xdr.c

Linux Kernel 2.6.9 for OMAP1710

/*
 * linux/net/sunrpc/xdr.c
 *
 * Generic XDR support.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <[e-mail]>
 */

#include <linux/types.h>
#include <linux/socket.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/pagemap.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/net.h>
#include <net/sock.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/msg_prot.h>

/*
 * XDR functions for basic NFS types
 */
u32 *
xdr_encode_netobj(u32 *p, const struct xdr_netobj *obj)
{
	unsigned int	quadlen = XDR_QUADLEN(obj->len);

	p[quadlen] = 0;		/* zero trailing bytes */
	*p++ = htonl(obj->len);
	memcpy(p, obj->data, obj->len);
	return p + XDR_QUADLEN(obj->len);
}

u32 *
xdr_decode_netobj_fixed(u32 *p, void *obj, unsigned int len)
{
	if (ntohl(*p++) != len)
		return NULL;
	memcpy(obj, p, len);
	return p + XDR_QUADLEN(len);
}

u32 *
xdr_decode_netobj(u32 *p, struct xdr_netobj *obj)
{
	unsigned int	len;

	if ((len = ntohl(*p++)) > XDR_MAX_NETOBJ)
		return NULL;
	obj->len  = len;
	obj->data = (u8 *) p;
	return p + XDR_QUADLEN(len);
}

/**
 * xdr_encode_opaque_fixed - Encode fixed length opaque data
 * @p - pointer to current position in XDR buffer.
 * @ptr - pointer to data to encode (or NULL)
 * @nbytes - size of data.
 *
 * Copy the array of data of length nbytes at ptr to the XDR buffer
 * at position p, then align to the next 32-bit boundary by padding
 * with zero bytes (see RFC1832).
 * Note: if ptr is NULL, only the padding is performed.
 *
 * Returns the updated current XDR buffer position
 *
 */
u32 *xdr_encode_opaque_fixed(u32 *p, const void *ptr, unsigned int nbytes)
{
	if (likely(nbytes != 0)) {
		unsigned int quadlen = XDR_QUADLEN(nbytes);
		unsigned int padding = (quadlen << 2) - nbytes;

		if (ptr != NULL)
			memcpy(p, ptr, nbytes);
		if (padding != 0)
			memset((char *)p + nbytes, 0, padding);
		p += quadlen;
	}
	return p;
}
EXPORT_SYMBOL(xdr_encode_opaque_fixed);

/**
 * xdr_encode_opaque - Encode variable length opaque data
 * @p - pointer to current position in XDR buffer.
 * @ptr - pointer to data to encode (or NULL)
 * @nbytes - size of data.
 *
 * Returns the updated current XDR buffer position
 */
u32 *xdr_encode_opaque(u32 *p, const void *ptr, unsigned int nbytes)
{
	*p++ = htonl(nbytes);
	return xdr_encode_opaque_fixed(p, ptr, nbytes);
}
EXPORT_SYMBOL(xdr_encode_opaque);

u32 *
xdr_encode_string(u32 *p, const char *string)
{
	return xdr_encode_array(p, string, strlen(string));
}

u32 *
xdr_decode_string(u32 *p, char **sp, int *lenp, int maxlen)
{
	unsigned int	len;
	char		*string;

	if ((len = ntohl(*p++)) > maxlen)
		return NULL;
	if (lenp)
		*lenp = len;
	if ((len % 4) != 0) {
		string = (char *) p;
	} else {
		string = (char *) (p - 1);
		memmove(string, p, len);
	}
	string[len] = '\0';
	*sp = string;
	return p + XDR_QUADLEN(len);
}

u32 *
xdr_decode_string_inplace(u32 *p, char **sp, int *lenp, int maxlen)
{
	unsigned int	len;

	if ((len = ntohl(*p++)) > maxlen)
		return NULL;
	*lenp = len;
	*sp = (char *) p;
	return p + XDR_QUADLEN(len);
}

void
xdr_encode_pages(struct xdr_buf *xdr, struct page **pages, unsigned int base,
		 unsigned int len)
{
	struct kvec *tail = xdr->tail;
	u32 *p;

	xdr->pages = pages;
	xdr->page_base = base;
	xdr->page_len = len;

	p = (u32 *)xdr->head[0].iov_base + XDR_QUADLEN(xdr->head[0].iov_len);
	tail->iov_base = p;
	tail->iov_len = 0;

