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 34 #if defined(LIBC_SCCS) && !defined(lint) 35 static char sccsid[] = "@(#)opendir.c 8.8 (Berkeley) 5/1/95"; 36 #endif /* LIBC_SCCS and not lint */ 37 38 #include <sys/param.h> 39 #include <sys/mount.h> 40 #include <sys/stat.h> 41 42 #include <dirent.h> 43 #include <errno.h> 44 #include <fcntl.h> 45 #include <stdlib.h> 46 #include <unistd.h> 47 48 /* 49 * Open a directory. 50 */ 51 DIR * 52 opendir(name) 53 const char *name; 54 { 55 56 return (__opendir2(name, DTF_HIDEW|DTF_NODUP)); 57 } 58 59 DIR * 60 __opendir2(name, flags) 61 const char *name; 62 int flags; 63 { 64 DIR *dirp; 65 int fd; 66 int incr; 67 int saved_errno; 68 int unionstack; 69 struct stat statb; 70 71 /* 72 * stat() before open() because opening of special files may be 73 * harmful. fstat() after open because the file may have changed. 74 */ 75 if (stat(name, &statb) != 0) 76 return (NULL); 77 if (!S_ISDIR(statb.st_mode)) { 78 errno = ENOTDIR; 79 return (NULL); 80 } 81 if ((fd = open(name, O_RDONLY | O_NONBLOCK)) == -1) 82 return (NULL); 83 dirp = NULL; 84 if (fstat(fd, &statb) != 0) 85 goto fail; 86 if (!S_ISDIR(statb.st_mode)) { 87 errno = ENOTDIR; 88 goto fail; 89 } 90 if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 || 91 (dirp = malloc(sizeof(DIR))) == NULL) 92 goto fail; 93 94 /* 95 * Use the system page size if that is a multiple of DIRBLKSIZ. 96 * Hopefully this can be a big win someday by allowing page 97 * trades to user space to be done by getdirentries(). 98 */ 99 incr = getpagesize(); 100 if ((incr % DIRBLKSIZ) != 0) 101 incr = DIRBLKSIZ; 102 103 /* 104 * Determine whether this directory is the top of a union stack. 105 */ 106 if (flags & DTF_NODUP) { 107 struct statfs sfb; 108 109 if (fstatfs(fd, &sfb) < 0) 110 goto fail; 111 unionstack = !strcmp(sfb.f_fstypename, "union"); 112 } else { 113 unionstack = 0; 114 } 115 116 if (unionstack) { 117 int len = 0; 118 int space = 0; 119 char *buf = 0; 120 char *ddptr = 0; 121 char *ddeptr; 122 int n; 123 struct dirent **dpv; 124 125 /* 126 * The strategy here is to read all the directory 127 * entries into a buffer, sort the buffer, and 128 * remove duplicate entries by setting the inode 129 * number to zero. 130 */ 131 132 do { 133 /* 134 * Always make at least DIRBLKSIZ bytes 135 * available to getdirentries 136 */ 137 if (space < DIRBLKSIZ) { 138 space += incr; 139 len += incr; 140 buf = reallocf(buf, len); 141 if (buf == NULL) 142 goto fail; 143 ddptr = buf + (len - space); 144 } 145 146 n = getdirentries(fd, ddptr, space, &dirp->dd_seek); 147 if (n > 0) { 148 ddptr += n; 149 space -= n; 150 } 151 } while (n > 0); 152 153 ddeptr = ddptr; 154 flags |= __DTF_READALL; 155 156 /* 157 * Re-open the directory. 158 * This has the effect of rewinding back to the 159 * top of the union stack and is needed by 160 * programs which plan to fchdir to a descriptor 161 * which has also been read -- see fts.c. 162 */ 163 if (flags & DTF_REWIND) { 164 (void) close(fd); 165 if ((fd = open(name, O_RDONLY)) == -1) { 166 saved_errno = errno; 167 free(buf); 168 free(dirp); 169 errno = saved_errno; 170 return (NULL); 171 } 172 } 173 174 /* 175 * There is now a buffer full of (possibly) duplicate 176 * names. 177 */ 178 dirp->dd_buf = buf; 179 180 /* 181 * Go round this loop twice... 182 * 183 * Scan through the buffer, counting entries. 184 * On the second pass, save pointers to each one. 185 * Then sort the pointers and remove duplicate names. 186 */ 187 for (dpv = 0;;) { 188 n = 0; 189 ddptr = buf; 190 while (ddptr < ddeptr) { 191 struct dirent *dp; 192 193 dp = (struct dirent *) ddptr; 194 if ((long)dp & 03L) 195 break; 196 if ((dp->d_reclen <= 0) || 197 (dp->d_reclen > (ddeptr + 1 - ddptr))) 198 break; 199 ddptr += dp->d_reclen; 200 if (dp->d_fileno) { 201 if (dpv) 202 dpv[n] = dp; 203 n++; 204 } 205 } 206 207 if (dpv) { 208 struct dirent *xp; 209 210 /* 211 * This sort must be stable. 212 */ 213 mergesort(dpv, n, sizeof(*dpv), alphasort); 214 215 dpv[n] = NULL; 216 xp = NULL; 217 218 /* 219 * Scan through the buffer in sort order, 220 * zapping the inode number of any 221 * duplicate names. 222 */ 223 for (n = 0; dpv[n]; n++) { 224 struct dirent *dp = dpv[n]; 225 226 if ((xp == NULL) || 227 strcmp(dp->d_name, xp->d_name)) { 228 xp = dp; 229 } else { 230 dp->d_fileno = 0; 231 } 232 if (dp->d_type == DT_WHT && 233 (flags & DTF_HIDEW)) 234 dp->d_fileno = 0; 235 } 236 237 free(dpv); 238 break; 239 } else { 240 dpv = malloc((n+1) * sizeof(struct dirent *)); 241 if (dpv == NULL) 242 break; 243 } 244 } 245 246 dirp->dd_len = len; 247 dirp->dd_size = ddptr - dirp->dd_buf; 248 } else { 249 dirp->dd_len = incr; 250 dirp->dd_buf = malloc(dirp->dd_len); 251 if (dirp->dd_buf == NULL) 252 goto fail; 253 dirp->dd_seek = 0; 254 flags &= ~DTF_REWIND; 255 } 256 257 dirp->dd_loc = 0; 258 dirp->dd_fd = fd; 259 dirp->dd_flags = flags; 260 261 /* 262 * Set up seek point for rewinddir. 263 */ 264 dirp->dd_rewind = telldir(dirp); 265 266 return (dirp); 267 268 fail: 269 saved_errno = errno; 270 free(dirp); 271 (void) close(fd); 272 errno = saved_errno; 273 return (NULL); 274 } 275