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MEDIUM: buffer: always assign a dummy empty buffer to channels

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Channels are now created with a valid pointer to a buffer before the
buffer is allocated. This buffer is a global one called "buf_empty" and
of size zero. Thus it prevents any activity from being performed on
the buffer and still ensures that chn->buf may always be dereferenced.
b_free() also resets the buffer to &buf_empty, and was split into
b_drop() which does not reset the buffer.
This commit is contained in:
Willy Tarreau 2014-11-24 11:39:34 +01:00
parent 7dfca9daec
commit 2a4b54359b
3 changed files with 23 additions and 3 deletions
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21
include/common/buffer.h
View File

@ -40,6 +40,7 @@ struct buffer {
};
extern struct pool_head *pool2_buffer;
extern struct buffer buf_empty;
int init_buffer();
int buffer_replace2(struct buffer *b, char *pos, char *end, const char *str, int len);
@ -409,13 +410,27 @@ static inline struct buffer *b_alloc(struct buffer **buf)
return *buf;
}
/* Releases buffer *buf.
*/
static inline void b_free(struct buffer **buf)
/* 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;
}
#endif /* _COMMON_BUFFER_H */
/*

1
include/proto/channel.h
View File

@ -51,6 +51,7 @@ int bo_getblk(struct channel *chn, char *blk, int len, int offset);
/* Initialize all fields in the channel. */
static inline void channel_init(struct channel *chn)
{
chn->buf = &buf_empty;
chn->to_forward = 0;
chn->last_read = now_ms;
chn->xfer_small = chn->xfer_large = 0;

4
src/buffer.c
View File

@ -22,6 +22,10 @@
struct pool_head *pool2_buffer;
/* this buffer is used to have a valid pointer to an empty buffer in channels
* which convey no more data.
*/
struct buffer buf_empty = { .p = buf_empty.data };
/* perform minimal intializations, report 0 in case of error, 1 if OK. */
int init_buffer()