Re: lockf missing ?

"Nils O." Selåsdal <[email protected]> 11 Apr 2003 09:36:31 +0200

Newsgroups	gmane.linux.lsb.discuss
Organization	UtelSystems
Message-ID	<1050046590.1229.11.camel@nos-rh>

On Thu, 10 Apr 2003, Nils O. [ISO-8859-1] Sel=E5sdal wrote:

>> Shouldn't the lockf be part of LSB ?

>Yes, and it is.
Ok. It's not always easy for me to determin what should/should not be
part of LSB, what's missing from lsbdev-base and so on.

>> The various flags (F_LOCK,F_TLOCK,F_ULOCK,F_TEST) also doesn't exist.

>Another bug that all of the review and testing missed. 8-(.

>The SUS says these flags belong in unistd.h, so attached is a unistd.h
>that contains them. Please let me know if this solves this problem.
Tried the new unistd.h with lsbdev-base 1.3
[noselasd@nos-rh utils]$ /opt/lsbdev-cc/bin/lsbcc     -o uniqnum
uniqnum.c
uniqnum.c: In function `my_lock':
uniqnum.c:10: too many arguments to function `lockf'
uniqnum.c: In function `my_unlock':
uniqnum.c:22: too many arguments to function `lockf'

lockf is defined as extern void lockf(void);
changing that to
int lockf(int fd, int cmd, off_t len);
makes it work.

Attached is uniqnum.c , the test program I'm trying, if anyone needs
a testcase.

-- 
Vennlig hilsen/Best Regards
Nils Olav Selåsdal
System Engineer
UtelSystems a/s

w w w . u t e l s y s t e m s . c o m

uniqnum.c (text/x-c, 1.3 KB)

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>


void my_lock( int fd )
{
   lseek( fd, 0L, 0 );   
   if ( lockf( fd, F_LOCK, 0L ) == -1 )
   {
      fprintf( stderr, "Cannot lock file\n" );
      exit(1);
   }
}


void my_unlock( int fd )
{
   lseek( fd, 0L, 0 );
   
   if ( lockf( fd, F_ULOCK, 0L ) == -1 )
   {
      fprintf( stderr, "Cannot unlock file\n" );
      exit(1);
   }
}


int main( int argc, char* argv[] )
{
   int fd;
   int bytes;
   int counter = 0;

   if (argc != 2)
   {
      printf("Usage: %s filename\n", argv[0]);
      exit(0);
   }

   fd = open(argv[1], O_RDWR | O_CREAT, 00700 );
   if (fd < 0)
   {
      fprintf( stderr, "Cannot open file\n" );
      exit(1);
   }
   
   my_lock( fd );
   
   lseek( fd, 0L, 0 );
   bytes = read( fd, &counter, sizeof(int) );
   if ( bytes  < 0 )
   { 
      fprintf( stderr, "Cannot read file\n" );
      exit(1);
   }
   else if (bytes == 0)
   {
      counter = 0; /* file is empty; start at zero */
   }

   counter++;
   if (counter >= 10000)
   {
      counter = 1;
   }
      
   lseek( fd, 0L, 0 );
   if ( write( fd, &counter, sizeof(int) ) <= 0 )
   { 
      fprintf( stderr, "Cannot write file\n" );
      exit(1);
   }
   my_unlock( fd );

   printf( "%d\n", counter );
   return 0;
}