sdk/fidl/fuchsia.io/file2.fidl - fuchsia - Git at Google

 // Copyright 2019 The Fuchsia Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 library fuchsia.io;

 using zx;

 // TODO: We should run some experiments to see what's the optimum value, or
 // what's the point of diminishing marginal returns.
 /// The maximum I/O size that is allowed for read/write operations using
 /// byte vectors.
 const MAX_TRANSFER_SIZE uint64 = 8192;

 /// The byte vector type used for read/write operations.
 alias Transfer = bytes:MAX_TRANSFER_SIZE;

 /// A [`Node2`] which contains a sequence of bytes of definite
 /// length.
 protocol File2 {
     compose Node2;
     compose AdvisoryLocking;

     /// Moves the offset at which the next invocation of [`Read`] or [`Write`]
     /// will occur. The seek offset is specific to each file connection.
     ///
     /// + request `origin` the reference point where `offset` will be based on.
     /// + request `offset` the number of bytes to seek.
     /// - response `offset_from_start` the adjusted seek offset, from the start
     ///   of the file.
     ///
     /// This method does not require any rights.
     @selector("fuchsia.io/File.Seek")
     Seek(struct {
         origin SeekOrigin;
         offset int64;
     }) -> (struct {
         offset_from_start uint64;
     }) error zx.status;

     /// Reads up to 'count' bytes at the seek offset.
     /// The seek offset is moved forward by the number of bytes read.
     ///
     /// ## Invariants
     ///
     /// * The returned `data.length` will never be greater than `count`.
     /// * If `data.length` is less than `count`, it means that the seek offset
     ///   has reached the end of file as part of this operation.
     /// * If `data.length` is zero while `count` is not, it means that the
     ///   seek offset is already at or beyond the end of file, and no data could
     ///   be read.
     /// * If `count` is zero, the server should perform all the checks ensuring
     ///   read access without actually read anything, and return an empty
     ///   `data` vector.
     ///
     /// This method requires the [`Rights.READ_BYTES`] right.
     ///
     /// Returns `ZX_ERR_OUT_OF_RANGE` if `count` is greater than `MAX_TRANSFER_SIZE`.
     @selector("fuchsia.io/File.Read")
     Read(struct {
         count uint64;
     }) -> (struct {
         data Transfer;
     }) error zx.status;

     /// Writes data at the seek offset.
     /// The seek offset is moved forward by the number of bytes written.
     /// If the file is in append mode, the seek offset is first set to the end
     /// of the file, followed by the write, in one atomic step.
     ///
     /// The file size may grow if the seek offset plus `data.length` is beyond
     /// the current end of file.
     ///
     /// + request `data` the byte buffer to write to the file.
     /// - response `actual_count` the number of bytes written.
     ///
     /// ## Invariants
     ///
     /// * The returned `actual_count` will never be greater than `data.length`.
     /// * If the server is unable to write all the data due to e.g. not enough
     ///   space, `actual_count` may be less than `data.length`.  If no bytes
     ///   could be written, an error is returned.
     /// * If `data.length` is zero, the server should perform all the checks
     ///   ensuring write access without mutating the file and return a
     ///   successful write of zero bytes.  The seek offset is still updated if
     ///   in append mode.
     ///
     /// This method requires the [`Rights.WRITE_BYTES`] right.
     @selector("fuchsia.io/File.Write")
     Write(struct {
         data Transfer;
     }) -> (struct {
         actual_count uint64;
     }) error zx.status;

     /// Reads up to 'count' bytes at the provided offset.
     /// Does not affect the seek offset.
     ///
     /// ## Invariants
     ///
     /// * The returned `data.length` will never be greater than `count`.
     /// * If `data.length` is less than `count`, it means that `ReadAt` has hit
     ///   the end of file as part of this operation.
     /// * If `data.length` is zero while `count` is not, it means that `offset`
     ///   is at or past the end of file, and no data can be read.
     /// * If `count` is zero, the server should perform all the checks ensuring
     ///   read access without actually reading anything, and return an empty
     ///   `data` vector.
     ///
     /// This method requires the [`Rights.READ_BYTES`] right.
     ///
     /// Returns `ZX_ERR_OUT_OF_RANGE` if `count` is greater than `MAX_TRANSFER_SIZE`.
     @selector("fuchsia.io/File.ReadAt")
     ReadAt(struct {
         count uint64;
         offset uint64;
     }) -> (struct {
         data Transfer;
     }) error zx.status;

