[PATCH] RPC: Encode and decode arbitrary XDR arrays

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

3 files changed, 275 insertions, 4 deletions

diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 5d1eed2b58a1..34ec3e8d99b3 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -146,7 +146,8 @@ extern void xdr_shift_buf(struct xdr_buf *, size_t);
 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.
  */
diff --git a/net/sunrpc/sunrpc_syms.c b/net/sunrpc/sunrpc_syms.c
index d8673f66acc3..32e8acbc60fe 100644
--- a/net/sunrpc/sunrpc_syms.c
+++ b/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);
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index b3ac3f72bf9c..8a4d9c106af1 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -887,8 +887,34 @@ 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;
@@ -900,6 +926,14 @@ read_u32_from_xdr_buf(struct xdr_buf *buf, int base, u32 *obj)
         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
@@ -910,7 +944,7 @@ 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))
+        if (xdr_decode_word(buf, offset, &obj->len))
                 goto out;
         obj_end_offset = offset + 4 + obj->len;
 
@@ -943,3 +977,219 @@ xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, int offset)
 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 = NULL, *c;
+        unsigned int copied = 0, todo, avail_here;
+        struct page **ppages = NULL;
+        int err;
+
+        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 (!elem) {
+                                elem = kmalloc(desc->elem_size, GFP_KERNEL);
+                                err = -ENOMEM;
+                                if (!elem)
+                                        goto out;
+                        }
+                        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) {
+                unsigned int avail_page;
+
+                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;
+                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 (!elem) {
+                                        elem = kmalloc(desc->elem_size,
+                                                       GFP_KERNEL);
+                                        err = -ENOMEM;
+                                        if (!elem)
+                                                goto out;
+                                }
+                                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 (!elem) {
+                                        elem = kmalloc(desc->elem_size,
+                                                       GFP_KERNEL);
+                                        err = -ENOMEM;
+                                        if (!elem)
+                                                goto out;
+                                }
+                                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;
+                }
+        }
+        err = 0;
+
+out:
+        if (elem)
+                kfree(elem);
+        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);
+}