Byte Arrays

Byte Arrays — arrays of bytes

Synopsis

#include <glib.h>

struct              GByteArray;
GByteArray *        g_byte_array_new                    (void);
GByteArray *        g_byte_array_new_take               (guint8 *data,
                                                         gsize len);
GByteArray *        g_byte_array_sized_new              (guint reserved_size);
GByteArray *        g_byte_array_ref                    (GByteArray *array);
void                g_byte_array_unref                  (GByteArray *array);
GByteArray *        g_byte_array_append                 (GByteArray *array,
                                                         const guint8 *data,
                                                         guint len);
GByteArray *        g_byte_array_prepend                (GByteArray *array,
                                                         const guint8 *data,
                                                         guint len);
GByteArray *        g_byte_array_remove_index           (GByteArray *array,
                                                         guint index_);
GByteArray *        g_byte_array_remove_index_fast      (GByteArray *array,
                                                         guint index_);
GByteArray *        g_byte_array_remove_range           (GByteArray *array,
                                                         guint index_,
                                                         guint length);
void                g_byte_array_sort                   (GByteArray *array,
                                                         GCompareFunc compare_func);
void                g_byte_array_sort_with_data         (GByteArray *array,
                                                         GCompareDataFunc compare_func,
                                                         gpointer user_data);
GByteArray *        g_byte_array_set_size               (GByteArray *array,
                                                         guint length);
guint8 *            g_byte_array_free                   (GByteArray *array,
                                                         gboolean free_segment);
GBytes *            g_byte_array_free_to_bytes          (GByteArray *array);

                    GBytes;
GBytes *            g_bytes_new                         (gconstpointer data,
                                                         gsize size);
GBytes *            g_bytes_new_take                    (gpointer data,
                                                         gsize size);
GBytes *            g_bytes_new_static                  (gconstpointer data,
                                                         gsize size);
GBytes *            g_bytes_new_with_free_func          (gconstpointer data,
                                                         gsize size,
                                                         GDestroyNotify free_func,
                                                         gpointer user_data);
GBytes *            g_bytes_new_from_bytes              (GBytes *bytes,
                                                         gsize offset,
                                                         gsize length);
gconstpointer       g_bytes_get_data                    (GBytes *bytes,
                                                         gsize *size);
gsize               g_bytes_get_size                    (GBytes *bytes);
guint               g_bytes_hash                        (gconstpointer bytes);
gboolean            g_bytes_equal                       (gconstpointer bytes1,
                                                         gconstpointer bytes2);
gint                g_bytes_compare                     (gconstpointer bytes1,
                                                         gconstpointer bytes2);
GBytes *            g_bytes_ref                         (GBytes *bytes);
void                g_bytes_unref                       (GBytes *bytes);
gpointer            g_bytes_unref_to_data               (GBytes *bytes,
                                                         gsize *size);
GByteArray *        g_bytes_unref_to_array              (GBytes *bytes);

Description

GByteArray is a mutable array of bytes based on GArray, to provide arrays of bytes which grow automatically as elements are added.

To create a new GByteArray use g_byte_array_new(). To add elements to a GByteArray, use g_byte_array_append(), and g_byte_array_prepend().

To set the size of a GByteArray, use g_byte_array_set_size().

To free a GByteArray, use g_byte_array_free().

Example 16. Using a GByteArray

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GByteArray *gbarray;
  gint i;

  gbarray = g_byte_array_new ();
  for (i = 0; i < 10000; i++)
    g_byte_array_append (gbarray, (guint8*) "abcd", 4);

  for (i = 0; i < 10000; i++)
    {
      g_assert (gbarray->data[4*i] == 'a');
      g_assert (gbarray->data[4*i+1] == 'b');
      g_assert (gbarray->data[4*i+2] == 'c');
      g_assert (gbarray->data[4*i+3] == 'd');
    }

  g_byte_array_free (gbarray, TRUE);


See GBytes if you are interested in an immutable object representing a sequence of bytes.

