1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Mike Olson. 7 * 8 * %sccs.include.redist.c% 9 */ 10 11 #if defined(LIBC_SCCS) && !defined(lint) 12 static char sccsid[] = "@(#)bt_open.c 5.22 (Berkeley) 11/13/92"; 13 #endif /* LIBC_SCCS and not lint */ 14 15 /* 16 * Implementation of btree access method for 4.4BSD. 17 * 18 * The design here was originally based on that of the btree access method 19 * used in the Postgres database system at UC Berkeley. This implementation 20 * is wholly independent of the Postgres code. 21 */ 22 23 #include <sys/param.h> 24 #include <sys/stat.h> 25 26 #define __DBINTERFACE_PRIVATE 27 #include <db.h> 28 #include <errno.h> 29 #include <fcntl.h> 30 #include <limits.h> 31 #include <signal.h> 32 #include <stdio.h> 33 #include <stdlib.h> 34 #include <string.h> 35 #include <unistd.h> 36 37 #include "btree.h" 38 39 static int nroot __P((BTREE *)); 40 static int tmp __P((void)); 41 42 /* 43 * __BT_OPEN -- Open a btree. 44 * 45 * Creates and fills a DB struct, and calls the routine that actually 46 * opens the btree. 47 * 48 * Parameters: 49 * fname: filename (NULL for in-memory trees) 50 * flags: open flag bits 51 * mode: open permission bits 52 * b: BTREEINFO pointer 53 * 54 * Returns: 55 * NULL on failure, pointer to DB on success. 56 * 57 */ 58 DB * 59 __bt_open(fname, flags, mode, openinfo) 60 const char *fname; 61 int flags, mode; 62 const BTREEINFO *openinfo; 63 { 64 BTMETA m; 65 BTREE *t; 66 BTREEINFO b; 67 DB *dbp; 68 pgno_t ncache; 69 struct stat sb; 70 int nr; 71 72 t = NULL; 73 74 /* 75 * Intention is to make sure all of the user's selections are okay 76 * here and then use them without checking. Can't be complete, since 77 * we don't know the right page size, lorder or flags until the backing 78 * file is opened. Also, the file's page size can cause the cachesize 79 * to change. 80 */ 81 if (openinfo) { 82 b = *openinfo; 83 84 /* Flags: R_DUP. */ 85 if (b.flags & ~(R_DUP)) 86 goto einval; 87 88 /* 89 * Page size must be index_t aligned and >= MINPSIZE. Default 90 * page size is set farther on, based on the underlying file 91 * transfer size. 92 */ 93 if (b.psize && 94 (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET || 95 b.psize & sizeof(index_t) - 1)) 96 goto einval; 97 98 /* Minimum number of keys per page; absolute minimum is 2. */ 99 if (b.minkeypage) { 100 if (b.minkeypage < 2) 101 goto einval; 102 } else 103 b.minkeypage = DEFMINKEYPAGE; 104 105 /* If no comparison, use default comparison and prefix. */ 106 if (b.compare == NULL) { 107 b.compare = __bt_defcmp; 108 if (b.prefix == NULL) 109 b.prefix = __bt_defpfx; 110 } 111 112 if (b.lorder == 0) 113 b.lorder = BYTE_ORDER; 114 else if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN) 115 goto einval; 116 } else { 117 b.compare = __bt_defcmp; 118 b.cachesize = 0; 119 b.flags = 0; 120 b.lorder = BYTE_ORDER; 121 b.minkeypage = DEFMINKEYPAGE; 122 b.prefix = __bt_defpfx; 123 b.psize = 0; 124 } 125 126 /* Allocate and initialize DB and BTREE structures. */ 127 if ((t = malloc(sizeof(BTREE))) == NULL) 128 goto err; 129 t->bt_fd = -1; /* Don't