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git.proxmox.com Git - mirror_ovs.git/blob - lib/ofpbuf.c
2 * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
22 #include "dynamic-string.h"
26 ofpbuf_use__(struct ofpbuf
*b
, void *base
, size_t allocated
,
27 enum ofpbuf_source source
)
29 b
->base
= b
->data
= base
;
30 b
->allocated
= allocated
;
33 b
->l2
= b
->l3
= b
->l4
= b
->l7
= NULL
;
34 list_poison(&b
->list_node
);
38 /* Initializes 'b' as an empty ofpbuf that contains the 'allocated' bytes of
39 * memory starting at 'base'. 'base' should be the first byte of a region
40 * obtained from malloc(). It will be freed (with free()) if 'b' is resized or
43 ofpbuf_use(struct ofpbuf
*b
, void *base
, size_t allocated
)
45 ofpbuf_use__(b
, base
, allocated
, OFPBUF_MALLOC
);
48 /* Initializes 'b' as an empty ofpbuf that contains the 'allocated' bytes of
49 * memory starting at 'base'. 'base' should point to a buffer on the stack.
50 * (Nothing actually relies on 'base' being allocated on the stack. It could
51 * be static or malloc()'d memory. But stack space is the most common use
54 * 'base' should be appropriately aligned. Using an array of uint32_t or
55 * uint64_t for the buffer is a reasonable way to ensure appropriate alignment
56 * for 32- or 64-bit data. OFPBUF_STACK_BUFFER is a convenient way to do so.
58 * An ofpbuf operation that requires reallocating data will assert-fail if this
59 * function was used to initialize it. Thus, one need not call ofpbuf_uninit()
60 * on an ofpbuf initialized by this function (though doing so is harmless),
61 * because it is guaranteed that 'b' does not own any heap-allocated memory. */
63 ofpbuf_use_stack(struct ofpbuf
*b
, void *base
, size_t allocated
)
65 ofpbuf_use__(b
, base
, allocated
, OFPBUF_STACK
);
68 /* Initializes 'b' as an empty ofpbuf that contains the 'allocated' bytes of
69 * memory starting at 'base'. 'base' should point to a buffer on the stack.
70 * (Nothing actually relies on 'base' being allocated on the stack. It could
71 * be static or malloc()'d memory. But stack space is the most common usen
74 * 'base' should be appropriately aligned. Using an array of uint32_t or
75 * uint64_t for the buffer is a reasonable way to ensure appropriate alignment
76 * for 32- or 64-bit data. OFPBUF_STACK_BUFFER is a convenient way to do so.
78 * An ofpbuf operation that requires reallocating data will copy the provided
79 * buffer into a malloc()'d buffer. Thus, it is wise to call ofpbuf_uninit()
80 * on an ofpbuf initialized by this function, so that if it expanded into the
81 * heap, that memory is freed. */
83 ofpbuf_use_stub(struct ofpbuf
*b
, void *base
, size_t allocated
)
85 ofpbuf_use__(b
, base
, allocated
, OFPBUF_STUB
);
88 /* Initializes 'b' as an ofpbuf whose data starts at 'data' and continues for
89 * 'size' bytes. This is appropriate for an ofpbuf that will be used to
90 * inspect existing data, without moving it around or reallocating it, and
91 * generally without modifying it at all.
