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363c745569
In ci_insert_line2() and b_rep_blk(), we can't afford to wrap, so don't use b_tail() to check if we do, use __b_tail() instead. This should be backported to previous versions.
611 lines
17 KiB
C
611 lines
17 KiB
C
/*
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* include/common/buf.h
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* Simple buffer handling.
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*
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* Copyright (C) 2000-2018 Willy Tarreau - w@1wt.eu
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#ifndef _COMMON_BUF_H
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#define _COMMON_BUF_H
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#include <stdint.h>
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#include <string.h>
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/* Structure defining a buffer's head */
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struct buffer {
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size_t size; /* buffer size in bytes */
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char *area; /* points to <size> bytes */
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size_t data; /* amount of data after head including wrapping */
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size_t head; /* start offset of remaining data relative to area */
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};
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/* A buffer may be in 3 different states :
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* - unallocated : size == 0, area == 0 (b_is_null() is true)
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* - waiting : size == 0, area != 0
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* - allocated : size > 0, area > 0
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*/
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/* initializers for certain buffer states. It is important that the NULL buffer
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* remains the one with all fields initialized to zero so that a calloc() or a
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* memset() on a struct automatically sets a NULL buffer.
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*/
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#define BUF_NULL ((struct buffer){ })
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#define BUF_WANTED ((struct buffer){ .area = (char *)1 })
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/***************************************************************************/
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/* Functions used to compute offsets and pointers. Most of them exist in */
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/* both wrapping-safe and unchecked ("__" prefix) variants. Some returning */
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/* a pointer are also provided with an "_ofs" suffix when they return an */
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/* offset relative to the storage area. */
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/***************************************************************************/
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/* b_is_null() : returns true if (and only if) the buffer is not yet allocated
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* and thus points to a NULL area.
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*/
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static inline int b_is_null(const struct buffer *buf)
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{
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return buf->area == NULL;
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}
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/* b_orig() : returns the pointer to the origin of the storage, which is the
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* location of byte at offset zero. This is mostly used by functions which
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* handle the wrapping by themselves.
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*/
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static inline char *b_orig(const struct buffer *b)
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{
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return b->area;
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}
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/* b_size() : returns the size of the buffer. */
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static inline size_t b_size(const struct buffer *b)
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{
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return b->size;
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}
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/* b_wrap() : returns the pointer to the wrapping position of the buffer area,
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* which is by definition the first byte not part of the buffer.
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*/
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static inline char *b_wrap(const struct buffer *b)
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{
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return b->area + b->size;
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}
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/* b_data() : returns the number of bytes present in the buffer. */
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static inline size_t b_data(const struct buffer *b)
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{
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return b->data;
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}
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/* b_room() : returns the amount of room left in the buffer */
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static inline size_t b_room(const struct buffer *b)
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{
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return b->size - b_data(b);
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}
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/* b_full() : returns true if the buffer is full. */
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static inline size_t b_full(const struct buffer *b)
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{
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return !b_room(b);
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}
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/* b_stop() : returns the pointer to the byte following the end of the buffer,
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* which may be out of the buffer if the buffer ends on the last byte of the
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* area.
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*/
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static inline size_t __b_stop_ofs(const struct buffer *b)
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{
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return b->head + b->data;
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}
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static inline const char *__b_stop(const struct buffer *b)
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{
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return b_orig(b) + __b_stop_ofs(b);
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}
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static inline size_t b_stop_ofs(const struct buffer *b)
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{
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size_t stop = __b_stop_ofs(b);
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if (stop > b->size)
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stop -= b->size;
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return stop;
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}
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static inline const char *b_stop(const struct buffer *b)
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{
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return b_orig(b) + b_stop_ofs(b);
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}
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/* b_peek() : returns a pointer to the data at position <ofs> relative to the
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* head of the buffer. Will typically point to input data if called with the
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* amount of output data. The wrapped versions will only support wrapping once
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* before the beginning or after the end.