     /// Writes data at the provided offset.
     /// Does not affect the seek offset.
     ///
     /// The file size may grow if `offset` plus `data.length` is past the
     /// current end of file.
     ///
     /// + request `data` the byte buffer to write to the file.
     /// + request `offset` the offset from start of the file to begin writing.
     /// - response `actual_count` the number of bytes written.
     ///
     /// ## Invariants
     ///
     /// * The returned `actual_count` will never be greater than `data.length`.
     /// * If the server is unable to write all the data due to e.g. not enough
     ///   space, `actual_count` may be less than `data.length`.  If no bytes
     ///   could be written, an error is returned.
     /// * If `data.length` is zero, the server should perform all the checks
     ///   ensuring write access without mutating the file, and will return a
     ///   successful write of zero bytes.
     ///
     /// This method requires the [`Rights.WRITE_BYTES`] right.
     @selector("fuchsia.io/File.WriteAt")
     WriteAt(struct {
         data Transfer;
         offset uint64;
     }) -> (struct {
         actual_count uint64;
     }) error zx.status;

     /// Shrinks or grows the file size to 'length' bytes.
     ///
     /// If file size is reduced by this operation, the extra trailing data'
     /// is discarded.
     /// If file size is increased by this operation, the extended area appears
     /// as if it was zeroed.
     ///
     /// This method requires the [`Rights.WRITE_BYTES`] right.
     @selector("fuchsia.io/File.Resize")
     Resize(struct {
         length uint64;
     }) -> (struct {}) error zx.status;

     /// Acquires a [`zx.handle:VMO`] representing this file, if
     /// there is one, with the requested access rights.
     ///
     /// + request `flags` a [`VmoFlags`] indicating the desired mode of access.
     /// - response `vmo` the requested [`zx.handle:VMO`].
     /// * error a [`zx.status`] value indicating the failure.
     ///
     /// This method requires the following rights:
     ///
     /// * [`Rights.READ_BYTES`] if `flags` includes [`VmoFlags.READ`].
     /// * [`Rights.WRITE_BYTES`] if `flags` includes [`VmoFlags.WRITE`].
     /// * [`Rights.EXECUTE`] if `flags` includes [`VmoFlags.EXECUTE`].
     @selector("fuchsia.io/File.GetBackingMemory")
     GetBackingMemory(struct {
         flags VmoFlags;
     }) -> (resource struct {
         vmo zx.handle:VMO;
     }) error zx.status;
 };

 type VmoFlags = strict bits : uint32 {
     /// Requests that the VMO be readable.
     READ = 0x00000001;

     /// Requests that the VMO be writable.
     WRITE = 0x00000002;

     /// Request that the VMO be executable.
     EXECUTE = 0x00000004;

     /// Require a copy-on-write clone of the underlying VMO.
     /// The request should fail if the VMO cannot be cloned.
     /// May not be supplied with `SHARED_BUFFER`.
     PRIVATE_CLONE = 0x00010000;

     /// Require an exact (non-cloned) handle to the underlying VMO.
     /// All clients using this flag would get a VMO with the same koid.
     /// The request should fail if a handle to the exact VMO cannot be returned.
     /// May not be supplied with `PRIVATE_CLONE`.
     SHARED_BUFFER = 0x00020000;
 };

 /// The reference point for updating the seek offset. See [`File.Seek`].
 ///
 /// This enum matches the `zx_stream_seek_origin_t` enum.
 type SeekOrigin = strict enum : uint32 {
     /// Seek from the start of the file.
     /// The seek offset will be set to `offset` bytes.
     /// The seek offset cannot be negative in this case.
     START = 0;

     /// Seek from the current position in the file.
     /// The seek offset will be the current seek offset plus `offset` bytes.
     CURRENT = 1;

     /// Seek from the end of the file.
     /// The seek offset will be the file size plus `offset` bytes.
     END = 2;
 };

 type FileSignal = strict bits : uint32 {
     /// Indicates the file is ready for reading.
     READABLE = 0x01000000; // ZX_USER_SIGNAL_0

