opendir.c revision 165903
1153317Ssam/* 2153317Ssam * Copyright (c) 1983, 1993 3153317Ssam * The Regents of the University of California. All rights reserved. 4153317Ssam * 5153317Ssam * Redistribution and use in source and binary forms, with or without 6153317Ssam * modification, are permitted provided that the following conditions 7153317Ssam * are met: 8153317Ssam * 1. Redistributions of source code must retain the above copyright 9153317Ssam * notice, this list of conditions and the following disclaimer. 10153317Ssam * 2. Redistributions in binary form must reproduce the above copyright 11153317Ssam * notice, this list of conditions and the following disclaimer in the 12153317Ssam * documentation and/or other materials provided with the distribution. 13153317Ssam * 4. Neither the name of the University nor the names of its contributors 14153317Ssam * may be used to endorse or promote products derived from this software 15153317Ssam * without specific prior written permission. 16153317Ssam * 17153317Ssam * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18153317Ssam * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19153317Ssam * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20153317Ssam * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21153317Ssam * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22153317Ssam * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23153317Ssam * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24153317Ssam * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25153317Ssam * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26153317Ssam * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27153317Ssam * SUCH DAMAGE. 28153317Ssam */ 29153317Ssam 30153317Ssam#if defined(LIBC_SCCS) && !defined(lint) 31153317Ssamstatic char sccsid[] = "@(#)opendir.c 8.8 (Berkeley) 5/1/95"; 32153317Ssam#endif /* LIBC_SCCS and not lint */ 33153317Ssam#include <sys/cdefs.h> 34153317Ssam__FBSDID("$FreeBSD: head/lib/libc/gen/opendir.c 165903 2007-01-09 00:28:16Z imp $"); 35153317Ssam 36153317Ssam#include "namespace.h" 37153317Ssam#include <sys/param.h> 38153317Ssam#include <sys/mount.h> 39153317Ssam#include <sys/stat.h> 40153317Ssam 41153317Ssam#include <dirent.h> 42153317Ssam#include <errno.h> 43153317Ssam#include <fcntl.h> 44153317Ssam#include <stdlib.h> 45153317Ssam#include <string.h> 46170534Ssam#include <unistd.h> 47153317Ssam#include "un-namespace.h" 48153317Ssam 49153317Ssam#include "telldir.h" 50170534Ssam/* 51153317Ssam * Open a directory. 52153317Ssam */ 53153317SsamDIR * 54153317Ssamopendir(name) 55153317Ssam const char *name; 56170534Ssam{ 57153317Ssam 58153317Ssam return (__opendir2(name, DTF_HIDEW|DTF_NODUP)); 59153317Ssam} 60153317Ssam 61153317SsamDIR * 62153317Ssam__opendir2(name, flags) 63153317Ssam const char *name; 64153317Ssam int flags; 65153317Ssam{ 66153317Ssam DIR *dirp; 67153317Ssam int fd; 68153317Ssam int incr; 69153317Ssam int saved_errno; 70153317Ssam int unionstack; 71153317Ssam struct stat statb; 72153317Ssam 73153317Ssam /* 74153317Ssam * stat() before _open() because opening of special files may be 75153317Ssam * harmful. _fstat() after open because the file may have changed. 76153317Ssam */ 77153317Ssam if (stat(name, &statb) != 0) 78153317Ssam return (NULL); 79153317Ssam if (!S_ISDIR(statb.st_mode)) { 80153317Ssam errno = ENOTDIR; 81153317Ssam return (NULL); 82164635Ssam } 83178359Ssam if ((fd = _open(name, O_RDONLY | O_NONBLOCK)) == -1) 84178359Ssam return (NULL); 85178359Ssam dirp = NULL; 86178359Ssam if (_fstat(fd, &statb) != 0) 87153317Ssam goto fail; 88153317Ssam if (!S_ISDIR(statb.st_mode)) { 89153317Ssam errno = ENOTDIR; 90153317Ssam goto fail; 91153317Ssam } 92170534Ssam if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 || 93153317Ssam (dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL) 94153317Ssam goto fail; 95153317Ssam 96153317Ssam dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR)); 97153317Ssam LIST_INIT(&dirp->dd_td->td_locq); 98153317Ssam dirp->dd_td->td_loccnt = 0; 99153317Ssam 100153317Ssam /* 101153317Ssam * Use the system page size if that is a multiple of DIRBLKSIZ. 102153317Ssam * Hopefully this can be a big win someday by allowing page 103153317Ssam * trades to user space to be done by _getdirentries(). 104153317Ssam */ 105153317Ssam incr = getpagesize(); 106165963Ssam if ((incr % DIRBLKSIZ) != 0) 107153317Ssam incr = DIRBLKSIZ; 108153317Ssam 109153317Ssam /* 110153317Ssam * Determine whether this directory is the top of a union stack. 