93 * An ofpbuf operation that requires reallocating data will assert-fail if this
94 * function was used to initialize it. */
96 ofpbuf_use_const(struct ofpbuf
*b
, const void *data
, size_t size
)
98 ofpbuf_use__(b
, (void *) data
, size
, OFPBUF_STACK
);
102 /* Initializes 'b' as an empty ofpbuf with an initial capacity of 'size'
105 ofpbuf_init(struct ofpbuf
*b
, size_t size
)
107 ofpbuf_use(b
, size
? xmalloc(size
) : NULL
, size
);
110 /* Frees memory that 'b' points to. */
112 ofpbuf_uninit(struct ofpbuf
*b
)
114 if (b
&& b
->source
== OFPBUF_MALLOC
) {
119 /* Returns a pointer that may be passed to free() to accomplish the same thing
120 * as ofpbuf_uninit(b). The return value is a null pointer if ofpbuf_uninit()
121 * would not free any memory. */
123 ofpbuf_get_uninit_pointer(struct ofpbuf
*b
)
125 return b
&& b
->source
== OFPBUF_MALLOC
? b
->base
: NULL
;
128 /* Frees memory that 'b' points to and allocates a new ofpbuf */
130 ofpbuf_reinit(struct ofpbuf
*b
, size_t size
)
133 ofpbuf_init(b
, size
);
136 /* Creates and returns a new ofpbuf with an initial capacity of 'size'
139 ofpbuf_new(size_t size
)
141 struct ofpbuf
*b
= xmalloc(sizeof *b
);
142 ofpbuf_init(b
, size
);
146 /* Creates and returns a new ofpbuf with an initial capacity of 'size +
147 * headroom' bytes, reserving the first 'headroom' bytes as headroom. */
149 ofpbuf_new_with_headroom(size_t size
, size_t headroom
)
151 struct ofpbuf
*b
= ofpbuf_new(size
+ headroom
);
152 ofpbuf_reserve(b
, headroom
);
156 /* Creates and returns a new ofpbuf that initially contains a copy of the
157 * 'buffer->size' bytes of data starting at 'buffer->data' with no headroom or
160 ofpbuf_clone(const struct ofpbuf
*buffer
)
162 return ofpbuf_clone_with_headroom(buffer
, 0);
165 /* Creates and returns a new ofpbuf whose data are copied from 'buffer'. The
166 * returned ofpbuf will additionally have 'headroom' bytes of headroom. */
168 ofpbuf_clone_with_headroom(const struct ofpbuf
*buffer
, size_t headroom
)
170 struct ofpbuf
*new_buffer
;
171 uintptr_t data_delta
;
173 new_buffer
= ofpbuf_clone_data_with_headroom(buffer
->data
, buffer
->size
,
175 data_delta
= (char *) new_buffer
->data
- (char *) buffer
->data
;
178 new_buffer
->l2
= (char *) buffer
->l2
+ data_delta
;
181 new_buffer
->l3
= (char *) buffer
->l3
+ data_delta
;
184 new_buffer
->l4
= (char *) buffer
->l4
+ data_delta
;
187 new_buffer
->l7
= (char *) buffer
->l7
+ data_delta
;
193 /* Creates and returns a new ofpbuf that initially contains a copy of the
194 * 'size' bytes of data starting at 'data' with no headroom or tailroom. */
196 ofpbuf_clone_data(const void *data
, size_t size
)
198 return ofpbuf_clone_data_with_headroom(data
, size
, 0);
201 /* Creates and returns a new ofpbuf that initially contains 'headroom' bytes of
202 * headroom followed by a copy of the 'size' bytes of data starting at
205 ofpbuf_clone_data_with_headroom(const void *data
, size_t size
, size_t headroom
)
207 struct ofpbuf
*b
= ofpbuf_new_with_headroom(size
, headroom
);
208 ofpbuf_put(b
, data
, size
);
212 /* Frees memory that 'b' points to, as well as 'b' itself. */
214 ofpbuf_delete(struct ofpbuf
*b
)
222 /* Returns the number of bytes of headroom in 'b', that is, the number of bytes
223 * of unused space in ofpbuf 'b' before the data that is in use. (Most
224 * commonly, the data in a ofpbuf is at its beginning, and thus the ofpbuf's
227 ofpbuf_headroom(const struct ofpbuf
*b
)
229 return (char*)b
->data
- (char*)b
->base
;
232 /* Returns the number of bytes that may be appended to the tail end of ofpbuf
233 * 'b' before the ofpbuf must be reallocated. */
235 ofpbuf_tailroom(const struct ofpbuf
*b
)
237 return (char*)ofpbuf_end(b
) - (char*)ofpbuf_tail(b
);
241 ofpbuf_copy__(struct ofpbuf
*b
, uint8_t *new_base
,
242 size_t new_headroom
