Re: [Libguestfs] [PATCH v3 3/4] common: Add isaligned helper module

is_aligned (size, align) returns true if size is aligned to align, assuming that align is power of 2. Suggested by Eric Blake in https://www.redhat.com/archives/libguestfs/2018-August/msg00036.html --- common/include/isaligned.h | 51 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 common/include/isaligned.h diff --git a/common/include/isaligned.h b/common/include/isaligned.h

new file mode 100644 index 0000000..e693820 --- /dev/null +++ b/common/include/isaligned.h @@ -0,0 +1,51 @@ +/* nbdkit + * Copyright (C) 2018 Red Hat Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * * Neither the name of Red Hat nor the names of its contributors may be + * used to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A + * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#ifndef NBDKIT_ISALIGNED_H +#define NBDKIT_ISALIGNED_H + +#include <assert.h> +#include <stdbool.h> + +#include "ispowerof2.h" + +/* Return true if size is a multiple of align. align must be power of 2. + */ +static inline bool +is_aligned (unsigned int size, unsigned int align) +{ + assert (is_power_of_2 (align)); + return !(size & (align - 1)); +} + +#endif /* NBDKIT_ISALIGNED_H */ -- 2.17.1