summaryrefslogtreecommitdiff
path: root/source3/lib/replace/repdir_getdirentries.c
diff options
context:
space:
mode:
Diffstat (limited to 'source3/lib/replace/repdir_getdirentries.c')
-rw-r--r--source3/lib/replace/repdir_getdirentries.c172
1 files changed, 172 insertions, 0 deletions
diff --git a/source3/lib/replace/repdir_getdirentries.c b/source3/lib/replace/repdir_getdirentries.c
new file mode 100644
index 0000000000..9e4b63145c
--- /dev/null
+++ b/source3/lib/replace/repdir_getdirentries.c
@@ -0,0 +1,172 @@
+/*
+ Unix SMB/CIFS implementation.
+
+ Copyright (C) Andrew Tridgell 2005
+
+ ** NOTE! The following LGPL license applies to the replace
+ ** library. This does NOT imply that all of Samba is released
+ ** under the LGPL
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2 of the License, or (at your option) any later version.
+
+ This library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this library; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+/*
+ a replacement for opendir/readdir/telldir/seekdir/closedir for BSD
+ systems using getdirentries
+
+ This is needed because the existing directory handling in FreeBSD
+ and OpenBSD (and possibly NetBSD) doesn't correctly handle unlink()
+ on files in a directory where telldir() has been used. On a block
+ boundary it will occasionally miss a file when seekdir() is used to
+ return to a position previously recorded with telldir().
+
+ This also fixes a severe performance and memory usage problem with
+ telldir() on BSD systems. Each call to telldir() in BSD adds an
+ entry to a linked list, and those entries are cleaned up on
+ closedir(). This means with a large directory closedir() can take an
+ arbitrary amount of time, causing network timeouts as millions of
+ telldir() entries are freed
+
+ Note! This replacement code is not portable. It relies on
+ getdirentries() always leaving the file descriptor at a seek offset
+ that is a multiple of DIR_BUF_SIZE. If the code detects that this
+ doesn't happen then it will abort(). It also does not handle
+ directories with offsets larger than can be stored in a long,
+
+ This code is available under other free software licenses as
+ well. Contact the author.
+*/
+
+#include "replace.h"
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <dirent.h>
+
+#define DIR_BUF_BITS 9
+#define DIR_BUF_SIZE (1<<DIR_BUF_BITS)
+
+struct dir_buf {
+ int fd;
+ int nbytes, ofs;
+ off_t seekpos;
+ char buf[DIR_BUF_SIZE];
+};
+
+DIR *opendir(const char *dname)
+{
+ struct dir_buf *d;
+ d = malloc(sizeof(*d));
+ if (d == NULL) {
+ errno = ENOMEM;
+ return NULL;
+ }
+ d->fd = open(dname, O_RDONLY);
+ if (d->fd == -1) {
+ free(d);
+ return NULL;
+ }
+ d->ofs = 0;
+ d->seekpos = 0;
+ d->nbytes = 0;
+ return (DIR *)d;
+}
+
+struct dirent *readdir(DIR *dir)
+{
+ struct dir_buf *d = (struct dir_buf *)dir;
+ struct dirent *de;
+
+ if (d->ofs >= d->nbytes) {
+ long pos;
+ d->nbytes = getdirentries(d->fd, d->buf, DIR_BUF_SIZE, &pos);
+ d->seekpos = pos;
+ d->ofs = 0;
+ }
+ if (d->ofs >= d->nbytes) {
+ return NULL;
+ }
+ de = (struct dirent *)&d->buf[d->ofs];
+ d->ofs += de->d_reclen;
+ return de;
+}
+
+#ifdef TELLDIR_TAKES_CONST_DIR
+long telldir(const DIR *dir)
+#else
+long telldir(DIR *dir)
+#endif
+{
+ struct dir_buf *d = (struct dir_buf *)dir;
+ if (d->ofs >= d->nbytes) {
+ d->seekpos = lseek(d->fd, 0, SEEK_CUR);
+ d->ofs = 0;
+ d->nbytes = 0;
+ }
+ /* this relies on seekpos always being a multiple of
+ DIR_BUF_SIZE. Is that always true on BSD systems? */
+ if (d->seekpos & (DIR_BUF_SIZE-1)) {
+ abort();
+ }
+ return d->seekpos + d->ofs;
+}
+
+#ifdef SEEKDIR_RETURNS_INT
+int seekdir(DIR *dir, long ofs)
+#else
+void seekdir(DIR *dir, long ofs)
+#endif
+{
+ struct dir_buf *d = (struct dir_buf *)dir;
+ long pos;
+ d->seekpos = lseek(d->fd, ofs & ~(DIR_BUF_SIZE-1), SEEK_SET);
+ d->nbytes = getdirentries(d->fd, d->buf, DIR_BUF_SIZE, &pos);
+ d->ofs = 0;
+ while (d->ofs < (ofs & (DIR_BUF_SIZE-1))) {
+ if (readdir(dir) == NULL) break;
+ }
+#ifdef SEEKDIR_RETURNS_INT
+ return -1;
+#endif
+}
+
+void rewinddir(DIR *dir)
+{
+ seekdir(dir, 0);
+}
+
+int closedir(DIR *dir)
+{
+ struct dir_buf *d = (struct dir_buf *)dir;
+ int r = close(d->fd);
+ if (r != 0) {
+ return r;
+ }
+ free(d);
+ return 0;
+}
+
+#ifndef dirfd
+/* darn, this is a macro on some systems. */
+int dirfd(DIR *dir)
+{
+ struct dir_buf *d = (struct dir_buf *)dir;
+ return d->fd;
+}
+#endif
+
+