From 23b61265b85f321ae2ceddc6c75771f8881566d8 Mon Sep 17 00:00:00 2001
From: Simo Sorce <idra@samba.org>
Date: Fri, 5 Sep 2008 10:13:10 -0400
Subject: Initial Import

---
 replace/repdir_getdents.c | 166 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 166 insertions(+)
 create mode 100644 replace/repdir_getdents.c

(limited to 'replace/repdir_getdents.c')

diff --git a/replace/repdir_getdents.c b/replace/repdir_getdents.c
new file mode 100644
index 000000000..afc634a79
--- /dev/null
+++ b/replace/repdir_getdents.c
@@ -0,0 +1,166 @@
+/* 
+   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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+/*
+  a replacement for opendir/readdir/telldir/seekdir/closedir for BSD systems
+
+  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 getdents()
+  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 <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;
+	struct stat sb;
+	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;
+	}
+	if (fstat(d->fd, &sb) < 0) {
+		close(d->fd);
+		free(d);
+		return NULL;
+	}
+	if (!S_ISDIR(sb.st_mode)) {
+		close(d->fd);
+		free(d);   
+		errno = ENOTDIR;
+		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) {
+		d->seekpos = lseek(d->fd, 0, SEEK_CUR);
+		d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE);
+		d->ofs = 0;
+	}
+	if (d->ofs >= d->nbytes) {
+		return NULL;
+	}
+	de = (struct dirent *)&d->buf[d->ofs];
+	d->ofs += de->d_reclen;
+	return de;
+}
+
+long telldir(DIR *dir)
+{
+	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;
+}
+
+void seekdir(DIR *dir, long ofs)
+{
+	struct dir_buf *d = (struct dir_buf *)dir;
+	d->seekpos = lseek(d->fd, ofs & ~(DIR_BUF_SIZE-1), SEEK_SET);
+	d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE);
+	d->ofs = 0;
+	while (d->ofs < (ofs & (DIR_BUF_SIZE-1))) {
+		if (readdir(dir) == NULL) break;
+	}
+}
+
+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
-- 
cgit