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*/
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static inline size_t __b_peek_ofs(const struct buffer *b, size_t ofs)
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{
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return b->head + ofs;
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}
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static inline char *__b_peek(const struct buffer *b, size_t ofs)
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{
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return b_orig(b) + __b_peek_ofs(b, ofs);
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}
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static inline size_t b_peek_ofs(const struct buffer *b, size_t ofs)
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{
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size_t ret = __b_peek_ofs(b, ofs);
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if (ret >= b->size)
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ret -= b->size;
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return ret;
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}
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static inline char *b_peek(const struct buffer *b, size_t ofs)
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{
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return b_orig(b) + b_peek_ofs(b, ofs);
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}
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/* b_head() : returns the pointer to the buffer's head, which is the location
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* of the next byte to be dequeued. Note that for buffers of size zero, the
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* returned pointer may be outside of the buffer or even invalid.
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*/
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static inline size_t __b_head_ofs(const struct buffer *b)
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{
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return b->head;
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}
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static inline char *__b_head(const struct buffer *b)
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{
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return b_orig(b) + __b_head_ofs(b);
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}
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static inline size_t b_head_ofs(const struct buffer *b)
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{
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return __b_head_ofs(b);
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}
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static inline char *b_head(const struct buffer *b)
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{
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return __b_head(b);
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}
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/* b_tail() : returns the pointer to the tail of the buffer, which is the
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* location of the first byte where it is possible to enqueue new data. Note
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* that for buffers of size zero, the returned pointer may be outside of the
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* buffer or even invalid.
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*/
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static inline size_t __b_tail_ofs(const struct buffer *b)
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{
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return __b_peek_ofs(b, b_data(b));
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}
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static inline char *__b_tail(const struct buffer *b)
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{
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return __b_peek(b, b_data(b));
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}
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static inline size_t b_tail_ofs(const struct buffer *b)
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{
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return b_peek_ofs(b, b_data(b));
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}
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static inline char *b_tail(const struct buffer *b)
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{
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return b_peek(b, b_data(b));
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}
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/* b_next() : for an absolute pointer <p> or a relative offset <o> pointing to
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* a valid location within buffer <b>, returns either the absolute pointer or
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* the relative offset pointing to the next byte, which usually is at (p + 1)
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* unless p reaches the wrapping point and wrapping is needed.
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*/
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static inline size_t b_next_ofs(const struct buffer *b, size_t o)
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{
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o++;
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if (o == b->size)
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o = 0;
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return o;
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}
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static inline char *b_next(const struct buffer *b, const char *p)
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{
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p++;
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if (p == b_wrap(b))
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p = b_orig(b);
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return (char *)p;
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}
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/* b_dist() : returns the distance between two pointers, taking into account
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* the ability to wrap around the buffer's end. The operation is not defined if
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* either of the pointers does not belong to the buffer or if their distance is
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* greater than the buffer's size.
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*/
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static inline size_t b_dist(const struct buffer *b, const char *from, const char *to)
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{
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ssize_t dist = to - from;
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dist += dist < 0 ? b_size(b) : 0;
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return dist;
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}
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/* b_almost_full() : returns 1 if the buffer uses at least 3/4 of its capacity,
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* otherwise zero. Buffers of size zero are considered full.
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*/
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static inline int b_almost_full(const struct buffer *b)
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{
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return b_data(b) >= b_size(b) * 3 / 4;
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}
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/* b_space_wraps() : returns non-zero only if the buffer's free space wraps :
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* [ |xxxx| ] => yes
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* [xxxx| ] => no
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* [ |xxxx] => no
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* [xxxx| |xxxx] => no
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* [xxxxxxxxxx|xxxxxxxxxxx] => no
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*
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* So the only case where the buffer does not wrap is when there's data either
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* at the beginning or at the end of the buffer. Thus we have this :
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* - if (head <= 0) ==> doesn't wrap
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* - if (tail >= size) ==> doesn't wrap
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* - otherwise wraps
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*/
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static inline int b_space_wraps(const struct buffer *b)
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{
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if ((ssize_t)__b_head_ofs(b) <= 0)
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return 0;
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if (__b_tail_ofs(b) >= b_size(b))
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return 0;
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return 1;
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}
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/* b_contig_data() : returns the amount of data that can contiguously be read
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* at once starting from a relative offset <start> (which allows to easily
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* pre-compute blocks for memcpy). The start point will typically contain the
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* amount of past data already returned by a previous call to this function.
