Commit 5fa0fea2 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

[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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent e962a653

crypto/scatterwalk.c

+22 −0
Original line number Diff line number Diff line
@@ -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);

crypto/scatterwalk.h

+3 −0
Original line number Diff line number Diff line
@@ -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 */

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