Provide various wrappers for memcpy (COPY_OBJ, BUF_...)

These wrappers avoid specifying the size separately or twice, and
COPY_OBJ can check for type safety.

No call sites yet.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/secnet.h b/secnet.h
index f0ab80b8cde32ab4214577205b7ae37b7a88fa18..6b20045709bbe51190c40c4096e27ea4f1e9837a 100644 (file)
--- a/secnet.h
+++ b/secnet.h
@@ -551,4 +551,17 @@ extern void log_from_fd(int fd, cstring_t prefix, struct log_if *log);
 
 #define FILLZERO(obj) (memset(&(obj),0,sizeof((obj))))
 
+/*
+ * void COPY_OBJ(  OBJECT& dst, const OBJECT& src);
+ * void COPY_ARRAY(OBJECT *dst, const OBJECT *src, INTEGER count);
+ *   // Typesafe: we check that the type OBJECT is the same in both cases.
+ *   // It is OK to use COPY_OBJ on an array object, provided it's
+ *   // _actually_ the whole array object and not decayed into a
+ *   // pointer (e.g. a formal parameter).
+ */
+#define COPY_OBJ(dst,src) \
+    (&(dst)==&(src), memcpy(&(dst),&(src),sizeof((dst))))
+#define COPY_ARRAY(dst,src,count) \
+    (&(dst)[0]==&(src)[0], memcpy((dst),(src),sizeof((dst)[0])*(count)))
+
 #endif /* secnet_h */

diff --git a/util.h b/util.h
index 5866e5784481376e9c2897ecabdb16b5c1f9c818..725f2333e9c9ef3c350a0dcca8ecbab4acbea242 100644 (file)
--- a/util.h
+++ b/util.h
@@ -29,6 +29,31 @@ extern void *buf_prepend(struct buffer_if *buf, int32_t amount);
 extern void *buf_unappend(struct buffer_if *buf, int32_t amount);
 extern void *buf_unprepend(struct buffer_if *buf, int32_t amount);
 
+/*
+ * void BUF_ADD_BYTES(append,    struct buffer_if*, const void*, int32_t size);
+ * void BUF_ADD_BYTES(prepend,   struct buffer_if*, const void*, int32_t size);
+ * void BUF_GET_BYTES(unappend,  struct buffer_if*,       void*, int32_t size);
+ * void BUF_GET_BYTES(unprepend, struct buffer_if*,       void*, int32_t size);
+ *     // all of these evaluate size twice
+ *
+ * void BUF_ADD_OBJ(append,    struct_buffer_if*, const OBJECT& something);
+ * void BUF_ADD_OBJ(prepend,   struct_buffer_if*, const OBJECT& something);
+ * void BUF_GET_OBJ(unappend,  struct_buffer_if*,       OBJECT& something);
+ * void BUF_GET_OBJ(unprepend, struct_buffer_if*,       OBJECT& something);
+ */
+#define BUF_ADD_BYTES(appendprepend, bufp, datap, size)                        \
+    (buf_un##appendprepend /* ensures we have correct direction */,    \
+     memcpy(buf_##appendprepend((bufp),(size)),(datap),(size)))
+#define BUF_ADD_OBJ(appendprepend, bufp, obj) \
+    BUF_ADD_BYTES(appendprepend,(bufp),&(obj),sizeof((obj)))
+#define BUF_GET_BYTES(unappendunprepend, bufp, datap, size)            \
+    (BUF_GET__DOESNOTEXIST__buf_un##unappendunprepend,                 \
+     memcpy((datap),buf_##unappendunprepend((bufp),(size)),(size)))
+#define BUF_GET_OBJ(unappendunprepend, bufp, obj) \
+    BUF_ADD_BYTES(unappendunprepend,&(obj),(bufp),sizeof((obj)))
+#define BUF_GET__DOESNOTEXIST__buf_ununappend  0
+#define BUF_GET__DOESNOTEXIST__buf_ununprepend 0
+
 static inline int32_t buf_remaining_space(const struct buffer_if *buf)
 {
     return (buf->base + buf->alloclen) - (buf->start + buf->size);