// Copyright 2020 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 zx;

type StreamSeekOrigin = strict enum : uint32 {
    START = 0;
    CURRENT = 1;
    END = 2;
};

type Iovec = struct {
    @voidptr
    buffer experimental_pointer<byte>;
    capacity usize64;
};

@transport("Syscall")
closed protocol Stream {
    /// ## Summary
    ///
    /// Create a stream from a VMO.
    ///
    /// ## Declaration
    ///
    /// ```c
    /// #include <zircon/syscalls.h>
    ///
    /// zx_status_t zx_stream_create(uint32_t options,
    ///                              zx_handle_t vmo,
    ///                              zx_off_t seek,
    ///                              zx_handle_t* out_stream);
    /// ```
    ///
    /// ## Description
    ///
    /// `zx_stream_create()` creates a stream, which reads and writes the data in an
    /// underlying VMO.
    ///
    /// The seek offset for the stream is initialized to *seek*.
    ///
    /// # Options
    ///
    /// `ZX_STREAM_MODE_READ`  The stream will be used for reading.  If the given
    /// *vmo* lacks `ZX_RIGHT_READ`, this function will return
    /// `ZX_ERR_ACCESS_DENIED`.  Otherwise, `ZX_RIGHT_READ` will be included as a
    /// right on the created stream object.
    ///
    /// `ZX_STREAM_MODE_WRITE`  The stream will be used for writing.  If the given
    /// *vmo* lacks `ZX_RIGHT_WRITE`, this function will return
    /// `ZX_ERR_ACCESS_DENIED`.  Otherwise, `ZX_RIGHT_WRITE` will be included as a
    /// right on the created stream object.
    ///
    /// `ZX_STREAM_MODE_APPEND`  The stream is created in append mode. A stream in
    /// append mode will atomically set the seek offset of the stream to the content
    /// size of the stream prior to writing data in `zx_stream_writev()`.
    ///
    /// ## Rights
    ///
    /// TODO(https://fxbug.dev/42107318)
    ///
    /// ## Return value
    ///
    /// `zx_stream_create()` returns `ZX_OK` on success. In the event of
    /// failure, one of the following values is returned.
    ///
    /// ## Errors
    ///
    /// `ZX_ERR_BAD_HANDLE`  *vmo* is not a valid handle.
    ///
    /// `ZX_ERR_WRONG_TYPE`  *vmo* is not a VMO handle.
    ///
    /// `ZX_ERR_ACCESS_DENIED`  *vmo* does not have the rights required for the given
    /// options.
    ///
    /// `ZX_ERR_INVALID_ARGS`  *out_stream* is an invalid pointer or NULL, *options*
    /// has an unsupported bit set to 1.
    ///
    /// `ZX_ERR_NO_MEMORY`  Failure due to lack of memory.
    ///
    /// ## See also
    ///
    ///  - [`zx_stream_readv()`]
    ///  - [`zx_stream_readv_at()`]
    ///  - [`zx_stream_seek()`]
    ///  - [`zx_stream_writev()`]
    ///  - [`zx_stream_writev_at()`]
    ///
    /// [`zx_stream_readv()`]: stream_readv.md
    /// [`zx_stream_readv_at()`]: stream_readv_at.md
    /// [`zx_stream_seek()`]: stream_seek.md
    /// [`zx_stream_writev()`]: stream_writev.md
    /// [`zx_stream_writev_at()`]: stream_writev_at.md
    strict Create(resource struct {
        options uint32;
        vmo Handle:VMO;
        seek Off;
    }) -> (resource struct {
        out_stream Handle:STREAM;
    }) error Status;

    /// ## Summary
    ///
    /// Write data to a stream at the current seek offset.
    ///
    /// ## Declaration
    ///
    /// ```c
    /// #include <zircon/syscalls.h>
    ///
    /// zx_status_t zx_stream_writev(zx_handle_t handle,
    ///                              uint32_t options,
    ///                              const zx_iovec_t* vectors,
    ///                              size_t num_vectors,
    ///                              size_t* actual);
    /// ```
    ///
    /// ## Description
    ///
    /// `zx_stream_writev()` attempts to write bytes to the stream, starting at the
    /// current seek offset, from the buffers specified by *vectors* and *num_vectors*.
