GLib.Bytes¶

Fields¶

None

Methods¶

class	`new` (data)
class	`new_take` (data)
	`compare` (bytes2)
	`equal` (bytes2)
	`get_data` ()
	`get_region` (element_size, offset, n_elements)
	`get_size` ()
	`hash` ()
	`new_from_bytes` (offset, length)
	`ref` ()
	`unref` ()
	`unref_to_array` ()
	`unref_to_data` ()

Details¶

class GLib.Bytes¶

A simple reference counted data type representing an immutable sequence of zero or more bytes from an unspecified origin.

The purpose of a GBytes is to keep the memory region that it holds alive for as long as anyone holds a reference to the bytes. When the last reference count is dropped, the memory is released. Multiple unrelated callers can use byte data in the GBytes without coordinating their activities, resting assured that the byte data will not change or move while they hold a reference.

A GBytes can come from many different origins that may have different procedures for freeing the memory region. Examples are memory from [func`GLib`.malloc], from memory slices, from a [struct`GLib`.MappedFile] or memory from other allocators.

GBytes work well as keys in [struct`GLib`.HashTable]. Use [method`GLib`.Bytes.equal] and [method`GLib`.Bytes.hash] as parameters to [func`GLib`.HashTable.new] or [func`GLib`.HashTable.new_full]. GBytes can also be used as keys in a [struct`GLib`.Tree] by passing the [method`GLib`.Bytes.compare] function to [ctor`GLib`.Tree.new].

The data pointed to by this bytes must not be modified. For a mutable array of bytes see [struct`GLib`.ByteArray]. Use [method`GLib`.Bytes.unref_to_array] to create a mutable array for a GBytes sequence. To create an immutable GBytes from a mutable [struct`GLib`.ByteArray], use the [func`GLib`.ByteArray.free_to_bytes] function.

New in version 2.32.

classmethod new(data)[source]¶

Parameters:: data (bytes or None) – the data to be used for the bytes
Returns:: a new [struct`GLib`.Bytes]
Return type:: GLib.Bytes

Creates a new [struct`GLib`.Bytes] from data.

data is copied. If size is 0, data may be NULL.

As an optimization, [ctor`GLib`.Bytes.new] may avoid an extra allocation by copying the data within the resulting bytes structure if sufficiently small (since GLib 2.84).

New in version 2.32.

classmethod new_take(data)[source]¶

Parameters:: data (bytes or None) – the data to be used for the bytes
Returns:: a new [struct`GLib`.Bytes]
Return type:: GLib.Bytes

Creates a new [struct`GLib`.Bytes] from data.

After this call, data belongs to the GBytes and may no longer be modified by the caller. The memory of data has to be dynamically allocated and will eventually be freed with [func`GLib`.free].

For creating GBytes with memory from other allocators, see [ctor`GLib`.Bytes.new_with_free_func].

data may be NULL if size is 0.

New in version 2.32.

compare(bytes2)[source]¶

Parameters:: bytes2 (GLib.Bytes) – a pointer to a [struct`GLib`.Bytes] to compare with self
Returns:: a negative value if self is less than bytes2, a positive value if self is greater than bytes2, and zero if self is equal to bytes2
Return type:: int

Compares the two [struct`GLib`.Bytes] values.

This function can be used to sort GBytes instances in lexicographical order.

If self and bytes2 have different length but the shorter one is a prefix of the longer one then the shorter one is considered to be less than the longer one. Otherwise the first byte where both differ is used for comparison. If self has a smaller value at that position it is considered less, otherwise greater than bytes2.

New in version 2.32.

equal(bytes2)[source]¶

Parameters:: bytes2 (GLib.Bytes) – a pointer to a [struct`GLib`.Bytes] to compare with self
Returns:: TRUE if the two keys match.
Return type:: bool

Compares the two [struct`GLib`.Bytes] values being pointed to and returns TRUE if they are equal.

This function can be passed to [func`GLib`.HashTable.new] as the key_equal_func parameter, when using non-NULL GBytes pointers as keys in a [struct`GLib`.HashTable].

New in version 2.32.

get_data()[source]¶

Returns:: a pointer to the byte data
Return type:: bytes or None

Get the byte data in the [struct`GLib`.Bytes].

