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 "gen-private.h" 50 #include "telldir.h" 51 52 static DIR * __opendir_common(int, int); 53 54 /* 55 * Open a directory. 56 */ 57 DIR * 58 opendir(const char *name) 59 { 60 61 return (__opendir2(name, DTF_HIDEW|DTF_NODUP)); 62 } 63 64 /* 65 * Open a directory with existing file descriptor. 66 */ 67 DIR * 68 fdopendir(int fd) 69 { 70 struct stat statb; 71 72 /* Check that fd is associated with a directory. */ 73 if (_fstat(fd, &statb) != 0) 74 return (NULL); 75 if (!S_ISDIR(statb.st_mode)) { 76 errno = ENOTDIR; 77 return (NULL); 78 } 79 if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) 80 return (NULL); 81 return (__opendir_common(fd, DTF_HIDEW|DTF_NODUP)); 82 } 83 84 DIR * 85 __opendir2(const char *name, int flags) 86 { 87 int fd; 88 DIR *dir; 89 int saved_errno; 90 91 if ((fd = _open(name, 92 O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC)) == -1) 93 return (NULL); 94 95 dir = __opendir_common(fd, flags); 96 if (dir == NULL) { 97 saved_errno = errno; 98 _close(fd); 99 errno = saved_errno; 100 } 101 return (dir); 102 } 103 104 static int 105 opendir_compar(const void *p1, const void *p2) 106 { 107 108 return (strcmp((*(const struct dirent **)p1)->d_name, 109 (*(const struct dirent **)p2)->d_name)); 110 } 111 112 /* 113 * Common routine for opendir(3), __opendir2(3) and fdopendir(3). 114 */ 115 static DIR * 116 __opendir_common(int fd, int flags) 117 { 118 DIR *dirp; 119 int incr; 120 int saved_errno; 121 int unionstack; 122 int fd2; 123 124 fd2 = -1; 125 126 if ((dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL) 127 return (NULL); 128 129 dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR)); 130 LIST_INIT(&dirp->dd_td->td_locq); 131 dirp->dd_td->td_loccnt = 0; 132 133 /* 134 * Use the system page size if that is a multiple of DIRBLKSIZ. 135 * Hopefully this can be a big win someday by allowing page 136 * trades to user space to be done by _getdirentries(). 137 */ 138 incr = getpagesize(); 139 if ((incr % DIRBLKSIZ) != 0) 140 incr = DIRBLKSIZ; 141 142 /* 143 * Determine whether this directory is the top of a union stack. 144 */ 145 if (flags & DTF_NODUP) { 146 struct statfs sfb; 147 148 if (_fstatfs(fd, &sfb) < 0) 149 goto fail; 150 unionstack = !strcmp(sfb.f_fstypename, "unionfs") 151 || (sfb.f_flags & MNT_UNION); 152 } else { 153 unionstack = 0; 154 } 155 156 if (unionstack) { 157 int len = 0; 158 int space = 0; 159 char *buf = 0; 160 char *ddptr = 0; 161 char *ddeptr; 162 int n; 163 struct dirent **dpv; 164 165 /* 166 * The strategy here is to read all the directory 167 * entries into a buffer, sort the buffer, and 168 * remove duplicate entries by setting the inode 169 * number to zero. 170 * 171 * We reopen the directory because _getdirentries() 172 * on a MNT_UNION mount modifies the open directory, 173 * making it refer to the lower directory after the 174 * upper directory's entries are exhausted. 175 * This would otherwise break software that uses 176 * the directory descriptor for fchdir or *at 177 * functions, such as fts.c. 178 */ 179 if ((fd2 = _openat(fd, ".", O_RDONLY | O_CLOEXEC)) == -1) { 180 saved_errno = errno; 181 free(buf); 182 free(dirp); 183 errno = saved_errno; 184 return (NULL); 185 } 186 187 do { 188 /* 189 * Always make at least DIRBLKSIZ bytes 190 * available to _getdirentries 191 */ 192 if (space < DIRBLKSIZ) { 193 space += incr; 194 len += incr; 195 buf = reallocf(buf, len); 196 if (buf == NULL) 197 goto fail; 198 ddptr = buf + (len - space); 199 } 200 201 n = _getdirentries(fd2, ddptr, space, &dirp->dd_seek); 202 if (n > 0) { 203 ddptr += n; 204 space -= n; 205 } 206 } while (n > 0); 207 208 ddeptr = ddptr; 209 flags |= __DTF_READALL; 210 211 _close(fd2); 212 fd2 = -1; 213 214 /* 215 * There is now a buffer full of (possibly) duplicate 216 * names. 217 */ 218 dirp->dd_buf = buf; 219 220 /* 221 * Go round this loop twice... 222 * 223 * Scan through the buffer, counting entries. 224 * On the second pass, save pointers to each one. 225 * Then sort the pointers and remove duplicate names. 226 */ 227 for (dpv = 0;;) { 228 n = 0; 229 ddptr = buf; 230 while (ddptr < ddeptr) { 231 struct dirent *dp; 232 233 dp = (struct dirent *) ddptr; 234 if ((long)dp & 03L) 235 break; 236 if ((dp->d_reclen <= 0) || 237 (dp->d_reclen > (ddeptr + 1 - ddptr))) 238 break; 239 ddptr += dp->d_reclen; 240 if (dp->d_fileno) { 241 if (dpv) 242 dpv[n] = dp; 243 n++; 244 } 245 } 246 247 if (dpv) { 248 struct dirent *xp; 249 250 /* 251 * This sort must be stable. 252 */ 253 mergesort(dpv, n, sizeof(*dpv), 254 opendir_compar); 255 256 dpv[n] = NULL; 257 xp = NULL; 258 259 /* 260 * Scan through the buffer in sort order, 261 * zapping the inode number of any 262 * duplicate names. 263 */ 264 for (n = 0; dpv[n]; n++) { 265 struct dirent *dp = dpv[n]; 266 267 if ((xp == NULL) || 268 strcmp(dp->d_name, xp->d_name)) { 269 xp = dp; 270 } else { 271 dp->d_fileno = 0; 272 } 273 if (dp->d_type == DT_WHT && 274 (flags & DTF_HIDEW)) 275 dp->d_fileno = 0; 276 } 277 278 free(dpv); 279 break; 280 } else { 281 dpv = malloc((n+1) * sizeof(struct dirent *)); 282 if (dpv == NULL) 283 break; 284 } 285 } 286 287 dirp->dd_len = len; 288 dirp->dd_size = ddptr - dirp->dd_buf; 289 } else { 290 dirp->dd_len = incr; 291 dirp->dd_size = 0; 292 dirp->dd_buf = malloc(dirp->dd_len); 293 if (dirp->dd_buf == NULL) 294 goto fail; 295 dirp->dd_seek = 0; 296 } 297 298 dirp->dd_loc = 0; 299 dirp->dd_fd = fd; 300 dirp->dd_flags = flags; 301 dirp->dd_lock = NULL; 302 303 /* 304 * Set up seek point for rewinddir. 305 */ 306 dirp->dd_rewind = telldir(dirp); 307 308 return (dirp); 309 310 fail: 311 saved_errno = errno; 312 if (fd2 != -1) 313 _close(fd2); 314 free(dirp); 315 errno = saved_errno; 316 return (NULL); 317 } 318