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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $FreeBSD: src/lib/libc/gen/opendir.c,v 1.10.2.1 2001/06/04 20:59:48 joerg Exp $ 34 * $DragonFly: src/lib/libc/gen/opendir.c,v 1.3 2005/01/31 22:29:15 dillon Exp $ 35 * 36 * @(#)opendir.c 8.8 (Berkeley) 5/1/95 37 */ 38 39 #include "namespace.h" 40 #include <sys/param.h> 41 #include <sys/mount.h> 42 #include <sys/stat.h> 43 44 #include <dirent.h> 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <stdlib.h> 48 #include <unistd.h> 49 #include "un-namespace.h" 50 51 /* 52 * Open a directory. 53 */ 54 DIR * 55 opendir(name) 56 const char *name; 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))) == NULL) 94 goto fail; 95 96 /* 97 * Use the system page size if that is a multiple of DIRBLKSIZ. 98 * Hopefully this can be a big win someday by allowing page 99 * trades to user space to be done by _getdirentries(). 100 */ 101 incr = getpagesize(); 102 if ((incr % DIRBLKSIZ) != 0) 103 incr = DIRBLKSIZ; 104 105 /* 106 * Determine whether this directory is the top of a union stack. 107 */ 108 if (flags & DTF_NODUP) { 109 struct statfs sfb; 110 111 if (_fstatfs(fd, &sfb) < 0) 112 goto fail; 113 unionstack = !strcmp(sfb.f_fstypename, "union") 114 || (sfb.f_flags & MNT_UNION); 115 } else { 116 unionstack = 0; 117 } 118 119 if (unionstack) { 120 int len = 0; 121 int space = 0; 122 char *buf = 0; 123 char *ddptr = 0; 124 char *ddeptr; 125 int n; 126 struct dirent **dpv; 127 128 /* 129 * The strategy here is to read all the directory 130 * entries into a buffer, sort the buffer, and 131 * remove duplicate entries by setting the inode 132 * number to zero. 133 */ 134 135 do { 136 /* 137 * Always make at least DIRBLKSIZ bytes 138 * available to _getdirentries 139 */ 140 if (space < DIRBLKSIZ) { 141 space += incr; 142 len += incr; 143 buf = reallocf(buf, len); 144 if (buf == NULL) 145 goto fail; 146 ddptr = buf + (len - space); 147 } 148 149 n = getdirentries(fd, ddptr, space, &dirp->dd_seek); 150 if (n > 0) { 151 ddptr += n; 152 space -= n; 153 } 154 } while (n > 0); 155 156 ddeptr = ddptr; 157 flags |= __DTF_READALL; 158 159 /* 160 * Re-open the directory. 161 * This has the effect of rewinding back to the 162 * top of the union stack and is needed by 163 * programs which plan to fchdir to a descriptor 164 * which has also been read -- see fts.c. 165 */ 166 if (flags & DTF_REWIND) { 167 (void)_close(fd); 168 if ((fd = _open(name, O_RDONLY)) == -1) { 169 saved_errno = errno; 170 free(buf); 171 free(dirp); 172 errno = saved_errno; 173 return (NULL); 174 } 175 } 176 177 /* 178 * There is now a buffer full of (possibly) duplicate 179 * names. 180 */ 181 dirp->dd_buf = buf; 182 183 /* 184 * Go round this loop twice... 185 * 186 * Scan through the buffer, counting entries. 187 * On the second pass, save pointers to each one. 188 * Then sort the pointers and remove duplicate names. 189 */ 190 for (dpv = 0;;) { 191 n = 0; 192 ddptr = buf; 193 while (ddptr < ddeptr) { 194 struct dirent *dp; 195 196 dp = (struct dirent *) ddptr; 197 if ((long)dp & 03L) 198 break; 199 if ((dp->d_reclen <= 0) || 200 (dp->d_reclen > (ddeptr + 1 - ddptr))) 201 break; 202 ddptr += dp->d_reclen; 203 if (dp->d_fileno) { 204 if (dpv) 205 dpv[n] = dp; 206 n++; 207 } 208 } 209 210 if (dpv) { 211 struct dirent *xp; 212 213 /* 214 * This sort must be stable. 215 */ 216 mergesort(dpv, n, sizeof(*dpv), alphasort); 217 218 dpv[n] = NULL; 219 xp = NULL; 220 221 /* 222 * Scan through the buffer in sort order, 223 * zapping the inode number of any 224 * duplicate names. 225 */ 226 for (n = 0; dpv[n]; n++) { 227 struct dirent *dp = dpv[n]; 228 229 if ((xp == NULL) || 230 strcmp(dp->d_name, xp->d_name)) { 231 xp = dp; 232 } else { 233 dp->d_fileno = 0; 234 } 235 if (dp->d_type == DT_WHT && 236 (flags & DTF_HIDEW)) 237 dp->d_fileno = 0; 238 } 239 240 free(dpv); 241 break; 242 } else { 243 dpv = malloc((n+1) * sizeof(struct dirent *)); 244 if (dpv == NULL) 245 break; 246 } 247 } 248 249 dirp->dd_len = len; 250 dirp->dd_size = ddptr - dirp->dd_buf; 251 } else { 252 dirp->dd_len = incr; 253 dirp->dd_buf = malloc(dirp->dd_len); 254 if (dirp->dd_buf == NULL) 255 goto fail; 256 dirp->dd_seek = 0; 257 flags &= ~DTF_REWIND; 258 } 259 260 dirp->dd_loc = 0; 261 dirp->dd_fd = fd; 262 dirp->dd_flags = flags; 263 dirp->dd_lock = NULL; 264 265 /* 266 * Set up seek point for rewinddir. 267 */ 268 dirp->dd_rewind = telldir(dirp); 269 270 return (dirp); 271 272 fail: 273 saved_errno = errno; 274 free(dirp); 275 (void)_close(fd); 276 errno = saved_errno; 277 return (NULL); 278 } 279