close unopened fd on error. */ 130 if ((t->bt_dbp = dbp = malloc(sizeof(DB))) == NULL) 131 goto err; 132 t->bt_bcursor.pgno = P_INVALID; 133 t->bt_bcursor.index = 0; 134 t->bt_stack = NULL; 135 t->bt_sp = t->bt_maxstack = 0; 136 t->bt_kbuf = t->bt_dbuf = NULL; 137 t->bt_kbufsz = t->bt_dbufsz = 0; 138 t->bt_order = NOT; 139 t->bt_cmp = b.compare; 140 t->bt_pfx = b.prefix; 141 t->bt_flags = 0; 142 143 dbp->type = DB_BTREE; 144 dbp->internal = t; 145 dbp->close = __bt_close; 146 dbp->del = __bt_delete; 147 dbp->get = __bt_get; 148 dbp->put = __bt_put; 149 dbp->seq = __bt_seq; 150 dbp->sync = __bt_sync; 151 152 /* 153 * If no file name was supplied, this is an in-memory btree and we 154 * open a backing temporary file. Otherwise, it's a disk-based tree. 155 */ 156 if (fname) { 157 switch(flags & O_ACCMODE) { 158 case O_RDONLY: 159 SET(t, BTF_RDONLY); 160 break; 161 case O_RDWR: 162 break; 163 case O_WRONLY: 164 default: 165 goto einval; 166 } 167 168 #define USEFLAGS \ 169 (O_CREAT|O_EXCL|O_EXLOCK|O_RDONLY|O_RDWR|O_SHLOCK|O_TRUNC) 170 if ((t->bt_fd = open(fname, flags & USEFLAGS, mode)) < 0) 171 goto err; 172 173 } else { 174 if ((flags & O_ACCMODE) != O_RDWR) 175 goto einval; 176 if ((t->bt_fd = tmp()) == -1) 177 goto err; 178 SET(t, BTF_INMEM); 179 } 180 181 if (fcntl(t->bt_fd, F_SETFD, 1) == -1) 182 goto err; 183 184 if (fstat(t->bt_fd, &sb)) 185 goto err; 186 if (sb.st_size) { 187 nr = read(t->bt_fd, &m, sizeof(BTMETA)); 188 if (nr < 0) 189 goto err; 190 if (nr != sizeof(BTMETA)) 191 goto eftype; 192 193 /* 194 * Read in the meta-data. This can change the notion of what 195 * the lorder, page size and flags are, and, when the page size 196 * changes the cachesize value can change as well. 197 * 198 * Lorder is always stored in host-independent format. 199 */ 200 m.m_lorder = ntohl(m.m_lorder); 201 if (m.m_lorder != BIG_ENDIAN && m.m_lorder != LITTLE_ENDIAN) 202 goto eftype; 203 if (m.m_lorder != BYTE_ORDER) { 204 BLSWAP(m.m_magic); 205 BLSWAP(m.m_version); 206 BLSWAP(m.m_psize); 207 BLSWAP(m.m_free); 208 BLSWAP(m.m_nrecs); 209 BLSWAP(m.m_flags); 210 } 211 if (m.m_magic != BTREEMAGIC || m.m_version != BTREEVERSION) 212 goto eftype; 213 if (m.m_psize < MINPSIZE || m.m_psize > MAX_PAGE_OFFSET || 214 m.m_psize & sizeof(index_t) - 1) 215 goto eftype; 216 if (m.m_flags & ~SAVEMETA) 217 goto eftype; 218 b.psize = m.m_psize; 219 t->bt_flags |= m.m_flags; 220 t->bt_free = m.m_free; 221 t->bt_lorder = m.m_lorder; 222 t->bt_nrecs = m.m_nrecs; 223 } else { 224 /* 225 * Set the page size to the best value for I/O to this file. 226 * Don't overflow the page offset type. 227 */ 228 if (b.psize == 0) { 229 b.psize = sb.st_blksize; 230 if (b.psize < MINPSIZE) 231 b.psize = MINPSIZE; 232 if (b.psize > MAX_PAGE_OFFSET) 233 b.psize = MAX_PAGE_OFFSET; 234 } 235 if (!