2 Unix SMB/CIFS implementation.
4 Copyright (C) Andrew Tridgell 2005
6 ** NOTE! The following LGPL license applies to the replace
7 ** library. This does NOT imply that all of Samba is released
10 This library is free software; you can redistribute it and/or
11 modify it under the terms of the GNU Lesser General Public
12 License as published by the Free Software Foundation; either
13 version 2 of the License, or (at your option) any later version.
15 This library is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public
21 License along with this library; if not, write to the Free Software
22 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
25 a replacement for opendir/readdir/telldir/seekdir/closedir for BSD systems
27 This is needed because the existing directory handling in FreeBSD
28 and OpenBSD (and possibly NetBSD) doesn't correctly handle unlink()
29 on files in a directory where telldir() has been used. On a block
30 boundary it will occasionally miss a file when seekdir() is used to
31 return to a position previously recorded with telldir().
33 This also fixes a severe performance and memory usage problem with
34 telldir() on BSD systems. Each call to telldir() in BSD adds an
35 entry to a linked list, and those entries are cleaned up on
36 closedir(). This means with a large directory closedir() can take an
37 arbitrary amount of time, causing network timeouts as millions of
38 telldir() entries are freed
40 Note! This replacement code is not portable. It relies on getdents()
41 always leaving the file descriptor at a seek offset that is a
42 multiple of DIR_BUF_SIZE. If the code detects that this doesn't
43 happen then it will abort(). It also does not handle directories
44 with offsets larger than can be stored in a long,
46 This code is available under other free software licenses as
47 well. Contact the author.
53 #include <sys/types.h>
58 #define DIR_BUF_BITS 9
59 #define DIR_BUF_SIZE (1<<DIR_BUF_BITS)
65 char buf[DIR_BUF_SIZE];
68 DIR *opendir(const char *dname)
72 d = malloc(sizeof(*d));
77 d->fd = open(dname, O_RDONLY);
82 if (fstat(d->fd, &sb) < 0) {
87 if (!S_ISDIR(sb.st_mode)) {
99 struct dirent *readdir(DIR *dir)
101 struct dir_buf *d = (struct dir_buf *)dir;
104 if (d->ofs >= d->nbytes) {
105 d->seekpos = lseek(d->fd, 0, SEEK_CUR);
106 d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE);
109 if (d->ofs >= d->nbytes) {
112 de = (struct dirent *)&d->buf[d->ofs];
113 d->ofs += de->d_reclen;
117 long telldir(DIR *dir)
119 struct dir_buf *d = (struct dir_buf *)dir;
120 if (d->ofs >= d->nbytes) {
121 d->seekpos = lseek(d->fd, 0, SEEK_CUR);
125 /* this relies on seekpos always being a multiple of
126 DIR_BUF_SIZE. Is that always true on BSD systems? */
127 if (d->seekpos & (DIR_BUF_SIZE-1)) {
130 return d->seekpos + d->ofs;
133 void seekdir(DIR *dir, long ofs)
135 struct dir_buf *d = (struct dir_buf *)dir;
136 d->seekpos = lseek(d->fd, ofs & ~(DIR_BUF_SIZE-1), SEEK_SET);
137 d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE);
139 while (d->ofs < (ofs & (DIR_BUF_SIZE-1))) {
140 if (readdir(dir) == NULL) break;
144 void rewinddir(DIR *dir)
149 int closedir(DIR *dir)
151 struct dir_buf *d = (struct dir_buf *)dir;
152 int r = close(d->fd);
161 /* darn, this is a macro on some systems. */
164 struct dir_buf *d = (struct dir_buf *)dir;