MINOR: buffers: add a new b_move() function
This function will be used to move parts of a buffer to another place
in the same buffer, even if the parts overlap. In order to keep things
under reasonable control, it only uses a length and absolute offsets
for the source and destination, and doesn't consider head nor data.
diff --git a/include/common/buf.h b/include/common/buf.h
index cc670bf..d495a19 100644
--- a/include/common/buf.h
+++ b/include/common/buf.h
@@ -564,6 +564,63 @@
return ret;
}
+/* Moves <len> bytes from absolute position <src> of buffer <b> by <shift>
+ * bytes, while supporting wrapping of both the source and the destination.
+ * The position is relative to the buffer's origin and may overlap with the
+ * target position. The <shift>'s absolute value must be strictly lower than
+ * the buffer's size. The main purpose is to aggregate data block during
+ * parsing while removing unused delimiters. The buffer's length is not
+ * modified, and the caller must take care of size adjustments and holes by
+ * itself.
+ */
+static inline void b_move(const struct buffer *b, size_t src, size_t len, ssize_t shift)
+{
+ char *orig = b_orig(b);
+ size_t size = b_size(b);
+ size_t dst = src + size + shift;
+ size_t cnt;
+
+ if (dst >= size)
+ dst -= size;
+
+ if (shift < 0) {
+ /* copy from left to right */
+ for (; (cnt = len); len -= cnt) {
+ if (cnt > size - src)
+ cnt = size - src;
+ if (cnt > size - dst)
+ cnt = size - dst;
+
+ memmove(orig + dst, orig + src, cnt);
+ dst += cnt;
+ src += cnt;
+ if (dst >= size)
+ dst -= size;
+ if (src >= size)
+ src -= size;
+ }
+ }
+ else if (shift > 0) {
+ /* copy from right to left */
+ for (; (cnt = len); len -= cnt) {
+ size_t src_end = src + len;
+ size_t dst_end = dst + len;
+
+ if (dst_end > size)
+ dst_end -= size;
+ if (src_end > size)
+ src_end -= size;
+
+ if (cnt > dst_end)
+ cnt = dst_end;
+ if (cnt > src_end)
+ cnt = src_end;
+
+ memmove(orig + dst_end - cnt, orig + src_end - cnt, cnt);
+ }
+ }
+}
+
/* b_rep_blk() : writes the block <blk> at position <pos> which must be in
* buffer <b>, and moves the part between <end> and the buffer's tail just
* after the end of the copy of <blk>. This effectively replaces the part