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 #include <sys/cdefs.h>
28 #include <err.h>
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <unistd.h>
33
34 #if defined(MKUZ_DEBUG)
35 # include <assert.h>
36 # include <stdio.h>
37 #endif
38
39 #include "mkuz_blockcache.h"
40 #include "mkuz_blk.h"
41
42 struct mkuz_blkcache_itm {
43 struct mkuz_blk_info hit;
44 struct mkuz_blkcache_itm *next;
45 };
46
47 static struct mkuz_blkcache {
48 struct mkuz_blkcache_itm first[256];
49 } blkcache;
50
51 static int
verify_match(int fd,const struct mkuz_blk * cbp,struct mkuz_blkcache_itm * bcep)52 verify_match(int fd, const struct mkuz_blk *cbp, struct mkuz_blkcache_itm *bcep)
53 {
54 void *vbuf;
55 ssize_t rlen;
56 int rval;
57
58 rval = -1;
59 vbuf = malloc(cbp->info.len);
60 if (vbuf == NULL) {
61 goto e0;
62 }
63 if (lseek(fd, bcep->hit.offset, SEEK_SET) < 0) {
64 goto e1;
65 }
66 rlen = read(fd, vbuf, cbp->info.len);
67 if (rlen < 0 || (unsigned)rlen != cbp->info.len) {
68 goto e2;
69 }
70 rval = (memcmp(cbp->data, vbuf, cbp->info.len) == 0) ? 1 : 0;
71 e2:
72 lseek(fd, cbp->info.offset, SEEK_SET);
73 e1:
74 free(vbuf);
75 e0:
76 return (rval);
77 }
78
79 #define I2J(x) ((intmax_t)(x))
80 #define U2J(x) ((uintmax_t)(x))
81
82 static unsigned char
digest_fold(const unsigned char * mdigest)83 digest_fold(const unsigned char *mdigest)
84 {
85 int i;
86 unsigned char rval;
87
88 rval = mdigest[0];
89 for (i = 1; i < 16; i++) {
90 rval = rval ^ mdigest[i];
91 }
92 return (rval);
93 }
94
95 struct mkuz_blk_info *
mkuz_blkcache_regblock(int fd,const struct mkuz_blk * bp)96 mkuz_blkcache_regblock(int fd, const struct mkuz_blk *bp)
97 {
98 struct mkuz_blkcache_itm *bcep;
99 int rval;
100 unsigned char h;
101
102 #if defined(MKUZ_DEBUG)
103 assert((unsigned)lseek(fd, 0, SEEK_CUR) == bp->info.offset);
104 #endif
105 h = digest_fold(bp->info.digest);
106 if (blkcache.first[h].hit.len == 0) {
107 bcep = &blkcache.first[h];
108 } else {
109 for (bcep = &blkcache.first[h]; bcep != NULL; bcep = bcep->next) {
110 if (bcep->hit.len != bp->info.len)
111 continue;
112 if (memcmp(bp->info.digest, bcep->hit.digest,
113 sizeof(bp->info.digest)) == 0) {
114 break;
115 }
116 }
117 if (bcep != NULL) {
118 rval = verify_match(fd, bp, bcep);
119 if (rval == 1) {
120 #if defined(MKUZ_DEBUG)
121 fprintf(stderr, "cache hit %jd, %jd, %jd, %jd\n",
122 I2J(bcep->hit.blkno), I2J(bcep->hit.offset),
123 I2J(bp->info.offset), I2J(bp->info.len));
124 #endif
125 return (&bcep->hit);
126 }
127 if (rval == 0) {
128 #if defined(MKUZ_DEBUG)
129 fprintf(stderr, "block MD5 collision, you should try lottery, "
130 "man!\n");
131 #endif
132 return (NULL);
133 }
134 warn("verify_match");
135 return (NULL);
136 }
137 bcep = malloc(sizeof(struct mkuz_blkcache_itm));
138 if (bcep == NULL)
139 return (NULL);
140 memset(bcep, '\0', sizeof(struct mkuz_blkcache_itm));
141 bcep->next = blkcache.first[h].next;
142 blkcache.first[h].next = bcep;
143 }
144 bcep->hit = bp->info;
145 return (NULL);
146 }
147