1 /* 2 * Copyright (c) 1983, 1993 3 * The Regents of the University of California. 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 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #if defined(LIBC_SCCS) && !defined(lint) 31 static char sccsid[] = "@(#)opendir.c 8.8 (Berkeley) 5/1/95"; 32 #endif /* LIBC_SCCS and not lint */ 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include "namespace.h" 37 #include <sys/param.h> 38 #include <sys/mount.h> 39 #include <sys/stat.h> 40 41 #include <dirent.h> 42 #include <errno.h> 43 #include <fcntl.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 #include "un-namespace.h" 48 49 #include "telldir.h" 50 /* 51 * Open a directory. 52 */ 53 DIR * 54 opendir(name) 55 const char *name; 56 { 57 58 return (__opendir2(name, DTF_HIDEW|DTF_NODUP)); 59 } 60 61 DIR * 62 __opendir2(name, flags) 63 const char *name; 64 int flags; 65 { 66 DIR *dirp; 67 int fd; 68 int incr; 69 int saved_errno; 70 int unionstack; 71 struct stat statb; 72 73 /* 74 * stat() before _open() because opening of special files may be 75 * harmful. _fstat() after open because the file may have changed. 76 */ 77 if (stat(name, &statb) != 0) 78 return (NULL); 79 if (!S_ISDIR(statb.st_mode)) { 80 errno = ENOTDIR; 81 return (NULL); 82 } 83 if ((fd = _open(name, O_RDONLY | O_NONBLOCK)) == -1) 84 return (NULL); 85 dirp = NULL; 86 if (_fstat(fd, &statb) != 0) 87 goto fail; 88 if (!S_ISDIR(statb.st_mode)) { 89 errno = ENOTDIR; 90 goto fail; 91 } 92 if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 || 93 (dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL) 94 goto fail; 95 96 dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR)); 97 LIST_INIT(&dirp->dd_td->td_locq); 98 dirp->dd_td->td_loccnt = 0; 99 100 /* 101 * Use the system page size if that is a multiple of DIRBLKSIZ. 102 * Hopefully this can be a big win someday by allowing page 103 * trades to user space to be done by _getdirentries(). 104 */ 105 incr = getpagesize(); 106 if ((incr % DIRBLKSIZ) != 0) 107 incr = DIRBLKSIZ; 108 109 /* 110 * Determine whether this directory is the top of a union stack. 111 */ 112 if (flags & DTF_NODUP) { 113 struct statfs sfb; 114 115 if (_fstatfs(fd, &sfb) < 0) 116 goto fail; 117 unionstack = !strcmp(sfb.f_fstypename, "unionfs") 118 || (sfb.f_flags & MNT_UNION); 119 } else { 120 unionstack = 0; 121 } 122 123 if (unionstack) { 124 int len = 0; 125 int space = 0; 126 char *buf = 0; 127 char *ddptr = 0; 128 char *ddeptr; 129 int n; 130 struct dirent **dpv; 131 132 /* 133 * The strategy here is to read all the directory 134 * entries into a buffer, sort the buffer, and 135 * remove duplicate entries by setting the inode 136 * number to zero. 137 */ 138 139 do { 140 /* 141 * Always make at least DIRBLKSIZ bytes 142 * available to _getdirentries 143 */ 144 if (space < DIRBLKSIZ) { 145 space += incr; 146 len += incr; 147 buf = reallocf(buf, len); 148 if (buf == NULL) 149 goto fail; 150 ddptr = buf + (len - space); 151 } 152 153 n = _getdirentries(fd, ddptr, space, &dirp->dd_seek); 154 if (n > 0) { 155 ddptr += n; 156 space -= n; 157 } 158 } while (n > 0); 159 160 ddeptr = ddptr; 161 flags |= __DTF_READALL; 162 163 /* 164 * Re-open the directory. 165 * This has the effect of rewinding back to the 166 * top of the union stack and is needed by 167 * programs which plan to fchdir to a descriptor 168 * which has also been read -- see fts.c. 169 */ 170 if (flags & DTF_REWIND) { 171 (void)_close(fd); 172 if ((fd = _open(name, O_RDONLY)) == -1) { 173 saved_errno = errno; 174 free(buf); 175 free(dirp); 176 errno = saved_errno; 177 return (NULL); 178 } 179 } 180 181 /* 182 * There is now a buffer full of (possibly) duplicate 183 * names. 184 */ 185 dirp->dd_buf = buf; 186 187 /* 188 * Go round this loop twice... 189 * 190 * Scan through the buffer, counting entries. 191 * On the second pass, save pointers to each one. 192 * Then sort the pointers and remove duplicate names. 193 */ 194 for (dpv = 0;;) { 195 n = 0; 196 ddptr = buf; 197 while (ddptr < ddeptr) { 198 struct dirent *dp; 199 200 dp = (struct dirent *) ddptr; 201 if ((long)dp & 03L) 202 break; 203 if ((dp->d_reclen <= 0) || 204 (dp->d_reclen > (ddeptr + 1 - ddptr))) 205 break; 206 ddptr += dp->d_reclen; 207 if (dp->d_fileno) { 208 if (dpv) 209 dpv[n] = dp; 210 n++; 211 } 212 } 213 214 if (dpv) { 215 struct dirent *xp; 216 217 /* 218 * This sort must be stable. 219 */ 220 mergesort(dpv, n, sizeof(*dpv), alphasort); 221 222 dpv[n] = NULL; 223 xp = NULL; 224 225 /* 226 * Scan through the buffer in sort order, 227 * zapping the inode number of any 228 * duplicate names. 229 */ 230 for (n = 0; dpv[n]; n++) { 231 struct dirent *dp = dpv[n]; 232 233 if ((xp == NULL) || 234 strcmp(dp->d_name, xp->d_name)) { 235 xp = dp; 236 } else { 237 dp->d_fileno = 0; 238 } 239 if (dp->d_type == DT_WHT && 240 (flags & DTF_HIDEW)) 241 dp->d_fileno = 0; 242 } 243 244 free(dpv); 245 break; 246 } else { 247 dpv = malloc((n+1) * sizeof(struct dirent *)); 248 if (dpv == NULL) 249 break; 250 } 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); 276 277 fail: 278 saved_errno = errno; 279 free(dirp); 280 (void)_close(fd); 281 errno = saved_errno; 282 return (NULL); 283 } 284