diff options
| author | Herbert Xu <herbert@gondor.apana.org.au> | 2007-08-29 16:31:34 +0800 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-10-10 16:55:42 -0700 |
| commit | 5fa0fea27461f5ff7fad07687618db08272e9502 (patch) | |
| tree | 4e1fe825e9e45e0d4dab028b8188fe1ceff1f768 /crypto | |
| parent | e962a653f3146330d99aefa5adadeaed60bc9bb5 (diff) | |
[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 81afd1790a1d..e93a8f6f35d4 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 f1592cc2d0f4..500a220ad908 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 */ |