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Unix SMB/CIFS implementation.
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Copyright (C) Andrew Tridgell 2005
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** NOTE! The following LGPL license applies to the replace
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** library. This does NOT imply that all of Samba is released
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 3 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, see <http://www.gnu.org/licenses/>.
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a replacement for opendir/readdir/telldir/seekdir/closedir for BSD systems
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This is needed because the existing directory handling in FreeBSD
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and OpenBSD (and possibly NetBSD) doesn't correctly handle unlink()
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on files in a directory where telldir() has been used. On a block
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boundary it will occasionally miss a file when seekdir() is used to
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return to a position previously recorded with telldir().
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This also fixes a severe performance and memory usage problem with
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telldir() on BSD systems. Each call to telldir() in BSD adds an
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entry to a linked list, and those entries are cleaned up on
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closedir(). This means with a large directory closedir() can take an
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arbitrary amount of time, causing network timeouts as millions of
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telldir() entries are freed
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Note! This replacement code is not portable. It relies on getdents()
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always leaving the file descriptor at a seek offset that is a
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multiple of DIR_BUF_SIZE. If the code detects that this doesn't
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happen then it will abort(). It also does not handle directories
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with offsets larger than can be stored in a long,
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This code is available under other free software licenses as
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well. Contact the author.
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#include <sys/types.h>
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#define DIR_BUF_BITS 9
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#define DIR_BUF_SIZE (1<<DIR_BUF_BITS)
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char buf[DIR_BUF_SIZE];
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DIR *opendir(const char *dname)
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d = malloc(sizeof(*d));
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d->fd = open(dname, O_RDONLY);
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if (fstat(d->fd, &sb) < 0) {
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if (!S_ISDIR(sb.st_mode)) {
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struct dirent *readdir(DIR *dir)
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struct dir_buf *d = (struct dir_buf *)dir;
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if (d->ofs >= d->nbytes) {
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d->seekpos = lseek(d->fd, 0, SEEK_CUR);
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d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE);
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if (d->ofs >= d->nbytes) {
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de = (struct dirent *)&d->buf[d->ofs];
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d->ofs += de->d_reclen;
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long telldir(DIR *dir)
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struct dir_buf *d = (struct dir_buf *)dir;
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if (d->ofs >= d->nbytes) {
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d->seekpos = lseek(d->fd, 0, SEEK_CUR);
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/* this relies on seekpos always being a multiple of
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DIR_BUF_SIZE. Is that always true on BSD systems? */
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if (d->seekpos & (DIR_BUF_SIZE-1)) {
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return d->seekpos + d->ofs;
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void seekdir(DIR *dir, long ofs)
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struct dir_buf *d = (struct dir_buf *)dir;
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d->seekpos = lseek(d->fd, ofs & ~(DIR_BUF_SIZE-1), SEEK_SET);
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d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE);
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while (d->ofs < (ofs & (DIR_BUF_SIZE-1))) {
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if (readdir(dir) == NULL) break;
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void rewinddir(DIR *dir)
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int closedir(DIR *dir)
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struct dir_buf *d = (struct dir_buf *)dir;
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int r = close(d->fd);
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/* darn, this is a macro on some systems. */
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struct dir_buf *d = (struct dir_buf *)dir;