2 * Copyright © 2009, 2010 Codethink Limited
3 * Copyright © 2011 Collabora Ltd.
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the licence, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 * Boston, MA 02111-1307, USA.
20 * Author: Ryan Lortie <desrt@desrt.ca>
21 * Stef Walter <stefw@collabora.co.uk>
28 #include <glib/garray.h>
29 #include <glib/gstrfuncs.h>
30 #include <glib/gatomic.h>
31 #include <glib/gslice.h>
32 #include <glib/gtestutils.h>
33 #include <glib/gmem.h>
34 #include <glib/gmessages.h>
41 * A simple refcounted data type representing an immutable sequence of zero or
42 * more bytes from an unspecified origin.
44 * The purpose of a #GBytes is to keep the memory region that it holds
45 * alive for as long as anyone holds a reference to the bytes. When
46 * the last reference count is dropped, the memory is released. Multiple
47 * unrelated callers can use byte data in the #GBytes without coordinating
48 * their activities, resting assured that the byte data will not change or
49 * move while they hold a reference.
51 * A #GBytes can come from many different origins that may have
52 * different procedures for freeing the memory region. Examples are
53 * memory from g_malloc(), from memory slices, from a #GMappedFile or
54 * memory from other allocators.
56 * #GBytes work well as keys in #GHashTable. Use g_bytes_equal() and
57 * g_bytes_hash() as parameters to g_hash_table_new() or g_hash_table_new_full().
58 * #GBytes can also be used as keys in a #GTree by passing the g_bytes_compare()
59 * function to g_tree_new().
61 * The data pointed to by this bytes must not be modified. For a mutable
62 * array of bytes see #GByteArray. Use g_bytes_unref_to_array() to create a
63 * mutable array for a #GBytes sequence. To create an immutable #GBytes from
64 * a mutable #GByteArray, use the g_byte_array_free_to_bytes() function.
71 gconstpointer data; /* may be NULL iff (size == 0) */
72 gsize size; /* may be 0 */
74 GDestroyNotify free_func;
80 * @data: (transfer none) (array length=size) (element-type guint8) (allow-none):
81 * the data to be used for the bytes
82 * @size: the size of @data
84 * Creates a new #GBytes from @data.
86 * @data is copied. If @size is 0, @data may be %NULL.
88 * Returns: (transfer full): a new #GBytes
93 g_bytes_new (gconstpointer data,
96 g_return_val_if_fail (data != NULL || size == 0, NULL);
98 return g_bytes_new_take (g_memdup (data, size), size);
103 * @data: (transfer full) (array length=size) (element-type guint8) (allow-none):
104 the data to be used for the bytes
105 * @size: the size of @data
107 * Creates a new #GBytes from @data.
109 * After this call, @data belongs to the bytes and may no longer be
110 * modified by the caller. g_free() will be called on @data when the
111 * bytes is no longer in use. Because of this @data must have been created by
112 * a call to g_malloc(), g_malloc0() or g_realloc() or by one of the many
113 * functions that wrap these calls (such as g_new(), g_strdup(), etc).
115 * For creating #GBytes with memory from other allocators, see
116 * g_bytes_new_with_free_func().
118 * @data may be %NULL if @size is 0.
120 * Returns: (transfer full): a new #GBytes
125 g_bytes_new_take (gpointer data,
128 return g_bytes_new_with_free_func (data, size, g_free, data);
133 * g_bytes_new_static: (skip)
134 * @data: (transfer full) (array length=size) (element-type guint8) (allow-none):
135 the data to be used for the bytes
136 * @size: the size of @data
138 * Creates a new #GBytes from static data.
140 * @data must be static (ie: never modified or freed). It may be %NULL if @size
143 * Returns: (transfer full): a new #GBytes
148 g_bytes_new_static (gconstpointer data,
151 return g_bytes_new_with_free_func (data, size, NULL, NULL);
155 * g_bytes_new_with_free_func:
156 * @data: (array length=size) (allow-none): the data to be used for the bytes
157 * @size: the size of @data
158 * @free_func: the function to call to release the data
159 * @user_data: data to pass to @free_func
161 * Creates a #GBytes from @data.