    /// If successful, the number of bytes actually written are return via *actual*.
    ///
    /// If *options* contains `ZX_STREAM_APPEND` or the stream is in append mode, the
    /// seek offset of the stream is atomically set to the content size of the stream
    /// prior to writing the data.
    ///
    /// If the write operation would write beyond the end of the stream, the function
    /// will attempt to increase the content size of the stream in order to receive the
    /// given data, filling any new, unwritten content with zero bytes.
    ///
    /// If the resize operation fails after some amount of data was written to the
    /// stream, the function will return successfully.  If no bytes were written to
    /// stream, the operation will return `ZX_ERR_FILE_BIG` or `ZX_ERR_NO_SPACE`,
    /// as appropriate.
    ///
    /// If a NULL *actual* is passed in, it will be ignored.
    ///
    /// Advances the seek offset of the stream by the actual number of bytes written.
    /// If the write fails, the seek offset could either remain the same or have
    /// been changed to an unspecified value.
    ///
    /// If the contents of *vectors* change during this operation, if any of the buffers
    /// overlap, or if any of the buffers overlap *vectors*, the behavior is unspecified.
    ///
    /// ## Rights
    ///
    /// *handle* must be of type `ZX_OBJ_TYPE_STREAM` and have `ZX_RIGHT_WRITE`.
    ///
    /// ## Return value
    ///
    /// `zx_stream_writev()` returns `ZX_OK` on success, and writes into
    /// *actual* (if non-NULL) the exact number of bytes written.
    ///
    /// ## Errors
    ///
    /// `ZX_ERR_BAD_HANDLE`  *handle* is not a valid handle.
    ///
    /// `ZX_ERR_WRONG_TYPE`  *handle* is not a stream handle.
    ///
    /// `ZX_ERR_ACCESS_DENIED`  *handle* does not have the `ZX_RIGHT_WRITE` right.
    ///
    /// `ZX_ERR_INVALID_ARGS`   *vectors* is an invalid `zx_iovec_t` or *options* has an
    /// unsupported bit set to 1.
    ///
    /// `ZX_ERR_NOT_FOUND`  the *vectors* address, or an address specified within
    /// *vectors* does not map to address in address space.
    ///
    /// `ZX_ERR_BAD_STATE`  the underlying data source cannot be written.
    ///
    /// `ZX_ERR_FILE_BIG`  the stream has exceeded a predefined maximum size limit.
    ///
    /// `ZX_ERR_NO_SPACE`  the underlying storage medium does not have sufficient space.
    ///
    /// ## See also
    ///
    ///  - [`zx_stream_create()`]
    ///  - [`zx_stream_readv()`]
    ///  - [`zx_stream_readv_at()`]
    ///  - [`zx_stream_seek()`]
    ///  - [`zx_stream_writev_at()`]
    ///
    /// [`zx_stream_create()`]: stream_create.md
    /// [`zx_stream_readv()`]: stream_readv.md
    /// [`zx_stream_readv_at()`]: stream_readv_at.md
    /// [`zx_stream_seek()`]: stream_seek.md
    /// [`zx_stream_writev_at()`]: stream_writev_at.md
    @blocking
    strict Writev(resource struct {
        handle Handle:STREAM;
        options uint32;
        vectors vector<Iovec>:MAX;
    }) -> (struct {
        actual usize64;
    }) error Status;

    /// ## Summary
    ///
    /// Write data to a stream at the given offset.
    ///
    /// ## Declaration
    ///
    /// ```c
    /// #include <zircon/syscalls.h>
    ///
    /// zx_status_t zx_stream_writev_at(zx_handle_t handle,
    ///                                 uint32_t options,
    ///                                 zx_off_t offset,
    ///                                 const zx_iovec_t* vectors,
    ///                                 size_t num_vectors,
    ///                                 size_t* actual);
    /// ```
    ///
    /// ## Description
    ///
    /// `zx_stream_writev_at()` attempts to write bytes to the stream, starting at the
    /// given *offset*, from the buffers specified by *vectors* and *num_vectors*.
    /// If successful, the number of bytes actually written are return via *actual*.
    ///
    /// If the write operation would write beyond the end of the stream, the function
    /// will attempt to increase the content size of the stream in order to receive the
    /// given data, filling any new, unwritten content with zero bytes.