This data should not be modified.

This function will always return the same pointer for a given GBytes.

NULL may be returned if size is 0. This is not guaranteed, as the GBytes may represent an empty string with data non-NULL and size as 0. NULL will not be returned if size is non-zero.

New in version 2.32.

get_region(element_size, offset, n_elements)[source]¶

Parameters:

element_size (int) – a non-zero element size
offset (int) – an offset to the start of the region within the self
n_elements (int) – the number of elements in the region

Returns:

the requested region, or NULL in case of an error

Return type:

object or None

Gets a pointer to a region in self.

The region starts at offset many bytes from the start of the data and contains n_elements many elements of element_size size.

n_elements may be zero, but element_size must always be non-zero. Ideally, element_size is a static constant (eg: sizeof a struct).

This function does careful bounds checking (including checking for arithmetic overflows) and returns a non-NULL pointer if the specified region lies entirely within the self. If the region is in some way out of range, or if an overflow has occurred, then NULL is returned.

Note: it is possible to have a valid zero-size region. In this case, the returned pointer will be equal to the base pointer of the data of self, plus offset. This will be non-NULL except for the case where self itself was a zero-sized region. Since it is unlikely that you will be using this function to check for a zero-sized region in a zero-sized self, NULL effectively always means ‘error’.

New in version 2.70.

get_size()[source]¶

Returns:: the size
Return type:: int

Get the size of the byte data in the [struct`GLib`.Bytes].

This function will always return the same value for a given GBytes.

New in version 2.32.

hash()[source]¶

Returns:: a hash value corresponding to the key.
Return type:: int

Creates an integer hash code for the byte data in the [struct`GLib`.Bytes].

This function can be passed to [func`GLib`.HashTable.new] as the key_hash_func parameter, when using non-NULL GBytes pointers as keys in a [struct`GLib`.HashTable].

New in version 2.32.

new_from_bytes(offset, length)[source]¶

Parameters:

offset (int) – offset which subsection starts at
length (int) – length of subsection

Returns:

a new [struct`GLib`.Bytes]

Return type:

GLib.Bytes

Creates a [struct`GLib`.Bytes] which is a subsection of another GBytes.

The offset + length may not be longer than the size of self.

A reference to self will be held by the newly created GBytes until the byte data is no longer needed.

Since 2.56, if offset is 0 and length matches the size of self, then self will be returned with the reference count incremented by 1. If self is a slice of another GBytes, then the resulting GBytes will reference the same GBytes instead of self. This allows consumers to simplify the usage of GBytes when asynchronously writing to streams.

New in version 2.32.

ref()[source]¶

Returns:: the [struct`GLib`.Bytes]
Return type:: GLib.Bytes

Increase the reference count on self.

New in version 2.32.

unref()[source]¶

Releases a reference on self.

This may result in the bytes being freed. If self is NULL, it will return immediately.

New in version 2.32.

unref_to_array()[source]¶

Returns:: a new mutable [struct`GLib`.ByteArray] containing the same byte data
Return type:: bytes

Unreferences the bytes, and returns a new mutable [struct`GLib`.ByteArray] containing the same byte data.

As an optimization, the byte data is transferred to the array without copying if this was the last reference to self and self was created with [ctor`GLib`.Bytes.new], [ctor`GLib`.Bytes.new_take] or [func`GLib`.ByteArray.free_to_bytes] and the buffer was larger than the size [struct`GLib`.Bytes] may internalize within its allocation. In all other cases the data is copied.

Do not use it if self contains more than %G_MAXUINT bytes. [struct`GLib`.ByteArray] stores the length of its data in guint, which may be shorter than gsize, that self is using.

New in version 2.32.

unref_to_data()[source]¶

Returns:: a pointer to the same byte data, which should be freed with [func`GLib`.free]
Return type:: bytes

Unreferences the bytes, and returns a pointer the same byte data contents.

As an optimization, the byte data is returned without copying if this was the last reference to self and self was created with [ctor`GLib`.Bytes.new], [ctor`GLib`.Bytes.new_take] or [func`GLib`.ByteArray.free_to_bytes] and the buffer was larger than the size [struct`GLib`.Bytes] may internalize within its allocation. In all other cases the data is copied.

New in version 2.32.