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[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>
This commit is contained in:
Herbert Xu 2007-08-29 16:31:34 +08:00 committed by David S. Miller
parent e962a653f3
commit 5fa0fea274
2 changed files with 25 additions and 0 deletions
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22
crypto/scatterwalk.c
View File

@ -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);

3
crypto/scatterwalk.h
View File

@ -74,4 +74,7 @@ void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
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 */