InputStream

class InputStream(**properties: Any)

Superclasses: Object

Subclasses: FileInputStream, FilterInputStream, MemoryInputStream, UnixInputStream

GInputStream is a base class for implementing streaming input.

It has functions to read from a stream (read), to close a stream (close) and to skip some content (skip).

To copy the content of an input stream to an output stream without manually handling the reads and writes, use splice.

See the documentation for IOStream for details of thread safety of streaming APIs.

All of these functions have async variants too.

Methods

class InputStream

clear_pending() → None: Clears the pending flag on stream.

close(cancellable: Cancellable | None = None) → bool

Closes the stream, releasing resources related to it.

Once the stream is closed, all other operations will return CLOSED. Closing a stream multiple times will not return an error.

Streams will be automatically closed when the last reference is dropped, but you might want to call this function to make sure resources are released as early as possible.

Some streams might keep the backing store of the stream (e.g. a file descriptor) open after the stream is closed. See the documentation for the individual stream for details.

On failure the first error that happened will be reported, but the close operation will finish as much as possible. A stream that failed to close will still return CLOSED for all operations. Still, it is important to check and report the error to the user.

If cancellable is not None, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error CANCELLED will be returned. Cancelling a close will still leave the stream closed, but some streams can use a faster close that doesn’t block to e.g. check errors.

Parameters:: cancellable – optional Cancellable object, None to ignore.

close_async(io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) → None

Requests an asynchronous closes of the stream, releasing resources related to it. When the operation is finished callback will be called. You can then call close_finish() to get the result of the operation.

For behaviour details see close().

The asynchronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

io_priority – the [I/O priority][io-priority] of the request
cancellable – optional cancellable object
callback – a AsyncReadyCallback to call when the request is satisfied
user_data – the data to pass to callback function

close_finish(result: AsyncResult) → bool

Finishes closing a stream asynchronously, started from close_async().

Parameters:: result – a AsyncResult.

has_pending() → bool: Checks if an input stream has pending actions.

is_closed() → bool: Checks if an input stream is closed.

read(cancellable: Cancellable | None = None) → tuple[int, bytes]

Tries to read count bytes from the stream into the buffer starting at buffer. Will block during this read.

If count is zero returns zero and does nothing. A value of count larger than %G_MAXSSIZE will cause a INVALID_ARGUMENT error.

On success, the number of bytes read into the buffer is returned. It is not an error if this is not the same as the requested size, as it can happen e.g. near the end of a file. Zero is returned on end of file (or if count is zero), but never otherwise.

The returned buffer is not a nul-terminated string, it can contain nul bytes at any position, and this function doesn’t nul-terminate the buffer.

If cancellable is not None, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error CANCELLED will be returned. If an operation was partially finished when the operation was cancelled the partial result will be returned, without an error.

On error -1 is returned and error is set accordingly.

Parameters:: cancellable – optional Cancellable object, None to ignore.

read_all(cancellable: Cancellable | None = None) → tuple[bool, bytes, int]

Tries to read count bytes from the stream into the buffer starting at buffer. Will block during this read.

This function is similar to read(), except it tries to read as many bytes as requested, only stopping on an error or end of stream.

On a successful read of count bytes, or if we reached the end of the stream, True is returned, and bytes_read is set to the number of bytes read into buffer.

If there is an error during the operation False is returned and error is set to indicate the error status.

As a special exception to the normal conventions for functions that use Error, if this function returns False (and sets error) then bytes_read will be set to the number of bytes that were successfully read before the error was encountered. This functionality is only available from C. If you need it from another language then you must write your own loop around read().

Parameters:: cancellable – optional Cancellable object, None to ignore.

read_all_async(io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) → bytes

Request an asynchronous read of count bytes from the stream into the buffer starting at buffer.

This is the asynchronous equivalent of read_all().

Call read_all_finish() to collect the result.

Any outstanding I/O request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is %G_PRIORITY_DEFAULT.

Added in version 2.44.

