path: root/net/sunrpc/xdr.c

/*
 * linux/net/sunrpc/xdr.c
 *
 * Generic XDR support.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/pagemap.h>
#include <linux/errno.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/msg_prot.h>

/*
 * XDR functions for basic NFS types
 */
__be32 *
xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
{
	unsigned int	quadlen = XDR_QUADLEN(obj->len);

	p[quadlen] = 0;		/* zero trailing bytes */
	*p++ = cpu_to_be32(obj->len);
	memcpy(p, obj->data, obj->len);
	return p + XDR_QUADLEN(obj->len);
}
EXPORT_SYMBOL_GPL(xdr_encode_netobj);

__be32 *
xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
{
	unsigned int	len;

	if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
		return NULL;
	obj->len  = len;
	obj->data = (u8 *) p;
	return p + XDR_QUADLEN(len);
}
EXPORT_SYMBOL_GPL(xdr_decode_netobj);

/**
 * 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
 *
 */
__be32 *xdr_encode_opaque_fixed(__be32 *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_GPL(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
 */
__be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
{
	*p++ = cpu_to_be32(nbytes);
	return xdr_encode_opaque_fixed(p, ptr, nbytes);
}
EXPORT_SYMBOL_GPL(xdr_encode_opaque);

__be32 *
xdr_encode_string(__be32 *p, const char *string)
{
	return xdr_encode_array(p, string, strlen(string));
}
EXPORT_SYMBOL_GPL(xdr_encode_string);

__be32 *
xdr_decode_string_inplace(__be32 *p, char **sp,
			  unsigned int *lenp, unsigned int maxlen)
{
	u32 len;

	len = be32_to_cpu(*p++);
	if (len > maxlen)
		return NULL;
	*lenp = len;
	*sp = (char *) p;
	return p + XDR_QUADLEN(len);
}
EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);

/**
 * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
 * @buf: XDR buffer where string resides
 * @len: length of string, in bytes
 *
 */
void
xdr_terminate_string(struct xdr_buf *buf, const u32 len)
{
	char *kaddr;

	kaddr = kmap_atomic(buf->pages[0]);
	kaddr[buf->page_base + len] = '\0';
	kunmap_atomic(kaddr);
}
EXPORT_SYMBOL_GPL(xdr_terminate_string);

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;
}
EXPORT_SYMBOL_GPL(xdr_inline_pages);

/*
 * 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_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_SHIFT);
	pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);

	pgto_base &= ~PAGE_MASK;
	pgfrom_base &= ~PAGE_MASK;

	do {
		/* Are any pointers crossing a page boundary? */
		if (pgto_base == 0) {
			pgto_base = PAGE_SIZE;
			pgto--;
		}
		if (pgfrom_base == 0) {
			pgfrom_base = PAGE_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);
		if (*pgto != *pgfrom) {
			vfrom = kmap_atomic(*pgfrom);
			memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
			kunmap_atomic(vfrom);
		} else
			memmove(vto + pgto_base, vto + pgfrom_base, copy);
		flush_dcache_page(*pgto);
		kunmap_atomic(vto);

	} 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_SHIFT);
	pgbase &= ~PAGE_MASK;

	for (;;) {
		copy = PAGE_SIZE - pgbase;
		if (copy > len)
			copy = len;

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

		len -= copy;
		if (len == 0)
			break;

		pgbase += copy;
		if (pgbase == PAGE_SIZE) {
			flush_dcache_page(*pgto);
			pgbase = 0;
			pgto++;
		}
		p += copy;
	}
	flush_dcache_page(*pgto);
}

/**
 * _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_SHIFT);
	pgbase &= ~PAGE_MASK;

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

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

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

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

/**
 * 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.
 */
static 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;

	WARN_ON_ONCE(len > head->iov_len);
	if (len > head->iov_len)
		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-