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 * $FreeBSD$ 34 */ 35 36 #if defined(LIBC_SCCS) && !defined(lint) 37 static char sccsid[] = "@(#)opendir.c 8.8 (Berkeley) 5/1/95"; 38 #endif /* LIBC_SCCS and not lint */ 39 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 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))) == 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 } else { 115 unionstack = 0; 116 } 117 118 if (unionstack) { 119 int len = 0; 120 int space = 0; 121 char *buf = 0; 122 char *ddptr = 0; 123 char *ddeptr; 124 int n; 125 struct dirent **dpv; 126 127 /* 128 * The strategy here is to read all the directory 129 * entries into a buffer, sort the buffer, and 130 * remove duplicate entries by setting the inode 131 * number to zero. 132 */ 133 134 do { 135 /* 136 * Always make at least DIRBLKSIZ bytes 137 * available to getdirentries 138 */ 139 if (space < DIRBLKSIZ) { 140 space += incr; 141 len += incr; 142 buf = reallocf(buf, len); 143 if (buf == NULL) 144 goto fail; 145 ddptr = buf + (len - space); 146 } 147 148 n = getdirentries(fd, ddptr, space, &dirp->dd_seek); 149 if (n > 0) { 150 ddptr += n; 151 space -= n; 152 } 153 } while (n > 0); 154 155 ddeptr = ddptr; 156 flags |= __DTF_READALL; 157 158 /* 159 * Re-open the directory. 160 * This has the effect of rewinding back to the 161 * top of the union stack and is needed by 162 * programs which plan to fchdir to a descriptor 163 * which has also been read -- see fts.c. 164 */ 165 if (flags & DTF_REWIND) { 166 (void)_close(fd); 167 if ((fd = _open(name, O_RDONLY)) == -1) { 168 saved_errno = errno; 169 free(buf); 170 free(dirp); 171 errno = saved_errno; 172 return (NULL); 173 } 174 } 175 176 /* 177 * There is now a buffer full of (possibly) duplicate 178 * names. 179 */ 180 dirp->dd_buf = buf; 181 182 /* 183 * Go round this loop twice... 184 * 185 * Scan through the buffer, counting entries. 186 * On the second pass, save pointers to each one. 187 * Then sort the pointers and remove duplicate names. 188 */ 189 for (dpv = 0;;) { 190 n = 0; 191 ddptr = buf; 192 while (ddptr < ddeptr) { 193 struct dirent *dp; 194 195 dp = (struct dirent *) ddptr; 196 if ((long)dp & 03L) 197 break; 198 if ((dp->d_reclen <= 0) || 199 (dp->d_reclen > (ddeptr + 1 - ddptr))) 200 break; 201 ddptr += dp->d_reclen; 202 if (dp->d_fileno) { 203 if (dpv) 204 dpv[n] = dp; 205 n++; 206 } 207 } 208 209 if (dpv) { 210 struct dirent *xp; 211 212 /* 213 * This sort must be stable. 214 */ 215 mergesort(dpv, n, sizeof(*dpv), alphasort); 216 217 dpv[n] = NULL; 218 xp = NULL; 219 220 /* 221 * Scan through the buffer in sort order, 222 * zapping the inode number of any 223 * duplicate names. 224 */ 225 for (n = 0; dpv[n]; n++) { 226 struct dirent *dp = dpv[n]; 227 228 if ((xp == NULL) || 229 strcmp(dp->d_name, xp->d_name)) { 230 xp = dp; 231 } else { 232 dp->d_fileno = 0; 233 } 234 if (dp->d_type == DT_WHT && 235 (flags & DTF_HIDEW)) 236 dp->d_fileno = 0; 237 } 238 239 free(dpv); 240 break; 241 } else { 242 dpv = malloc((n+1) * sizeof(struct dirent *)); 243 if (dpv == NULL) 244 break; 245 } 246 } 247 248 dirp->dd_len = len; 249 dirp->dd_size = ddptr - dirp->dd_buf; 250 } else { 251 dirp->dd_len = incr; 252 dirp->dd_buf = malloc(dirp->dd_len); 253 if (dirp->dd_buf == NULL) 254 goto fail; 255 dirp->dd_seek = 0; 256 flags &= ~DTF_REWIND; 257 } 258 259 dirp->dd_loc = 0; 260 dirp->dd_fd = fd; 261 dirp->dd_flags = flags; 262 263 /* 264 * Set up seek point for rewinddir. 265 */ 266 dirp->dd_rewind = telldir(dirp); 267 268 return (dirp); 269 270 fail: 271 saved_errno = errno; 272 free(dirp); 273 (void)_close(fd); 274 errno = saved_errno; 275 return (NULL); 276 } 277