    ///
    /// If the resize operation fails after some amount of data was written to the
    /// stream, the function will return successfully.  If no bytes were written to
    /// stream, the operation will return `ZX_ERR_FILE_BIG` or `ZX_ERR_NO_SPACE`,
    /// as appropriate.
    ///
    /// If a NULL *actual* is passed in, it will be ignored.
    ///
    /// Does not advance the seek offset of the stream.
    ///
    /// If the contents of *vectors* change during this operation, if any of the buffers
    /// overlap, or if any of the buffers overlap *vectors*, the behavior is unspecified.
    ///
    /// *options* is reserved for future use and must be 0.
    ///
    /// ## Rights
    ///
    /// *handle* must be of type `ZX_OBJ_TYPE_STREAM` and have `ZX_RIGHT_WRITE`.
    ///
    /// ## Return value
    ///
    /// `zx_stream_writev_at()` returns `ZX_OK` on success, and writes into
    /// *actual* (if non-NULL) the exact number of bytes written.
    ///
    /// ## Errors
    ///
    /// `ZX_ERR_BAD_HANDLE`  *handle* is not a valid handle.
    ///
    /// `ZX_ERR_WRONG_TYPE`  *handle* is not a stream handle.
    ///
    /// `ZX_ERR_ACCESS_DENIED`  *handle* does not have the ZX_RIGHT_WRITE right.
    ///
    /// `ZX_ERR_INVALID_ARGS` *vectors* is an invalid zx_iovec_t or *options* has an
    /// unsupported bit set to 1.
    ///
    /// `ZX_ERR_NOT_FOUND`  the *vectors* address, or an address specified within
    /// *vectors* does not map to address in address space.
    ///
    /// `ZX_ERR_BAD_STATE`  the underlying data source cannot be written.
    ///
    /// `ZX_ERR_FILE_BIG`  the stream has exceeded a predefined maximum size limit.
    ///
    /// `ZX_ERR_NO_SPACE`  the underlying storage medium does not have sufficient space.
    ///
    /// ## See also
    ///
    ///  - [`zx_stream_create()`]
    ///  - [`zx_stream_readv()`]
    ///  - [`zx_stream_readv_at()`]
    ///  - [`zx_stream_seek()`]
    ///  - [`zx_stream_writev()`]
    ///
    /// [`zx_stream_create()`]: stream_create.md
    /// [`zx_stream_readv()`]: stream_readv.md
    /// [`zx_stream_readv_at()`]: stream_readv_at.md
    /// [`zx_stream_seek()`]: stream_seek.md
    /// [`zx_stream_writev()`]: stream_writev.md
    @blocking
    strict WritevAt(resource struct {
        handle Handle:STREAM;
        options uint32;
        offset Off;
        vectors vector<Iovec>:MAX;
    }) -> (struct {
        actual usize64;
    }) error Status;

    /// ## Summary
    ///
    /// Read data from a stream at the current seek offset.
    ///
    /// ## Declaration
    ///
    /// ```c
    /// #include <zircon/syscalls.h>
    ///
    /// zx_status_t zx_stream_readv(zx_handle_t handle,
    ///                             uint32_t options,
    ///                             zx_iovec_t* vectors,
    ///                             size_t num_vectors,
    ///                             size_t* actual);
    /// ```
    ///
    /// ## Description
    ///
    /// `zx_stream_readv()` attempts to read bytes from the stream, starting at the
    /// current seek offset, into the buffers specified by *vectors* and *num_vectors*.
    /// If successful, the number of bytes actually read are return via *actual*.
    ///
    /// If the current seek offset is beyond the end of the stream, `zx_stream_readv()`
    /// will succeed in reading zero bytes.
    ///
    /// If a NULL *actual* is passed in, it will be ignored.
    ///
    /// Advances the seek offset of the stream by the actual number of bytes read.
    /// If the read fails, the seek offset could either remain the same or have
    /// been changed to an unspecified value.
    ///
    /// If the contents of *vectors* change during this operation, if any of the buffers
    /// overlap, or if any of the buffers overlap *vectors*, the behavior is unspecified.
    ///
    /// *options* is reserved for future use and must be 0.