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*/
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static inline size_t b_contig_data(const struct buffer *b, size_t start)
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{
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size_t data = b_wrap(b) - b_peek(b, start);
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size_t limit = b_data(b) - start;
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if (data > limit)
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data = limit;
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return data;
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}
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/* b_contig_space() : returns the amount of bytes that can be appended to the
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* buffer at once. We have 8 possible cases :
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*
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* [____________________] return size
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* [______|_____________] return size - tail_ofs
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* [XXXXXX|_____________] return size - tail_ofs
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* [___|XXXXXX|_________] return size - tail_ofs
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* [______________XXXXXX] return head_ofs
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* [XXXX|___________|XXX] return head_ofs - tail_ofs
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* [XXXXXXXXXX|XXXXXXXXX] return 0
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* [XXXXXXXXXXXXXXXXXXXX] return 0
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*/
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static inline size_t b_contig_space(const struct buffer *b)
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{
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size_t left, right;
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right = b_head_ofs(b);
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left = right + b_data(b);
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left = b_size(b) - left;
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if ((ssize_t)left <= 0)
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left += right;
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return left;
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}
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/* b_getblk() : gets one full block of data at once from a buffer, starting
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* from offset <offset> after the buffer's head, and limited to no more than
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* <len> bytes. The caller is responsible for ensuring that neither <offset>
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* nor <offset>+<len> exceed the total number of bytes available in the buffer.
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* Return values :
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* >0 : number of bytes read, equal to requested size.
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* =0 : not enough data available. <blk> is left undefined.
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* The buffer is left unaffected.
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*/
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static inline size_t b_getblk(const struct buffer *buf, char *blk, size_t len, size_t offset)
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{
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size_t firstblock;
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if (len + offset > b_data(buf))
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return 0;
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firstblock = b_wrap(buf) - b_head(buf);
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if (firstblock > offset) {
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if (firstblock >= len + offset) {
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memcpy(blk, b_head(buf) + offset, len);
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return len;
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}
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memcpy(blk, b_head(buf) + offset, firstblock - offset);
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memcpy(blk + firstblock - offset, b_orig(buf), len - firstblock + offset);
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return len;
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}
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memcpy(blk, b_orig(buf) + offset - firstblock, len);
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return len;
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}
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/* b_getblk_nc() : gets one or two blocks of data at once from a buffer,
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* starting from offset <ofs> after the beginning of its output, and limited to
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* no more than <max> bytes. The caller is responsible for ensuring that
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* neither <ofs> nor <ofs>+<max> exceed the total number of bytes available in
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* the buffer. Return values :
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* >0 : number of blocks filled (1 or 2). blk1 is always filled before blk2.
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* =0 : not enough data available. <blk*> are left undefined.
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* The buffer is left unaffected. Unused buffers are left in an undefined state.
