Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:43441 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752642AbaEVTcn (ORCPT ); Thu, 22 May 2014 15:32:43 -0400 From: "J. Bruce Fields" To: linux-nfs@vger.kernel.org Cc: Christoph Hellwig , "J. Bruce Fields" Subject: [PATCH 33/52] rpc: define xdr_restrict_buflen Date: Thu, 22 May 2014 15:32:08 -0400 Message-Id: <1400787148-25941-34-git-send-email-bfields@redhat.com> In-Reply-To: <1400787148-25941-1-git-send-email-bfields@redhat.com> References: <1400787148-25941-1-git-send-email-bfields@redhat.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: From: "J. Bruce Fields" With this xdr_reserve_space can help us enforce various limits. Signed-off-by: J. Bruce Fields --- include/linux/sunrpc/xdr.h | 1 + net/sunrpc/xdr.c | 29 +++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h index b23d69f..70c6b92 100644 --- a/include/linux/sunrpc/xdr.h +++ b/include/linux/sunrpc/xdr.h @@ -217,6 +217,7 @@ extern void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 extern __be32 *xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes); extern void xdr_commit_encode(struct xdr_stream *xdr); extern void xdr_truncate_encode(struct xdr_stream *xdr, size_t len); +extern int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen); extern void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base, unsigned int len); extern unsigned int xdr_stream_pos(const struct xdr_stream *xdr); diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 40198c5..aa4eb70 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -650,6 +650,35 @@ void xdr_truncate_encode(struct xdr_stream *xdr, size_t len) EXPORT_SYMBOL(xdr_truncate_encode); /** + * xdr_restrict_buflen - decrease available buffer space + * @xdr: pointer to xdr_stream + * @newbuflen: new maximum number of bytes available + * + * Adjust our idea of how much space is available in the buffer. + * If we've already used too much space in the buffer, returns -1. + * If the available space is already smaller than newbuflen, returns 0 + * and does nothing. Otherwise, adjusts xdr->buf->buflen to newbuflen + * and ensures xdr->end is set at most offset newbuflen from the start + * of the buffer. + */ +int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen) +{ + struct xdr_buf *buf = xdr->buf; + int left_in_this_buf = (void *)xdr->end - (void *)xdr->p; + int end_offset = buf->len + left_in_this_buf; + + if (newbuflen < 0 || newbuflen < buf->len) + return -1; + if (newbuflen > buf->buflen) + return 0; + if (newbuflen < end_offset) + xdr->end = (void *)xdr->end + newbuflen - end_offset; + buf->buflen = newbuflen; + return 0; +} +EXPORT_SYMBOL(xdr_restrict_buflen); + +/** * xdr_write_pages - Insert a list of pages into an XDR buffer for sending * @xdr: pointer to xdr_stream * @pages: list of pages -- 1.9.0