Parameters:

io_priority – the [I/O priority][io-priority] of the request
cancellable – optional Cancellable object, None to ignore
callback – a AsyncReadyCallback to call when the request is satisfied
user_data – the data to pass to callback function

read_all_finish(result: AsyncResult) → tuple[bool, int]

Finishes an asynchronous stream read operation started with read_all_async().

Added in version 2.44.

Parameters:: result – a AsyncResult

read_async(io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) → bytes

Request an asynchronous read of count bytes from the stream into the buffer starting at buffer. When the operation is finished callback will be called. You can then call read_finish() to get the result of the operation.

During an async request no other sync and async calls are allowed on stream, and will result in PENDING errors.

A value of count larger than %G_MAXSSIZE will cause a INVALID_ARGUMENT error.

On success, the number of bytes read into the buffer will be passed to the callback. It is not an error if this is not the same as the requested size, as it can happen e.g. near the end of a file, but generally we try to read as many bytes as requested. Zero is returned on end of file (or if count is zero), but never otherwise.

Any outstanding i/o request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is %G_PRIORITY_DEFAULT.

The asynchronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

io_priority – the [I/O priority][io-priority] of the request.
cancellable – optional Cancellable object, None to ignore.
callback – a AsyncReadyCallback to call when the request is satisfied
user_data – the data to pass to callback function

read_bytes(count: int, cancellable: Cancellable | None = None) → Bytes

Like read(), this tries to read count bytes from the stream in a blocking fashion. However, rather than reading into a user-supplied buffer, this will create a new Bytes containing the data that was read. This may be easier to use from language bindings.

If count is zero, returns a zero-length Bytes and does nothing. A value of count larger than %G_MAXSSIZE will cause a INVALID_ARGUMENT error.

On success, a new Bytes is returned. It is not an error if the size of this object is not the same as the requested size, as it can happen e.g. near the end of a file. A zero-length Bytes is returned on end of file (or if count is zero), but never otherwise.

If cancellable is not None, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error CANCELLED will be returned. If an operation was partially finished when the operation was cancelled the partial result will be returned, without an error.

On error None is returned and error is set accordingly.

Added in version 2.34.

Parameters:

count – maximum number of bytes that will be read from the stream. Common values include 4096 and 8192.
cancellable – optional Cancellable object, None to ignore.

read_bytes_async(count: int, io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) → None

Request an asynchronous read of count bytes from the stream into a new Bytes. When the operation is finished callback will be called. You can then call read_bytes_finish() to get the result of the operation.

During an async request no other sync and async calls are allowed on stream, and will result in PENDING errors.

A value of count larger than %G_MAXSSIZE will cause a INVALID_ARGUMENT error.

On success, the new Bytes will be passed to the callback. It is not an error if this is smaller than the requested size, as it can happen e.g. near the end of a file, but generally we try to read as many bytes as requested. Zero is returned on end of file (or if count is zero), but never otherwise.

Any outstanding I/O request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is %G_PRIORITY_DEFAULT.

Added in version 2.34.

Parameters:

count – the number of bytes that will be read from the stream
io_priority – the [I/O priority][io-priority] of the request
cancellable – optional Cancellable object, None to ignore.
callback – a AsyncReadyCallback to call when the request is satisfied
user_data – the data to pass to callback function

read_bytes_finish(result: AsyncResult) → Bytes

Finishes an asynchronous stream read-into-Bytes operation.

Added in version 2.34.

Parameters:: result – a AsyncResult.

read_finish(result: AsyncResult) → int

Finishes an asynchronous stream read operation.

Parameters:: result – a AsyncResult.

set_pending() → bool: Sets stream to have actions pending. If the pending flag is already set or stream is closed, it will return False and set error.

skip(count: int, cancellable: Cancellable | None = None) → int

Tries to skip count bytes from the stream. Will block during the operation.

This is identical to read(), from a behaviour standpoint, but the bytes that are skipped are not returned to the user. Some streams have an implementation that is more efficient than reading the data.

This function is optional for inherited classes, as the default implementation emulates it using read.

