From 5fa0fea27461f5ff7fad07687618db08272e9502 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Wed, 29 Aug 2007 16:31:34 +0800 Subject: [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 --- crypto/scatterwalk.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'crypto/scatterwalk.c') diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c index 81afd1790a1..e93a8f6f35d 100644 --- a/crypto/scatterwalk.c +++ b/crypto/scatterwalk.c @@ -107,3 +107,25 @@ void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, } } EXPORT_SYMBOL_GPL(scatterwalk_copychunks); + +void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, + unsigned int start, unsigned int nbytes, int out) +{ + struct scatter_walk walk; + unsigned int offset = 0; + + for (;;) { + scatterwalk_start(&walk, sg); + + if (start < offset + sg->length) + break; + + offset += sg->length; + sg = sg_next(sg); + } + + scatterwalk_advance(&walk, start - offset); + scatterwalk_copychunks(buf, &walk, nbytes, out); + scatterwalk_done(&walk, out, 0); +} +EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); -- cgit v1.2.3-18-g5258