This is `nvi' (tweaked to install as vi), version 1.01.

[unix-history] / usr.bin / vi / clib / flock.c

#include <sys/types.h>
/*
* Include <sys/file.h>, not <fcntl.h>, the flock(2)
* #defines were found there on historical systems.
*/
#include <sys/file.h>

#include <errno.h>
#include <fcntl.h>
#include <unistd.h>

#include <compat.h>

/*
* Use fcntl(2) locking to fake flock(2) locking.
*
* DO NOT USE fcntl(2) UNLESS YOU HAVE TO, THERE ARE SOME SYSTEMS
* (I.E. ULTRIX) WHERE LOCKS AREN'T RELEASED WHEN PROCESSES DIE.
*/
int
flock(fd, operation)
       int fd, operation;
{
       struct flock arg;

       switch (operation & ~LOCK_NB) {
       case LOCK_EX:
               arg.l_type = F_WRLCK;
               break;
       case LOCK_SH:
               arg.l_type = F_RDLCK;
               break;
       case LOCK_UN:
               arg.l_type = F_UNLCK;
               break;
       default:
               abort();
       }

       arg.l_start = arg.l_len = 0;
       arg.l_pid = 0;
       arg.l_whence = 0;               /* SEEK_SET */
       
       if (!fcntl(fd, operation & LOCK_NB ? F_SETLK : F_SETLKW, &arg))
               return (0);
       if (errno == EACCES || errno == EAGAIN)
               errno = EWOULDBLOCK;
       return (-1);
}