m4: Rename compat.at to compat.m4.

[cascardo/ovs.git] / lib / ofpbuf.h

diff --git a/lib/ofpbuf.h b/lib/ofpbuf.h
index 80b0dc4..489a543 100644 (file)
--- a/lib/ofpbuf.h
+++ b/lib/ofpbuf.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2015, 2016 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,6 +43,10 @@ enum OVS_PACKED_ENUM ofpbuf_source {
  *    When parsing, the 'data' will move past these, as data is being
  *    pulled from the OpenFlow message.
  *
+ *    Caution: buffer manipulation of 'struct ofpbuf' must always update
+ *             the 'header' and 'msg' pointers.
+ *
+ *
  * Actions: When encoding OVS action lists, the 'header' is used
  *    as a pointer to the beginning of the current action (see ofpact_put()).
  *
@@ -60,7 +64,48 @@ struct ofpbuf {
     enum ofpbuf_source source;  /* Source of memory allocated as 'base'. */
 };
 
-void ofpbuf_use(struct ofpbuf *, void *, size_t);
+/* An initializer for a struct ofpbuf that will be initially empty and uses the
+ * space in STUB (which should be an array) as a stub.  This is the initializer
+ * form of ofpbuf_use_stub().
+ *
+ * Usage example:
+ *
+ *     uint64_t stub[1024 / 8]; // 1 kB stub properly aligned for 64-bit data.
+ *     struct ofpbuf ofpbuf = OFPBUF_STUB_INITIALIZER(stub);
+ */
+#define OFPBUF_STUB_INITIALIZER(STUB) {         \
+        .base = (STUB),                         \
+        .data = (STUB),                         \
+        .size = 0,                              \
+        .allocated = sizeof (STUB),             \
+        .header = NULL,                         \
+        .msg = NULL,                            \
+        .list_node = OVS_LIST_POISON,           \
+        .source = OFPBUF_STUB,                  \
+    }
+
+/* An initializer for a struct ofpbuf whose data starts at DATA and continues
+ * for SIZE bytes.  This is appropriate for an ofpbuf that will be used to
+ * inspect existing data, without moving it around or reallocating it, and
+ * generally without modifying it at all.  This is the initializer form of
+ * ofpbuf_use_const().
+ */
+static inline struct ofpbuf
+ofpbuf_const_initializer(const void *data, size_t size)
+{
+    return (struct ofpbuf) {
+        .base = CONST_CAST(void *, data),
+        .data = CONST_CAST(void *, data),
+        .size = size,
+        .allocated = size,
+        .header = NULL,
+        .msg = NULL,
+        .list_node = OVS_LIST_POISON,
+        .source = OFPBUF_STACK,
+    };
+}
+
+void ofpbuf_use_ds(struct ofpbuf *, const struct ds *);
 void ofpbuf_use_stack(struct ofpbuf *, void *, size_t);
 void ofpbuf_use_stub(struct ofpbuf *, void *, size_t);
 void ofpbuf_use_const(struct ofpbuf *, const void *, size_t);
@@ -97,6 +142,7 @@ void *ofpbuf_push(struct ofpbuf *b, const void *, size_t);
 
 static inline size_t ofpbuf_headroom(const struct ofpbuf *);
 static inline size_t ofpbuf_tailroom(const struct ofpbuf *);
+static inline size_t ofpbuf_msgsize(const struct ofpbuf *);
 void ofpbuf_prealloc_headroom(struct ofpbuf *, size_t);
 void ofpbuf_prealloc_tailroom(struct ofpbuf *, size_t);
 void ofpbuf_trim(struct ofpbuf *);
@@ -170,6 +216,22 @@ static inline size_t ofpbuf_tailroom(const struct ofpbuf *b)
     return (char*)ofpbuf_end(b) - (char*)ofpbuf_tail(b);
 }
 
+/* Returns the number of bytes from 'b->header' to 'b->msg', that is, the
+ * length of 'b''s header. */
+static inline size_t
+ofpbuf_headersize(const struct ofpbuf *b)
+{
+    return (char *)b->msg - (char *)b->header;
+}
+
+/* Returns the number of bytes from 'b->msg' to 'b->data + b->size', that is,
+ * the length of the used space in 'b' starting from 'msg'. */
+static inline size_t
+ofpbuf_msgsize(const struct ofpbuf *b)
+{
+    return (char *)ofpbuf_tail(b) - (char *)b->msg;
+}
+
 /* Clears any data from 'b'. */
 static inline void ofpbuf_clear(struct ofpbuf *b)
 {