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