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SUNRPC: Add a helper function xdr_inline_peek 

We sometimes need to be able to read ahead in an xdr_stream without
incrementing the current pointer position.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2010-10-19 19:58:49 -04:00
parent 0715dc632a
commit ba8e452a4f
2 changed files with 22 additions and 0 deletions
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1
include/linux/sunrpc/xdr.h
View File

@ -201,6 +201,7 @@ extern __be32 *xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes);
extern void xdr_write_pages(struct xdr_stream *xdr, struct page **pages,
unsigned int base, unsigned int len);
extern void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p);
extern __be32 *xdr_inline_peek(struct xdr_stream *xdr, size_t nbytes);
extern __be32 *xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes);
extern void xdr_read_pages(struct xdr_stream *xdr, unsigned int len);
extern void xdr_enter_page(struct xdr_stream *xdr, unsigned int len);

21
net/sunrpc/xdr.c
View File

@ -572,6 +572,27 @@ void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
}
EXPORT_SYMBOL_GPL(xdr_init_decode);
/**
* xdr_inline_peek - Allow read-ahead in the XDR data stream
* @xdr: pointer to xdr_stream struct
* @nbytes: number of bytes of data to decode
*
* Check if the input buffer is long enough to enable us to decode
* 'nbytes' more bytes of data starting at the current position.
* If so return the current pointer without updating the current
* pointer position.
*/
__be32 * xdr_inline_peek(struct xdr_stream *xdr, size_t nbytes)
{
__be32 *p = xdr->p;
__be32 *q = p + XDR_QUADLEN(nbytes);
if (unlikely(q > xdr->end || q < p))
return NULL;
return p;
}
EXPORT_SYMBOL_GPL(xdr_inline_peek);
/**
* xdr_inline_decode - Retrieve non-page XDR data to decode
* @xdr: pointer to xdr_stream struct