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*/
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static inline size_t b_getblk_nc(const struct buffer *buf, const char **blk1, size_t *len1, const char **blk2, size_t *len2, size_t ofs, size_t max)
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{
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size_t l1;
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if (!max)
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return 0;
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*blk1 = b_peek(buf, ofs);
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l1 = b_wrap(buf) - *blk1;
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if (l1 < max) {
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*len1 = l1;
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*len2 = max - l1;
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*blk2 = b_orig(buf);
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return 2;
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}
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*len1 = max;
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return 1;
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}
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/*********************************************/
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/* Functions used to modify the buffer state */
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/*********************************************/
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/* b_reset() : resets a buffer. The size is not touched. */
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static inline void b_reset(struct buffer *b)
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{
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b->head = 0;
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b->data = 0;
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}
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/* b_sub() : decreases the buffer length by <count> */
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static inline void b_sub(struct buffer *b, size_t count)
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{
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b->data -= count;
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}
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/* b_add() : increase the buffer length by <count> */
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static inline void b_add(struct buffer *b, size_t count)
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{
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b->data += count;
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}
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/* b_set_data() : sets the buffer's length */
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static inline void b_set_data(struct buffer *b, size_t len)
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{
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b->data = len;
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}
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/* b_del() : skips <del> bytes in a buffer <b>. Covers both the output and the
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* input parts so it's up to the caller to know where it plays and that <del>
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* is always smaller than the amount of data in the buffer.
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*/
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static inline void b_del(struct buffer *b, size_t del)
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{
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b->data -= del;
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b->head += del;
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if (b->head >= b->size)
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b->head -= b->size;
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}
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/* b_realign_if_empty() : realigns a buffer if it's empty */
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static inline void b_realign_if_empty(struct buffer *b)
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{
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if (!b_data(b))
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b->head = 0;
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}
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/* b_slow_realign() : this function realigns a possibly wrapping buffer so that
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* the part remaining to be parsed is contiguous and starts at the beginning of
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* the buffer and the already parsed output part ends at the end of the buffer.
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* This provides the best conditions since it allows the largest inputs to be
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* processed at once and ensures that once the output data leaves, the whole
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* buffer is available at once. The number of output bytes supposedly present
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* at the beginning of the buffer and which need to be moved to the end must be
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* passed in <output>. A temporary swap area at least as large as b->size must
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* be provided in <swap>. It's up to the caller to ensure <output> is no larger
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* than the difference between the whole buffer's length and its input.
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*/
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static inline void b_slow_realign(struct buffer *b, char *swap, size_t output)
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{
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size_t block1 = output;
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size_t block2 = 0;
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/* process output data in two steps to cover wrapping */
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if (block1 > b_size(b) - b_head_ofs(b)) {
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block2 = b_size(b) - b_head_ofs(b);
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block1 -= block2;
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}
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memcpy(swap + b_size(b) - output, b_head(b), block1);
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memcpy(swap + b_size(b) - block2, b_orig(b), block2);
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/* process input data in two steps to cover wrapping */
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block1 = b_data(b) - output;
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block2 = 0;
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if (block1 > b_tail_ofs(b)) {
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block2 = b_tail_ofs(b);
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block1 = block1 - block2;
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}
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memcpy(swap, b_peek(b, output), block1);
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memcpy(swap + block1, b_orig(b), block2);
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/* reinject changes into the buffer */
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memcpy(b_orig(b), swap, b_data(b) - output);
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memcpy(b_wrap(b) - output, swap + b_size(b) - output, output);
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b->head = (output ? b_size(b) - output : 0);
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}
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/* b_putchar() : tries to append char <c> at the end of buffer <b>. Supports
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* wrapping. Data are truncated if buffer is full.
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*/
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static inline void b_putchr(struct buffer *b, char c)
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{
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if (b_full(b))
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return;
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*b_tail(b) = c;
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b->data++;
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}
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/* __b_putblk() : tries to append <len> bytes from block <blk> to the end of
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* buffer <b> without checking for free space (it's up to the caller to do it).
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* Supports wrapping. It must not be called with len == 0.