Details

struct GByteArray

struct GByteArray {
  guint8 *data;
  guint	  len;
};

The GByteArray struct allows access to the public fields of a GByteArray.

guint8 *data;

a pointer to the element data. The data may be moved as elements are added to the GByteArray.

guint len;

the number of elements in the GByteArray.

g_byte_array_new ()

GByteArray *        g_byte_array_new                    (void);

Creates a new GByteArray with a reference count of 1.

Returns :

the new GByteArray. [transfer full]

g_byte_array_new_take ()

GByteArray *        g_byte_array_new_take               (guint8 *data,
                                                         gsize len);

Create byte array containing the data. The data will be owned by the array and will be freed with g_free(), i.e. it could be allocated using g_strdup().

data :

byte data for the array. [transfer full][array length=len]

len :

length of data

Returns :

a new GByteArray. [transfer full]

Since 2.32


g_byte_array_sized_new ()

GByteArray *        g_byte_array_sized_new              (guint reserved_size);

Creates a new GByteArray with reserved_size bytes preallocated. This avoids frequent reallocation, if you are going to add many bytes to the array. Note however that the size of the array is still 0.

reserved_size :

number of bytes preallocated.

Returns :

the new GByteArray.

g_byte_array_ref ()

GByteArray *        g_byte_array_ref                    (GByteArray *array);

Atomically increments the reference count of array by one. This function is MT-safe and may be called from any thread.

array :

A GByteArray.

Returns :

The passed in GByteArray.

Since 2.22


g_byte_array_unref ()

void                g_byte_array_unref                  (GByteArray *array);

Atomically decrements the reference count of array by one. If the reference count drops to 0, all memory allocated by the array is released. This function is MT-safe and may be called from any thread.

array :

A GByteArray.

Since 2.22


g_byte_array_append ()

GByteArray *        g_byte_array_append                 (GByteArray *array,
                                                         const guint8 *data,
                                                         guint len);

Adds the given bytes to the end of the GByteArray. The array will grow in size automatically if necessary.

array :

a GByteArray.

data :

the byte data to be added.

len :

the number of bytes to add.

Returns :

the GByteArray.

g_byte_array_prepend ()

GByteArray *        g_byte_array_prepend                (GByteArray *array,
                                                         const guint8 *data,
                                                         guint len);

Adds the given data to the start of the GByteArray. The array will grow in size automatically if necessary.

array :

a GByteArray.

data :

the byte data to be added.

len :

the number of bytes to add.

Returns :

the GByteArray.

g_byte_array_remove_index ()

GByteArray *        g_byte_array_remove_index           (GByteArray *array,
                                                         guint index_);

Removes the byte at the given index from a GByteArray. The following bytes are moved down one place.

array :

a GByteArray.

index_ :

the index of the byte to remove.

Returns :

the GByteArray.

g_byte_array_remove_index_fast ()

GByteArray *        g_byte_array_remove_index_fast      (GByteArray *array,
                                                         guint index_);

Removes the byte at the given index from a GByteArray. The last element in the array is used to fill in the space, so this function does not preserve the order of the GByteArray. But it is faster than g_byte_array_remove_index().

array :

a GByteArray.

index_ :

the index of the byte to remove.

Returns :

the GByteArray.

g_byte_array_remove_range ()

GByteArray *        g_byte_array_remove_range           (GByteArray *array,
                                                         guint index_,
                                                         guint length);

Removes the given number of bytes starting at the given index from a GByteArray. The following elements are moved to close the gap.

array :

a GByteArray.

index_ :

the index of the first byte to remove.

length :

the number of bytes to remove.

Returns :

the GByteArray.

Since 2.4


g_byte_array_sort ()

void                g_byte_array_sort                   (GByteArray *array,
                                                         GCompareFunc compare_func);

Sorts a byte array, using compare_func which should be a qsort()-style comparison function (returns less than zero for first arg is less than second arg, zero for equal, greater than zero if first arg is greater than second arg).

