MEDIUM: buffer: always assign a dummy empty buffer to channels
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.
diff --git a/include/common/buffer.h b/include/common/buffer.h
index 2c992c7..5ea8fab 100644
--- a/include/common/buffer.h
+++ b/include/common/buffer.h
@@ -40,6 +40,7 @@
};
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 @@
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 */
/*
diff --git a/include/proto/channel.h b/include/proto/channel.h
index cf7b413..1c175e9 100644
--- a/include/proto/channel.h
+++ b/include/proto/channel.h
@@ -51,6 +51,7 @@
/* 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;
diff --git a/src/buffer.c b/src/buffer.c
index 9037dd3..7691026 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -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()