(b.flags & R_DUP)) 236 SET(t, BTF_NODUPS); 237 t->bt_free = P_INVALID; 238 t->bt_lorder = b.lorder; 239 t->bt_nrecs = 0; 240 SET(t, BTF_METADIRTY); 241 } 242 243 t->bt_psize = b.psize; 244 245 /* Set the cache size; must be a multiple of the page size. */ 246 if (b.cachesize && b.cachesize & b.psize - 1) 247 b.cachesize += (~b.cachesize & b.psize - 1) + 1; 248 if (b.cachesize < b.psize * MINCACHE) 249 b.cachesize = b.psize * MINCACHE; 250 251 /* Calculate number of pages to cache. */ 252 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize; 253 254 /* 255 * The btree data structure requires that at least two keys can fit on 256 * a page, but other than that there's no fixed requirement. The user 257 * specified a minimum number per page, and we translated that into the 258 * number of bytes a key/data pair can use before being placed on an 259 * overflow page. This calculation includes the page header, the size 260 * of the index referencing the leaf item and the size of the leaf item 261 * structure. Also, don't let the user specify a minkeypage such that 262 * a key/data pair won't fit even if both key and data are on overflow 263 * pages. 264 */ 265 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage - 266 (sizeof(index_t) + NBLEAFDBT(0, 0)); 267 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(index_t)) 268 t->bt_ovflsize = 269 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(index_t); 270 271 /* Initialize the buffer pool. */ 272 if ((t->bt_mp = 273 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL) 274 goto err; 275 if (!ISSET(t, BTF_INMEM)) 276 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t); 277 278 /* Create a root page if new tree. */ 279 if (nroot(t) == RET_ERROR) 280 goto err; 281 282 return (dbp); 283 284 einval: errno = EINVAL; 285 goto err; 286 287 eftype: errno = EFTYPE; 288 goto err; 289 290 err: if (t) { 291 if (t->bt_dbp) 292 free(t->bt_dbp); 293 if (t->bt_fd != -1) 294 (void)close(t->bt_fd); 295 free(t); 296 } 297 return (NULL); 298 } 299 300 /* 301 * NROOT -- Create the root of a new tree. 302 * 303 * Parameters: 304 * t: tree 305 * 306 * Returns: 307 * RET_ERROR, RET_SUCCESS 308 */ 309 static int 310 nroot(t) 311 BTREE *t; 312 { 313 PAGE *meta, *root; 314 pgno_t npg; 315 316 if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) { 317 mpool_put(t->bt_mp, meta, 0); 318 return (RET_SUCCESS); 319 } 320 if (errno != EINVAL) 321 return (RET_ERROR); 322 323 if ((meta = mpool_new(t->bt_mp, &npg)) == NULL) 324 return (RET_ERROR); 325 326 if ((root = mpool_new(t->bt_mp, &npg)) == NULL) 327 return (RET_ERROR); 328 329 if (npg != P_ROOT) 330 return (RET_ERROR); 331 root->pgno = npg; 332 root->prevpg = root->nextpg = P_INVALID; 333 root->lower = BTDATAOFF; 334 root->upper = t->bt_psize; 335 root->flags = P_BLEAF; 336 bzero(meta, t->bt_psize); 337 mpool_put(t->bt_mp, meta, MPOOL_DIRTY); 338 mpool_put(t->bt_mp, root, MPOOL_DIRTY); 339 return (RET_SUCCESS); 340 } 341 342 static int 343 tmp() 344 { 345 sigset_t set, oset; 346 int fd; 347 char *envtmp; 348 char path[MAXPATHLEN]; 349 350 envtmp = getenv("TMPDIR"); 351 (void)snprintf(path, 352 sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : "/tmp"); 353 354 (void)sigfillset(&set); 355 (void)sigprocmask(SIG_BLOCK, &set, &oset); 356 if ((fd = mkstemp(path)) != -1) 357 (void)unlink(path); 358 (void)sigprocmask(SIG_SETMASK, &oset, NULL); 359 return(fd); 360 } 361