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

		*p = 0;
		tail->iov_base = (char *)p + (len & 3);
		tail->iov_len  = pad;
		len += pad;
	}
	xdr->buflen += len;
	xdr->len += len;
}

void
xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
		 struct page **pages, unsigned int base, unsigned int len)
{
	struct kvec *head = xdr->head;
	struct kvec *tail = xdr->tail;
	char *buf = (char *)head->iov_base;
	unsigned int buflen = head->iov_len;

	head->iov_len  = offset;

	xdr->pages = pages;
	xdr->page_base = base;
	xdr->page_len = len;

	tail->iov_base = buf + offset;
	tail->iov_len = buflen - offset;

	xdr->buflen += len;
}

/*
 * Realign the kvec if the server missed out some reply elements
 * (such as post-op attributes,...)
 * Note: This is a simple implementation that assumes that
 *            len <= iov->iov_len !!!
 *       The RPC header (assumed to be the 1st element in the iov array)
 *            is not shifted.
 */
void xdr_shift_iovec(struct kvec *iov, int nr, size_t len)
{
	struct kvec *pvec;

	for (pvec = iov + nr - 1; nr > 1; nr--, pvec--) {
		struct kvec *svec = pvec - 1;

		if (len > pvec->iov_len) {
			printk(KERN_DEBUG "RPC: Urk! Large shift of short iovec.\n");
			return;
		}
		memmove((char *)pvec->iov_base + len, pvec->iov_base,
			pvec->iov_len - len);

		if (len > svec->iov_len) {
			printk(KERN_DEBUG "RPC: Urk! Large shift of short iovec.\n");
			return;
		}
		memcpy(pvec->iov_base,
		       (char *)svec->iov_base + svec->iov_len - len, len);
	}
}

/*
 * Map a struct xdr_buf into an kvec array.
 */
int xdr_kmap(struct kvec *iov_base, struct xdr_buf *xdr, size_t base)
{
	struct kvec	*iov = iov_base;
	struct page	**ppage = xdr->pages;
	unsigned int	len, pglen = xdr->page_len;

	len = xdr->head[0].iov_len;
	if (base < len) {
		iov->iov_len = len - base;
		iov->iov_base = (char *)xdr->head[0].iov_base + base;
		iov++;
		base = 0;
	} else
		base -= len;

	if (pglen == 0)
		goto map_tail;
	if (base >= pglen) {
		base -= pglen;
		goto map_tail;
	}
	if (base || xdr->page_base) {
		pglen -= base;
		base  += xdr->page_base;
		ppage += base >> PAGE_CACHE_SHIFT;
		base &= ~PAGE_CACHE_MASK;
	}
	do {
		len = PAGE_CACHE_SIZE;
		iov->iov_base = kmap(*ppage);
		if (base) {
			iov->iov_base += base;
			len -= base;
			base = 0;
		}
		if (pglen < len)
			len = pglen;
		iov->iov_len = len;
		iov++;
		ppage++;
	} while ((pglen -= len) != 0);
map_tail:
	if (xdr->tail[0].iov_len) {
		iov->iov_len = xdr->tail[0].iov_len - base;
		iov->iov_base = (char *)xdr->tail[0].iov_base + base;
		iov++;
	}
	return (iov - iov_base);
}

void xdr_kunmap(struct xdr_buf *xdr, size_t base)
{
	struct page	**ppage = xdr->pages;
	unsigned int	pglen = xdr->page_len;

	if (!pglen)
		return;
	if (base > xdr->head[0].iov_len)
		base -= xdr->head[0].iov_len;
	else
		base = 0;

	if (base >= pglen)
		return;
	if (base || xdr->page_base) {
		pglen -= base;
		base  += xdr->page_base;
		ppage += base >> PAGE_CACHE_SHIFT;
		/* Note: The offset means that the length of the first
		 * page is really (PAGE_CACHE_SIZE - (base & ~PAGE_CACHE_MASK)).
		 * In order to avoid an extra test inside the loop,
		 * we bump pglen here, and just subtract PAGE_CACHE_SIZE... */
		pglen += base & ~PAGE_CACHE_MASK;
	}
	for (;;) {
		flush_dcache_page(*ppage);
		kunmap(*ppage);
		if (pglen <= PAGE_CACHE_SIZE)
			break;
		pglen -= PAGE_CACHE_SIZE;
		ppage++;
	}
}

void
xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base,
			  skb_reader_t *desc,
			  skb_read_actor_t copy_actor)
{
	struct page	**ppage = xdr->pages;
	unsigned int	len, pglen = xdr->page_len;
	int		ret;

	len = xdr->head[0].iov_len;
	if (base < len) {
		len -= base;
		ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
		if (ret != len || !desc->count)
			return;
		base = 0;
	} else
		base -= len;

	if (pglen == 0)
		goto copy_tail;
	if (base >= pglen) {
		base -= pglen;
		goto copy_tail;
	}
	if (base || xdr->page_base) {
		pglen -= base;
		base  += xdr->page_base;
		ppage += base >> PAGE_CACHE_SHIFT;
		base &= ~PAGE_CACHE_MASK;
	}
	do {
		char *kaddr;