     /// Indicates the file is ready for writing.
     WRITABLE = 0x02000000; // ZX_USER_SIGNAL_1
 };
	// Copyright 2019 The Fuchsia Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.
	library fuchsia.io;

	using zx;

	// TODO: We should run some experiments to see what's the optimum value, or
	// what's the point of diminishing marginal returns.
	/// The maximum I/O size that is allowed for read/write operations using
	/// byte vectors.
	const MAX_TRANSFER_SIZE uint64 = 8192;

	/// The byte vector type used for read/write operations.
	alias Transfer = bytes:MAX_TRANSFER_SIZE;

	/// A [`Node2`] which contains a sequence of bytes of definite
	/// length.
	protocol File2 {
	compose Node2;
	compose AdvisoryLocking;

	/// Moves the offset at which the next invocation of [`Read`] or [`Write`]
	/// will occur. The seek offset is specific to each file connection.
	///
	/// + request `origin` the reference point where `offset` will be based on.
	/// + request `offset` the number of bytes to seek.
	/// - response `offset_from_start` the adjusted seek offset, from the start
	/// of the file.
	///
	/// This method does not require any rights.
	@selector("fuchsia.io/File.Seek")
	Seek(struct {
	origin SeekOrigin;
	offset int64;
	}) -> (struct {
	offset_from_start uint64;
	}) error zx.status;

	/// Reads up to 'count' bytes at the seek offset.
	/// The seek offset is moved forward by the number of bytes read.
	///
	/// ## Invariants
	///
	/// * The returned `data.length` will never be greater than `count`.
	/// * If `data.length` is less than `count`, it means that the seek offset
	/// has reached the end of file as part of this operation.
	/// * If `data.length` is zero while `count` is not, it means that the
	/// seek offset is already at or beyond the end of file, and no data could
	/// be read.
	/// * If `count` is zero, the server should perform all the checks ensuring
	/// read access without actually read anything, and return an empty
	/// `data` vector.
	///
	/// This method requires the [`Rights.READ_BYTES`] right.
	///
	/// Returns `ZX_ERR_OUT_OF_RANGE` if `count` is greater than `MAX_TRANSFER_SIZE`.
	@selector("fuchsia.io/File.Read")
	Read(struct {
	count uint64;
	}) -> (struct {
	data Transfer;
	}) error zx.status;

	/// Writes data at the seek offset.
	/// The seek offset is moved forward by the number of bytes written.
	/// If the file is in append mode, the seek offset is first set to the end
	/// of the file, followed by the write, in one atomic step.
	///
	/// The file size may grow if the seek offset plus `data.length` is beyond
	/// the current end of file.
	///
	/// + request `data` the byte buffer to write to the file.
	/// - response `actual_count` the number of bytes written.
	///
	/// ## Invariants
	///
	/// * The returned `actual_count` will never be greater than `data.length`.
	/// * If the server is unable to write all the data due to e.g. not enough
	/// space, `actual_count` may be less than `data.length`. If no bytes
	/// could be written, an error is returned.
	/// * If `data.length` is zero, the server should perform all the checks
	/// ensuring write access without mutating the file and return a
	/// successful write of zero bytes. The seek offset is still updated if
	/// in append mode.
	///
	/// This method requires the [`Rights.WRITE_BYTES`] right.
	@selector("fuchsia.io/File.Write")
	Write(struct {
	data Transfer;
	}) -> (struct {
	actual_count uint64;
	}) error zx.status;

	/// Reads up to 'count' bytes at the provided offset.
	/// Does not affect the seek offset.
	///
	/// ## Invariants
	///
	/// * The returned `data.length` will never be greater than `count`.
	/// * If `data.length` is less than `count`, it means that `ReadAt` has hit
	/// the end of file as part of this operation.
	/// * If `data.length` is zero while `count` is not, it means that `offset`
	/// is at or past the end of file, and no data can be read.
	/// * If `count` is zero, the server should perform all the checks ensuring
	/// read access without actually reading anything, and return an empty
	/// `data` vector.
	///
	/// This method requires the [`Rights.READ_BYTES`] right.
	///
	/// Returns `ZX_ERR_OUT_OF_RANGE` if `count` is greater than `MAX_TRANSFER_SIZE`.
	@selector("fuchsia.io/File.ReadAt")
	ReadAt(struct {
	count uint64;
	offset uint64;
	}) -> (struct {
	data Transfer;
	}) error zx.status;

