opendir.c revision 178253
11556Srgrimes/*- 21556Srgrimes * Copyright (c) 1983, 1993 31556Srgrimes * The Regents of the University of California. All rights reserved. 41556Srgrimes * 51556Srgrimes * Redistribution and use in source and binary forms, with or without 61556Srgrimes * modification, are permitted provided that the following conditions 71556Srgrimes * are met: 81556Srgrimes * 1. Redistributions of source code must retain the above copyright 91556Srgrimes * notice, this list of conditions and the following disclaimer. 101556Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 111556Srgrimes * notice, this list of conditions and the following disclaimer in the 121556Srgrimes * documentation and/or other materials provided with the distribution. 131556Srgrimes * 4. Neither the name of the University nor the names of its contributors 141556Srgrimes * may be used to endorse or promote products derived from this software 151556Srgrimes * without specific prior written permission. 161556Srgrimes * 171556Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 181556Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 191556Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 201556Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 211556Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 221556Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 231556Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 241556Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 251556Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 261556Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 271556Srgrimes * SUCH DAMAGE. 281556Srgrimes */ 291556Srgrimes 301556Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 311556Srgrimesstatic char sccsid[] = "@(#)opendir.c 8.8 (Berkeley) 5/1/95"; 321556Srgrimes#endif /* LIBC_SCCS and not lint */ 331556Srgrimes#include <sys/cdefs.h> 3450471Speter__FBSDID("$FreeBSD: head/lib/libc/gen/opendir.c 178253 2008-04-16 18:40:52Z delphij $"); 351556Srgrimes 361556Srgrimes#include "namespace.h" 371556Srgrimes#include <sys/param.h> 381556Srgrimes#include <sys/mount.h> 391556Srgrimes#include <sys/stat.h> 401556Srgrimes 411556Srgrimes#include <dirent.h> 421556Srgrimes#include <errno.h> 431556Srgrimes#include <fcntl.h> 4446684Skris#include <stdlib.h> 451556Srgrimes#include <string.h> 461556Srgrimes#include <unistd.h> 471556Srgrimes#include "un-namespace.h" 481556Srgrimes 491556Srgrimes#include "telldir.h" 5046684Skris/* 511556Srgrimes * Open a directory. 521556Srgrimes */ 531556SrgrimesDIR * 541556Srgrimesopendir(const char *name) 551556Srgrimes{ 561556Srgrimes 571556Srgrimes return (__opendir2(name, DTF_HIDEW|DTF_NODUP)); 581556Srgrimes} 591556Srgrimes 601556SrgrimesDIR * 611556Srgrimes__opendir2(const char *name, int flags) 621556Srgrimes{ 631556Srgrimes DIR *dirp; 641556Srgrimes int fd; 651556Srgrimes int incr; 661556Srgrimes int saved_errno; 671556Srgrimes int unionstack; 681556Srgrimes struct stat statb; 691556Srgrimes 701556Srgrimes /* 711556Srgrimes * stat() before _open() because opening of special files may be 721556Srgrimes * harmful. _fstat() after open because the file may have changed. 731556Srgrimes */ 741556Srgrimes if (stat(name, &statb) != 0) 751556Srgrimes return (NULL); 761556Srgrimes if (!S_ISDIR(statb.st_mode)) { 771556Srgrimes errno = ENOTDIR; 781556Srgrimes return (NULL); 791556Srgrimes } 801556Srgrimes if ((fd = _open(name, O_RDONLY | O_NONBLOCK)) == -1) 811556Srgrimes return (NULL); 821556Srgrimes dirp = NULL; 831556Srgrimes if (_fstat(fd, &statb) != 0) 841556Srgrimes goto fail; 851556Srgrimes if (!S_ISDIR(statb.st_mode)) { 861556Srgrimes errno = ENOTDIR; 871556Srgrimes goto fail; 881556Srgrimes } 891556Srgrimes if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 || 901556Srgrimes (dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL) 911556Srgrimes goto fail; 921556Srgrimes 931556Srgrimes dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR)); 941556Srgrimes LIST_INIT(&dirp->dd_td->td_locq); 951556Srgrimes dirp->dd_td->td_loccnt = 0; 961556Srgrimes 971556Srgrimes /* 981556Srgrimes * Use the system page size if that is a multiple of DIRBLKSIZ. 99203613Simp * Hopefully this can be a big win someday by allowing page 1001556Srgrimes * trades to user space to be done by _getdirentries(). 