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 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 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 * 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