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-rw-r--r--source3/smbd/predict.c146
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;
+}
+