + pub fn flush_async(&self) -> Result<()> { + let len = self.len(); + self.inner.flush_async(0, len) + } + + /// Flushes outstanding memory map modifications in the range to disk. + /// + /// The offset and length must be in the bounds of the memory map. + /// + /// When this method returns with a non-error result, all outstanding changes to a file-backed + /// memory in the range are guaranteed to be durable stored. The file's metadata (including + /// last modification timestamp) may not be updated. It is not guaranteed the only the changes + /// in the specified range are flushed; other outstanding changes to the memory map may be + /// flushed as well. + pub fn flush_range(&self, offset: usize, len: usize) -> Result<()> { + self.inner.flush(offset, len) + } + + /// Asynchronously flushes outstanding memory map modifications in the range to disk. + /// + /// The offset and length must be in the bounds of the memory map. + /// + /// This method initiates flushing modified pages to durable storage, but it will not wait for + /// the operation to complete before returning. The file's metadata (including last + /// modification timestamp) may not be updated. It is not guaranteed that the only changes + /// flushed are those in the specified range; other outstanding changes to the memory map may + /// be flushed as well. + pub fn flush_async_range(&self, offset: usize, len: usize) -> Result<()> { + self.inner.flush_async(offset, len) + } + + /// Returns an immutable version of this memory mapped buffer. + /// + /// If the memory map is file-backed, the file must have been opened with read permissions. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file has not been opened with read permissions. + /// + /// # Example + /// + /// ``` + /// # extern crate memmap2; + /// # + /// use std::io::Write; + /// use std::path::PathBuf; + /// + /// use memmap2::{Mmap, MmapMut}; + /// + /// # fn main() -> std::io::Result<()> { + /// let mut mmap = MmapMut::map_anon(128)?; + /// + /// (&mut mmap[..]).write(b"Hello, world!")?; + /// + /// let mmap: Mmap = mmap.make_read_only()?; + /// # Ok(()) + /// # } + /// ``` + pub fn make_read_only(mut self) -> Result<Mmap> { + self.inner.make_read_only()?; + Ok(Mmap { inner: self.inner }) + } + + /// Transition the memory map to be readable and executable. + /// + /// If the memory map is file-backed, the file must have been opened with execute permissions. + /// + /// # Errors + /// + /// This method returns an error when the underlying system call fails, which can happen for a + /// variety of reasons, such as when the file has not been opened with execute permissions. + pub fn make_exec(mut self) -> Result<Mmap> { + self.inner.make_exec()?; + Ok(Mmap { inner: self.inner }) + } + + /// Advise OS how this memory map will be accessed. Only supported on Unix. + /// + /// See [madvise()](https://man7.org/linux/man-pages/man2/madvise.2.html) map page. + #[cfg(unix)] + pub fn advise(&self, advice: Advice) -> Result<()> { + self.inner.advise(advice) + } +} + +#[cfg(feature = "stable_deref_trait")] +unsafe impl stable_deref_trait::StableDeref for MmapMut {} + +impl Deref for MmapMut { + type Target = [u8]; + + #[inline] + fn deref(&self) -> &[u8] { + unsafe { slice::from_raw_parts(self.inner.ptr(), self.inner.len()) } + } +} + +impl DerefMut for MmapMut { + #[inline] + fn deref_mut(&mut self) -> &mut [u8] { + unsafe { slice::from_raw_parts_mut(self.inner.mut_ptr(), self.inner.len()) } + } +} + +impl AsRef<[u8]> for MmapMut { + #[inline] + fn as_ref(&self) -> &[u8] { + self.deref() + } +} + +impl AsMut<[u8]> for MmapMut { + #[inline] + fn as_mut(&mut self) -> &mut [u8] { + self.deref_mut() + } +} + +impl fmt::Debug for MmapMut { + fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { + fmt.debug_struct("MmapMut") + .field("ptr", &self.as_ptr()) + .field("len", &self.len()) + .finish() + } +} + +#[cfg(test)] +mod test { + extern crate tempfile; + + #[cfg(unix)] + use crate::advice::Advice; + use