2 * Copyright © 2009, 2010 Codethink Limited
3 * Copyright © 2011 Collabora Ltd.
5 * SPDX-License-Identifier: LGPL-2.1-or-later
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
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>
35 #include <glib/grefcount.h>
42 * A simple refcounted data type representing an immutable sequence of zero or
43 * more bytes from an unspecified origin.
45 * The purpose of a #GBytes is to keep the memory region that it holds
46 * alive for as long as anyone holds a reference to the bytes. When
47 * the last reference count is dropped, the memory is released. Multiple
48 * unrelated callers can use byte data in the #GBytes without coordinating
49 * their activities, resting assured that the byte data will not change or
50 * move while they hold a reference.
52 * A #GBytes can come from many different origins that may have
53 * different procedures for freeing the memory region. Examples are
54 * memory from g_malloc(), from memory slices, from a #GMappedFile or
55 * memory from other allocators.
57 * #GBytes work well as keys in #GHashTable. Use g_bytes_equal() and
58 * g_bytes_hash() as parameters to g_hash_table_new() or g_hash_table_new_full().
59 * #GBytes can also be used as keys in a #GTree by passing the g_bytes_compare()
60 * function to g_tree_new().
62 * The data pointed to by this bytes must not be modified. For a mutable
63 * array of bytes see #GByteArray. Use g_bytes_unref_to_array() to create a
64 * mutable array for a #GBytes sequence. To create an immutable #GBytes from
65 * a mutable #GByteArray, use the g_byte_array_free_to_bytes() function.
70 /* Keep in sync with glib/tests/bytes.c */
73 gconstpointer data; /* may be NULL iff (size == 0) */
74 gsize size; /* may be 0 */
75 gatomicrefcount ref_count;
76 GDestroyNotify free_func;
82 * @data: (transfer none) (array length=size) (element-type guint8) (nullable):
83 * the data to be used for the bytes
84 * @size: the size of @data
86 * Creates a new #GBytes from @data.
88 * @data is copied. If @size is 0, @data may be %NULL.
90 * Returns: (transfer full): a new #GBytes
95 g_bytes_new (gconstpointer data,
98 g_return_val_if_fail (data != NULL || size == 0, NULL);
100 return g_bytes_new_take (g_memdup2 (data, size), size);
105 * @data: (transfer full) (array length=size) (element-type guint8) (nullable):
106 * the data to be used for the bytes
107 * @size: the size of @data
109 * Creates a new #GBytes from @data.
111 * After this call, @data belongs to the #GBytes and may no longer be
112 * modified by the caller. The memory of @data has to be dynamically
113 * allocated and will eventually be freed with g_free().
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) (nullable):
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: (skip)
156 * @data: (array length=size) (element-type guint8) (nullable):
157 * the data to be used for the bytes
158 * @size: the size of @data
159 * @free_func: the function to call to release the data
160 * @user_data: data to pass to @free_func
162 * Creates a #GBytes from @data.
164 * When the last reference is dropped, @free_func will be called with the
165 * @user_data argument.
167 * @data must not be modified after this call is made until @free_func has
168 * been called to indicate that the bytes is no longer in use.
170 * @data may be %NULL if @size is 0.
172 * Returns: (transfer full): a new #GBytes
177 g_bytes_new_with_free_func (gconstpointer data,
179 GDestroyNotify free_func,
184 g_return_val_if_fail (data != NULL || size == 0, NULL);
186 bytes = g_slice_new (GBytes);
189 bytes->free_func = free_func;
190 bytes->user_data = user_data;
191 g_atomic_ref_count_init (&bytes->ref_count);
193 return (GBytes *)bytes;
197 * g_bytes_new_from_bytes:
199 * @offset: offset which subsection starts at
200 * @length: length of subsection
202 * Creates a #GBytes which is a subsection of another #GBytes. The @offset +
203 * @length may not be longer than the size of @bytes.
205 * A reference to @bytes will be held by the newly created #GBytes until
206 * the byte data is no longer needed.
208 * Since 2.56, if @offset is 0 and @length matches the size of @bytes, then
209 * @bytes will be returned with the reference count incremented by 1. If @bytes
210 * is a slice of another #GBytes, then the resulting #GBytes will reference
211 * the same #GBytes instead of @bytes. This allows consumers to simplify the
212 * usage of #GBytes when asynchronously writing to streams.
