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 static DIR * __opendir_common(int, const char *, int); 52 53 /* 54 * Open a directory. 55 */ 56 DIR * 57 opendir(const char *name) 58 { 59 60 return (__opendir2(name, DTF_HIDEW|DTF_NODUP)); 61 } 62 63 /* 64 * Open a directory with existing file descriptor. 65 */ 66 DIR * 67 fdopendir(int fd) 68 { 69 70 return (__opendir_common(fd, NULL, DTF_HIDEW|DTF_NODUP)); 71 } 72 73 DIR * 74 __opendir2(const char *name, int flags) 75 { 76 int fd; 77 struct stat statb; 78 DIR *dir; 79 int saved_errno; 80 81 /* 82 * stat() before _open() because opening of special files may be 83 * harmful. 84 */ 85 if (stat(name, &statb) != 0) 86 return (NULL); 87 if (!S_ISDIR(statb.st_mode)) { 88 errno = ENOTDIR; 89 return (NULL); 90 } 91 if ((fd = _open(name, O_RDONLY | O_NONBLOCK | O_DIRECTORY)) == -1) 92 return (NULL); 93 94 dir = __opendir_common(fd, name, flags); 95 if (dir == NULL) { 96 saved_errno = errno; 97 _close(fd); 98 errno = saved_errno; 99 } 100 return (dir); 101 } 102 103 static int 104 opendir_compar(const void *p1, const void *p2) 105 { 106 107 return (strcmp((*(const struct dirent **)p1)->d_name, 108 (*(const struct dirent **)p2)->d_name)); 109 } 110 111 /* 112 * Common routine for opendir(3), __opendir2(3) and fdopendir(3). 113 */ 114 static DIR * 115 __opendir_common(int fd, const char *name, int flags) 116 { 117 DIR *dirp; 118 int incr; 119 int saved_errno; 120 int unionstack; 121 int fd2; 122 struct stat statb; 123 124 dirp = NULL; 125 /* _fstat() the open handler because the file may have changed. */ 126 if (_fstat(fd, &statb) != 0) 127 goto fail; 128 if (!S_ISDIR(statb.st_mode)) { 129 errno = ENOTDIR; 130 goto fail; 131 } 132 if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 || 133 (dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL) 134 goto fail; 135 136 dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR)); 137 LIST_INIT(&dirp->dd_td->td_locq); 138 dirp->dd_td->td_loccnt = 0; 139 140 /* 141 * Use the system page size if that is a multiple of DIRBLKSIZ. 142 * Hopefully this can be a big win someday by allowing page 143 * trades to user space to be done by _getdirentries(). 144 */ 145 incr = getpagesize(); 146 if ((incr % DIRBLKSIZ) != 0) 147 incr = DIRBLKSIZ; 148 149 /* 150 * Determine whether this directory is the top of a union stack. 151 */ 152 if (flags & DTF_NODUP) { 153 struct statfs sfb; 154 155 if (_fstatfs(fd, &sfb) < 0) 156 goto fail; 157 unionstack = !strcmp(sfb.f_fstypename, "unionfs") 158 || (sfb.f_flags & MNT_UNION); 159 } else { 160 unionstack = 0; 161 } 162 163 if (unionstack) { 164 int len = 0; 165 int space = 0; 166 char *buf = 0; 167 char *ddptr = 0; 168 char *ddeptr; 169 int n; 170 struct dirent **dpv; 171 172 /* 173 * The strategy here is to read all the directory 174 * entries into a buffer, sort the buffer, and 175 * remove duplicate entries by setting the inode 176 * number to zero. 177 */ 178 179 do { 180 /* 181 * Always make at least DIRBLKSIZ bytes 182 * available to _getdirentries 183 */ 184 if (space < DIRBLKSIZ) { 185 space += incr; 186 len += incr; 187 buf = reallocf(buf, len); 188 if (buf == NULL) 189 goto fail; 190 ddptr = buf + (len - space); 191 } 192 193 n = _getdirentries(fd, ddptr, space, &dirp->dd_seek); 194 if (n > 0) { 195 ddptr += n; 196 space -= n; 197 } 198 } while (n > 0); 199 200 ddeptr = ddptr; 201 flags |= __DTF_READALL; 202 203 /* 204 * Re-open the directory. 205 * This has the effect of rewinding back to the 206 * top of the union stack and is needed by 207 * programs which plan to fchdir to a descriptor 208 * which has also been read -- see fts.c. 209 */ 210 if (flags & DTF_REWIND) { 211 if ((fd2 = _open(name, O_RDONLY | O_DIRECTORY)) == -1) { 212 saved_errno = errno; 213 free(buf); 214 free(dirp); 215 errno = saved_errno; 216 return (NULL); 217 } 218 (void)_dup2(fd2, fd); 219 _close(fd2); 220 } 221 222 /* 223 * There is now a buffer full of (possibly) duplicate 224 * names. 225 */ 226 dirp->dd_buf = buf; 227 228 /* 229 * Go round this loop twice... 230 * 231 * Scan through the buffer, counting entries. 232 * On the second pass, save pointers to each one. 233 * Then sort the pointers and remove duplicate names. 234 */ 235 for (dpv = 0;;) { 236 n = 0; 237 ddptr = buf; 238 while (ddptr < ddeptr) { 239 struct dirent *dp; 240 241 dp = (struct dirent *) ddptr; 242 if ((long)dp & 03L) 243 break; 244 if ((dp->d_reclen <= 0) || 245 (dp->d_reclen > (ddeptr + 1 - ddptr))) 246 break; 247 ddptr += dp->d_reclen; 248 if (dp->d_fileno) { 249 if (dpv) 250 dpv[n] = dp; 251 n++; 252 } 253 } 254 255 if (dpv) { 256 struct dirent *xp; 257 258 /* 259 * This sort must be stable. 260 */ 261 mergesort(dpv, n, sizeof(*dpv), 262 opendir_compar); 263 264 dpv[n] = NULL; 265 xp = NULL; 266 267 /* 268 * Scan through the buffer in sort order, 269 * zapping the inode number of any 270 * duplicate names. 271 */ 272 for (n = 0; dpv[n]; n++) { 273 struct dirent *dp = dpv[n]; 274 275 if ((xp == NULL) || 276 strcmp(dp->d_name, xp->d_name)) { 277 xp = dp; 278 } else { 279 dp->d_fileno = 0; 280 } 281 if (dp->d_type == DT_WHT && 282 (flags & DTF_HIDEW)) 283 dp->d_fileno = 0; 284 } 285 286 free(dpv); 287 break; 288 } else { 289 dpv = malloc((n+1) * sizeof(struct dirent *)); 290 if (dpv == NULL) 291 break; 292 } 293 } 294 295 dirp->dd_len = len; 296 dirp->dd_size = ddptr - dirp->dd_buf; 297 } else { 298 dirp->dd_len = incr; 299 dirp->dd_size = 0; 300 dirp->dd_buf = malloc(dirp->dd_len); 301 if (dirp->dd_buf == NULL) 302 goto fail; 303 dirp->dd_seek = 0; 304 flags &= ~DTF_REWIND; 305 } 306 307 dirp->dd_loc = 0; 308 dirp->dd_fd = fd; 309 dirp->dd_flags = flags; 310 dirp->dd_lock = NULL; 311 312 /* 313 * Set up seek point for rewinddir. 314 */ 315 dirp->dd_rewind = telldir(dirp); 316 317 return (dirp); 318 319 fail: 320 saved_errno = errno; 321 free(dirp); 322 errno = saved_errno; 323 return (NULL); 324 } 325