Hello,
I've down loaded version 1.7 onto my Windows XP laptop (uname -a reports
CYGWIN_NT-5.1 XXXXXXXXXX 1.7.0(0.217/5/3) 2009-11-10 13:03 i686 Cygwin) and I'm
having some problems with the fcntl() function.
I've written the following sample to demonstrate the problem:
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#define LOCK_FILE_MODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH |
S_IWOTH)
int main(int argc, char* argv[])
{
struct flock lock ;
// Open the file
int fd = open("lockfile", O_RDWR | O_CREAT, LOCK_FILE_MODE) ;
// define the lock
lock.l_type = F_WRLCK ;
lock.l_start = 0 ;
lock.l_whence = SEEK_SET ;
lock.l_len = 1 ;
lock.l_pid = 0 ;
// Check if the lock will work
if ( fcntl(fd, F_GETLK, &lock) < 0 )
perror("fcntl error") ;
if ( lock.l_type == F_UNLCK )
{
printf("No blocking lock\n") ;
lock.l_type = F_WRLCK ;
}
printf("Trying to get lock\n") ;
if ( fcntl(fd, F_SETLKW, &lock) < 0 )
perror("fcntl error") ;
printf("Holding onto lock\n") ;
// Hold the lock for ever.
loop:
sleep(60) ;
goto loop ;
return 0 ;
}
If I run this code in the same directory in two seperate shells I'd expect only
the first instance to print 'No blocking lock' however both do and the second
then goes on to block waiting for the actual lock (which it gets when I
terminate the first instance). So the locking functionality works just fine;
however the lock reporting does seem not to work and always returns F_UNLCK.
Can someone confirm if this is a known limittaion of the current version, a
limitation of the underlying windows API or a bug?
Jackson
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