+
+ ret = mmap(NULL, size * 2, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0);
+ if (ret == MAP_FAILED) {
+ ret = NULL;
+ goto close;
+ }
+
+ if (mmap(ret, size, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED,
+ fd, 0) != ret ||
+ mmap(ret + size, size, PROT_READ | PROT_WRITE,
+ MAP_FIXED | MAP_SHARED, fd, 0) != ret + size) {
+ munmap(ret, size * 2);
+ ret = NULL;
+ }
+
+close:
+ close(fd);
+ return ret;
+}
+
+void cbuf_free(void *ptr, unsigned int order)
+{
+ munmap(ptr, cbuf_size(order) * 2);
+}