From: Willy Tarreau <w@1wt.eu>
Date: Thu, 23 Feb 2023 08:52:58 +0000 (+0100)
Subject: MINOR: buf: add b_rel_ofs() to turn an absolute offset into a relative one
X-Git-Tag: v3.0-dev6~51
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c5004ccb3680847cf0fc42a2fd7afc9df32c64d5;p=thirdparty%2Fhaproxy.git

MINOR: buf: add b_rel_ofs() to turn an absolute offset into a relative one

It basically does the opposite of b_peek_ofs(). If x=b_peek_ofs(y), then
y=b_rel_ofs(x).
---

diff --git a/include/haproxy/buf.h b/include/haproxy/buf.h
index b24ec7902e..d9f3a7727e 100644
--- a/include/haproxy/buf.h
+++ b/include/haproxy/buf.h
@@ -103,6 +103,15 @@ static inline size_t b_add_ofs(const struct buffer *b, size_t ofs, size_t count)
 	return ofs;
 }
 
+/* b_rel_ofs() : take an absolute offset in the buffer, and return it relative
+ * to the buffer's head for use with b_peek().
+ */
+static inline size_t b_rel_ofs(const struct buffer *b, size_t ofs)
+{
+	if (ofs < b->head)
+		ofs += b->size;
+	return ofs - b->head;
+}
 
 /* b_stop() : returns the pointer to the byte following the end of the buffer,
  * which may be out of the buffer if the buffer ends on the last byte of the