, size_t new_tailroom
)
244 const uint8_t *old_base
= b
->base
;
245 size_t old_headroom
= ofpbuf_headroom(b
);
246 size_t old_tailroom
= ofpbuf_tailroom(b
);
247 size_t copy_headroom
= MIN(old_headroom
, new_headroom
);
248 size_t copy_tailroom
= MIN(old_tailroom
, new_tailroom
);
250 memcpy(&new_base
[new_headroom
- copy_headroom
],
251 &old_base
[old_headroom
- copy_headroom
],
252 copy_headroom
+ b
->size
+ copy_tailroom
);
255 /* Reallocates 'b' so that it has exactly 'new_headroom' and 'new_tailroom'
256 * bytes of headroom and tailroom, respectively. */
258 ofpbuf_resize__(struct ofpbuf
*b
, size_t new_headroom
, size_t new_tailroom
)
260 void *new_base
, *new_data
;
261 size_t new_allocated
;
263 new_allocated
= new_headroom
+ b
->size
+ new_tailroom
;
267 if (new_headroom
== ofpbuf_headroom(b
)) {
268 new_base
= xrealloc(b
->base
, new_allocated
);
270 new_base
= xmalloc(new_allocated
);
271 ofpbuf_copy__(b
, new_base
, new_headroom
, new_tailroom
);
280 b
->source
= OFPBUF_MALLOC
;
281 new_base
= xmalloc(new_allocated
);
282 ofpbuf_copy__(b
, new_base
, new_headroom
, new_tailroom
);
289 b
->allocated
= new_allocated
;
292 new_data
= (char *) new_base
+ new_headroom
;
293 if (b
->data
!= new_data
) {
294 uintptr_t data_delta
= (char *) new_data
- (char *) b
->data
;
297 b
->l2
= (char *) b
->l2
+ data_delta
;
300 b
->l3
= (char *) b
->l3
+ data_delta
;
303 b
->l4
= (char *) b
->l4
+ data_delta
;
306 b
->l7
= (char *) b
->l7
+ data_delta
;
311 /* Ensures that 'b' has room for at least 'size' bytes at its tail end,
312 * reallocating and copying its data if necessary. Its headroom, if any, is
315 ofpbuf_prealloc_tailroom(struct ofpbuf
*b
, size_t size
)
317 if (size
> ofpbuf_tailroom(b
)) {
318 ofpbuf_resize__(b
, ofpbuf_headroom(b
), MAX(size
, 64));
322 /* Ensures that 'b' has room for at least 'size' bytes at its head,
323 * reallocating and copying its data if necessary. Its tailroom, if any, is
326 ofpbuf_prealloc_headroom(struct ofpbuf
*b
, size_t size
)
328 if (size
> ofpbuf_headroom(b
)) {
329 ofpbuf_resize__(b
, MAX(size
, 64), ofpbuf_tailroom(b
));
333 /* Trims the size of 'b' to fit its actual content, reducing its tailroom to
334 * 0. Its headroom, if any, is preserved.
336 * Buffers not obtained from malloc() are not resized, since that wouldn't save
339 ofpbuf_trim(struct ofpbuf
*b
)
341 if (b
->source
== OFPBUF_MALLOC
342 && (ofpbuf_headroom(b
) || ofpbuf_tailroom(b
))) {
343 ofpbuf_resize__(b
, 0, 0);
347 /* If 'b' is shorter than 'length' bytes, pads its tail out with zeros to that
350 ofpbuf_padto(struct ofpbuf
*b
, size_t length
)
352 if (b
->size
< length
) {
353 ofpbuf_put_zeros(b
, length
- b
->size
);
357 /* Appends 'size' bytes of data to the tail end of 'b', reallocating and
358 * copying its data if necessary. Returns a pointer to the first byte of the
359 * new data, which is left uninitialized. */
361 ofpbuf_put_uninit(struct ofpbuf
*b
, size_t size
)
364 ofpbuf_prealloc_tailroom(b
, size
);
370 /* Appends 'size' zeroed bytes to the tail end of 'b'. Data in 'b' is
371 * reallocated and copied if necessary. Returns a pointer to the first byte of
372 * the data's location in the ofpbuf. */
374 ofpbuf_put_zeros(struct ofpbuf
*b
, size_t size
)
376 void *dst
= ofpbuf_put_uninit(b
, size
);
377 memset(dst
, 0, size
);
381 /* Appends the 'size' bytes of data in 'p' to the tail end of 'b'. Data in 'b'
382 * is reallocated and copied if necessary. Returns a pointer to the first
383 * byte of the data's location in the ofpbuf. */
385 ofpbuf_put(struct ofpbuf
*b
, const void *p
, size_t size
)
387 void *dst
= ofpbuf_put_uninit(b
, size
);
388 memcpy(dst
, p
, size
);
392 /* Parses as many pairs of hex digits as possible (possibly separated by
393 * spaces) from the beginning of 's', appending bytes for their values to 'b'.
