mirror of
https://github.com/samba-team/samba.git
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cac6a060af
with gcc. (Not a big change although it looks like it :-).
Jeremy.
(This used to be commit cd2613c572
)
163 lines
4.2 KiB
C
163 lines
4.2 KiB
C
/*
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Unix SMB/Netbios implementation.
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Version 1.9.
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file read prediction routines
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Copyright (C) Andrew Tridgell 1992-1998
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "includes.h"
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extern int DEBUGLEVEL;
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#if USE_READ_PREDICTION
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/* variables used by the read prediction module */
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static int rp_fd = -1;
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static int rp_offset = 0;
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static int rp_length = 0;
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static int rp_alloced = 0;
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static int rp_predict_fd = -1;
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static int rp_predict_offset = 0;
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static int rp_predict_length = 0;
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static int rp_timeout = 5;
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static time_t rp_time = 0;
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static char *rp_buffer = NULL;
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static BOOL predict_skip=False;
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extern time_t smb_last_time;
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/****************************************************************************
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handle read prediction on a file
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****************************************************************************/
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int read_predict(int fd,int offset,char *buf,char **ptr,int num)
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{
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int ret = 0;
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int possible = rp_length - (offset - rp_offset);
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possible = MIN(possible,num);
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/* give data if possible */
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if (fd == rp_fd &&
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offset >= rp_offset &&
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possible>0 &&
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smb_last_time-rp_time < rp_timeout)
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{
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ret = possible;
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if (buf)
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memcpy(buf,rp_buffer + (offset-rp_offset),possible);
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else
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*ptr = rp_buffer + (offset-rp_offset);
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DEBUG(5,("read-prediction gave %d bytes of %d\n",ret,num));
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}
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if (ret == num) {
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predict_skip = True;
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} else {
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struct stat rp_stat;
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/* Find the end of the file - ensure we don't
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read predict beyond it. */
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if(fstat(fd,&rp_stat) < 0)
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{
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DEBUG(0,("read-prediction failed on fstat. Error was %s\n", strerror(errno)));
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predict_skip = True;
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}
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else
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{
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predict_skip = False;
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/* prepare the next prediction */
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rp_predict_fd = fd;
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/* Make sure we don't seek beyond the end of the file. */
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rp_predict_offset = MIN((offset + num),rp_stat.st_size);
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rp_predict_length = num;
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}
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}
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if (ret < 0) ret = 0;
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return(ret);
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}
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/****************************************************************************
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pre-read some data
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****************************************************************************/
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void do_read_prediction(void)
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{
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static int readsize = 0;
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if (predict_skip) return;
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if (rp_predict_fd == -1)
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return;
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rp_fd = rp_predict_fd;
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rp_offset = rp_predict_offset;
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rp_length = 0;
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rp_predict_fd = -1;
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if (readsize == 0) {
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readsize = lp_readsize();
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readsize = MAX(readsize,1024);
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}
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rp_predict_length = MIN(rp_predict_length,2*readsize);
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rp_predict_length = MAX(rp_predict_length,1024);
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rp_offset = (rp_offset/1024)*1024;
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rp_predict_length = (rp_predict_length/1024)*1024;
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if (rp_predict_length > rp_alloced)
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{
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rp_buffer = Realloc(rp_buffer,rp_predict_length);
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rp_alloced = rp_predict_length;
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if (!rp_buffer)
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{
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DEBUG(0,("can't allocate read-prediction buffer\n"));
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rp_predict_fd = -1;
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rp_fd = -1;
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rp_alloced = 0;
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return;
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}
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}
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if (lseek(rp_fd,rp_offset,SEEK_SET) != rp_offset) {
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rp_fd = -1;
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rp_predict_fd = -1;
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return;
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}
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rp_length = read(rp_fd,rp_buffer,rp_predict_length);
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rp_time = time(NULL);
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if (rp_length < 0)
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rp_length = 0;
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}
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/****************************************************************************
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invalidate read-prediction on a fd
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****************************************************************************/
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void invalidate_read_prediction(int fd)
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{
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if (rp_fd == fd)
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rp_fd = -1;
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if (rp_predict_fd == fd)
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rp_predict_fd = -1;
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}
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#else
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void read_prediction_dummy(void) ;
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#endif
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