101 строка
2.6 KiB
C
101 строка
2.6 KiB
C
/*
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* Copyright (c) 2013
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/pagemap.h>
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#include "page_actor.h"
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/*
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* This file contains implementations of page_actor for decompressing into
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* an intermediate buffer, and for decompressing directly into the
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* page cache.
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*
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* Calling code should avoid sleeping between calls to squashfs_first_page()
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* and squashfs_finish_page().
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*/
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/* Implementation of page_actor for decompressing into intermediate buffer */
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static void *cache_first_page(struct squashfs_page_actor *actor)
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{
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actor->next_page = 1;
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return actor->buffer[0];
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}
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static void *cache_next_page(struct squashfs_page_actor *actor)
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{
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if (actor->next_page == actor->pages)
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return NULL;
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return actor->buffer[actor->next_page++];
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}
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static void cache_finish_page(struct squashfs_page_actor *actor)
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{
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/* empty */
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}
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struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
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int pages, int length)
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{
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struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);
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if (actor == NULL)
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return NULL;
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actor->length = length ? : pages * PAGE_CACHE_SIZE;
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actor->buffer = buffer;
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actor->pages = pages;
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actor->next_page = 0;
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actor->squashfs_first_page = cache_first_page;
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actor->squashfs_next_page = cache_next_page;
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actor->squashfs_finish_page = cache_finish_page;
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return actor;
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}
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/* Implementation of page_actor for decompressing directly into page cache. */
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static void *direct_first_page(struct squashfs_page_actor *actor)
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{
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actor->next_page = 1;
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return actor->pageaddr = kmap_atomic(actor->page[0]);
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}
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static void *direct_next_page(struct squashfs_page_actor *actor)
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{
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if (actor->pageaddr)
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kunmap_atomic(actor->pageaddr);
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return actor->pageaddr = actor->next_page == actor->pages ? NULL :
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kmap_atomic(actor->page[actor->next_page++]);
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}
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static void direct_finish_page(struct squashfs_page_actor *actor)
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{
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if (actor->pageaddr)
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kunmap_atomic(actor->pageaddr);
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}
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struct squashfs_page_actor *squashfs_page_actor_init_special(struct page **page,
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int pages, int length)
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{
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struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);
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if (actor == NULL)
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return NULL;
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actor->length = length ? : pages * PAGE_CACHE_SIZE;
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actor->page = page;
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actor->pages = pages;
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actor->next_page = 0;
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actor->pageaddr = NULL;
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actor->squashfs_first_page = direct_first_page;
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actor->squashfs_next_page = direct_next_page;
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actor->squashfs_finish_page = direct_finish_page;
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return actor;
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}
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