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32 #include <sys/cdefs.h>
33 __SCCSID("@(#)opendir.c 8.8 (Berkeley) 5/1/95");
34 #include "namespace.h"
35 #include <sys/param.h>
43 #include "un-namespace.h"
45 #include "gen-private.h"
48 static DIR * __opendir_common(int, int, bool);
54 opendir(const char *name)
57 return (__opendir2(name, DTF_HIDEW|DTF_NODUP));
61 * Open a directory with existing file descriptor.
67 if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
69 return (__opendir_common(fd, DTF_HIDEW|DTF_NODUP, true));
73 __opendir2(const char *name, int flags)
79 if ((flags & (__DTF_READALL | __DTF_SKIPREAD)) != 0)
82 O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC)) == -1)
85 dir = __opendir_common(fd, flags, false);
95 opendir_compar(const void *p1, const void *p2)
98 return (strcmp((*(const struct dirent * const *)p1)->d_name,
99 (*(const struct dirent * const *)p2)->d_name));
103 * For a directory at the top of a unionfs stack, the entire directory's
104 * contents are read and cached locally until the next call to rewinddir().
105 * For the fdopendir() case, the initial seek position must be preserved.
106 * For rewinddir(), the full directory should always be re-read from the
109 * If an error occurs, the existing buffer and state of 'dirp' is left
113 _filldir(DIR *dirp, bool use_current_pos)
116 char *buf, *ddptr, *ddeptr;
118 int fd2, incr, len, n, saved_errno, space;
126 * Use the system page size if that is a multiple of DIRBLKSIZ.
127 * Hopefully this can be a big win someday by allowing page
128 * trades to user space to be done by _getdirentries().
130 incr = getpagesize();
131 if ((incr % DIRBLKSIZ) != 0)
135 * The strategy here is to read all the directory
136 * entries into a buffer, sort the buffer, and
137 * remove duplicate entries by setting the inode
140 * We reopen the directory because _getdirentries()
141 * on a MNT_UNION mount modifies the open directory,
142 * making it refer to the lower directory after the
143 * upper directory's entries are exhausted.
144 * This would otherwise break software that uses
145 * the directory descriptor for fchdir or *at
146 * functions, such as fts.c.
148 if ((fd2 = _openat(dirp->dd_fd, ".", O_RDONLY | O_CLOEXEC)) == -1)
151 if (use_current_pos) {
152 pos = lseek(dirp->dd_fd, 0, SEEK_CUR);
153 if (pos == -1 || lseek(fd2, pos, SEEK_SET) == -1) {
163 * Always make at least DIRBLKSIZ bytes
164 * available to _getdirentries
166 if (space < DIRBLKSIZ) {
169 buf = reallocf(buf, len);
176 ddptr = buf + (len - space);
179 n = _getdirentries(fd2, ddptr, space, &dirp->dd_seek);
196 * There is now a buffer full of (possibly) duplicate
202 * Go round this loop twice...
204 * Scan through the buffer, counting entries.
205 * On the second pass, save pointers to each one.
206 * Then sort the pointers and remove duplicate names.
211 while (ddptr < ddeptr) {
214 dp = (struct dirent *) ddptr;
217 if ((dp->d_reclen <= 0) ||
218 (dp->d_reclen > (ddeptr + 1 - ddptr)))
220 ddptr += dp->d_reclen;
232 * This sort must be stable.
234 mergesort(dpv, n, sizeof(*dpv), opendir_compar);
240 * Scan through the buffer in sort order,
241 * zapping the inode number of any
244 for (n = 0; dpv[n]; n++) {
245 struct dirent *dp = dpv[n];
248 strcmp(dp->d_name, xp->d_name)) {
253 if (dp->d_type == DT_WHT &&
254 (dirp->dd_flags & DTF_HIDEW))
261 dpv = malloc((n+1) * sizeof(struct dirent *));
268 dirp->dd_size = ddptr - dirp->dd_buf;
273 is_unionstack(int fd)
277 unionstack = _fcntl(fd, F_ISUNIONSTACK, 0);
278 if (unionstack != -1)
282 * Should not happen unless running on a kernel without the op,
283 * but no use rendering the system useless in such a case.
289 * Common routine for opendir(3), __opendir2(3) and fdopendir(3).
292 __opendir_common(int fd, int flags, bool use_current_pos)
299 if ((dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL)
304 dirp->dd_flags = flags;
306 dirp->dd_lock = NULL;
307 dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
308 LIST_INIT(&dirp->dd_td->td_locq);
309 dirp->dd_td->td_loccnt = 0;
310 dirp->dd_compat_de = NULL;
313 * Use the system page size if that is a multiple of DIRBLKSIZ.
314 * Hopefully this can be a big win someday by allowing page
315 * trades to user space to be done by _getdirentries().
317 incr = getpagesize();
318 if ((incr % DIRBLKSIZ) != 0)
322 * Determine whether this directory is the top of a union stack.
325 if (flags & DTF_NODUP) {
326 unionstack = is_unionstack(fd);
330 if (!_filldir(dirp, use_current_pos))
332 dirp->dd_flags |= __DTF_READALL;
335 dirp->dd_buf = malloc(dirp->dd_len);
336 if (dirp->dd_buf == NULL)
338 if (use_current_pos) {
340 * Read the first batch of directory entries
341 * to prime dd_seek. This also checks if the
342 * fd passed to fdopendir() is a directory.
344 dirp->dd_size = _getdirentries(dirp->dd_fd,
345 dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
346 if (dirp->dd_size < 0) {
351 dirp->dd_flags |= __DTF_SKIPREAD;