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Subject[patch 7/13] Encode and decode arbitrary XDR arrays
Add xdr_encode_array2 and xdr_decode_array2 functions for encoding
end decoding arrays with arbitrary entries, such as acl entries. The
goal here is to do this without allocating a contiguous temporary
buffer.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Olaf Kirch <okir@suse.de>

Index: linux-2.6.11-rc2/include/linux/sunrpc/xdr.h
===================================================================
--- linux-2.6.11-rc2.orig/include/linux/sunrpc/xdr.h
+++ linux-2.6.11-rc2/include/linux/sunrpc/xdr.h
@@ -146,7 +146,8 @@ extern void xdr_shift_buf(struct xdr_buf
extern void xdr_buf_from_iov(struct kvec *, struct xdr_buf *);
extern int xdr_buf_subsegment(struct xdr_buf *, struct xdr_buf *, int, int);
extern int xdr_buf_read_netobj(struct xdr_buf *, struct xdr_netobj *, int);
-extern int read_bytes_from_xdr_buf(struct xdr_buf *buf, int base, void *obj, int len);
+extern int read_bytes_from_xdr_buf(struct xdr_buf *, int, void *, int);
+extern int write_bytes_to_xdr_buf(struct xdr_buf *, int, void *, int);

/*
* Helper structure for copying from an sk_buff.
@@ -168,6 +169,22 @@ struct sockaddr;
extern int xdr_sendpages(struct socket *, struct sockaddr *, int,
struct xdr_buf *, unsigned int, int);

+extern int xdr_encode_word(struct xdr_buf *, int, u32);
+extern int xdr_decode_word(struct xdr_buf *, int, u32 *);
+
+struct xdr_array2_desc;
+typedef int (*xdr_xcode_elem_t)(struct xdr_array2_desc *desc, void *elem);
+struct xdr_array2_desc {
+ unsigned int elem_size;
+ unsigned int array_len;
+ xdr_xcode_elem_t xcode;
+};
+
+extern int xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
+ struct xdr_array2_desc *desc);
+extern int xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
+ struct xdr_array2_desc *desc);
+
/*
* Provide some simple tools for XDR buffer overflow-checking etc.
*/
Index: linux-2.6.11-rc2/net/sunrpc/sunrpc_syms.c
===================================================================
--- linux-2.6.11-rc2.orig/net/sunrpc/sunrpc_syms.c
+++ linux-2.6.11-rc2/net/sunrpc/sunrpc_syms.c
@@ -129,6 +129,10 @@ EXPORT_SYMBOL(xdr_encode_netobj);
EXPORT_SYMBOL(xdr_encode_pages);
EXPORT_SYMBOL(xdr_inline_pages);
EXPORT_SYMBOL(xdr_shift_buf);
+EXPORT_SYMBOL(xdr_encode_word);
+EXPORT_SYMBOL(xdr_decode_word);
+EXPORT_SYMBOL(xdr_encode_array2);
+EXPORT_SYMBOL(xdr_decode_array2);
EXPORT_SYMBOL(xdr_buf_from_iov);
EXPORT_SYMBOL(xdr_buf_subsegment);
EXPORT_SYMBOL(xdr_buf_read_netobj);
Index: linux-2.6.11-rc2/net/sunrpc/xdr.c
===================================================================
--- linux-2.6.11-rc2.orig/net/sunrpc/xdr.c
+++ linux-2.6.11-rc2/net/sunrpc/xdr.c
@@ -868,8 +868,34 @@ out:
return status;
}

-static int
-read_u32_from_xdr_buf(struct xdr_buf *buf, int base, u32 *obj)
+/* obj is assumed to point to allocated memory of size at least len: */
+int
+write_bytes_to_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(subbuf.head[0].iov_base, obj, this_len);
+ len -= this_len;
+ obj += this_len;
+ this_len = min(len, (int)subbuf.page_len);
+ if (this_len)
+ _copy_to_pages(subbuf.pages, subbuf.page_base, obj, this_len);
+ len -= this_len;
+ obj += this_len;
+ this_len = min(len, (int)subbuf.tail[0].iov_len);
+ memcpy(subbuf.tail[0].iov_base, obj, this_len);
+out:
+ return status;
+}
+
+int
+xdr_decode_word(struct xdr_buf *buf, int base, u32 *obj)
{
u32 raw;
int status;
@@ -881,6 +907,14 @@ read_u32_from_xdr_buf(struct xdr_buf *bu
return 0;
}

+int
+xdr_encode_word(struct xdr_buf *buf, int base, u32 obj)
+{
+ u32 raw = htonl(obj);
+
+ return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
+}
+
/* 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
@@ -891,7 +925,7 @@ xdr_buf_read_netobj(struct xdr_buf *buf,
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))
+ if (xdr_decode_word(buf, offset, &obj->len))
goto out;
obj_end_offset = offset + 4 + obj->len;

