90 lines
1.7 KiB
C++
90 lines
1.7 KiB
C++
/* One of many ways to emulate flock() on top of real (good) POSIX locks.
|
|
*
|
|
* This flock() emulation is based upon source taken from the Red Hat
|
|
* implementation used in their imap-2002d SRPM.
|
|
*
|
|
* $RH: flock.c,v 1.2 2000/08/23 17:07:00 nalin Exp $
|
|
*/
|
|
/* flock.c
|
|
|
|
Copyright 2003 Red Hat, Inc.
|
|
|
|
This file is part of Cygwin.
|
|
|
|
This software is a copyrighted work licensed under the terms of the
|
|
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
|
|
details. */
|
|
|
|
#include "winsup.h"
|
|
#include "cygerrno.h"
|
|
#include <sys/file.h>
|
|
#include <fcntl.h>
|
|
#include <unistd.h>
|
|
|
|
int
|
|
flock (int fd, int operation)
|
|
{
|
|
int i, cmd;
|
|
struct __flock64 l = { 0, 0, 0, 0, 0 };
|
|
if (operation & LOCK_NB)
|
|
{
|
|
cmd = F_SETLK;
|
|
}
|
|
else
|
|
{
|
|
cmd = F_SETLKW;
|
|
}
|
|
l.l_whence = SEEK_SET;
|
|
switch (operation & (~LOCK_NB))
|
|
{
|
|
case LOCK_EX:
|
|
l.l_type = F_WRLCK;
|
|
i = fcntl_worker (fd, cmd, &l);
|
|
if (i == -1)
|
|
{
|
|
if ((get_errno () == EAGAIN) || (get_errno () == EACCES))
|
|
{
|
|
set_errno (EWOULDBLOCK);
|
|
}
|
|
}
|
|
break;
|
|
case LOCK_SH:
|
|
l.l_type = F_RDLCK;
|
|
i = fcntl_worker (fd, cmd, &l);
|
|
if (i == -1)
|
|
{
|
|
if ((get_errno () == EAGAIN) || (get_errno () == EACCES))
|
|
{
|
|
set_errno (EWOULDBLOCK);
|
|
}
|
|
}
|
|
break;
|
|
case LOCK_UN:
|
|
l.l_type = F_UNLCK;
|
|
i = fcntl_worker (fd, cmd, &l);
|
|
if (i == -1)
|
|
{
|
|
if ((get_errno () == EAGAIN) || (get_errno () == EACCES))
|
|
{
|
|
set_errno (EWOULDBLOCK);
|
|
}
|
|
}
|
|
break;
|
|
default:
|
|
i = -1;
|
|
set_errno (EINVAL);
|
|
break;
|
|
}
|
|
return i;
|
|
}
|
|
|
|
#ifdef FLOCK_EMULATE_IS_MAIN
|
|
int
|
|
main (int argc, char **argv)
|
|
{
|
|
int fd = open (argv[1], O_WRONLY);
|
|
flock (fd, LOCK_EX);
|
|
return 0;
|
|
}
|
|
#endif
|