	/// Writes data at the provided offset.
	/// Does not affect the seek offset.
	///
	/// The file size may grow if `offset` plus `data.length` is past the
	/// current end of file.
	///
	/// + request `data` the byte buffer to write to the file.
	/// + request `offset` the offset from start of the file to begin writing.
	/// - response `actual_count` the number of bytes written.
	///
	/// ## Invariants
	///
	/// * The returned `actual_count` will never be greater than `data.length`.
	/// * If the server is unable to write all the data due to e.g. not enough
	/// space, `actual_count` may be less than `data.length`. If no bytes
	/// could be written, an error is returned.
	/// * If `data.length` is zero, the server should perform all the checks
	/// ensuring write access without mutating the file, and will return a
	/// successful write of zero bytes.
	///
	/// This method requires the [`Rights.WRITE_BYTES`] right.
	@selector("fuchsia.io/File.WriteAt")
	WriteAt(struct {
	data Transfer;
	offset uint64;
	}) -> (struct {
	actual_count uint64;
	}) error zx.status;

	/// Shrinks or grows the file size to 'length' bytes.
	///
	/// If file size is reduced by this operation, the extra trailing data'
	/// is discarded.
	/// If file size is increased by this operation, the extended area appears
	/// as if it was zeroed.
	///
	/// This method requires the [`Rights.WRITE_BYTES`] right.
	@selector("fuchsia.io/File.Resize")
	Resize(struct {
	length uint64;
	}) -> (struct {}) error zx.status;

	/// Acquires a [`zx.handle:VMO`] representing this file, if
	/// there is one, with the requested access rights.
	///
	/// + request `flags` a [`VmoFlags`] indicating the desired mode of access.
	/// - response `vmo` the requested [`zx.handle:VMO`].
	/// * error a [`zx.status`] value indicating the failure.
	///
	/// This method requires the following rights:
	///
	/// * [`Rights.READ_BYTES`] if `flags` includes [`VmoFlags.READ`].
	/// * [`Rights.WRITE_BYTES`] if `flags` includes [`VmoFlags.WRITE`].
	/// * [`Rights.EXECUTE`] if `flags` includes [`VmoFlags.EXECUTE`].
	@selector("fuchsia.io/File.GetBackingMemory")
	GetBackingMemory(struct {
	flags VmoFlags;
	}) -> (resource struct {
	vmo zx.handle:VMO;
	}) error zx.status;
	};

	type VmoFlags = strict bits : uint32 {
	/// Requests that the VMO be readable.
	READ = 0x00000001;

	/// Requests that the VMO be writable.
	WRITE = 0x00000002;

	/// Request that the VMO be executable.
	EXECUTE = 0x00000004;

	/// Require a copy-on-write clone of the underlying VMO.
	/// The request should fail if the VMO cannot be cloned.
	/// May not be supplied with `SHARED_BUFFER`.
	PRIVATE_CLONE = 0x00010000;

	/// Require an exact (non-cloned) handle to the underlying VMO.
	/// All clients using this flag would get a VMO with the same koid.
	/// The request should fail if a handle to the exact VMO cannot be returned.
	/// May not be supplied with `PRIVATE_CLONE`.
	SHARED_BUFFER = 0x00020000;
	};

	/// The reference point for updating the seek offset. See [`File.Seek`].
	///
	/// This enum matches the `zx_stream_seek_origin_t` enum.
	type SeekOrigin = strict enum : uint32 {
	/// Seek from the start of the file.
	/// The seek offset will be set to `offset` bytes.
	/// The seek offset cannot be negative in this case.
	START = 0;

	/// Seek from the current position in the file.
	/// The seek offset will be the current seek offset plus `offset` bytes.
	CURRENT = 1;

	/// Seek from the end of the file.
	/// The seek offset will be the file size plus `offset` bytes.
	END = 2;
	};

	type FileSignal = strict bits : uint32 {
	/// Indicates the file is ready for reading.
	READABLE = 0x01000000; // ZX_USER_SIGNAL_0

	/// Indicates the file is ready for writing.
	WRITABLE = 0x02000000; // ZX_USER_SIGNAL_1
	};