xref: /freebsd/usr.bin/mkuzip/mkuz_blockcache.c (revision acc1a9ef8333c798c210fa94be6af4d5fe2dd794)
1 /*
2  * Copyright (c) 2016 Maxim Sobolev <sobomax@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 
31 #include <sys/types.h>
32 #include <md5.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36 
37 #if defined(MKUZ_DEBUG)
38 # include <stdio.h>
39 #endif
40 
41 #include "mkuz_blockcache.h"
42 
43 struct mkuz_blkcache {
44     struct mkuz_blkcache_hit hit;
45     off_t data_offset;
46     unsigned char digest[16];
47     struct mkuz_blkcache *next;
48 };
49 
50 static struct mkuz_blkcache blkcache;
51 
52 struct mkuz_blkcache_hit *
53 mkuz_blkcache_regblock(int fd, uint32_t blkno, off_t offset, ssize_t len,
54   void *data)
55 {
56     struct mkuz_blkcache *bcep;
57     MD5_CTX mcontext;
58     off_t data_offset;
59     unsigned char mdigest[16];
60 
61     data_offset = lseek(fd, 0, SEEK_CUR);
62     if (data_offset < 0) {
63         return (NULL);
64     }
65     MD5Init(&mcontext);
66     MD5Update(&mcontext, data, len);
67     MD5Final(mdigest, &mcontext);
68     if (blkcache.hit.len == 0) {
69         bcep = &blkcache;
70     } else {
71         for (bcep = &blkcache; bcep != NULL; bcep = bcep->next) {
72             if (bcep->hit.len != len)
73                 continue;
74             if (memcmp(mdigest, bcep->digest, sizeof(mdigest)) == 0) {
75                 break;
76             }
77         }
78         if (bcep != NULL) {
79 #if defined(MKUZ_DEBUG)
80             printf("cache hit %d, %d, %d\n", (int)bcep->hit.offset, (int)data_offset, (int)len);
81 #endif
82             return (&bcep->hit);
83         }
84         bcep = malloc(sizeof(struct mkuz_blkcache));
85         if (bcep == NULL)
86             return (NULL);
87         memset(bcep, '\0', sizeof(struct mkuz_blkcache));
88         bcep->next = blkcache.next;
89         blkcache.next = bcep;
90     }
91     memcpy(bcep->digest, mdigest, sizeof(mdigest));
92     bcep->data_offset = data_offset;
93     bcep->hit.offset = offset;
94     bcep->hit.len = len;
95     bcep->hit.blkno = blkno;
96     return (NULL);
97 }
98