1011556Srgrimes */ 1021556Srgrimes incr = getpagesize(); 1031556Srgrimes if ((incr % DIRBLKSIZ) != 0) 1041556Srgrimes incr = DIRBLKSIZ; 1051556Srgrimes 1061556Srgrimes /* 1071556Srgrimes * Determine whether this directory is the top of a union stack. 1081556Srgrimes */ 1091556Srgrimes if (flags & DTF_NODUP) { 1101556Srgrimes struct statfs sfb; 1111556Srgrimes 1121556Srgrimes if (_fstatfs(fd, &sfb) < 0) 1131556Srgrimes goto fail; 1141556Srgrimes unionstack = !strcmp(sfb.f_fstypename, "unionfs") 1151556Srgrimes || (sfb.f_flags & MNT_UNION); 1161556Srgrimes } else { 1171556Srgrimes unionstack = 0; 1181556Srgrimes } 1191556Srgrimes 1201556Srgrimes if (unionstack) { 1211556Srgrimes int len = 0; 1221556Srgrimes int space = 0; 1231556Srgrimes char *buf = 0; 1241556Srgrimes char *ddptr = 0; 1251556Srgrimes char *ddeptr; 1261556Srgrimes int n; 1271556Srgrimes struct dirent **dpv; 1281556Srgrimes 1291556Srgrimes /* 1301556Srgrimes * The strategy here is to read all the directory 1311556Srgrimes * entries into a buffer, sort the buffer, and 1321556Srgrimes * remove duplicate entries by setting the inode 1331556Srgrimes * number to zero. 1341556Srgrimes */ 1351556Srgrimes 1361556Srgrimes do { 1371556Srgrimes /* 1381556Srgrimes * Always make at least DIRBLKSIZ bytes 1391556Srgrimes * available to _getdirentries 1401556Srgrimes */ 1411556Srgrimes if (space < DIRBLKSIZ) { 1421556Srgrimes space += incr; 1431556Srgrimes len += incr; 1441556Srgrimes buf = reallocf(buf, len); 145203613Simp if (buf == NULL) 146 goto fail; 147 ddptr = buf + (len - space); 148 } 149 150 n = _getdirentries(fd, ddptr, space, &dirp->dd_seek); 151 if (n > 0) { 152 ddptr += n; 153 space -= n; 154 } 155 } while (n > 0); 156 157 ddeptr = ddptr; 158 flags |= __DTF_READALL; 159 160 /* 161 * Re-open the directory. 162 * This has the effect of rewinding back to the 163 * top of the union stack and is needed by 164 * programs which plan to fchdir to a descriptor 165 * which has also been read -- see fts.c. 166 */ 167 if (flags & DTF_REWIND) { 168 (void)_close(fd); 169 if ((fd = _open(name, O_RDONLY)) == -1) { 170 saved_errno = errno; 171 free(buf); 172 free(dirp); 173 errno = saved_errno; 174 return (NULL); 175 } 176 } 177 178 /* 179 * There is now a buffer full of (possibly) duplicate 180 * names. 181 */ 182 dirp->dd_buf = buf; 183 184 /* 185 * Go round this loop twice... 186 * 187 * Scan through the buffer, counting entries. 188 * On the second pass, save pointers to each one. 189 * Then sort the pointers and remove duplicate names. 190 */ 191 for (dpv = 0;;) { 192 n = 0; 193 ddptr = buf; 194 while (ddptr < ddeptr) { 195 struct dirent *dp; 196 197 dp = (struct dirent *) ddptr; 198 if ((long)dp & 03L) 199 break; 200 if ((dp->d_reclen <= 0) || 201 (dp->d_reclen > (ddeptr + 1 - ddptr))) 202 break; 203 ddptr += dp->d_reclen; 204 if (dp->d_fileno) { 205 if (dpv) 206 dpv[n] = dp; 207 n++; 208 } 209 } 210 211 if (dpv) { 212 struct dirent *xp; 213 214 /* 215 * This sort must be stable. 216 */ 217 mergesort(dpv, n, sizeof(*dpv), alphasort); 218 219 dpv[n] = NULL; 220 xp = NULL; 221 222 /* 223 * Scan through the buffer in sort order, 224 * zapping the inode number of any 225 * duplicate names. 226 */ 227 for (n = 0; dpv[n]; n++) { 228 struct dirent *dp = dpv[n]; 229 230 if ((xp == NULL) || 231 strcmp(dp->d_name, xp->d_name)) { 232 xp = dp; 233 } else { 234 dp->d_fileno = 0; 235 } 236 if (dp->d_type == DT_WHT && 237 (flags & DTF_HIDEW)) 238 dp->d_fileno = 0; 239 } 240 241 free(dpv); 242 break; 243 } else { 244 dpv = malloc((n+1) * sizeof(struct dirent *)); 245 if (dpv == NULL) 246 break; 247 } 248 } 249 250 dirp->dd_len = len; 251 dirp->dd_size = ddptr - dirp->dd_buf; 252 } else { 253 dirp->dd_len = incr; 254 dirp->dd_size = 0; 255 dirp->dd_buf = malloc(dirp->dd_len); 256 if (dirp->dd_buf == NULL) 257 goto fail; 258 dirp->dd_seek = 0; 259 flags &= ~DTF_REWIND; 260 } 261 262 dirp->dd_loc = 0; 263 dirp->dd_fd = fd; 264 dirp->dd_flags = flags; 265 dirp->dd_lock = NULL; 266 267 /* 268 * Set up seek point for rewinddir. 269 */ 270 dirp->dd_rewind = telldir(dirp); 271 272 return (dirp); 273 274fail: 275 saved_errno = errno; 276 free(dirp); 277 (void)_close(fd); 278 errno = saved_errno; 279 return (NULL); 280} 281