111153317Ssam */ 112153317Ssam if (flags & DTF_NODUP) { 113153317Ssam struct statfs sfb; 114153317Ssam 115153317Ssam if (_fstatfs(fd, &sfb) < 0) 116153317Ssam goto fail; 117153317Ssam unionstack = !strcmp(sfb.f_fstypename, "unionfs") 118164635Ssam || (sfb.f_flags & MNT_UNION); 119178359Ssam } else { 120178359Ssam unionstack = 0; 121178359Ssam } 122178359Ssam 123153317Ssam if (unionstack) { 124153317Ssam int len = 0; 125153317Ssam int space = 0; 126153317Ssam char *buf = 0; 127153317Ssam char *ddptr = 0; 128153317Ssam char *ddeptr; 129153317Ssam int n; 130153317Ssam struct dirent **dpv; 131153317Ssam 132153317Ssam /* 133153317Ssam * The strategy here is to read all the directory 134153317Ssam * entries into a buffer, sort the buffer, and 135153317Ssam * remove duplicate entries by setting the inode 136153317Ssam * number to zero. 137153317Ssam */ 138153317Ssam 139153317Ssam do { 140153317Ssam /* 141153317Ssam * Always make at least DIRBLKSIZ bytes 142153317Ssam * available to _getdirentries 143153317Ssam */ 144153317Ssam if (space < DIRBLKSIZ) { 145153317Ssam space += incr; 146153317Ssam len += incr; 147153317Ssam buf = reallocf(buf, len); 148153317Ssam if (buf == NULL) 149153317Ssam goto fail; 150153317Ssam ddptr = buf + (len - space); 151153317Ssam } 152153317Ssam 153153317Ssam n = _getdirentries(fd, ddptr, space, &dirp->dd_seek); 154153317Ssam if (n > 0) { 155153317Ssam ddptr += n; 156153317Ssam space -= n; 157153317Ssam } 158153317Ssam } while (n > 0); 159178359Ssam 160178359Ssam ddeptr = ddptr; 161178359Ssam flags |= __DTF_READALL; 162178359Ssam 163178359Ssam /* 164178359Ssam * Re-open the directory. 165178359Ssam * This has the effect of rewinding back to the 166178359Ssam * top of the union stack and is needed by 167178359Ssam * programs which plan to fchdir to a descriptor 168178359Ssam * which has also been read -- see fts.c. 169178359Ssam */ 170178359Ssam if (flags & DTF_REWIND) { 171178359Ssam (void)_close(fd); 172178359Ssam if ((fd = _open(name, O_RDONLY)) == -1) { 173153317Ssam saved_errno = errno; 174153317Ssam free(buf); 175153317Ssam free(dirp); 176153317Ssam errno = saved_errno; 177153317Ssam return (NULL); 178170534Ssam } 179153317Ssam } 180153317Ssam 181178359Ssam /* 182153317Ssam * There is now a buffer full of (possibly) duplicate 183153317Ssam * names. 184178359Ssam */ 185153317Ssam dirp->dd_buf = buf; 186153317Ssam 187153317Ssam /* 188153317Ssam * Go round this loop twice... 189178359Ssam * 190178359Ssam * Scan through the buffer, counting entries. 191178359Ssam * On the second pass, save pointers to each one. 192153317Ssam * Then sort the pointers and remove duplicate names. 193153317Ssam */ 194153317Ssam for (dpv = 0;;) { 195153317Ssam n = 0; 196153317Ssam ddptr = buf; 197153317Ssam while (ddptr < ddeptr) { 198153317Ssam struct dirent *dp; 199153317Ssam 200153317Ssam dp = (struct dirent *) ddptr; 201153317Ssam if ((long)dp & 03L) 202153317Ssam break; 203153317Ssam if ((dp->d_reclen <= 0) || 204153317Ssam (dp->d_reclen > (ddeptr + 1 - ddptr))) 205153317Ssam break; 206153317Ssam ddptr += dp->d_reclen; 207153317Ssam if (dp->d_fileno) { 208153317Ssam if (dpv) 209153317Ssam dpv[n] = dp; 210153317Ssam n++; 211153317Ssam } 212153317Ssam } 213153317Ssam 214153317Ssam if (dpv) { 215153317Ssam struct dirent *xp; 216153317Ssam 217153317Ssam /* 218153317Ssam * This sort must be stable. 219153317Ssam */ 220153317Ssam mergesort(dpv, n, sizeof(*dpv), alphasort); 221153317Ssam 222153317Ssam dpv[n] = NULL; 223170534Ssam xp = NULL; 224170534Ssam 225153317Ssam /* 226153317Ssam * Scan through the buffer in sort order, 227153317Ssam * zapping the inode number of any 228170534Ssam * duplicate names. 229153317Ssam */ 230153317Ssam for (n = 0; dpv[n]; n++) { 231153317Ssam struct dirent *dp = dpv[n]; 232153317Ssam 233153317Ssam if ((xp == NULL) || 234153317Ssam strcmp(dp->d_name, xp->d_name)) { 235153317Ssam xp = dp; 236153317Ssam } else { 237153317Ssam dp->d_fileno = 0; 238153317Ssam } 239153317Ssam if (dp->d_type == DT_WHT && 240153317Ssam (flags & DTF_HIDEW)) 241153317Ssam dp->d_fileno = 0; 242153317Ssam } 243153317Ssam 244153317Ssam free(dpv); 245153317Ssam break; 246153317Ssam } else { 247153317Ssam dpv = malloc((n+1) * sizeof(struct dirent *)); 248153317Ssam if (dpv == NULL) 249153317Ssam break; 250153317Ssam } 251 } 252 253 dirp->dd_len = len; 254 dirp->dd_size = ddptr - dirp->dd_buf; 255 } else { 256 dirp->dd_len = incr; 257 dirp->dd_size = 0; 258 dirp->dd_buf = malloc(dirp->dd_len); 259 if (dirp->dd_buf == NULL) 260 goto fail; 261 dirp->dd_seek = 0; 262 flags &= ~DTF_REWIND; 263 } 264 265 dirp->dd_loc = 0; 266 dirp->dd_fd = fd; 267 dirp->dd_flags = flags; 268 dirp->dd_lock = NULL; 269 270 /* 271 * Set up seek point for rewinddir. 272 */ 273 dirp->dd_rewind = telldir(dirp); 274 275 return (dirp); 276 277fail: 278 saved_errno = errno; 279 free(dirp); 280 (void)_close(fd); 281 errno = saved_errno; 282 return (NULL); 283} 284