2 Unix SMB/Netbios implementation.
4 file read prediction routines
5 Copyright (C) Andrew Tridgell 1992-1997
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 extern int DEBUGLEVEL;
27 /* variables used by the read prediction module */
28 static int rp_fd = -1;
29 static int rp_offset = 0;
30 static int rp_length = 0;
31 static int rp_alloced = 0;
32 static int rp_predict_fd = -1;
33 static int rp_predict_offset = 0;
34 static int rp_predict_length = 0;
35 static int rp_timeout = 5;
36 static time_t rp_time = 0;
37 static char *rp_buffer = NULL;
38 static BOOL predict_skip=False;
39 time_t smb_last_time=(time_t)0;
41 /****************************************************************************
42 handle read prediction on a file
43 ****************************************************************************/
44 int read_predict(int fd,int offset,char *buf,char **ptr,int num)
47 int possible = rp_length - (offset - rp_offset);
49 possible = MIN(possible,num);
51 /* give data if possible */
53 offset >= rp_offset &&
55 smb_last_time-rp_time < rp_timeout)
59 memcpy(buf,rp_buffer + (offset-rp_offset),possible);
61 *ptr = rp_buffer + (offset-rp_offset);
62 DEBUG(5,("read-prediction gave %d bytes of %d\n",ret,num));
70 /* Find the end of the file - ensure we don't
71 read predict beyond it. */
72 if(fstat(fd,&rp_stat) < 0)
74 DEBUG(0,("read-prediction failed on fstat. Error was %s\n", strerror(errno)));
81 /* prepare the next prediction */
83 /* Make sure we don't seek beyond the end of the file. */
84 rp_predict_offset = MIN((offset + num),rp_stat.st_size);
85 rp_predict_length = num;
94 /****************************************************************************
96 ****************************************************************************/
97 void do_read_prediction()
99 static int readsize = 0;
101 if (predict_skip) return;
103 if (rp_predict_fd == -1)
106 rp_fd = rp_predict_fd;
107 rp_offset = rp_predict_offset;
113 readsize = lp_readsize();
114 readsize = MAX(readsize,1024);
117 rp_predict_length = MIN(rp_predict_length,2*readsize);
118 rp_predict_length = MAX(rp_predict_length,1024);
119 rp_offset = (rp_offset/1024)*1024;
120 rp_predict_length = (rp_predict_length/1024)*1024;
122 if (rp_predict_length > rp_alloced)
124 rp_buffer = Realloc(rp_buffer,rp_predict_length);
125 rp_alloced = rp_predict_length;
128 DEBUG(0,("can't allocate read-prediction buffer\n"));
136 if (lseek(rp_fd,rp_offset,SEEK_SET) != rp_offset) {
142 rp_length = read(rp_fd,rp_buffer,rp_predict_length);
143 rp_time = time(NULL);
148 /****************************************************************************
149 invalidate read-prediction on a fd
150 ****************************************************************************/
151 void invalidate_read_prediction(int fd)
155 if (rp_predict_fd == fd)