394 * Returns the first character of 's' that is not the first of a pair of hex
395 * digits. If 'n' is nonnull, stores the number of bytes added to 'b' in
398 ofpbuf_put_hex(struct ofpbuf
*b
, const char *s
, size_t *n
)
400 size_t initial_size
= b
->size
;
406 byte
= hexits_value(s
, 2, &ok
);
409 *n
= b
->size
- initial_size
;
414 ofpbuf_put(b
, &byte
, 1);
419 /* Reserves 'size' bytes of headroom so that they can be later allocated with
420 * ofpbuf_push_uninit() without reallocating the ofpbuf. */
422 ofpbuf_reserve(struct ofpbuf
*b
, size_t size
)
425 ofpbuf_prealloc_tailroom(b
, size
);
426 b
->data
= (char*)b
->data
+ size
;
429 /* Prefixes 'size' bytes to the head end of 'b', reallocating and copying its
430 * data if necessary. Returns a pointer to the first byte of the data's
431 * location in the ofpbuf. The new data is left uninitialized. */
433 ofpbuf_push_uninit(struct ofpbuf
*b
, size_t size
)
435 ofpbuf_prealloc_headroom(b
, size
);
436 b
->data
= (char*)b
->data
- size
;
441 /* Prefixes 'size' zeroed bytes to the head end of 'b', reallocating and
442 * copying its data if necessary. Returns a pointer to the first byte of the
443 * data's location in the ofpbuf. */
445 ofpbuf_push_zeros(struct ofpbuf
*b
, size_t size
)
447 void *dst
= ofpbuf_push_uninit(b
, size
);
448 memset(dst
, 0, size
);
452 /* Copies the 'size' bytes starting at 'p' to the head end of 'b', reallocating
453 * and copying its data if necessary. Returns a pointer to the first byte of
454 * the data's location in the ofpbuf. */
456 ofpbuf_push(struct ofpbuf
*b
, const void *p
, size_t size
)
458 void *dst
= ofpbuf_push_uninit(b
, size
);
459 memcpy(dst
, p
, size
);
463 /* If 'b' contains at least 'offset + size' bytes of data, returns a pointer to
464 * byte 'offset'. Otherwise, returns a null pointer. */
466 ofpbuf_at(const struct ofpbuf
*b
, size_t offset
, size_t size
)
468 return offset
+ size
<= b
->size
? (char *) b
->data
+ offset
: NULL
;
471 /* Returns a pointer to byte 'offset' in 'b', which must contain at least
472 * 'offset + size' bytes of data. */
474 ofpbuf_at_assert(const struct ofpbuf
*b
, size_t offset
, size_t size
)
476 assert(offset
+ size
<= b
->size
);
477 return ((char *) b
->data
) + offset
;
480 /* Returns the byte following the last byte of data in use in 'b'. */
482 ofpbuf_tail(const struct ofpbuf
*b
)
484 return (char *) b
->data
+ b
->size
;
487 /* Returns the byte following the last byte allocated for use (but not
488 * necessarily in use) by 'b'. */
490 ofpbuf_end(const struct ofpbuf
*b
)
492 return (char *) b
->base
+ b
->allocated
;
495 /* Clears any data from 'b'. */
497 ofpbuf_clear(struct ofpbuf
*b
)
503 /* Removes 'size' bytes from the head end of 'b', which must contain at least
504 * 'size' bytes of data. Returns the first byte of data removed. */
506 ofpbuf_pull(struct ofpbuf
*b
, size_t size
)
508 void *data
= b
->data
;
509 assert(b
->size
>= size
);
510 b
->data
= (char*)b
->data
+ size
;
515 /* If 'b' has at least 'size' bytes of data, removes that many bytes from the
516 * head end of 'b' and returns the first byte removed. Otherwise, returns a
517 * null pointer without modifying 'b'. */
519 ofpbuf_try_pull(struct ofpbuf
*b
, size_t size
)
521 return b
->size
>= size
? ofpbuf_pull(b
, size
) : NULL
;
524 /* Returns the data in 'b' as a block of malloc()'d memory and frees the buffer
525 * within 'b'. (If 'b' itself was dynamically allocated, e.g. with
526 * ofpbuf_new(), then it should still be freed with, e.g., ofpbuf_delete().) */
528 ofpbuf_steal_data(struct ofpbuf
*b
)
531 if (b
->source
== OFPBUF_MALLOC
&& b
->data
== b
->base
) {
534 p
= xmemdup(b
->data
, b
->size
);
535 if (b
->source
== OFPBUF_MALLOC
) {
539 b
->base
= b
->data
= NULL
;
543 /* Returns a string that describes some of 'b''s metadata plus a hex dump of up
544 * to 'maxbytes' from the start of the buffer. */
546 ofpbuf_to_string(const struct ofpbuf
*b
, size_t maxbytes
)
551 ds_put_format(&s
, "size=%zu, allocated=%zu, head=%zu, tail=%zu\n",
552 b
->size
, b
->allocated
,
553 ofpbuf_headroom(b
), ofpbuf_tailroom(b
));
554 ds_put_hex_dump(&s
, b
->data
, MIN(b
->size
, maxbytes
), 0, false);
558 /* Removes each of the "struct ofpbuf"s on 'list' from the list and frees
561 ofpbuf_list_delete(struct list
*list
)
563 struct ofpbuf
*b
, *next
;
565 LIST_FOR_EACH_SAFE (b
, next
, list_node
, list
) {
566 list_remove(&b
->list_node
);