163 * When the last reference is dropped, @free_func will be called with the
164 * @user_data argument.
166 * @data must not be modified after this call is made until @free_func has
167 * been called to indicate that the bytes is no longer in use.
169 * @data may be %NULL if @size is 0.
171 * Returns: (transfer full): a new #GBytes
176 g_bytes_new_with_free_func (gconstpointer data,
178 GDestroyNotify free_func,
183 g_return_val_if_fail (data != NULL || size == 0, NULL);
185 bytes = g_slice_new (GBytes);
188 bytes->free_func = free_func;
189 bytes->user_data = user_data;
190 bytes->ref_count = 1;
192 return (GBytes *)bytes;
196 * g_bytes_new_from_bytes:
198 * @offset: offset which subsection starts at
199 * @length: length of subsection
201 * Creates a #GBytes which is a subsection of another #GBytes. The @offset +
202 * @length may not be longer than the size of @bytes.
204 * A reference to @bytes will be held by the newly created #GBytes until
205 * the byte data is no longer needed.
207 * Returns: (transfer full): a new #GBytes
212 g_bytes_new_from_bytes (GBytes *bytes,
216 /* Note that length may be 0. */
217 g_return_val_if_fail (bytes != NULL, NULL);
218 g_return_val_if_fail (offset <= bytes->size, NULL);
219 g_return_val_if_fail (offset + length <= bytes->size, NULL);
221 return g_bytes_new_with_free_func ((gchar *)bytes->data + offset, length,
222 (GDestroyNotify)g_bytes_unref, g_bytes_ref (bytes));
228 * @size: (out) (allow-none): location to return size of byte data
230 * Get the byte data in the #GBytes. This data should not be modified.
232 * This function will always return the same pointer for a given #GBytes.
234 * %NULL may be returned if @size is 0. This is not guaranteed, as the #GBytes
235 * may represent an empty string with @data non-%NULL and @size as 0. %NULL will
236 * not be returned if @size is non-zero.
238 * Returns: (transfer none) (array length=size) (type guint8) (allow-none): a pointer to the
239 * byte data, or %NULL
244 g_bytes_get_data (GBytes *bytes,
247 g_return_val_if_fail (bytes != NULL, NULL);
257 * Get the size of the byte data in the #GBytes.
259 * This function will always return the same value for a given #GBytes.
266 g_bytes_get_size (GBytes *bytes)
268 g_return_val_if_fail (bytes != NULL, 0);
277 * Increase the reference count on @bytes.
279 * Returns: the #GBytes
284 g_bytes_ref (GBytes *bytes)
286 g_return_val_if_fail (bytes != NULL, NULL);
288 g_atomic_int_inc (&bytes->ref_count);
295 * @bytes: (allow-none): a #GBytes
297 * Releases a reference on @bytes. This may result in the bytes being
303 g_bytes_unref (GBytes *bytes)
308 if (g_atomic_int_dec_and_test (&bytes->ref_count))
310 if (bytes->free_func != NULL)
311 bytes->free_func (bytes->user_data);
312 g_slice_free (GBytes, bytes);
318 * @bytes1: (type GLib.Bytes): a pointer to a #GBytes
319 * @bytes2: (type GLib.Bytes): a pointer to a #GBytes to compare with @bytes1
321 * Compares the two #GBytes values being pointed to and returns
322 * %TRUE if they are equal.
324 * This function can be passed to g_hash_table_new() as the @key_equal_func
325 * parameter, when using non-%NULL #GBytes pointers as keys in a #GHashTable.
327 * Returns: %TRUE if the two keys match.
332 g_bytes_equal (gconstpointer bytes1,
333 gconstpointer bytes2)
335 const GBytes *b1 = bytes1;
336 const GBytes *b2 = bytes2;
338 g_return_val_if_fail (bytes1 != NULL, FALSE);
339 g_return_val_if_fail (bytes2 != NULL, FALSE);
341 return b1->size == b2->size &&
342 memcmp (b1->data, b2->data, b1->size) == 0;
347 * @bytes: (type GLib.Bytes): a pointer to a #GBytes key
349 * Creates an integer hash code for the byte data in the #GBytes.