If two array elements compare equal, their order in the sorted array is undefined. If you want equal elements to keep their order (i.e. you want a stable sort) you can write a comparison function that, if two elements would otherwise compare equal, compares them by their addresses.

array :

a GByteArray.

compare_func :

comparison function.

g_byte_array_sort_with_data ()

void                g_byte_array_sort_with_data         (GByteArray *array,
                                                         GCompareDataFunc compare_func,
                                                         gpointer user_data);

Like g_byte_array_sort(), but the comparison function takes an extra user data argument.

array :

a GByteArray.

compare_func :

comparison function.

user_data :

data to pass to compare_func.

g_byte_array_set_size ()

GByteArray *        g_byte_array_set_size               (GByteArray *array,
                                                         guint length);

Sets the size of the GByteArray, expanding it if necessary.

array :

a GByteArray.

length :

the new size of the GByteArray.

Returns :

the GByteArray.

g_byte_array_free ()

guint8 *            g_byte_array_free                   (GByteArray *array,
                                                         gboolean free_segment);

Frees the memory allocated by the GByteArray. If free_segment is TRUE it frees the actual byte data. If the reference count of array is greater than one, the GByteArray wrapper is preserved but the size of array will be set to zero.

array :

a GByteArray.

free_segment :

if TRUE the actual byte data is freed as well.

Returns :

the element data if free_segment is FALSE, otherwise NULL. The element data should be freed using g_free().

g_byte_array_free_to_bytes ()

GBytes *            g_byte_array_free_to_bytes          (GByteArray *array);

Transfers the data from the GByteArray into a new immutable GBytes.

The GByteArray is freed unless the reference count of array is greater than one, the GByteArray wrapper is preserved but the size of array will be set to zero.

This is identical to using g_bytes_new_take() and g_byte_array_free() together.

array :

a GByteArray. [transfer full]

Returns :

a new immutable GBytes representing same byte data that was in the array. [transfer full]

Since 2.32


GBytes

typedef struct _GBytes GBytes;

A simple refcounted data type representing an immutable byte sequence 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 g_malloc(), from memory slices, from a GMappedFile or memory from other allocators.

GBytes work well as keys in GHashTable. Use g_bytes_equal() and g_bytes_hash() as parameters to g_hash_table_new() or g_hash_table_new_full(). GBytes can also be used as keys in a GTree by passing the g_bytes_compare() function to g_tree_new().

The data pointed to by this bytes must not be modified. For a mutable array of bytes see GByteArray. Use g_bytes_unref_to_array() to create a mutable array for a GBytes sequence. To create an immutable GBytes from a mutable GByteArray, use the g_byte_array_free_to_bytes() function.

Since 2.32


g_bytes_new ()

GBytes *            g_bytes_new                         (gconstpointer data,
                                                         gsize size);

Creates a new GBytes from data.

data is copied.

data :

the data to be used for the bytes. [transfer none][array length=size][element-type guint8]

size :

the size of data

Returns :

a new GBytes. [transfer full]

Since 2.32


g_bytes_new_take ()

GBytes *            g_bytes_new_take                    (gpointer data,
                                                         gsize size);

Creates a new GBytes from data.

After this call, data belongs to the bytes and may no longer be modified by the caller. g_free() will be called on data when the bytes is no longer in use. Because of this data must have been created by a call to g_malloc(), g_malloc0() or g_realloc() or by one of the many functions that wrap these calls (such as g_new(), g_strdup(), etc).

For creating GBytes with memory from other allocators, see g_bytes_new_with_free_func().

data :

the data to be used for the bytes. [transfer full][array length=size][element-type guint8]

size :

the size of data

Returns :

a new GBytes. [transfer full]

Since 2.32


g_bytes_new_static ()

GBytes *            g_bytes_new_static                  (gconstpointer data,
                                                         gsize size);

Creates a new GBytes from static data.

data must be static (ie: never modified or freed).

data :

the data to be used for the bytes. [transfer full][array length=size][element-type guint8]

size :

the size of data

Returns :

a new GBytes. [transfer full]

Since 2.32


g_bytes_new_with_free_func ()

GBytes *            g_bytes_new_with_free_func          (gconstpointer data,
                                                         gsize size,
                                                         GDestroyNotify free_func,
                                                         gpointer user_data);

Creates a GBytes from data.

