xdr.c

Linux Kernel 2.6.9 for OMAP1710

	} while ((len -= copy) != 0);
}

/*
 * _copy_to_pages
 * @pages: array of pages
 * @pgbase: page vector address of destination
 * @p: pointer to source data
 * @len: length
 *
 * Copies data from an arbitrary memory location into an array of pages
 * The copy is assumed to be non-overlapping.
 */
static void
_copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
{
	struct page **pgto;
	char *vto;
	size_t copy;

	pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
	pgbase &= ~PAGE_CACHE_MASK;

	do {
		copy = PAGE_CACHE_SIZE - pgbase;
		if (copy > len)
			copy = len;

		vto = kmap_atomic(*pgto, KM_USER0);
		memcpy(vto + pgbase, p, copy);
		kunmap_atomic(vto, KM_USER0);

		pgbase += copy;
		if (pgbase == PAGE_CACHE_SIZE) {
			pgbase = 0;
			pgto++;
		}
		p += copy;

	} while ((len -= copy) != 0);
}

/*
 * _copy_from_pages
 * @p: pointer to destination
 * @pages: array of pages
 * @pgbase: offset of source data
 * @len: length
 *
 * Copies data into an arbitrary memory location from an array of pages
 * The copy is assumed to be non-overlapping.
 */
void
_copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
{
	struct page **pgfrom;
	char *vfrom;
	size_t copy;

	pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
	pgbase &= ~PAGE_CACHE_MASK;

	do {
		copy = PAGE_CACHE_SIZE - pgbase;
		if (copy > len)
			copy = len;

		vfrom = kmap_atomic(*pgfrom, KM_USER0);
		memcpy(p, vfrom + pgbase, copy);
		kunmap_atomic(vfrom, KM_USER0);

		pgbase += copy;
		if (pgbase == PAGE_CACHE_SIZE) {
			pgbase = 0;
			pgfrom++;
		}
		p += copy;

	} while ((len -= copy) != 0);
}

/*
 * xdr_shrink_bufhead
 * @buf: xdr_buf
 * @len: bytes to remove from buf->head[0]
 *
 * Shrinks XDR buffer's header kvec buf->head[0] by 
 * 'len' bytes. The extra data is not lost, but is instead
 * moved into the inlined pages and/or the tail.
 */
void
xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
{
	struct kvec *head, *tail;
	size_t copy, offs;
	unsigned int pglen = buf->page_len;

	tail = buf->tail;
	head = buf->head;
	BUG_ON (len > head->iov_len);

	/* Shift the tail first */
	if (tail->iov_len != 0) {
		if (tail->iov_len > len) {
			copy = tail->iov_len - len;
			memmove((char *)tail->iov_base + len,
					tail->iov_base, copy);
		}
		/* Copy from the inlined pages into the tail */
		copy = len;
		if (copy > pglen)
			copy = pglen;
		offs = len - copy;
		if (offs >= tail->iov_len)
			copy = 0;
		else if (copy > tail->iov_len - offs)
			copy = tail->iov_len - offs;
		if (copy != 0)
			_copy_from_pages((char *)tail->iov_base + offs,
					buf->pages,
					buf->page_base + pglen + offs - len,
					copy);
		/* Do we also need to copy data from the head into the tail ? */
		if (len > pglen) {
			offs = copy = len - pglen;
			if (copy > tail->iov_len)
				copy = tail->iov_len;
			memcpy(tail->iov_base,
					(char *)head->iov_base +
					head->iov_len - offs,
					copy);
		}
	}
	/* Now handle pages */
	if (pglen != 0) {
		if (pglen > len)
			_shift_data_right_pages(buf->pages,
					buf->page_base + len,
					buf->page_base,
					pglen - len);
		copy = len;
		if (len > pglen)
			copy = pglen;
		_copy_to_pages(buf->pages, buf->page_base,
				(char *)head->iov_base + head->iov_len - len,
				copy);
	}
	head->iov_len -= len;
	buf->buflen -= len;
	/* Have we truncated the message? */
	if (buf->len > buf->buflen)
		buf->len = buf->buflen;
}

/*
 * xdr_shrink_pagelen
 * @buf: xdr_buf
 * @len: bytes to remove from buf->pages
 *
 * Shrinks XDR buffer's page array buf->pages by 
 * 'len' bytes. The extra data is not lost, but is instead
 * moved into the tail.
 */
void
xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
{
	struct kvec *tail;
	size_t copy;
	char *p;
	unsigned int pglen = buf->page_len;

	tail = buf->tail;
	BUG_ON (len > pglen);

	/* Shift the tail first */
	if (tail->iov_len != 0) {
		p = (char *)tail->iov_base + len;
		if (tail->iov_len > len) {
			copy = tail->iov_len - len;
			memmove(p, tail->iov_base, copy);
		} else
			buf->buflen -= len;
		/* Copy from the inlined pages into the tail */
		copy = len;
		if (copy > tail->iov_len)
			copy = tail->iov_len;
		_copy_from_pages((char *)tail->iov_base,
				buf->pages, buf->page_base + pglen - len,
				copy);
	}
	buf->page_len -= len;
	buf->buflen -= len;
	/* Have we truncated the message? */
	if (buf->len > buf->buflen)
		buf->len = buf->buflen;
}

void
xdr_shift_buf(struct xdr_buf *buf, size_t len)
{
	xdr_shrink_bufhead(buf, len);
}