351 * This function can be passed to g_hash_table_new() as the @key_equal_func
352 * parameter, when using non-%NULL #GBytes pointers as keys in a #GHashTable.
354 * Returns: a hash value corresponding to the key.
359 g_bytes_hash (gconstpointer bytes)
361 const GBytes *a = bytes;
362 const signed char *p, *e;
365 g_return_val_if_fail (bytes != NULL, 0);
367 for (p = (signed char *)a->data, e = (signed char *)a->data + a->size; p != e; p++)
368 h = (h << 5) + h + *p;
375 * @bytes1: (type GLib.Bytes): a pointer to a #GBytes
376 * @bytes2: (type GLib.Bytes): a pointer to a #GBytes to compare with @bytes1
378 * Compares the two #GBytes values.
380 * This function can be used to sort GBytes instances in lexographical order.
382 * Returns: a negative value if bytes2 is lesser, a positive value if bytes2 is
383 * greater, and zero if bytes2 is equal to bytes1
388 g_bytes_compare (gconstpointer bytes1,
389 gconstpointer bytes2)
391 const GBytes *b1 = bytes1;
392 const GBytes *b2 = bytes2;
395 g_return_val_if_fail (bytes1 != NULL, 0);
396 g_return_val_if_fail (bytes2 != NULL, 0);
398 ret = memcmp (b1->data, b2->data, MIN (b1->size, b2->size));
399 if (ret == 0 && b1->size != b2->size)
400 ret = b1->size < b2->size ? -1 : 1;
405 try_steal_and_unref (GBytes *bytes,
406 GDestroyNotify free_func,
411 if (bytes->free_func != free_func || bytes->data == NULL)
414 /* Are we the only reference? */
415 if (g_atomic_int_get (&bytes->ref_count) == 1)
418 result = (gpointer)bytes->data;
419 g_slice_free (GBytes, bytes);
428 * g_bytes_unref_to_data:
429 * @bytes: (transfer full): a #GBytes
430 * @size: location to place the length of the returned data
432 * Unreferences the bytes, and returns a pointer the same byte data
435 * As an optimization, the byte data is returned without copying if this was
436 * the last reference to bytes and bytes was created with g_bytes_new(),
437 * g_bytes_new_take() or g_byte_array_free_to_bytes(). In all other cases the
440 * Returns: (transfer full): a pointer to the same byte data, which should
441 * be freed with g_free()
446 g_bytes_unref_to_data (GBytes *bytes,
451 g_return_val_if_fail (bytes != NULL, NULL);
452 g_return_val_if_fail (size != NULL, NULL);
455 * Optimal path: if this is was the last reference, then we can return
456 * the data from this GBytes without copying.
459 result = try_steal_and_unref (bytes, g_free, size);
463 * Copy: Non g_malloc (or compatible) allocator, or static memory,
464 * so we have to copy, and then unref.
466 result = g_memdup (bytes->data, bytes->size);
468 g_bytes_unref (bytes);
475 * g_bytes_unref_to_array:
476 * @bytes: (transfer full): a #GBytes
478 * Unreferences the bytes, and returns a new mutable #GByteArray containing
479 * the same byte data.
481 * As an optimization, the byte data is transferred to the array without copying
482 * if this was the last reference to bytes and bytes was created with
483 * g_bytes_new(), g_bytes_new_take() or g_byte_array_free_to_bytes(). In all
484 * other cases the data is copied.
486 * Returns: (transfer full): a new mutable #GByteArray containing the same byte data
491 g_bytes_unref_to_array (GBytes *bytes)
496 g_return_val_if_fail (bytes != NULL, NULL);
498 data = g_bytes_unref_to_data (bytes, &size);
499 return g_byte_array_new_take (data, size);