214 * Returns: (transfer full): a new #GBytes
219 g_bytes_new_from_bytes (GBytes *bytes,
225 /* Note that length may be 0. */
226 g_return_val_if_fail (bytes != NULL, NULL);
227 g_return_val_if_fail (offset <= bytes->size, NULL);
228 g_return_val_if_fail (offset + length <= bytes->size, NULL);
230 /* Avoid an extra GBytes if all bytes were requested */
231 if (offset == 0 && length == bytes->size)
232 return g_bytes_ref (bytes);
234 base = (gchar *)bytes->data + offset;
236 /* Avoid referencing intermediate GBytes. In practice, this should
239 while (bytes->free_func == (gpointer)g_bytes_unref)
240 bytes = bytes->user_data;
242 g_return_val_if_fail (bytes != NULL, NULL);
243 g_return_val_if_fail (base >= (gchar *)bytes->data, NULL);
244 g_return_val_if_fail (base <= (gchar *)bytes->data + bytes->size, NULL);
245 g_return_val_if_fail (base + length <= (gchar *)bytes->data + bytes->size, NULL);
247 return g_bytes_new_with_free_func (base, length,
248 (GDestroyNotify)g_bytes_unref, g_bytes_ref (bytes));
254 * @size: (out) (optional): location to return size of byte data
256 * Get the byte data in the #GBytes. This data should not be modified.
258 * This function will always return the same pointer for a given #GBytes.
260 * %NULL may be returned if @size is 0. This is not guaranteed, as the #GBytes
261 * may represent an empty string with @data non-%NULL and @size as 0. %NULL will
262 * not be returned if @size is non-zero.
264 * Returns: (transfer none) (array length=size) (element-type guint8) (nullable):
265 * a pointer to the byte data, or %NULL
270 g_bytes_get_data (GBytes *bytes,
273 g_return_val_if_fail (bytes != NULL, NULL);
283 * Get the size of the byte data in the #GBytes.
285 * This function will always return the same value for a given #GBytes.
292 g_bytes_get_size (GBytes *bytes)
294 g_return_val_if_fail (bytes != NULL, 0);
303 * Increase the reference count on @bytes.
305 * Returns: the #GBytes
310 g_bytes_ref (GBytes *bytes)
312 g_return_val_if_fail (bytes != NULL, NULL);
314 g_atomic_ref_count_inc (&bytes->ref_count);
321 * @bytes: (nullable): a #GBytes
323 * Releases a reference on @bytes. This may result in the bytes being
324 * freed. If @bytes is %NULL, it will return immediately.
329 g_bytes_unref (GBytes *bytes)
334 if (g_atomic_ref_count_dec (&bytes->ref_count))
336 if (bytes->free_func != NULL)
337 bytes->free_func (bytes->user_data);
338 g_slice_free (GBytes, bytes);
344 * @bytes1: (type GLib.Bytes): a pointer to a #GBytes
345 * @bytes2: (type GLib.Bytes): a pointer to a #GBytes to compare with @bytes1
347 * Compares the two #GBytes values being pointed to and returns
348 * %TRUE if they are equal.
350 * This function can be passed to g_hash_table_new() as the @key_equal_func
351 * parameter, when using non-%NULL #GBytes pointers as keys in a #GHashTable.
353 * Returns: %TRUE if the two keys match.
358 g_bytes_equal (gconstpointer bytes1,
359 gconstpointer bytes2)
361 const GBytes *b1 = bytes1;
362 const GBytes *b2 = bytes2;
364 g_return_val_if_fail (bytes1 != NULL, FALSE);
365 g_return_val_if_fail (bytes2 != NULL, FALSE);
367 return b1->size == b2->size &&
368 (b1->size == 0 || memcmp (b1->data, b2->data, b1->size) == 0);
373 * @bytes: (type GLib.Bytes): a pointer to a #GBytes key
375 * Creates an integer hash code for the byte data in the #GBytes.
377 * This function can be passed to g_hash_table_new() as the @key_hash_func
378 * parameter, when using non-%NULL #GBytes pointers as keys in a #GHashTable.
380 * Returns: a hash value corresponding to the key.
385 g_bytes_hash (gconstpointer bytes)
387 const GBytes *a = bytes;
388 const signed char *p, *e;
391 g_return_val_if_fail (bytes != NULL, 0);
393 for (p = (signed char *)a->data, e = (signed char *)a->data + a->size; p != e; p++)
394 h = (h << 5) + h + *p;
401 * @bytes1: (type GLib.Bytes): a pointer to a #GBytes
402 * @bytes2: (type GLib.Bytes): a pointer to a #GBytes to compare with @bytes1
404 * Compares the two #GBytes values.
406 * This function can be used to sort GBytes instances in lexicographical order.
408 * If @bytes1 and @bytes2 have different length but the shorter one is a
409 * prefix of the longer one then the shorter one is considered to be less than
410 * the longer one. Otherwise the first byte where both differ is used for
411 * comparison. If @bytes1 has a smaller value at that position it is
412 * considered less, otherwise greater than @bytes2.