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*/
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static inline void __b_putblk(struct buffer *b, const char *blk, size_t len)
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{
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size_t half = b_contig_space(b);
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if (half > len)
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half = len;
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memcpy(b_tail(b), blk, half);
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if (len > half)
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memcpy(b_peek(b, b_data(b) + half), blk + half, len - half);
|
|
b->data += len;
|
|
}
|
|
|
|
/* b_putblk() : tries to append block <blk> at the end of buffer <b>. Supports
|
|
* wrapping. Data are truncated if buffer is too short. It returns the number
|
|
* of bytes copied.
|
|
*/
|
|
static inline size_t b_putblk(struct buffer *b, const char *blk, size_t len)
|
|
{
|
|
if (len > b_room(b))
|
|
len = b_room(b);
|
|
if (len)
|
|
__b_putblk(b, blk, len);
|
|
return len;
|
|
}
|
|
|
|
/* b_xfer() : transfers at most <count> bytes from buffer <src> to buffer <dst>
|
|
* and returns the number of bytes copied. The bytes are removed from <src> and
|
|
* added to <dst>. The caller is responsible for ensuring that <count> is not
|
|
* larger than b_room(dst). Whenever possible (if the destination is empty and
|
|
* at least as much as the source was requested), the buffers are simply
|
|
* swapped instead of copied.
|
|
*/
|
|
static inline size_t b_xfer(struct buffer *dst, struct buffer *src, size_t count)
|
|
{
|
|
size_t ret, block1, block2;
|
|
|
|
ret = 0;
|
|
if (!count)
|
|
goto leave;
|
|
|
|
ret = b_data(src);
|
|
if (!ret)
|
|
goto leave;
|
|
|
|
if (ret > count)
|
|
ret = count;
|
|
else if (!b_data(dst)) {
|
|
/* zero copy is possible by just swapping buffers */
|
|
struct buffer tmp = *dst;
|
|
*dst = *src;
|
|
*src = tmp;
|
|
goto leave;
|
|
}
|
|
|
|
block1 = b_contig_data(src, 0);
|
|
if (block1 > ret)
|
|
block1 = ret;
|
|
block2 = ret - block1;
|
|
|
|
if (block1)
|
|
__b_putblk(dst, b_head(src), block1);
|
|
|
|
if (block2)
|
|
__b_putblk(dst, b_peek(src, block1), block2);
|
|
|
|
b_del(src, ret);
|
|
leave:
|
|
return ret;
|
|
}
|
|
|
|
/* b_rep_blk() : writes the block <blk> at position <pos> which must be in
|
|
* buffer <b>, and moves the part between <end> and the buffer's tail just
|
|
* after the end of the copy of <blk>. This effectively replaces the part
|
|
* located between <pos> and <end> with a copy of <blk> of length <len>. The
|
|
* buffer's length is automatically updated. This is used to replace a block
|
|
* with another one inside a buffer. The shift value (positive or negative) is
|
|
* returned. If there's no space left, the move is not done. If <len> is null,
|
|
* the <blk> pointer is allowed to be null, in order to erase a block.
|
|
*/
|
|
static inline int b_rep_blk(struct buffer *b, char *pos, char *end, const char *blk, size_t len)
|
|
{
|
|
int delta;
|
|
|
|
delta = len - (end - pos);
|
|
|
|
if (__b_tail(b) + delta > b_wrap(b))
|
|
return 0; /* no space left */
|
|
|
|
if (b_data(b) &&
|
|
b_tail(b) + delta > b_head(b) &&
|
|
b_head(b) >= b_tail(b))
|
|
return 0; /* no space left before wrapping data */
|
|
|
|
/* first, protect the end of the buffer */
|
|
memmove(end + delta, end, b_tail(b) - end);
|
|
|
|
/* now, copy blk over pos */
|
|
if (len)
|
|
memcpy(pos, blk, len);
|
|
|
|
b_add(b, delta);
|
|
b_realign_if_empty(b);
|
|
|
|
return delta;
|
|
}
|
|
|
|
|
|
#endif /* _COMMON_BUF_H */
|
|
|
|
/*
|
|
* Local variables:
|
|
* c-indent-level: 8
|
|
* c-basic-offset: 8
|
|
* End:
|
|
*/
|