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/*
* include/common/buffer.h
* Buffer management definitions, macros and inline functions.
*
* Copyright (C) 2000-2012 Willy Tarreau - w@1wt.eu
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _COMMON_BUFFER_H
#define _COMMON_BUFFER_H
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <common/config.h>
struct buffer {
char *p; /* buffer's start pointer, separates in and out data */
unsigned int size; /* buffer size in bytes */
unsigned int i; /* number of input bytes pending for analysis in the buffer */
unsigned int o; /* number of out bytes the sender can consume from this buffer */
char data[0]; /* <size> bytes */
};
int buffer_replace2(struct buffer *b, char *pos, char *end, const char *str, int len);
int buffer_insert_line2(struct buffer *b, char *pos, const char *str, int len);
void buffer_dump(FILE *o, struct buffer *b, int from, int to);
void buffer_slow_realign(struct buffer *buf);
void buffer_bounce_realign(struct buffer *buf);
/*****************************************************************/
/* These functions are used to compute various buffer area sizes */
/*****************************************************************/
/* Returns an absolute pointer for a position relative to the current buffer's
* pointer. It is written so that it is optimal when <ofs> is a const. It is
* written as a macro instead of an inline function so that the compiler knows
* when it can optimize out the sign test on <ofs> when passed an unsigned int.
*/
#define b_ptr(b, ofs) \
({ \
char *__ret = (b)->p + (ofs); \
if ((ofs) > 0 && __ret >= (b)->data + (b)->size) \
__ret -= (b)->size; \
else if ((ofs) < 0 && __ret < (b)->data) \
__ret += (b)->size; \
__ret; \
})
/* Advances the buffer by <adv> bytes, which means that the buffer
* pointer advances, and that as many bytes from in are transferred
* to out. The caller is responsible for ensuring that adv is always
* smaller than or equal to b->i.
*/
static inline void b_adv(struct buffer *b, unsigned int adv)
{
b->i -= adv;
b->o += adv;
b->p = b_ptr(b, adv);
}
/* Rewinds the buffer by <adv> bytes, which means that the buffer pointer goes
* backwards, and that as many bytes from out are moved to in. The caller is
* responsible for ensuring that adv is always smaller than or equal to b->o.
*/
static inline void b_rew(struct buffer *b, unsigned int adv)
{
b->i += adv;
b->o -= adv;
b->p = b_ptr(b, (int)-adv);
}
/* Returns the start of the input data in a buffer */
static inline char *bi_ptr(const struct buffer *b)
{
return b->p;
}
/* Returns the end of the input data in a buffer (pointer to next
* insertion point).
*/
static inline char *bi_end(const struct buffer *b)
{
char *ret = b->p + b->i;
if (ret >= b->data + b->size)
ret -= b->size;
return ret;
}
/* Returns the amount of input data that can contiguously be read at once */
static inline int bi_contig_data(const struct buffer *b)
{
int data = b->data + b->size - b->p;
if (data > b->i)
data = b->i;
return data;
}
/* Returns the start of the output data in a buffer */
static inline char *bo_ptr(const struct buffer *b)
{
char *ret = b->p - b->o;
if (ret < b->data)
ret += b->size;
return ret;
}
/* Returns the end of the output data in a buffer */
static inline char *bo_end(const struct buffer *b)
{
return b->p;
}
/* Returns the amount of output data that can contiguously be read at once */
static inline int bo_contig_data(const struct buffer *b)
{
char *beg = b->p - b->o;
if (beg < b->data)
return b->data - beg;
return b->o;
}
/* Return the buffer's length in bytes by summing the input and the output */
static inline int buffer_len(const struct buffer *buf)
{
return buf->i + buf->o;
}
/* Return non-zero only if the buffer is not empty */
static inline int buffer_not_empty(const struct buffer *buf)
{
return buf->i | buf->o;
}
/* Return non-zero only if the buffer is empty */
static inline int buffer_empty(const struct buffer *buf)
{
return !buffer_not_empty(buf);
}
/* Returns non-zero if the buffer's INPUT is considered full, which means that
* it holds at least as much INPUT data as (size - reserve). This also means
* that data that are scheduled for output are considered as potential free
* space, and that the reserved space is always considered as not usable. This
* information alone cannot be used as a general purpose free space indicator.
* However it accurately indicates that too many data were fed in the buffer
* for an analyzer for instance. See the channel_full() function for a more
* generic function taking everything into account.
*/
static inline int buffer_full(const struct buffer *b, unsigned int reserve)
{
return (b->i + reserve >= b->size);
}
/* Normalizes a pointer after a subtract */
static inline char *buffer_wrap_sub(const struct buffer *buf, char *ptr)
{
if (ptr < buf->data)
ptr += buf->size;
return ptr;
}
/* Normalizes a pointer after an addition */
static inline char *buffer_wrap_add(const struct buffer *buf, char *ptr)
{
if (ptr - buf->size >= buf->data)
ptr -= buf->size;
return ptr;
}
/* Return the maximum amount of bytes that can be written into the buffer,
* including reserved space which may be overwritten.