414 * Returns: a negative value if @bytes1 is less than @bytes2, a positive value
415 * if @bytes1 is greater than @bytes2, and zero if @bytes1 is equal to
422 g_bytes_compare (gconstpointer bytes1,
423 gconstpointer bytes2)
425 const GBytes *b1 = bytes1;
426 const GBytes *b2 = bytes2;
429 g_return_val_if_fail (bytes1 != NULL, 0);
430 g_return_val_if_fail (bytes2 != NULL, 0);
432 ret = memcmp (b1->data, b2->data, MIN (b1->size, b2->size));
433 if (ret == 0 && b1->size != b2->size)
434 ret = b1->size < b2->size ? -1 : 1;
439 try_steal_and_unref (GBytes *bytes,
440 GDestroyNotify free_func,
445 if (bytes->free_func != free_func || bytes->data == NULL ||
446 bytes->user_data != bytes->data)
449 /* Are we the only reference? */
450 if (g_atomic_ref_count_compare (&bytes->ref_count, 1))
453 result = (gpointer)bytes->data;
454 g_slice_free (GBytes, bytes);
463 * g_bytes_unref_to_data:
464 * @bytes: (transfer full): a #GBytes
465 * @size: (out): location to place the length of the returned data
467 * Unreferences the bytes, and returns a pointer the same byte data
470 * As an optimization, the byte data is returned without copying if this was
471 * the last reference to bytes and bytes was created with g_bytes_new(),
472 * g_bytes_new_take() or g_byte_array_free_to_bytes(). In all other cases the
475 * Returns: (transfer full) (array length=size) (element-type guint8)
476 * (not nullable): a pointer to the same byte data, which should be
477 * freed with g_free()
482 g_bytes_unref_to_data (GBytes *bytes,
487 g_return_val_if_fail (bytes != NULL, NULL);
488 g_return_val_if_fail (size != NULL, NULL);
491 * Optimal path: if this is was the last reference, then we can return
492 * the data from this GBytes without copying.
495 result = try_steal_and_unref (bytes, g_free, size);
499 * Copy: Non g_malloc (or compatible) allocator, or static memory,
500 * so we have to copy, and then unref.
502 result = g_memdup2 (bytes->data, bytes->size);
504 g_bytes_unref (bytes);
511 * g_bytes_unref_to_array:
512 * @bytes: (transfer full): a #GBytes
514 * Unreferences the bytes, and returns a new mutable #GByteArray containing
515 * the same byte data.
517 * As an optimization, the byte data is transferred to the array without copying
518 * if this was the last reference to bytes and bytes was created with
519 * g_bytes_new(), g_bytes_new_take() or g_byte_array_free_to_bytes(). In all
520 * other cases the data is copied.
522 * Do not use it if @bytes contains more than %G_MAXUINT
523 * bytes. #GByteArray stores the length of its data in #guint, which
524 * may be shorter than #gsize, that @bytes is using.
526 * Returns: (transfer full): a new mutable #GByteArray containing the same byte data
531 g_bytes_unref_to_array (GBytes *bytes)
536 g_return_val_if_fail (bytes != NULL, NULL);
538 data = g_bytes_unref_to_data (bytes, &size);
539 return g_byte_array_new_take (data, size);
543 * g_bytes_get_region:
545 * @element_size: a non-zero element size
546 * @offset: an offset to the start of the region within the @bytes
547 * @n_elements: the number of elements in the region
549 * Gets a pointer to a region in @bytes.
551 * The region starts at @offset many bytes from the start of the data
552 * and contains @n_elements many elements of @element_size size.
554 * @n_elements may be zero, but @element_size must always be non-zero.
555 * Ideally, @element_size is a static constant (eg: sizeof a struct).
557 * This function does careful bounds checking (including checking for
558 * arithmetic overflows) and returns a non-%NULL pointer if the
559 * specified region lies entirely within the @bytes. If the region is
560 * in some way out of range, or if an overflow has occurred, then %NULL
563 * Note: it is possible to have a valid zero-size region. In this case,
564 * the returned pointer will be equal to the base pointer of the data of
565 * @bytes, plus @offset. This will be non-%NULL except for the case
566 * where @bytes itself was a zero-sized region. Since it is unlikely
567 * that you will be using this function to check for a zero-sized region
568 * in a zero-sized @bytes, %NULL effectively always means "error".
570 * Returns: (nullable): the requested region, or %NULL in case of an error
575 g_bytes_get_region (GBytes *bytes,
583 g_return_val_if_fail (element_size > 0, NULL);
585 /* No other assertion checks here. If something is wrong then we will
586 * simply crash (via NULL dereference or divide-by-zero).
589 if (!g_size_checked_mul (&total_size, element_size, n_elements))
592 if (!g_size_checked_add (&end_offset, offset, total_size))
597 * 0 <= offset <= end_offset
599 * So we need only check that end_offset is within the range of the
600 * size of @bytes and we're good to go.
603 if (end_offset > bytes->size)
608 * 0 <= offset <= end_offset <= bytes->size
611 return ((guchar *) bytes->data) + offset;