linux/crypto/scatterwalk.h
Herbert Xu 5fa0fea274 [CRYPTO] scatterwalk: Add scatterwalk_map_and_copy
This patch adds the function scatterwalk_map_and_copy which reads or
writes a chunk of data from a scatterlist at a given offset.  It will
be used by authenc which would read/write the authentication data at
the end of the cipher/plain text.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2007-10-10 16:55:42 -07:00

81 lines
2.4 KiB
C

/*
* Cryptographic API.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
* Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
* Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#ifndef _CRYPTO_SCATTERWALK_H
#define _CRYPTO_SCATTERWALK_H
#include <linux/mm.h>
#include <linux/scatterlist.h>
#include "internal.h"
static inline struct scatterlist *sg_next(struct scatterlist *sg)
{
return (++sg)->length ? sg : (void *)sg->page;
}
static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
struct scatter_walk *walk_out)
{
return !(((walk_in->sg->page - walk_out->sg->page) << PAGE_SHIFT) +
(int)(walk_in->offset - walk_out->offset));
}
static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
{
unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
return len_this_page > len ? len : len_this_page;
}
static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
unsigned int nbytes)
{
unsigned int len_this_page = scatterwalk_pagelen(walk);
return nbytes > len_this_page ? len_this_page : nbytes;
}
static inline void scatterwalk_advance(struct scatter_walk *walk,
unsigned int nbytes)
{
walk->offset += nbytes;
}
static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
unsigned int alignmask)
{
return !(walk->offset & alignmask);
}
static inline struct page *scatterwalk_page(struct scatter_walk *walk)
{
return walk->sg->page + (walk->offset >> PAGE_SHIFT);
}
static inline void scatterwalk_unmap(void *vaddr, int out)
{
crypto_kunmap(vaddr, out);
}
void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
size_t nbytes, int out);
void *scatterwalk_map(struct scatter_walk *walk, int out);
void scatterwalk_done(struct scatter_walk *walk, int out, int more);
void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
unsigned int start, unsigned int nbytes, int out);
#endif /* _CRYPTO_SCATTERWALK_H */