1 files changed, 146 insertions, 0 deletions
diff --git a/source3/smbd/predict.c b/source3/smbd/predict.c
new file mode 100644
index 0000000000..8df381b367
--- /dev/null
+++ b/source3/smbd/predict.c
@@ -0,0 +1,146 @@
+/* 
+   Unix SMB/Netbios implementation.
+   Version 1.9.
+   file read prediction routines
+   Copyright (C) Andrew Tridgell 1992-1995
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program 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 General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "includes.h"
+#include "loadparm.h"
+
+extern int DEBUGLEVEL;
+
+
+/* variables used by the read prediction module */
+static int rp_fd = -1;
+static int rp_offset = 0;
+static int rp_length = 0;
+static int rp_alloced = 0;
+static int rp_predict_fd = -1;
+static int rp_predict_offset = 0;
+static int rp_predict_length = 0;
+static int rp_timeout = 5;
+static time_t rp_time = 0;
+static char *rp_buffer = NULL;
+static BOOL predict_skip=False;
+time_t smb_last_time=(time_t)0;
+
+/****************************************************************************
+handle read prediction on a file
+****************************************************************************/
+int read_predict(int fd,int offset,char *buf,char **ptr,int num)
+{
+  int ret = 0;
+  int possible = rp_length - (offset - rp_offset);
+
+  possible = MIN(possible,num);
+
+  /* give data if possible */
+  if (fd == rp_fd && 
+      offset >= rp_offset && 
+      possible>0 &&
+      smb_last_time-rp_time < rp_timeout)
+    {
+      ret = possible;
+      if (buf)
+	memcpy(buf,rp_buffer + (offset-rp_offset),possible);
+      else
+	*ptr = rp_buffer + (offset-rp_offset);
+      DEBUG(5,("read-prediction gave %d bytes of %d\n",ret,num));
+    }
+
+  if (ret == num) {
+    predict_skip = True;
+  } else {
+    predict_skip = False;
+
+    /* prepare the next prediction */
+    rp_predict_fd = fd;
+    rp_predict_offset = offset + num;
+    rp_predict_length = num;
+  }
+
+  if (ret < 0) ret = 0;
+
+  return(ret);
+}
+
+/****************************************************************************
+pre-read some data
+****************************************************************************/
+void do_read_prediction()
+{
+  static int readsize = 0;
+
+  if (predict_skip) return;
+
+  if (rp_predict_fd == -1) 
+    return;
+
+  rp_fd = rp_predict_fd;
+  rp_offset = rp_predict_offset;
+  rp_length = 0;
+
+  rp_predict_fd = -1;
+
+  if (readsize == 0) {
+    readsize = lp_readsize();
+    readsize = MAX(readsize,1024);
+  }
+
+  rp_predict_length = MIN(rp_predict_length,2*readsize);
+  rp_predict_length = MAX(rp_predict_length,1024);
+  rp_offset = (rp_offset/1024)*1024;
+  rp_predict_length = (rp_predict_length/1024)*1024;
+
+  if (rp_predict_length > rp_alloced)
+    {
+      rp_buffer = Realloc(rp_buffer,rp_predict_length);
+      rp_alloced = rp_predict_length;
+      if (!rp_buffer)
+	{
+	  DEBUG(0,("can't allocate read-prediction buffer\n"));
+	  rp_predict_fd = -1;
+	  rp_fd = -1;
+	  rp_alloced = 0;
+	  return;
+	}
+    }
+
+  if (lseek(rp_fd,rp_offset,SEEK_SET) != rp_offset) {
+    rp_fd = -1;
+    rp_predict_fd = -1;
+    return;
+  }
+
+  rp_length = read(rp_fd,rp_buffer,rp_predict_length);
+  rp_time = time(NULL);
+  if (rp_length < 0)
+    rp_length = 0;
+}
+
+/****************************************************************************
+invalidate read-prediction on a fd
+****************************************************************************/
+void invalidate_read_prediction(int fd)
+{
+ if (rp_fd == fd) 
+   rp_fd = -1;
+ if (rp_predict_fd == fd)
+   rp_predict_fd = -1;
+}
+