std::fs::OpenOptions; + use std::io::{Read, Write}; + #[cfg(unix)] + use std::os::unix::io::AsRawFd; + #[cfg(windows)] + use std::os::windows::fs::OpenOptionsExt; + + #[cfg(windows)] + const GENERIC_ALL: u32 = 0x10000000; + + use super::{Mmap, MmapMut, MmapOptions}; + + #[test] + fn map_file() { + let expected_len = 128; + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let file = OpenOptions::new() + .read(true) + .write(true) + .create(true) + .open(&path) + .unwrap(); + + file.set_len(expected_len as u64).unwrap(); + + let mut mmap = unsafe { MmapMut::map_mut(&file).unwrap() }; + let len = mmap.len(); + assert_eq!(expected_len, len); + + let zeros = vec![0; len]; + let incr: Vec<u8> = (0..len as u8).collect(); + + // check that the mmap is empty + assert_eq!(&zeros[..], &mmap[..]); + + // write values into the mmap + (&mut mmap[..]).write_all(&incr[..]).unwrap(); + + // read values back + assert_eq!(&incr[..], &mmap[..]); + } + + #[test] + #[cfg(unix)] + fn map_fd() { + let expected_len = 128; + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let file = OpenOptions::new() + .read(true) + .write(true) + .create(true) + .open(&path) + .unwrap(); + + file.set_len(expected_len as u64).unwrap(); + + let mut mmap = unsafe { MmapMut::map_mut(file.as_raw_fd()).unwrap() }; + let len = mmap.len(); + assert_eq!(expected_len, len); + + let zeros = vec![0; len]; + let incr: Vec<u8> = (0..len as u8).collect(); + + // check that the mmap is empty + assert_eq!(&zeros[..], &mmap[..]); + + // write values into the mmap + (&mut mmap[..]).write_all(&incr[..]).unwrap(); + + // read values back + assert_eq!(&incr[..], &mmap[..]); + } + + /// Checks that "mapping" a 0-length file derefs to an empty slice. + #[test] + fn map_empty_file() { + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let file = OpenOptions::new() + .read(true) + .write(true) + .create(true) + .open(&path) + .unwrap(); + let mmap = unsafe { Mmap::map(&file).unwrap() }; + assert!(mmap.is_empty()); + let mmap = unsafe { MmapMut::map_mut(&file).unwrap() }; + assert!(mmap.is_empty()); + } + + #[test] + fn map_anon() { + let expected_len = 128; + let mut mmap = MmapMut::map_anon(expected_len).unwrap(); + let len = mmap.len(); + assert_eq!(expected_len, len); + + let zeros = vec![0; len]; + let incr: Vec<u8> = (0..len as u8).collect(); + + // check that the mmap is empty + assert_eq!(&zeros[..], &mmap[..]); + + // write values into the mmap + (&mut mmap[..]).write_all(&incr[..]).unwrap(); + + // read values back + assert_eq!(&incr[..], &mmap[..]); + } + + #[test] + fn map_anon_zero_len() { + assert!(MmapOptions::new().map_anon().unwrap().is_empty()) + } + + #[test] + fn file_write() { + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let mut file = OpenOptions::new() + .read(true) + .write(true) + .create(true) + .open(&path) + .unwrap(); + file.set_len(128).unwrap(); + + let write = b"abc123"; + let mut read = [0u8; 6]; + + let mut mmap = unsafe { MmapMut::map_mut(&file).unwrap() }; + (&mut mmap[..]).write_all(write).unwrap(); + mmap.flush().unwrap(); + + file.read_exact(&mut read).unwrap(); + assert_eq!(write, &read); + } + + #[test] + fn flush_range() { + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let file = OpenOptions::new() + .read(true) + .write(true) + .create(true) + .open(&path) + .unwrap(); + file.set_len(128).unwrap(); + let write = b"abc123"; + + let mut mmap = unsafe { + MmapOptions::new() + .offset(2) + .len(write.len()) + .map_mut(&file) + .unwrap() + }; + (&mut mmap[..]).write_all(write).unwrap(); + mmap.flush_async_range(0, write.len()).unwrap(); + mmap.flush_range(0, write.len()).unwrap(); + } + + #[test] + fn map_copy() { + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let mut file = OpenOptions::new() + .read(true) + .write(true) + .create(true) + .open(&path) + .unwrap(); + file.set_len(128).unwrap(); + + let nulls = b"\0\0\0\0\0\0"; + let write = b"abc123"; + let mut read = [0u8; 6]; + + let mut mmap = unsafe { MmapOptions::new().map_copy(&file).unwrap() }; + + (&mut mmap[..]).write_all(write).unwrap(); + mmap.flush().unwrap(); + + // The mmap contains the write + (&mmap[..]).read_exact(&mut read).unwrap(); + assert_eq!