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author | Herbert Xu <herbert@gondor.apana.org.au> | 2007-08-29 16:31:34 +0800 |
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committer | David S. Miller <davem@sunset.davemloft.net> | 2007-10-10 16:55:42 -0700 |
commit | 01a3a6ff03401e686287b14915d7238f9fbbfb1f (patch) | |
tree | 165007f8d6a1fef526584fa347f094929e9858a3 /crypto | |
parent | b74ee7097fc1306e1f66c269c7c533e50531de3c (diff) | |
download | linux-crypto-01a3a6ff03401e686287b14915d7238f9fbbfb1f.tar.gz linux-crypto-01a3a6ff03401e686287b14915d7238f9fbbfb1f.zip |
[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>
Diffstat (limited to 'crypto')
-rw-r--r-- | crypto/scatterwalk.c | 22 | ||||
-rw-r--r-- | crypto/scatterwalk.h | 3 |
2 files changed, 25 insertions, 0 deletions
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c index 81afd179..e93a8f6f 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); diff --git a/crypto/scatterwalk.h b/crypto/scatterwalk.h index f1592cc2..500a220a 100644 --- a/crypto/scatterwalk.h +++ b/crypto/scatterwalk.h @@ -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 */ |