From a2e954a817d3b988f333d9ed706543735f9db14b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20L=C3=A9caille?= <flecaille@haproxy.com>
Date: Wed, 4 Aug 2021 14:53:06 +0200
Subject: [PATCH] MINOR: quic: Make circular buffer internal buffers be
 variable-sized.

For now on thanks to this simple patch we can use circular buffers with
a variable-sized internal buffer.
---
 include/haproxy/cbuf-t.h | 11 +++++------
 include/haproxy/cbuf.h   | 36 +++++++++++++++++-------------------
 src/cbuf.c               |  8 ++++++--
 3 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/include/haproxy/cbuf-t.h b/include/haproxy/cbuf-t.h
index 876c804b5..8f917bb47 100644
--- a/include/haproxy/cbuf-t.h
+++ b/include/haproxy/cbuf-t.h
@@ -29,18 +29,17 @@
 
 #include <haproxy/list-t.h>
 
-/* QUIC circular buffer internal buffer size (must be a power of 2) */
-#define CBUF_BUFSZ  (1UL << 11)
-
 extern struct pool_head *pool_head_cbuf;
 
 struct cbuf {
 	/* buffer */
-	unsigned char buf[CBUF_BUFSZ];
+	unsigned char *buf;
+	/* buffer size */
+	size_t sz;
 	/* Writer index */
-	int wr;
+	size_t wr;
 	/* Reader index */
-	int rd;
+	size_t rd;
 };
 
 #endif /* _HAPROXY_CBUF_T_H */
diff --git a/include/haproxy/cbuf.h b/include/haproxy/cbuf.h
index 2b0ea656e..f3d8839b8 100644
--- a/include/haproxy/cbuf.h
+++ b/include/haproxy/cbuf.h
@@ -32,7 +32,7 @@
 #include <haproxy/list.h>
 #include <haproxy/cbuf-t.h>
 
-struct cbuf *cbuf_new(void);
+struct cbuf *cbuf_new(unsigned char *buf, size_t sz);
 void cbuf_free(struct cbuf *cbuf);
 
 /* Amount of data between <rd> and <wr> */
@@ -67,7 +67,7 @@ static inline void cb_wr_reset(struct cbuf *cbuf)
  */
 static inline void cb_add(struct cbuf *cbuf, size_t count)
 {
-	cbuf->wr = (cbuf->wr + count) & (CBUF_BUFSZ - 1);
+	cbuf->wr = (cbuf->wr + count) & (cbuf->sz - 1);
 }
 
 /* Return the reader position in <cbuf>.
@@ -83,55 +83,53 @@ static inline unsigned char *cb_rd(struct cbuf *cbuf)
  */
 static inline void cb_del(struct cbuf *cbuf, size_t count)
 {
-	cbuf->rd = (cbuf->rd + count) & (CBUF_BUFSZ - 1);
+	cbuf->rd = (cbuf->rd + count) & (cbuf->sz - 1);
 }
 
 /* Return the amount of data left in <cbuf>.
  * To be used only by the writer!
  */
-static inline int cb_data(struct cbuf *cbuf)
+static inline size_t cb_data(struct cbuf *cbuf)
 {
-	int rd;
+	size_t rd;
 
 	rd = HA_ATOMIC_LOAD(&cbuf->rd);
-	return CBUF_DATA(cbuf->wr, rd, CBUF_BUFSZ);
+	return CBUF_DATA(cbuf->wr, rd, cbuf->sz);
 }
 
 /* Return the amount of room left in <cbuf> minus 1 to distinguish
  * the case where the buffer is full from the case where is is empty
  * To be used only by the write!
  */
-static inline int cb_room(struct cbuf *cbuf)
+static inline size_t cb_room(struct cbuf *cbuf)
 {
-	int rd;
+	size_t rd;
 
 	rd = HA_ATOMIC_LOAD(&cbuf->rd);
-	return CBUF_DATA(rd, cbuf->wr + 1, CBUF_BUFSZ);
+	return CBUF_DATA(rd, cbuf->wr + 1, cbuf->sz);
 }
 
 /* Return the amount of contiguous data left in <cbuf>.
  * To be used only by the reader!
  */
-static inline int cb_contig_data(struct cbuf *cbuf)
+static inline size_t cb_contig_data(struct cbuf *cbuf)
 {
-	int end, n;
-
-	end = CBUF_BUFSZ - cbuf->rd;
-	n = (HA_ATOMIC_LOAD(&cbuf->wr) + end) & (CBUF_BUFSZ - 1);
+	size_t end, n;
 
+	end = cbuf->sz - cbuf->rd;
+	n = (HA_ATOMIC_LOAD(&cbuf->wr) + end) & (cbuf->sz - 1);
 	return n < end ? n : end;
 }
 
 /* Return the amount of contiguous space left in <cbuf>.
  * To be used only by the writer!
  */
-static inline int cb_contig_space(struct cbuf *cbuf)
+static inline size_t cb_contig_space(struct cbuf *cbuf)
 {
-	int end, n;
-
-	end = CBUF_BUFSZ - 1 - cbuf->wr;
-	n = (HA_ATOMIC_LOAD(&cbuf->rd) + end) & (CBUF_BUFSZ - 1);
+	size_t end, n;
 
+	end = cbuf->sz - 1 - cbuf->wr;
+	n = (HA_ATOMIC_LOAD(&cbuf->rd) + end) & (cbuf->sz - 1);
 	return n <= end ? n : end + 1;
 }
 
diff --git a/src/cbuf.c b/src/cbuf.c
index d58ff973e..f719435e1 100644
--- a/src/cbuf.c
+++ b/src/cbuf.c
@@ -24,13 +24,17 @@
 
 DECLARE_POOL(pool_head_cbuf, "cbuf_pool", sizeof(struct cbuf));
 
-/* Allocate and return a new circular buffer if succeeded, NULL if not. */
-struct cbuf *cbuf_new(void)
+/* Allocate and return a new circular buffer with <buf> as <sz> byte internal buffer
+ * if succeeded, NULL if not.
+ */
+struct cbuf *cbuf_new(unsigned char *buf, size_t sz)
 {
 	struct cbuf *cbuf;
 
 	cbuf = pool_alloc(pool_head_cbuf);
 	if (cbuf) {
+		cbuf->sz = sz;
+		cbuf->buf = buf;
 		cbuf->wr = 0;
 		cbuf->rd = 0;
 	}