(write, &read); + + // The file does not contain the write + file.read_exact(&mut read).unwrap(); + assert_eq!(nulls, &read); + + // another mmap does not contain the write + let mmap2 = unsafe { MmapOptions::new().map(&file).unwrap() }; + (&mmap2[..]).read_exact(&mut read).unwrap(); + assert_eq!(nulls, &read); + } + + #[test] + fn map_copy_read_only() { + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let file = OpenOptions::new() + .read(true) + .write(true) + .create(true) + .open(&path) + .unwrap(); + file.set_len(128).unwrap(); + + let nulls = b"\0\0\0\0\0\0"; + let mut read = [0u8; 6]; + + let mmap = unsafe { MmapOptions::new().map_copy_read_only(&file).unwrap() }; + (&mmap[..]).read_exact(&mut read).unwrap(); + assert_eq!(nulls, &read); + + let mmap2 = unsafe { MmapOptions::new().map(&file).unwrap() }; + (&mmap2[..]).read_exact(&mut read).unwrap(); + assert_eq!(nulls, &read); + } + + #[test] + fn map_offset() { + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let file = OpenOptions::new() + .read(true) + .write(true) + .create(true) + .open(&path) + .unwrap(); + + let offset = u32::max_value() as u64 + 2; + let len = 5432; + file.set_len(offset + len as u64).unwrap(); + + // Check inferred length mmap. + let mmap = unsafe { MmapOptions::new().offset(offset).map_mut(&file).unwrap() }; + assert_eq!(len, mmap.len()); + + // Check explicit length mmap. + let mut mmap = unsafe { + MmapOptions::new() + .offset(offset) + .len(len) + .map_mut(&file) + .unwrap() + }; + assert_eq!(len, mmap.len()); + + let zeros = vec![0; len]; + let incr: Vec<_> = (0..len).map(|i| i as u8).collect(); + + // check that the mmap is empty + assert_eq!(&zeros[..], &mmap[..]); + + // write values into the mmap + (&mut mmap[..]).write_all(&incr[..]).unwrap(); + + // read values back + assert_eq!(&incr[..], &mmap[..]); + } + + #[test] + fn index() { + let mut mmap = MmapMut::map_anon(128).unwrap(); + mmap[0] = 42; + assert_eq!(42, mmap[0]); + } + + #[test] + fn sync_send() { + let mmap = MmapMut::map_anon(129).unwrap(); + + fn is_sync_send<T>(_val: T) + where + T: Sync + Send, + { + } + + is_sync_send(mmap); + } + + #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] + fn jit_x86(mut mmap: MmapMut) { + use std::mem; + mmap[0] = 0xB8; // mov eax, 0xAB + mmap[1] = 0xAB; + mmap[2] = 0x00; + mmap[3] = 0x00; + mmap[4] = 0x00; + mmap[5] = 0xC3; // ret + + let mmap = mmap.make_exec().expect("make_exec"); + + let jitfn: extern "C" fn() -> u8 = unsafe { mem::transmute(mmap.as_ptr()) }; + assert_eq!(jitfn(), 0xab); + } + + #[test] + #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] + fn jit_x86_anon() { + jit_x86(MmapMut::map_anon(4096).unwrap()); + } + + #[test] + #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] + fn jit_x86_file() { + let tempdir = tempfile::tempdir().unwrap(); + let mut options = OpenOptions::new(); + #[cfg(windows)] + options.access_mode(GENERIC_ALL); + + let file = options + .read(true) + .write(true) + .create(true) + .open(&tempdir.path().join("jit_x86")) + .expect("open"); + + file.set_len(4096).expect("set_len"); + jit_x86(unsafe { MmapMut::map_mut(&file).expect("map_mut") }); + } + + #[test] + fn mprotect_file() { + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let mut options = OpenOptions::new(); + #[cfg(windows)] + options.access_mode(GENERIC_ALL); + + let mut file = options + .read(true) + .write(true) + .create(true) + .open(&path) + .expect("open"); + file.set_len(256_u64).expect("set_len"); + + let mmap = unsafe { MmapMut::map_mut(&file).expect("map_mut") }; + + let mmap = mmap.make_read_only().expect("make_read_only"); + let mut mmap = mmap.make_mut().expect("make_mut"); + + let write = b"abc123"; + let mut read = [0u8; 6]; + + (&mut mmap[..]).write_all(write).unwrap(); + mmap.flush().unwrap(); + + // The mmap contains the write + (&mmap[..]).read_exact(&mut read).unwrap(); + assert_eq!