diff options
Diffstat (limited to 'source/smbd/predict.c')
| -rw-r--r-- | source/smbd/predict.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/source/smbd/predict.c b/source/smbd/predict.c new file mode 100644 index 00000000000..5f015139cf3 --- /dev/null +++ b/source/smbd/predict.c @@ -0,0 +1,162 @@ +/* + Unix SMB/Netbios implementation. + Version 1.9. + file read prediction routines + Copyright (C) Andrew Tridgell 1992-1998 + + 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" + +extern int DEBUGLEVEL; + +#if USE_READ_PREDICTION + +/* variables used by the read prediction module */ +static int rp_fd = -1; +static SMB_OFF_T rp_offset = 0; +static ssize_t rp_length = 0; +static ssize_t rp_alloced = 0; +static int rp_predict_fd = -1; +static SMB_OFF_T rp_predict_offset = 0; +static size_t 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; +extern time_t smb_last_time; + +/**************************************************************************** +handle read prediction on a file +****************************************************************************/ +ssize_t read_predict(int fd,SMB_OFF_T offset,char *buf,char **ptr,size_t num) +{ + ssize_t ret = 0; + ssize_t 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 { + SMB_STRUCT_STAT rp_stat; + + /* Find the end of the file - ensure we don't + read predict beyond it. */ + if(sys_fstat(fd,&rp_stat) < 0) + { + DEBUG(0,("read-prediction failed on fstat. Error was %s\n", strerror(errno))); + predict_skip = True; + } + else + { + predict_skip = False; + + /* prepare the next prediction */ + rp_predict_fd = fd; + /* Make sure we don't seek beyond the end of the file. */ + rp_predict_offset = MIN((offset + num),rp_stat.st_size); + rp_predict_length = num; + } + } + + if (ret < 0) ret = 0; + + return(ret); +} + +/**************************************************************************** +pre-read some data +****************************************************************************/ +void do_read_prediction(void) +{ + static size_t 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 (sys_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; +} + +#else + void read_prediction_dummy(void) ; +#endif |