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 __FBSDID("$FreeBSD$"); 29 30 #include <err.h> 31 #include <stdio.h> 32 #include <stdlib.h> 33 #include <string.h> 34 #include <unistd.h> 35 36 #if defined(MKUZ_DEBUG) 37 # include <assert.h> 38 # include <stdio.h> 39 #endif 40 41 #include "mkuz_blockcache.h" 42 #include "mkuz_blk.h" 43 44 struct mkuz_blkcache_itm { 45 struct mkuz_blk_info hit; 46 struct mkuz_blkcache_itm *next; 47 }; 48 49 static struct mkuz_blkcache { 50 struct mkuz_blkcache_itm first[256]; 51 } blkcache; 52 53 static int 54 verify_match(int fd, const struct mkuz_blk *cbp, struct mkuz_blkcache_itm *bcep) 55 { 56 void *vbuf; 57 ssize_t rlen; 58 int rval; 59 60 rval = -1; 61 vbuf = malloc(cbp->info.len); 62 if (vbuf == NULL) { 63 goto e0; 64 } 65 if (lseek(fd, bcep->hit.offset, SEEK_SET) < 0) { 66 goto e1; 67 } 68 rlen = read(fd, vbuf, cbp->info.len); 69 if (rlen < 0 || (unsigned)rlen != cbp->info.len) { 70 goto e2; 71 } 72 rval = (memcmp(cbp->data, vbuf, cbp->info.len) == 0) ? 1 : 0; 73 e2: 74 lseek(fd, cbp->info.offset, SEEK_SET); 75 e1: 76 free(vbuf); 77 e0: 78 return (rval); 79 } 80 81 #define I2J(x) ((intmax_t)(x)) 82 #define U2J(x) ((uintmax_t)(x)) 83 84 static unsigned char 85 digest_fold(const unsigned char *mdigest) 86 { 87 int i; 88 unsigned char rval; 89 90 rval = mdigest[0]; 91 for (i = 1; i < 16; i++) { 92 rval = rval ^ mdigest[i]; 93 } 94 return (rval); 95 } 96 97 struct mkuz_blk_info * 98 mkuz_blkcache_regblock(int fd, const struct mkuz_blk *bp) 99 { 100 struct mkuz_blkcache_itm *bcep; 101 int rval; 102 unsigned char h; 103 104 #if defined(MKUZ_DEBUG) 105 assert((unsigned)lseek(fd, 0, SEEK_CUR) == bp->info.offset); 106 #endif 107 h = digest_fold(bp->info.digest); 108 if (blkcache.first[h].hit.len == 0) { 109 bcep = &blkcache.first[h]; 110 } else { 111 for (bcep = &blkcache.first[h]; bcep != NULL; bcep = bcep->next) { 112 if (bcep->hit.len != bp->info.len) 113 continue; 114 if (memcmp(bp->info.digest, bcep->hit.digest, 115 sizeof(bp->info.digest)) == 0) { 116 break; 117 } 118 } 119 if (bcep != NULL) { 120 rval = verify_match(fd, bp, bcep); 121 if (rval == 1) { 122 #if defined(MKUZ_DEBUG) 123 fprintf(stderr, "cache hit %jd, %jd, %jd, %jd\n", 124 I2J(bcep->hit.blkno), I2J(bcep->hit.offset), 125 I2J(bp->info.offset), I2J(bp->info.len)); 126 #endif 127 return (&bcep->hit); 128 } 129 if (rval == 0) { 130 #if defined(MKUZ_DEBUG) 131 fprintf(stderr, "block MD5 collision, you should try lottery, " 132 "man!\n"); 133 #endif 134 return (NULL); 135 } 136 warn("verify_match"); 137 return (NULL); 138 } 139 bcep = malloc(sizeof(struct mkuz_blkcache_itm)); 140 if (bcep == NULL) 141 return (NULL); 142 memset(bcep, '\0', sizeof(struct mkuz_blkcache_itm)); 143 bcep->next = blkcache.first[h].next; 144 blkcache.first[h].next = bcep; 145 } 146 bcep->hit = bp->info; 147 return (NULL); 148 } 149