When the last reference is dropped, free_func will be called with the user_data argument.

data must not be modified after this call is made until free_func has been called to indicate that the bytes is no longer in use.

data :

the data to be used for the bytes. [array length=size]

size :

the size of data

free_func :

the function to call to release the data

user_data :

data to pass to free_func

Returns :

a new GBytes. [transfer full]

Since 2.32


g_bytes_new_from_bytes ()

GBytes *            g_bytes_new_from_bytes              (GBytes *bytes,
                                                         gsize offset,
                                                         gsize length);

Creates a GBytes which is a subsection of another GBytes. The offset + length may not be longer than the size of bytes.

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

bytes :

a GBytes

offset :

offset which subsection starts at

length :

length of subsection

Returns :

a new GBytes. [transfer full]

Since 2.32


g_bytes_get_data ()

gconstpointer       g_bytes_get_data                    (GBytes *bytes,
                                                         gsize *size);

Get the byte data in the GBytes. This data should not be modified.

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

bytes :

a GBytes

size :

location to return size of byte data. [out][allow-none]

Returns :

a pointer to the byte data. [transfer none][array length=size][type guint8]

Since 2.32


g_bytes_get_size ()

gsize               g_bytes_get_size                    (GBytes *bytes);

Get the size of the byte data in the GBytes.

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

bytes :

a GBytes

Returns :

the size

Since 2.32


g_bytes_hash ()

guint               g_bytes_hash                        (gconstpointer bytes);

Creates an integer hash code for the byte data in the GBytes.

This function can be passed to g_hash_table_new() as the key_equal_func parameter, when using non-NULL GBytes pointers as keys in a GHashTable.

bytes :

a pointer to a GBytes key. [type GLib.Bytes]

Returns :

a hash value corresponding to the key.

Since 2.32


g_bytes_equal ()

gboolean            g_bytes_equal                       (gconstpointer bytes1,
                                                         gconstpointer bytes2);

Compares the two GBytes values being pointed to and returns TRUE if they are equal.

This function can be passed to g_hash_table_new() as the key_equal_func parameter, when using non-NULL GBytes pointers as keys in a GHashTable.

bytes1 :

a pointer to a GBytes. [type GLib.Bytes]

bytes2 :

a pointer to a GBytes to compare with bytes1. [type GLib.Bytes]

Returns :

TRUE if the two keys match.

Since 2.32


g_bytes_compare ()

gint                g_bytes_compare                     (gconstpointer bytes1,
                                                         gconstpointer bytes2);

Compares the two GBytes values.

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

bytes1 :

a pointer to a GBytes. [type GLib.Bytes]

bytes2 :

a pointer to a GBytes to compare with bytes1. [type GLib.Bytes]

Returns :

a negative value if bytes2 is lesser, a positive value if bytes2 is greater, and zero if bytes2 is equal to bytes1

Since 2.32


g_bytes_ref ()

GBytes *            g_bytes_ref                         (GBytes *bytes);

Increase the reference count on bytes.

bytes :

a GBytes

Returns :

the GBytes

Since 2.32


g_bytes_unref ()

void                g_bytes_unref                       (GBytes *bytes);

Releases a reference on bytes. This may result in the bytes being freed.

bytes :

a GBytes. [allow-none]

Since 2.32


g_bytes_unref_to_data ()

gpointer            g_bytes_unref_to_data               (GBytes *bytes,
                                                         gsize *size);

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 bytes and bytes was created with g_bytes_new(), g_bytes_new_take() or g_byte_array_free_to_bytes(). In all other cases the data is copied.

bytes :

a GBytes. [transfer full]

size :

location to place the length of the returned data

Returns :

a pointer to the same byte data, which should be freed with g_free(). [transfer full]

Since 2.32


g_bytes_unref_to_array ()

GByteArray *        g_bytes_unref_to_array              (GBytes *bytes);

Unreferences the bytes, and returns a new mutable GByteArray 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 bytes and bytes was created with g_bytes_new(), g_bytes_new_take() or g_byte_array_free_to_bytes(). In all other cases the data is copied.

bytes :

a GBytes. [transfer full]

Returns :

a new mutable GByteArray containing the same byte data. [transfer full]

Since 2.32