    ///
    /// ## Rights
    ///
    /// *handle* must be of type `ZX_OBJ_TYPE_STREAM` and have `ZX_RIGHT_READ`.
    ///
    /// ## Return value
    ///
    /// `zx_stream_readv()` returns `ZX_OK` on success, and writes into
    /// *actual* (if non-NULL) the exact number of bytes read.
    ///
    /// ## Errors
    ///
    /// `ZX_ERR_BAD_HANDLE`  *handle* is not a valid handle.
    ///
    /// `ZX_ERR_WRONG_TYPE`  *handle* is not a stream handle.
    ///
    /// `ZX_ERR_ACCESS_DENIED`  *handle* does not have the `ZX_RIGHT_READ` right.
    ///
    /// `ZX_ERR_INVALID_ARGS`  *vectors* is an invalid `zx_iovec_t` or *options* is
    /// nonzero.
    ///
    /// `ZX_ERR_NOT_FOUND`  the *vectors* address, or an address specified within
    /// *vectors* does not map to address in address space.
    ///
    /// `ZX_ERR_BAD_STATE`  the underlying data source cannot be read.
    ///
    /// ## See also
    ///
    ///  - [`zx_stream_create()`]
    ///  - [`zx_stream_readv_at()`]
    ///  - [`zx_stream_seek()`]
    ///  - [`zx_stream_writev()`]
    ///  - [`zx_stream_writev_at()`]
    ///
    /// [`zx_stream_create()`]: stream_create.md
    /// [`zx_stream_readv_at()`]: stream_readv_at.md
    /// [`zx_stream_seek()`]: stream_seek.md
    /// [`zx_stream_writev()`]: stream_writev.md
    /// [`zx_stream_writev_at()`]: stream_writev_at.md
    @blocking
    strict Readv(resource struct {
        handle Handle:STREAM;
        options uint32;
    }) -> (struct {
        vectors vector<Iovec>:MAX;
        actual usize64;
    }) error Status;

    /// ## Summary
    ///
    /// Read data from a stream at the given offset.
    ///
    /// ## Declaration
    ///
    /// ```c
    /// #include <zircon/syscalls.h>
    ///
    /// zx_status_t zx_stream_readv_at(zx_handle_t handle,
    ///                                uint32_t options,
    ///                                zx_off_t offset,
    ///                                zx_iovec_t* vectors,
    ///                                size_t num_vectors,
    ///                                size_t* actual);
    /// ```
    ///
    /// ## Description
    ///
    /// `zx_stream_readv_at()` attempts to read bytes from the stream, starting at the
    /// given *offset*, into the buffers specified by *vectors* and *num_vectors*. If
    /// successful, the number of bytes actually read are return via *actual*.
    ///
    /// If the given *offset* is beyond the end of the stream, `zx_stream_readv_at()`
    /// will succeed in reading zero bytes.
    ///
    /// If a NULL *actual* is passed in, it will be ignored.
    ///
    /// Does not advance the seek offset of the stream.
    ///
    /// If the contents of *vectors* change during this operation, if any of the buffers
    /// overlap, or if any of the buffers overlap *vectors*, the behavior is unspecified.
    ///
    /// *options* is reserved for future use and must be 0.
    ///
    /// ## Rights
    ///
    /// *handle* must be of type `ZX_OBJ_TYPE_STREAM` and have `ZX_RIGHT_READ`.
    ///
    /// ## Return value
    ///
    /// `zx_stream_readv_at()` returns `ZX_OK` on success, and writes into
    /// *actual* (if non-NULL) the exact number of bytes read.
    ///
    /// ## Errors
    ///
    /// `ZX_ERR_BAD_HANDLE`  *handle* is not a valid handle.
    ///
    /// `ZX_ERR_WRONG_TYPE`   *handle* is not a stream handle.
    ///
    /// `ZX_ERR_ACCESS_DENIED`  *handle* does not have the `ZX_RIGHT_READ` right.
    ///
    /// `ZX_ERR_INVALID_ARGS`  vectors is an invalid `zx_iovec_t` or *options* is
    /// nonzero.
    ///
    /// `ZX_ERR_NOT_FOUND`  the *vectors* address, or an address specified within
    /// *vectors* does not map to address in address space.
    ///
    /// `ZX_ERR_BAD_STATE`  the underlying data source cannot be read.