/**
 * xdr_init_encode - Initialize a struct xdr_stream for sending data.
 * @xdr: pointer to xdr_stream struct
 * @buf: pointer to XDR buffer in which to encode data
 * @p: current pointer inside XDR buffer
 *
 * Note: at the moment the RPC client only passes the length of our
 *	 scratch buffer in the xdr_buf's header kvec. Previously this
 *	 meant we needed to call xdr_adjust_iovec() after encoding the
 *	 data. With the new scheme, the xdr_stream manages the details
 *	 of the buffer length, and takes care of adjusting the kvec
 *	 length for us.
 */
void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
{
	struct kvec *iov = buf->head;

	xdr->buf = buf;
	xdr->iov = iov;
	xdr->end = (uint32_t *)((char *)iov->iov_base + iov->iov_len);
	buf->len = iov->iov_len = (char *)p - (char *)iov->iov_base;
	xdr->p = p;
}
EXPORT_SYMBOL(xdr_init_encode);

/**
 * xdr_reserve_space - Reserve buffer space for sending
 * @xdr: pointer to xdr_stream
 * @nbytes: number of bytes to reserve
 *
 * Checks that we have enough buffer space to encode 'nbytes' more
 * bytes of data. If so, update the total xdr_buf length, and
 * adjust the length of the current kvec.
 */
uint32_t * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
{
	uint32_t *p = xdr->p;
	uint32_t *q;

	/* align nbytes on the next 32-bit boundary */
	nbytes += 3;
	nbytes &= ~3;
	q = p + (nbytes >> 2);
	if (unlikely(q > xdr->end || q < p))
		return NULL;
	xdr->p = q;
	xdr->iov->iov_len += nbytes;
	xdr->buf->len += nbytes;
	return p;
}
EXPORT_SYMBOL(xdr_reserve_space);

/**
 * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
 * @xdr: pointer to xdr_stream
 * @pages: list of pages
 * @base: offset of first byte
 * @len: length of data in bytes
 *
 */
void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
		 unsigned int len)
{
	struct xdr_buf *buf = xdr->buf;
	struct kvec *iov = buf->tail;
	buf->pages = pages;
	buf->page_base = base;
	buf->page_len = len;

	iov->iov_base = (char *)xdr->p;
	iov->iov_len  = 0;
	xdr->iov = iov;

	if (len & 3) {
		unsigned int pad = 4 - (len & 3);

		BUG_ON(xdr->p >= xdr->end);
		iov->iov_base = (char *)xdr->p + (len & 3);
		iov->iov_len  += pad;
		len += pad;
		*xdr->p++ = 0;
	}
	buf->buflen += len;
	buf->len += len;
}
EXPORT_SYMBOL(xdr_write_pages);

/**
 * xdr_init_decode - Initialize an xdr_stream for decoding data.
 * @xdr: pointer to xdr_stream struct
 * @buf: pointer to XDR buffer from which to decode data
 * @p: current pointer inside XDR buffer
 */
void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
{
	struct kvec *iov = buf->head;
	unsigned int len = iov->iov_len;

	if (len > buf->len)
		len = buf->len;
	xdr->buf = buf;
	xdr->iov = iov;
	xdr->p = p;
	xdr->end = (uint32_t *)((char *)iov->iov_base + len);
}
EXPORT_SYMBOL(xdr_init_decode);

/**
 * xdr_inline_decode - Retrieve non-page XDR data to decode
 * @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, then update the current
 * pointer position.
 */
uint32_t * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
{
	uint32_t *p = xdr->p;
	uint32_t *q = p + XDR_QUADLEN(nbytes);

	if (unlikely(q > xdr->end || q < p))
		return NULL;
	xdr->p = q;
	return p;
}
EXPORT_SYMBOL(xdr_inline_decode);

/**
 * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
 * @xdr: pointer to xdr_stream struct
 * @len: number of bytes of page data
 *
 * Moves data beyond the current pointer position from the XDR head[] buffer
 * into the page list. Any data that lies beyond current position + "len"
 * bytes is moved into the XDR tail[]. The current pointer is then
 * repositioned at the beginning of the XDR tail.
 */
void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
{
	struct xdr_buf *buf = xdr->buf;
	struct kvec *iov;
	ssize_t shift;
	unsigned int end;
	int padding;

	/* Realign pages to current pointer position */
	iov  = buf->head;
	shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
	if (shift > 0)
		xdr_shrink_bufhead(buf, shift);

