haproxy/include/common/buffer.h
Christopher Faulet a36b311b9f BUG/MINOR: buffers: Fix bi/bo_contig_space to handle full buffers
These functions was added in commit 637f8f2c ("BUG/MEDIUM: buffers: Fix how
input/output data are injected into buffers").

This patch fixes hidden bugs. When a buffer is full (buf->i + buf->o ==
buf->size), instead of returning 0, these functions can return buf->size. Today,
this never happens because callers already check if the buffer is full before
calling bi/bo_contig_space. But to avoid possible bugs if calling conditions
changed, we slightly refactored these functions.
2017-06-14 16:20:20 +02:00

545 lines
16 KiB
C

/*
* 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/chunk.h>
#include <common/config.h>
#include <common/memory.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 */
};
/* an element of the <buffer_wq> list. It represents an object that need to
* acquire a buffer to continue its process. */
struct buffer_wait {
void *target; /* The waiting object that should be woken up */
int (*wakeup_cb)(void *); /* The function used to wake up the <target>, passed as argument */
struct list list; /* Next element in the <buffer_wq> list */
};
extern struct pool_head *pool2_buffer;
extern struct buffer buf_empty;
extern struct buffer buf_wanted;
extern struct list buffer_wq;
int init_buffer();
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);
/*****************************************************************/
/* 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.
* Note that callers MUST cast <ofs> to int if they expect negative values.
*/
#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 amount of bytes that can be written into the input area at once
* including reserved space which may be overwritten (this is the caller
* responsibility to know if the reserved space is protected or not).
*/
static inline int bi_contig_space(const struct buffer *b)
{
const char *left, *right;
left = b->p + b->i;
right = b->p - b->o;
if (left >= b->data + b->size)
left -= b->size;
else {
if (right < b->data)
right += b->size;
else
right = b->data + b->size;
}
return (right - left);
}
/* Return the amount of bytes that can be written into the output area at once
* including reserved space which may be overwritten (this is the caller
* responsibility to know if the reserved space is protected or not). Input data
* are assumed to not exist.
*/
static inline int bo_contig_space(const struct buffer *b)
{
const char *left, *right;
left = b->p;
right = b->p - b->o;
if (right < b->data)
right += b->size;
else
right = b->data + b->size;
return (right - left);
}
/* 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_may_recv() function for a more
* generic function taking everything into account.
*/
static inline int buffer_full(const struct buffer *b, unsigned int reserve)
{
if (b == &buf_empty)
return 0;
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 amount of byte that can be written starting from <p> into the
* input buffer at once, including reserved space which may be overwritten.
* This is used by Lua to insert data in the input side just before the other
* data using buffer_replace(). The goal is to transfer these new data in the
* output buffer.
*/
static inline int bi_space_for_replace(const struct buffer *buf)
{
const char *end;
/* If the input side data overflows, we cannot insert data contiguously. */
if (buf->p + buf->i >= buf->data + buf->size)
return 0;
/* Check the last byte used in the buffer, it may be a byte of the output
* side if the buffer wraps, or its the end of the buffer.
*/
end = buffer_wrap_sub(buf, buf->p - buf->o);
if (end <= buf->p)
end = buf->data + buf->size;
/* Compute the amount of bytes which can be written. */
return end - (buf->p + buf->i);
}
/* 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;
count += count < 0 ? buf->size : 0;
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;
}
/* 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 (buf == &buf_empty)
return 0;
if (!buf->size || 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. */
static inline void buffer_realign(struct buffer *buf)
{
if (!(buf->i | buf->o)) {
/* let's realign the buffer to optimize I/O */
buf->p = buf->data;
}
}