		len = PAGE_CACHE_SIZE;
		kaddr = kmap_atomic(*ppage, KM_SKB_SUNRPC_DATA);
		if (base) {
			len -= base;
			if (pglen < len)
				len = pglen;
			ret = copy_actor(desc, kaddr + base, len);
			base = 0;
		} else {
			if (pglen < len)
				len = pglen;
			ret = copy_actor(desc, kaddr, len);
		}
		flush_dcache_page(*ppage);
		kunmap_atomic(kaddr, KM_SKB_SUNRPC_DATA);
		if (ret != len || !desc->count)
			return;
		ppage++;
	} while ((pglen -= len) != 0);
copy_tail:
	len = xdr->tail[0].iov_len;
	if (base < len)
		copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
}


int
xdr_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen,
		struct xdr_buf *xdr, unsigned int base, int msgflags)
{
	struct page **ppage = xdr->pages;
	unsigned int len, pglen = xdr->page_len;
	int err, ret = 0;
	ssize_t (*sendpage)(struct socket *, struct page *, int, size_t, int);

	len = xdr->head[0].iov_len;
	if (base < len || (addr != NULL && base == 0)) {
		struct kvec iov = {
			.iov_base = xdr->head[0].iov_base + base,
			.iov_len  = len - base,
		};
		struct msghdr msg = {
			.msg_name    = addr,
			.msg_namelen = addrlen,
			.msg_flags   = msgflags,
		};
		if (xdr->len > len)
			msg.msg_flags |= MSG_MORE;

		if (iov.iov_len != 0)
			err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
		else
			err = kernel_sendmsg(sock, &msg, NULL, 0, 0);
		if (ret == 0)
			ret = err;
		else if (err > 0)
			ret += err;
		if (err != iov.iov_len)
			goto out;
		base = 0;
	} else
		base -= len;

	if (pglen == 0)
		goto copy_tail;
	if (base >= pglen) {
		base -= pglen;
		goto copy_tail;
	}
	if (base || xdr->page_base) {
		pglen -= base;
		base  += xdr->page_base;
		ppage += base >> PAGE_CACHE_SHIFT;
		base &= ~PAGE_CACHE_MASK;
	}

	sendpage = sock->ops->sendpage ? : sock_no_sendpage;
	do {
		int flags = msgflags;

		len = PAGE_CACHE_SIZE;
		if (base)
			len -= base;
		if (pglen < len)
			len = pglen;

		if (pglen != len || xdr->tail[0].iov_len != 0)
			flags |= MSG_MORE;

		/* Hmm... We might be dealing with highmem pages */
		if (PageHighMem(*ppage))
			sendpage = sock_no_sendpage;
		err = sendpage(sock, *ppage, base, len, flags);
		if (ret == 0)
			ret = err;
		else if (err > 0)
			ret += err;
		if (err != len)
			goto out;
		base = 0;
		ppage++;
	} while ((pglen -= len) != 0);
copy_tail:
	len = xdr->tail[0].iov_len;
	if (base < len) {
		struct kvec iov = {
			.iov_base = xdr->tail[0].iov_base + base,
			.iov_len  = len - base,
		};
		struct msghdr msg = {
			.msg_flags   = msgflags,
		};
		err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
		if (ret == 0)
			ret = err;
		else if (err > 0)
			ret += err;
	}
out:
	return ret;
}


/*
 * Helper routines for doing 'memmove' like operations on a struct xdr_buf
 *
 * _shift_data_right_pages
 * @pages: vector of pages containing both the source and dest memory area.
 * @pgto_base: page vector address of destination
 * @pgfrom_base: page vector address of source
 * @len: number of bytes to copy
 *
 * Note: the addresses pgto_base and pgfrom_base are both calculated in
 *       the same way:
 *            if a memory area starts at byte 'base' in page 'pages[i]',
 *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
 * Also note: pgfrom_base must be < pgto_base, but the memory areas
 * 	they point to may overlap.
 */
static void
_shift_data_right_pages(struct page **pages, size_t pgto_base,
		size_t pgfrom_base, size_t len)
{
	struct page **pgfrom, **pgto;
	char *vfrom, *vto;
	size_t copy;

	BUG_ON(pgto_base <= pgfrom_base);

	pgto_base += len;
	pgfrom_base += len;

	pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
	pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);

	pgto_base &= ~PAGE_CACHE_MASK;
	pgfrom_base &= ~PAGE_CACHE_MASK;

	do {
		/* Are any pointers crossing a page boundary? */
		if (pgto_base == 0) {
			pgto_base = PAGE_CACHE_SIZE;
			pgto--;
		}
		if (pgfrom_base == 0) {
			pgfrom_base = PAGE_CACHE_SIZE;
			pgfrom--;
		}

		copy = len;
		if (copy > pgto_base)
			copy = pgto_base;
		if (copy > pgfrom_base)
			copy = pgfrom_base;
		pgto_base -= copy;
		pgfrom_base -= copy;

		vto = kmap_atomic(*pgto, KM_USER0);
		vfrom = kmap_atomic(*pgfrom, KM_USER1);
		memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
		kunmap_atomic(vfrom, KM_USER1);
		kunmap_atomic(vto, KM_USER0);