@@ -924,3 +958,194 @@ xdr_buf_read_netobj(struct xdr_buf *buf,
out:
return -1;
}
+
+/* Returns 0 on success, or else a negative error code. */
+static int
+xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
+ struct xdr_array2_desc *desc, int encode)
+{
+ char elem[desc->elem_size], *c;
+ unsigned int copied = 0, todo, avail_here;
+ struct page **ppages = NULL;
+ int err = 0;
+
+ if (encode) {
+ if (xdr_encode_word(buf, base, desc->array_len) != 0)
+ return -EINVAL;
+ } else {
+ if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
+ (unsigned long) base + 4 + desc->array_len *
+ desc->elem_size > buf->len)
+ return -EINVAL;
+ }
+ base += 4;
+
+ if (!desc->xcode)
+ return 0;
+
+ todo = desc->array_len * desc->elem_size;
+
+ /* process head */
+ if (todo && base < buf->head->iov_len) {
+ c = buf->head->iov_base + base;
+ avail_here = min_t(unsigned int, todo,
+ buf->head->iov_len - base);
+ todo -= avail_here;
+
+ while (avail_here >= desc->elem_size) {
+ err = desc->xcode(desc, c);
+ if (err)
+ goto out;
+ c += desc->elem_size;
+ avail_here -= desc->elem_size;
+ }
+ if (avail_here) {
+ if (encode) {
+ err = desc->xcode(desc, elem);
+ if (err)
+ goto out;
+ memcpy(c, elem, avail_here);
+ } else
+ memcpy(elem, c, avail_here);
+ copied = avail_here;
+ }
+ base = buf->head->iov_len; /* align to start of pages */
+ }
+
+ /* process pages array */
+ base -= buf->head->iov_len;
+ if (todo && base < buf->page_len) {
+ avail_here = min(todo, buf->page_len - base);
+ todo -= avail_here;
+
+ base += buf->page_base;
+ ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
+ base &= ~PAGE_CACHE_MASK;
+ unsigned int avail_page = min_t(unsigned int,
+ PAGE_CACHE_SIZE - base, avail_here);
+ c = kmap(*ppages) + base;
+
+ while (avail_here) {
+ avail_here -= avail_page;
+ if (copied || avail_page < desc->elem_size) {
+ unsigned int l = min(avail_page,
+ desc->elem_size - copied);
+ if (encode) {
+ if (!copied) {
+ err = desc->xcode(desc, elem);
+ if (err)
+ goto out;
+ }
+ memcpy(c, elem + copied, l);
+ copied += l;
+ if (copied == desc->elem_size)
+ copied = 0;
+ } else {
+ memcpy(elem + copied, c, l);
+ copied += l;
+ if (copied == desc->elem_size) {
+ err = desc->xcode(desc, elem);
+ if (err)
+ goto out;
+ copied = 0;
+ }
+ }
+ avail_page -= l;
+ c += l;
+ }
+ while (avail_page >= desc->elem_size) {
+ err = desc->xcode(desc, c);
+ if (err)
+ goto out;
+ c += desc->elem_size;
+ avail_page -= desc->elem_size;
+ }
+ if (avail_page) {
+ unsigned int l = min(avail_page,
+ desc->elem_size - copied);
+ if (encode) {
+ if (!copied) {
+ err = desc->xcode(desc, elem);
+ if (err)
+ goto out;
+ }
+ memcpy(c, elem + copied, l);
+ copied += l;
+ if (copied == desc->elem_size)
+ copied = 0;
+ } else {
+ memcpy(elem + copied, c, l);
+ copied += l;
+ if (copied == desc->elem_size) {
+ err = desc->xcode(desc, elem);
+ if (err)
+ goto out;
+ copied = 0;
+ }
+ }
+ }
+ if (avail_here) {
+ kunmap(*ppages);
+ ppages++;
+ c = kmap(*ppages);
+ }
+
+ avail_page = min(avail_here,
+ (unsigned int) PAGE_CACHE_SIZE);
+ }
+ base = buf->page_len; /* align to start of tail */
+ }
+
+ /* process tail */
+ base -= buf->page_len;
+ if (todo) {
+ c = buf->tail->iov_base + base;
+ if (copied) {
+ unsigned int l = desc->elem_size - copied;
+
+ if (encode)
+ memcpy(c, elem + copied, l);
+ else {
+ memcpy(elem + copied, c, l);
+ err = desc->xcode(desc, elem);
+ if (err)
+ goto out;
+ }
+ todo -= l;
+ c += l;
+ }
+ while (todo) {
+ err = desc->xcode(desc, c);
+ if (err)
+ goto out;
+ c += desc->elem_size;
+ todo -= desc->elem_size;
+ }
+ }
+
+out:
+ if (ppages)
+ kunmap(*ppages);
+ return err;
+}
+
+int
+xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
+ struct xdr_array2_desc *desc)
+{
+ if (base >= buf->len)
+ return -EINVAL;
+
+ return xdr_xcode_array2(buf, base, desc, 0);
+}
+
+int
+xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
+ struct xdr_array2_desc *desc)
+{
+ if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
+ buf->head->iov_len + buf->page_len + buf->tail->iov_len)
+ return -EINVAL;
+
+ return xdr_xcode_array2(buf, base, desc, 1);
+}
--
Andreas Gruenbacher <agruen@suse.de>
SUSE Labs, SUSE LINUX PRODUCTS GMBH

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