*/
static inline int buffer_total_space(const struct buffer *buf)
{
return buf->size - buffer_len(buf);
}
/* Returns the number of contiguous bytes between <start> and <start>+<count>,
* and enforces a limit on buf->data + buf->size. <start> must be within the
* buffer.
*/
static inline int buffer_contig_area(const struct buffer *buf, const char *start, int count)
{
if (count > buf->data - start + buf->size)
count = buf->data - start + buf->size;
return count;
}
/* Return the amount of bytes that can be written into the buffer at once,
* including reserved space which may be overwritten.
*/
static inline int buffer_contig_space(const struct buffer *buf)
{
const char *left, *right;
if (buf->data + buf->o <= buf->p)
right = buf->data + buf->size;
else
right = buf->p + buf->size - buf->o;
left = buffer_wrap_add(buf, buf->p + buf->i);
return right - left;
}
/* Return the amount of bytes that can be written into the buffer at once,
* excluding the amount of reserved space passed in <res>, which is
* preserved.
*/
static inline int buffer_contig_space_with_res(const struct buffer *buf, int res)
{
/* Proceed differently if the buffer is full, partially used or empty.
* The hard situation is when it's partially used and either data or
* reserved space wraps at the end.
*/
int spare = buf->size - res;
if (buffer_len(buf) >= spare)
spare = 0;
else if (buffer_len(buf)) {
spare = buffer_contig_space(buf) - res;
if (spare < 0)
spare = 0;
}
return spare;
}
/* Normalizes a pointer which is supposed to be relative to the beginning of a
* buffer, so that wrapping is correctly handled. The intent is to use this
* when increasing a pointer. Note that the wrapping test is only performed
* once, so the original pointer must be between ->data-size and ->data+2*size-1,
* otherwise an invalid pointer might be returned.
*/
static inline const char *buffer_pointer(const struct buffer *buf, const char *ptr)
{
if (ptr < buf->data)
ptr += buf->size;
else if (ptr - buf->size >= buf->data)
ptr -= buf->size;
return ptr;
}
/* Returns the distance between two pointers, taking into account the ability
* to wrap around the buffer's end.
*/
static inline int buffer_count(const struct buffer *buf, const char *from, const char *to)
{
int count = to - from;
if (count < 0)
count += buf->size;
return count;
}
/* returns the amount of pending bytes in the buffer. It is the amount of bytes
* that is not scheduled to be sent.
*/
static inline int buffer_pending(const struct buffer *buf)
{
return buf->i;
}
/* Returns the size of the working area which the caller knows ends at <end>.
* If <end> equals buf->r (modulo size), then it means that the free area which
* follows is part of the working area. Otherwise, the working area stops at
* <end>. It always starts at buf->p. The work area includes the
* reserved area.
*/
static inline int buffer_work_area(const struct buffer *buf, const char *end)
{
end = buffer_pointer(buf, end);
if (end == buffer_wrap_add(buf, buf->p + buf->i))
/* pointer exactly at end, lets push forwards */
end = buffer_wrap_sub(buf, buf->p - buf->o);
return buffer_count(buf, buf->p, end);
}
/* Return 1 if the buffer has less than 1/4 of its capacity free, otherwise 0 */
static inline int buffer_almost_full(const struct buffer *buf)
{
if (buffer_total_space(buf) < buf->size / 4)
return 1;
return 0;
}
/* Cut the first <n> pending bytes in a contiguous buffer. It is illegal to
* call this function with remaining data waiting to be sent (o > 0). The
* caller must ensure that <n> is smaller than the actual buffer's length.
* This is mainly used to remove empty lines at the beginning of a request
* or a response.
*/
static inline void bi_fast_delete(struct buffer *buf, int n)
{
buf->i -= n;
buf->p += n;
}
/*
* Tries to realign the given buffer, and returns how many bytes can be written
* there at once without overwriting anything.
*/
static inline int buffer_realign(struct buffer *buf)
{
if (!(buf->i | buf->o)) {
/* let's realign the buffer to optimize I/O */
buf->p = buf->data;
}
return buffer_contig_space(buf);
}
/* Schedule all remaining buffer data to be sent. ->o is not touched if it
* already covers those data. That permits doing a flush even after a forward,
* although not recommended.
*/
static inline void buffer_flush(struct buffer *buf)
{
buf->p = buffer_wrap_add(buf, buf->p + buf->i);
buf->o += buf->i;
buf->i = 0;
}
/* This function writes the string <str> at position <pos> which must be in
* buffer <b>, and moves <end> just after the end of <str>. <b>'s parameters
* (l, r, lr) are updated to be valid after the shift. the shift value
* (positive or negative) is returned. If there's no space left, the move is
* not done. The function does not adjust ->o because it does not make sense
* to use it on data scheduled to be sent.
*/
static inline int buffer_replace(struct buffer *b, char *pos, char *end, const char *str)
{
return buffer_replace2(b, pos, end, str, strlen(str));
}
#endif /* _COMMON_BUFFER_H */
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/