    ///
    /// ## See also
    ///
    ///  - [`zx_stream_create()`]
    ///  - [`zx_stream_readv()`]
    ///  - [`zx_stream_seek()`]
    ///  - [`zx_stream_writev()`]
    ///  - [`zx_stream_writev_at()`]
    ///
    /// [`zx_stream_create()`]: stream_create.md
    /// [`zx_stream_readv()`]: stream_readv.md
    /// [`zx_stream_seek()`]: stream_seek.md
    /// [`zx_stream_writev()`]: stream_writev.md
    /// [`zx_stream_writev_at()`]: stream_writev_at.md
    @blocking
    strict ReadvAt(resource struct {
        handle Handle:STREAM;
        options uint32;
        offset Off;
    }) -> (struct {
        vectors vector<Iovec>:MAX;
        actual usize64;
    }) error Status;

    /// ## Summary
    ///
    /// Modify the seek offset.
    ///
    /// ## Declaration
    ///
    /// ```c
    /// #include <zircon/syscalls.h>
    ///
    /// zx_status_t zx_stream_seek(zx_handle_t handle,
    ///                            zx_stream_seek_origin_t whence,
    ///                            int64_t offset,
    ///                            zx_off_t* out_seek);
    /// ```
    ///
    /// ## Description
    ///
    /// `zx_stream_seek()` sets the seek offset of the stream to *offset* relative to
    /// *whence*.
    ///
    /// If the resulting seek offset were to be negative or exceed the maximum
    /// representable `zx_off_t`, `zx_stream_seek()` returns `ZX_ERR_INVALID_ARGS`.
    ///
    /// The resulting seek offset might extend beyond the end of the stream. Setting
    /// such a seek offset does not cause `zx_stream_seek()` to return an error, but
    /// attempting to read or write data at that seek offset might generate an error.
    ///
    /// ## WHENCE
    ///
    /// `ZX_STREAM_SEEK_ORIGIN_START`  set the seek offset relative to the start of
    /// the stream.
    ///
    /// `ZX_STREAM_SEEK_ORIGIN_CURRENT`  set the seek offset relative to the current
    /// seek offset of the stream.
    ///
    /// `ZX_STREAM_SEEK_ORIGIN_END`  set the seek offset relative to the end of the
    /// stream, as defined by the content size of the stream.
    ///
    /// ## Rights
    ///
    /// *handle* must be of type `ZX_OBJ_TYPE_STREAM` and have `ZX_RIGHT_WRITE` or have `ZX_RIGHT_WRITE`.
    ///
    /// ## Return value
    ///
    /// `zx_stream_seek()` returns `ZX_OK` on success, and writes the resulting seek
    /// offset, relative to the start of the stream, into *out_offset* (if non-NULL).
    ///
    /// ## Errors
    ///
    /// `ZX_ERR_BAD_HANDLE`  *handle* is not a valid handle.
    ///
    /// `ZX_ERR_WRONG_TYPE`  *handle* is not a stream handle.
    ///
    /// `ZX_ERR_ACCESS_DENIED`  *handle* does not have the `ZX_RIGHT_READ` or
    /// `ZX_RIGHT_WRITE` right.
    ///
    /// `ZX_ERR_INVALID_ARGS`  *whence* is an invalid `zx_stream_seek_origin_t` or
    /// the resulting seek would be negative or exceed the maximum representable
    /// `zx_off_t`.
    ///
    /// ## See also
    ///
    ///  - [`zx_stream_create()`]
    ///  - [`zx_stream_readv()`]
    ///  - [`zx_stream_readv_at()`]
    ///  - [`zx_stream_writev()`]
    ///  - [`zx_stream_writev_at()`]
    ///
    /// [`zx_stream_create()`]: stream_create.md
    /// [`zx_stream_readv()`]: stream_readv.md
    /// [`zx_stream_readv_at()`]: stream_readv_at.md
    /// [`zx_stream_writev()`]: stream_writev.md
    /// [`zx_stream_writev_at()`]: stream_writev_at.md
    strict Seek(resource struct {
        handle Handle:STREAM;
        whence StreamSeekOrigin;
        offset int64;
    }) -> (struct {
        out_seek Off;
    }) error Status;
};