98 lines
3.1 KiB
C
98 lines
3.1 KiB
C
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/*
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* Copyright (c) 2016 Maxim Sobolev <sobomax@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <md5.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#if defined(MKUZ_DEBUG)
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# include <stdio.h>
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#endif
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#include "mkuz_blockcache.h"
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struct mkuz_blkcache {
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struct mkuz_blkcache_hit hit;
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off_t data_offset;
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unsigned char digest[16];
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struct mkuz_blkcache *next;
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};
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static struct mkuz_blkcache blkcache;
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struct mkuz_blkcache_hit *
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mkuz_blkcache_regblock(int fd, uint32_t blkno, off_t offset, ssize_t len,
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void *data)
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{
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struct mkuz_blkcache *bcep;
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MD5_CTX mcontext;
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off_t data_offset;
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unsigned char mdigest[16];
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data_offset = lseek(fd, 0, SEEK_CUR);
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if (data_offset < 0) {
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return (NULL);
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}
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MD5Init(&mcontext);
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MD5Update(&mcontext, data, len);
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MD5Final(mdigest, &mcontext);
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if (blkcache.hit.len == 0) {
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bcep = &blkcache;
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} else {
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for (bcep = &blkcache; bcep != NULL; bcep = bcep->next) {
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if (bcep->hit.len != len)
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continue;
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if (memcmp(mdigest, bcep->digest, sizeof(mdigest)) == 0) {
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break;
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}
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}
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if (bcep != NULL) {
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#if defined(MKUZ_DEBUG)
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printf("cache hit %d, %d, %d\n", (int)bcep->hit.offset, (int)data_offset, (int)len);
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#endif
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return (&bcep->hit);
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}
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bcep = malloc(sizeof(struct mkuz_blkcache));
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if (bcep == NULL)
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return (NULL);
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memset(bcep, '\0', sizeof(struct mkuz_blkcache));
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bcep->next = blkcache.next;
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blkcache.next = bcep;
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}
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memcpy(bcep->digest, mdigest, sizeof(mdigest));
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bcep->data_offset = data_offset;
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bcep->hit.offset = offset;
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bcep->hit.len = len;
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bcep->hit.blkno = blkno;
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return (NULL);
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}
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