diff options
Diffstat (limited to 'net/sunrpc/xdr.c')
| -rw-r--r-- | net/sunrpc/xdr.c | 917 |
1 files changed, 917 insertions, 0 deletions
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c new file mode 100644 index 000000000000..4484931018eb --- /dev/null +++ b/net/sunrpc/xdr.c @@ -0,0 +1,917 @@ +/* + * linux/net/sunrpc/xdr.c + * + * Generic XDR support. + * + * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> + */ + +#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(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; +} + +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) { + flush_dcache_page(*pgto); + 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); + + } while ((len -= copy) != 0); + flush_dcache_page(*pgto); +} + +/* + * _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) { + flush_dcache_page(*pgto); + pgbase = 0; + pgto++; + } + p += copy; + + } while ((len -= copy) != 0); + 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. + */ +static 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. + */ +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; + 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. + */ +static 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; +} |