opendir.c revision 261813
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) 31static 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: stable/9/lib/libc/gen/opendir.c 261813 2014-02-12 21:10:40Z jilles $"); 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 51static DIR * __opendir_common(int, const char *, int); 52 53/* 54 * Open a directory. 55 */ 56DIR * 57opendir(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 */ 66DIR * 67fdopendir(int fd) 68{ 69 struct stat statb; 70 71 /* Check that fd is associated with a directory. */ 72 if (_fstat(fd, &statb) != 0) 73 return (NULL); 74 if (!S_ISDIR(statb.st_mode)) { 75 errno = ENOTDIR; 76 return (NULL); 77 } 78 if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) 79 return (NULL); 80 return (__opendir_common(fd, NULL, DTF_HIDEW|DTF_NODUP)); 81} 82 83DIR * 84__opendir2(const char *name, int flags) 85{ 86 int fd; 87 88 if ((fd = _open(name, 89 O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC)) == -1) 90 return (NULL); 91 92 return __opendir_common(fd, name, flags); 93} 94 95static int 96opendir_compar(const void *p1, const void *p2) 97{ 98 99 return (strcmp((*(const struct dirent **)p1)->d_name, 100 (*(const struct dirent **)p2)->d_name)); 101} 102 103/* 104 * Common routine for opendir(3), __opendir2(3) and fdopendir(3). 105 */ 106static DIR * 107__opendir_common(int fd, const char *name, int flags) 108{ 109 DIR *dirp; 110 int incr; 111 int saved_errno; 112 int unionstack; 113 114 if ((dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL) 115 return (NULL); 116 117 dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR)); 118 LIST_INIT(&dirp->dd_td->td_locq); 119 dirp->dd_td->td_loccnt = 0; 120 121 /* 122 * Use the system page size if that is a multiple of DIRBLKSIZ. 123 * Hopefully this can be a big win someday by allowing page 124 * trades to user space to be done by _getdirentries(). 125 */ 126 incr = getpagesize(); 127 if ((incr % DIRBLKSIZ) != 0) 128 incr = DIRBLKSIZ; 129 130 /* 131 * Determine whether this directory is the top of a union stack. 132 */ 133 if (flags & DTF_NODUP) { 134 struct statfs sfb; 135 136 if (_fstatfs(fd, &sfb) < 0) 137 goto fail; 138 unionstack = !strcmp(sfb.f_fstypename, "unionfs") 139 || (sfb.f_flags & MNT_UNION); 140 } else { 141 unionstack = 0; 142 } 143 144 if (unionstack) { 145 int len = 0; 146 int space = 0; 147 char *buf = 0; 148 char *ddptr = 0; 149 char *ddeptr; 150 int n; 151 struct dirent **dpv; 152 153 /* 154 * The strategy here is to read all the directory 155 * entries into a buffer, sort the buffer, and 156 * remove duplicate entries by setting the inode 157 * number to zero. 158 */ 159 160 do { 161 /* 162 * Always make at least DIRBLKSIZ bytes 163 * available to _getdirentries 164 */ 165 if (space < DIRBLKSIZ) { 166 space += incr; 167 len += incr; 168 buf = reallocf(buf, len); 169 if (buf == NULL) 170 goto fail; 171 ddptr = buf + (len - space); 172 } 173 174 n = _getdirentries(fd, ddptr, space, &dirp->dd_seek); 175 if (n > 0) { 176 ddptr += n; 177 space -= n; 178 } 179 } while (n > 0); 180 181 ddeptr = ddptr; 182 flags |= __DTF_READALL; 183 184 /* 185 * Re-open the directory. 186 * This has the effect of rewinding back to the 187 * top of the union stack and is needed by 188 * programs which plan to fchdir to a descriptor 189 * which has also been read -- see fts.c. 190 */ 191 if (flags & DTF_REWIND) { 192 (void)_close(fd); 193 if ((fd = _open(name, O_RDONLY | O_DIRECTORY | 194 O_CLOEXEC)) == -1) { 195 saved_errno = errno; 196 free(buf); 197 free(dirp); 198 errno = saved_errno; 199 return (NULL); 200 } 201 } 202 203 /* 204 * There is now a buffer full of (possibly) duplicate 205 * names. 206 */ 207 dirp->dd_buf = buf; 208 209 /* 210 * Go round this loop twice... 211 * 212 * Scan through the buffer, counting entries. 213 * On the second pass, save pointers to each one. 214 * Then sort the pointers and remove duplicate names. 215 */ 216 for (dpv = 0;;) { 217 n = 0; 218 ddptr = buf; 219 while (ddptr < ddeptr) { 220 struct dirent *dp; 221 222 dp = (struct dirent *) ddptr; 223 if ((long)dp & 03L) 224 break; 225 if ((dp->d_reclen <= 0) || 226 (dp->d_reclen > (ddeptr + 1 - ddptr))) 227 break; 228 ddptr += dp->d_reclen; 229 if (dp->d_fileno) { 230 if (dpv) 231 dpv[n] = dp; 232 n++; 233 } 234 } 235 236 if (dpv) { 237 struct dirent *xp; 238 239 /* 240 * This sort must be stable. 241 */ 242 mergesort(dpv, n, sizeof(*dpv), 243 opendir_compar); 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 300fail: 301 saved_errno = errno; 302 free(dirp); 303 (void)_close(fd); 304 errno = saved_errno; 305 return (NULL); 306} 307