If cancellable is not None, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error CANCELLED will be returned. If an operation was partially finished when the operation was cancelled the partial result will be returned, without an error.

Parameters:

count – the number of bytes that will be skipped from the stream
cancellable – optional Cancellable object, None to ignore.

skip_async(count: int, io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) → None

Request an asynchronous skip of count bytes from the stream. When the operation is finished callback will be called. You can then call skip_finish() to get the result of the operation.

During an async request no other sync and async calls are allowed, and will result in PENDING errors.

A value of count larger than %G_MAXSSIZE will cause a INVALID_ARGUMENT error.

On success, the number of bytes skipped will be passed to the callback. It is not an error if this is not the same as the requested size, as it can happen e.g. near the end of a file, but generally we try to skip as many bytes as requested. Zero is returned on end of file (or if count is zero), but never otherwise.

Any outstanding i/o request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is %G_PRIORITY_DEFAULT.

The asynchronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one, you must override all.

Parameters:

count – the number of bytes that will be skipped from the stream
io_priority – the [I/O priority][io-priority] of the request
cancellable – optional Cancellable object, None to ignore.
callback – a AsyncReadyCallback to call when the request is satisfied
user_data – the data to pass to callback function

skip_finish(result: AsyncResult) → int

Finishes a stream skip operation.

Parameters:: result – a AsyncResult.

Virtual Methods

class InputStream

do_close_async(io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) → None

For behaviour details see close().

The asynchronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

io_priority – the [I/O priority][io-priority] of the request
cancellable – optional cancellable object
callback – a AsyncReadyCallback to call when the request is satisfied
user_data – the data to pass to callback function

do_close_finish(result: AsyncResult) → bool

Finishes closing a stream asynchronously, started from close_async().

Parameters:: result – a AsyncResult.

do_close_fn(cancellable: Cancellable | None = None) → bool

Parameters:: cancellable

do_read_async(io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) → bytes

During an async request no other sync and async calls are allowed on stream, and will result in PENDING errors.

A value of count larger than %G_MAXSSIZE will cause a INVALID_ARGUMENT error.

Any outstanding i/o request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is %G_PRIORITY_DEFAULT.

The asynchronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

io_priority – the [I/O priority][io-priority] of the request.
cancellable – optional Cancellable object, None to ignore.
callback – a AsyncReadyCallback to call when the request is satisfied
user_data – the data to pass to callback function

do_read_finish(result: AsyncResult) → int

Finishes an asynchronous stream read operation.

Parameters:: result – a AsyncResult.

do_read_fn(buffer: None, count: int, cancellable: Cancellable | None = None) → int

Parameters:

buffer
count
cancellable

do_skip(count: int, cancellable: Cancellable | None = None) → int

Tries to skip count bytes from the stream. Will block during the operation.

This function is optional for inherited classes, as the default implementation emulates it using read.

If cancellable is not None, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error CANCELLED will be returned. If an operation was partially finished when the operation was cancelled the partial result will be returned, without an error.

Parameters:

count – the number of bytes that will be skipped from the stream
cancellable – optional Cancellable object, None to ignore.

do_skip_async(count: int, io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) → None

Request an asynchronous skip of count bytes from the stream. When the operation is finished callback will be called. You can then call skip_finish() to get the result of the operation.

During an async request no other sync and async calls are allowed, and will result in PENDING errors.

A value of count larger than %G_MAXSSIZE will cause a INVALID_ARGUMENT error.

Any outstanding i/o request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is %G_PRIORITY_DEFAULT.

The asynchronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one, you must override all.

Parameters:

count – the number of bytes that will be skipped from the stream
io_priority – the [I/O priority][io-priority] of the request
cancellable – optional Cancellable object, None to ignore.
callback – a AsyncReadyCallback to call when the request is satisfied
user_data – the data to pass to callback function

do_skip_finish(result: AsyncResult) → int

Finishes a stream skip operation.

Parameters:: result – a AsyncResult.

Fields

class InputStream

parent_instance

priv