	/* Truncate page data and move it into the tail */
	if (buf->page_len > len)
		xdr_shrink_pagelen(buf, buf->page_len - len);
	padding = (XDR_QUADLEN(len) << 2) - len;
	xdr->iov = iov = buf->tail;
	/* Compute remaining message length.  */
	end = iov->iov_len;
	shift = buf->buflen - buf->len;
	if (shift < end)
		end -= shift;
	else if (shift > 0)
		end = 0;
	/*
	 * Position current pointer at beginning of tail, and
	 * set remaining message length.
	 */
	xdr->p = (uint32_t *)((char *)iov->iov_base + padding);
	xdr->end = (uint32_t *)((char *)iov->iov_base + end);
}
EXPORT_SYMBOL(xdr_read_pages);

static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};

void
xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
{
	buf->head[0] = *iov;
	buf->tail[0] = empty_iov;
	buf->page_len = 0;
	buf->buflen = buf->len = iov->iov_len;
}

/* Sets subiov to the intersection of iov with the buffer of length len
 * starting base bytes after iov.  Indicates empty intersection by setting
 * length of subiov to zero.  Decrements len by length of subiov, sets base
 * to zero (or decrements it by length of iov if subiov is empty). */
static void
iov_subsegment(struct kvec *iov, struct kvec *subiov, int *base, int *len)
{
	if (*base > iov->iov_len) {
		subiov->iov_base = NULL;
		subiov->iov_len = 0;
		*base -= iov->iov_len;
	} else {
		subiov->iov_base = iov->iov_base + *base;
		subiov->iov_len = min(*len, (int)iov->iov_len - *base);
		*base = 0;
	}
	*len -= subiov->iov_len; 
}

/* Sets subbuf to the portion of buf of length len beginning base bytes
 * from the start of buf. Returns -1 if base of length are out of bounds. */
int
xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
			int base, int len)
{
	int i;

	subbuf->buflen = subbuf->len = len;
	iov_subsegment(buf->head, subbuf->head, &base, &len);

	if (base < buf->page_len) {
		i = (base + buf->page_base) >> PAGE_CACHE_SHIFT;
		subbuf->pages = &buf->pages[i];
		subbuf->page_base = (base + buf->page_base) & ~PAGE_CACHE_MASK;
		subbuf->page_len = min((int)buf->page_len - base, len);
		len -= subbuf->page_len;
		base = 0;
	} else {
		base -= buf->page_len;
		subbuf->page_len = 0;
	}

	iov_subsegment(buf->tail, subbuf->tail, &base, &len);
	if (base || len)
		return -1;
	return 0;
}

/* obj is assumed to point to allocated memory of size at least len: */
int
read_bytes_from_xdr_buf(struct xdr_buf *buf, int base, void *obj, int len)
{
	struct xdr_buf subbuf;
	int this_len;
	int status;

	status = xdr_buf_subsegment(buf, &subbuf, base, len);
	if (status)
		goto out;
	this_len = min(len, (int)subbuf.head[0].iov_len);
	memcpy(obj, subbuf.head[0].iov_base, this_len);
	len -= this_len;
	obj += this_len;
	this_len = min(len, (int)subbuf.page_len);
	if (this_len)
		_copy_from_pages(obj, subbuf.pages, subbuf.page_base, this_len);
	len -= this_len;
	obj += this_len;
	this_len = min(len, (int)subbuf.tail[0].iov_len);
	memcpy(obj, subbuf.tail[0].iov_base, this_len);
out:
	return status;
}

static int
read_u32_from_xdr_buf(struct xdr_buf *buf, int base, u32 *obj)
{
	u32	raw;
	int	status;

	status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
	if (status)
		return status;
	*obj = ntohl(raw);
	return 0;
}

/* If the netobj starting offset bytes from the start of xdr_buf is contained
 * entirely in the head or the tail, set object to point to it; otherwise
 * try to find space for it at the end of the tail, copy it there, and
 * set obj to point to it. */
int
xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, int offset)
{
	u32	tail_offset = buf->head[0].iov_len + buf->page_len;
	u32	obj_end_offset;

	if (read_u32_from_xdr_buf(buf, offset, &obj->len))
		goto out;
	obj_end_offset = offset + 4 + obj->len;

	if (obj_end_offset <= buf->head[0].iov_len) {
		/* The obj is contained entirely in the head: */
		obj->data = buf->head[0].iov_base + offset + 4;
	} else if (offset + 4 >= tail_offset) {
		if (obj_end_offset - tail_offset
				> buf->tail[0].iov_len)
			goto out;
		/* The obj is contained entirely in the tail: */
		obj->data = buf->tail[0].iov_base
			+ offset - tail_offset + 4;
	} else {
		/* use end of tail as storage for obj:
		 * (We don't copy to the beginning because then we'd have
		 * to worry about doing a potentially overlapping copy.
		 * This assumes the object is at most half the length of the
		 * tail.) */
		if (obj->len > buf->tail[0].iov_len)
			goto out;
		obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len - 
				obj->len;
		if (read_bytes_from_xdr_buf(buf, offset + 4,
					obj->data, obj->len))
			goto out;

	}
	return 0;
out:
	return -1;
}