/* 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));
}
/* Tries to write char <c> into output data at buffer <b>. Supports wrapping.
* Data are truncated if buffer is full.
*/
static inline void bo_putchr(struct buffer *b, char c)
{
if (buffer_len(b) == b->size)
return;
*b->p = c;
b->p = b_ptr(b, 1);
b->o++;
}
/* Tries to copy block <blk> into output data at buffer <b>. Supports wrapping.
* Data are truncated if buffer is too short. It returns the number of bytes
* copied.
*/
static inline int bo_putblk(struct buffer *b, const char *blk, int len)
{
int cur_len = buffer_len(b);
int half;
if (len > b->size - cur_len)
len = (b->size - cur_len);
if (!len)
return 0;
half = bo_contig_space(b);
if (half > len)
half = len;
memcpy(b->p, blk, half);
b->p = b_ptr(b, half);
if (len > half) {
memcpy(b->p, blk, len - half);
b->p = b_ptr(b, half);
}
b->o += len;
return len;
}
/* Tries to copy string <str> into output data at buffer <b>. Supports wrapping.
* Data are truncated if buffer is too short. It returns the number of bytes
* copied.
*/
static inline int bo_putstr(struct buffer *b, const char *str)
{
return bo_putblk(b, str, strlen(str));
}
/* Tries to copy chunk <chk> into output data at buffer <b>. Supports wrapping.
* Data are truncated if buffer is too short. It returns the number of bytes
* copied.
*/
static inline int bo_putchk(struct buffer *b, const struct chunk *chk)
{
return bo_putblk(b, chk->str, chk->len);
}
/* Resets a buffer. The size is not touched. */
static inline void b_reset(struct buffer *buf)
{
buf->o = 0;
buf->i = 0;
buf->p = buf->data;
}
/* Allocates a buffer and replaces *buf with this buffer. If no memory is
* available, &buf_wanted is used instead. No control is made to check if *buf
* already pointed to another buffer. The allocated buffer is returned, or
* NULL in case no memory is available.
*/
static inline struct buffer *b_alloc(struct buffer **buf)
{
struct buffer *b;
*buf = &buf_wanted;
b = pool_alloc_dirty(pool2_buffer);
if (likely(b)) {
b->size = pool2_buffer->size - sizeof(struct buffer);
b_reset(b);
*buf = b;
}
return b;
}
/* Allocates a buffer and replaces *buf with this buffer. If no memory is
* available, &buf_wanted is used instead. No control is made to check if *buf
* already pointed to another buffer. The allocated buffer is returned, or
* NULL in case no memory is available. The difference with b_alloc() is that
* this function only picks from the pool and never calls malloc(), so it can
* fail even if some memory is available.
*/
static inline struct buffer *b_alloc_fast(struct buffer **buf)
{
struct buffer *b;
*buf = &buf_wanted;
b = pool_get_first(pool2_buffer);
if (likely(b)) {
b->size = pool2_buffer->size - sizeof(struct buffer);
b_reset(b);
*buf = b;
}
return b;
}
/* Releases buffer *buf (no check of emptiness) */
static inline void __b_drop(struct buffer **buf)
{
pool_free2(pool2_buffer, *buf);
}
/* Releases buffer *buf if allocated. */
static inline void b_drop(struct buffer **buf)
{
if (!(*buf)->size)
return;
__b_drop(buf);
}
/* Releases buffer *buf if allocated, and replaces it with &buf_empty. */
static inline void b_free(struct buffer **buf)
{
b_drop(buf);
*buf = &buf_empty;
}
/* Ensures that <buf> is allocated. If an allocation is needed, it ensures that
* there are still at least <margin> buffers available in the pool after this
* allocation so that we don't leave the pool in a condition where a session or
* a response buffer could not be allocated anymore, resulting in a deadlock.
* This means that we sometimes need to try to allocate extra entries even if
* only one buffer is needed.
*/
static inline struct buffer *b_alloc_margin(struct buffer **buf, int margin)
{
struct buffer *next;
if ((*buf)->size)
return *buf;
/* fast path */
if ((pool2_buffer->allocated - pool2_buffer->used) > margin)
return b_alloc_fast(buf);
next = pool_refill_alloc(pool2_buffer, margin);
if (!next)
return next;
next->size = pool2_buffer->size - sizeof(struct buffer);
b_reset(next);
*buf = next;
return next;
}
void __offer_buffer(void *from, unsigned int threshold);
static inline void offer_buffers(void *from, unsigned int threshold)
{
if (LIST_ISEMPTY(&buffer_wq))
return;
__offer_buffer(from, threshold);
}
#endif /* _COMMON_BUFFER_H */
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/