svn commit: samba r18492 - in branches/SAMBA_4_0/source/lib/replace: .

[tridge at samba.org]

Author: tridge
Date: 2006-09-14 02:25:57 +0000 (Thu, 14 Sep 2006)
New Revision: 18492

WebSVN: http://websvn.samba.org/cgi-bin/viewcvs.cgi?view=rev&root=samba&rev=18492

Log:

an attempt at replacing readdir() with something based on
getdirentries()

This is untested on any of the platforms that matter, so we'll just
have to see if the build farm machines like it

Modified:
   branches/SAMBA_4_0/source/lib/replace/repdir_getdirentries.c


Changeset:
Modified: branches/SAMBA_4_0/source/lib/replace/repdir_getdirentries.c
===================================================================
--- branches/SAMBA_4_0/source/lib/replace/repdir_getdirentries.c	2006-09-13 23:13:44 UTC (rev 18491)
+++ branches/SAMBA_4_0/source/lib/replace/repdir_getdirentries.c	2006-09-14 02:25:57 UTC (rev 18492)
@@ -1 +1,157 @@
-#error "the readdir() replacement using getdirentried() isn't implemented yet"
+/* 
+   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 <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) {
+		d->nbytes = getdirentries(d->fd, d->buf, DIR_BUF_SIZE, &d->seekpos);
+		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 = getdirentries(d->fd, d->buf, DIR_BUF_SIZE, &d->seekpos);
+	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
+
+