(write, &read); + + // The file should contain the write + file.read_exact(&mut read).unwrap(); + assert_eq!(write, &read); + + // another mmap should contain the write + let mmap2 = unsafe { MmapOptions::new().map(&file).unwrap() }; + (&mmap2[..]).read_exact(&mut read).unwrap(); + assert_eq!(write, &read); + + let mmap = mmap.make_exec().expect("make_exec"); + + drop(mmap); + } + + #[test] + fn mprotect_copy() { + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap"); + + let mut options = OpenOptions::new(); + #[cfg(windows)] + options.access_mode(GENERIC_ALL); + + let mut file = options + .read(true) + .write(true) + .create(true) + .open(&path) + .expect("open"); + file.set_len(256_u64).expect("set_len"); + + let mmap = unsafe { MmapOptions::new().map_copy(&file).expect("map_mut") }; + + let mmap = mmap.make_read_only().expect("make_read_only"); + let mut mmap = mmap.make_mut().expect("make_mut"); + + let nulls = b"\0\0\0\0\0\0"; + let write = b"abc123"; + let mut read = [0u8; 6]; + + (&mut mmap[..]).write_all(write).unwrap(); + mmap.flush().unwrap(); + + // The mmap contains the write + (&mmap[..]).read_exact(&mut read).unwrap(); + assert_eq!(write, &read); + + // The file does not contain the write + file.read_exact(&mut read).unwrap(); + assert_eq!(nulls, &read); + + // another mmap does not contain the write + let mmap2 = unsafe { MmapOptions::new().map(&file).unwrap() }; + (&mmap2[..]).read_exact(&mut read).unwrap(); + assert_eq!(nulls, &read); + + let mmap = mmap.make_exec().expect("make_exec"); + + drop(mmap); + } + + #[test] + fn mprotect_anon() { + let mmap = MmapMut::map_anon(256).expect("map_mut"); + + let mmap = mmap.make_read_only().expect("make_read_only"); + let mmap = mmap.make_mut().expect("make_mut"); + let mmap = mmap.make_exec().expect("make_exec"); + drop(mmap); + } + + #[test] + fn raw() { + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmapraw"); + + let mut options = OpenOptions::new(); + let mut file = options + .read(true) + .write(true) + .create(true) + .open(&path) + .expect("open"); + file.write_all(b"abc123").unwrap(); + let mmap = MmapOptions::new().map_raw(&file).unwrap(); + assert_eq!(mmap.len(), 6); + assert!(!mmap.as_ptr().is_null()); + assert_eq!(unsafe { std::ptr::read(mmap.as_ptr()) }, b'a'); + } + + /// Something that relies on StableDeref + #[test] + #[cfg(feature = "stable_deref_trait")] + fn owning_ref() { + extern crate owning_ref; + + let mut map = MmapMut::map_anon(128).unwrap(); + map[10] = 42; + let owning = owning_ref::OwningRef::new(map); + let sliced = owning.map(|map| &map[10..20]); + assert_eq!(42, sliced[0]); + + let map = sliced.into_owner().make_read_only().unwrap(); + let owning = owning_ref::OwningRef::new(map); + let sliced = owning.map(|map| &map[10..20]); + assert_eq!(42, sliced[0]); + } + + #[test] + #[cfg(unix)] + fn advise() { + let expected_len = 128; + let tempdir = tempfile::tempdir().unwrap(); + let path = tempdir.path().join("mmap_advise"); + + let file = OpenOptions::new() + .read(true) + .write(true) + .create(true) + .open(&path) + .unwrap(); + + file.set_len(expected_len as u64).unwrap(); + + // Test MmapMut::advise + let mut mmap = unsafe { MmapMut::map_mut(&file).unwrap() }; + mmap.advise(Advice::Random) + .expect("mmap advising should be supported on unix"); + + let len = mmap.len(); + assert_eq!(expected_len, len); + + let zeros = vec![0; len]; + let incr: Vec<u8> = (0..len as u8).collect(); + + // check that the mmap is empty + assert_eq!(&zeros[..], &mmap[..]); + + // write values into the mmap + (&mut mmap[..]).write_all(&incr[..]).unwrap(); + + // read values back + assert_eq!(&incr[..], &mmap[..]); + + // Set advice and Read from the read-only map + let mmap = unsafe { Mmap::map(&file).unwrap() }; + + mmap.advise(Advice::Random) + .expect("mmap advising should be supported on unix"); + + // read values back + assert_eq!(&incr[..], &mmap[..]); + } +} |