Conference turris::decc_bugs

1268.0. "Representing values on UFS or ADVFS different 4.0B" by MDR01::ARANCHA (MCS Madrid) Wed Mar 05 1997 05:04

Hi,
My customer has reported the following error on Digital UNIX 4.0B.

 This program osftest.c uses only system calls, it creates a file veria.bdf
of 18944 bytes,  fills the first blocks with 1.1 and then writes from 
address 6656 on 12000 bytes (representing 3000 floating point values going 
from 0.0 to 29.99 in steps of 0.01).

All system calls execute successfully. But when you do

	> od -f veria.bdf


you see that the last value written is only: 2.4309999e+01.

This happens on a directory which is set up with DEC's advanced file system.

If I do the same in a directory set up with DEC's UFS the program
works o.k. (last value = 2.9990000e+01)

This is very critical for the application customer.
Has anybody  any idea ??
Thanks in the advance,
Arancha

*************************

Program : OSFTEST.C                                                   

#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>

/*
#define O_write         (O_WRONLY | O_CREAT)
*/

#define O_write         O_RDWR

/*
*/


long oskseek(fid, address)
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
.PURPOSE moves the file pointer.
         The argument fid is the file identification
         obtained from osdopen. The address defines
         the pointer position in bytes relative to:
         start of the file, current position or end of the file as
         defined by the variable mode (FILE_START, FILE_CURRENT, FILE_END).
         (see midas/osparms.h). (i.e. : an address=0 and OS_START set means
         first byte of the file).
.RETURNS Upon successful completion, the resulting pointer position
.RETURNS measured in bytes is returned, in case of error -1L.
.REMARKS System dependencies:
 -- UNIX: lseek(2)
------------------------------------------------------------*/
int fid;                        /* file identification */
long address;                   /* file pointer */
{
int  mode;
off_t ret;

mode = SEEK_SET;

if ((ret = lseek(fid, (off_t)address, mode)) == (off_t)-1)
   printf("oskseek: error...\n");
else
   printf("oskseek: addr = %ld, retpntr = %ld\n",address,(long)ret);

return((long)ret);
}


/*
*/


main()

{
char    *mypntr;
char    *cbuf;

int size, status, kk;
int  fid, nr, n, allbytes;
long int addr;

float *fpntr, fbuf[512];


for (nr=0; nr<512; nr++) fbuf[nr] = 1.1;
cbuf = (char *)fbuf;

/* create file on disk with size = 18944 bytes */

fid = creat("veria.bdf",0666);
if (fid < 0)
   printf("creat: problems with creat...\n");
n = 18944;
addr = n - 1;				/* move to last byte */
status = oskseek(fid,addr);
if (status != -1)
   {
   char  c;

   c = ' ';
   n = 1;				/* write 1 byte */
   if ((kk = write(fid,&c,(unsigned int)n)) == -1) 
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }
if (close(fid) < 0) printf("'roblems with close...\n");


fid = open("veria.bdf",O_write,0666);


allbytes = 12000;

mypntr = (char *) malloc((size_t) allbytes);
printf("mypntr = %x\n",mypntr);

fpntr = (float *) mypntr;
for (nr=0; nr<3000; nr++)
   {
   *fpntr++ = 0.01 * nr;
   }



addr = 0;
n = 512;
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,cbuf,(unsigned int)n)) == -1) 
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }

addr += 512;				/* 512 */
n = 2048;
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,cbuf,(unsigned int)n)) == -1)
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }

addr +=2048;				/* 2560 */
n = 2048;
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,cbuf,(unsigned int)n)) == -1)
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }

addr +=2048;				/* 4608 */
n = 2048;
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,cbuf,(unsigned int)n)) == -1)
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }

addr +=2048;				/* 6656 */
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,mypntr,(unsigned int)allbytes)) == -1) 
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",allbytes,kk);
   }

close(fid);

}

 

    
    
    Arancha,
    
    As this sounds like UNIX problem, and not a C problem, could you
    re-post this question in TURRIS::DIGITAL_UNIX?
    
    					Ed