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/*
* lib/krb5/os/lock_file.c
*
* Copyright 1990 by the Massachusetts Institute of Technology.
* All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
*
* libos: krb5_lock_file routine
*/
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "k5-int.h"
#include <stdio.h>
#ifdef POSIX_FILE_LOCKS
#include <errno.h>
#include <fcntl.h>
#define SHARED_LOCK F_RDLCK
#define EXCLUSIVE_LOCK F_WRLCK
#define UNLOCK_LOCK F_UNLCK
#else
#include <sys/file.h>
#define SHARED_LOCK LOCK_SH
#define EXCLUSIVE_LOCK LOCK_EX
#define UNLOCK_LOCK LOCK_UN
#endif
#include <sys/types.h>
extern int errno;
/*ARGSUSED*/
krb5_error_code
krb5_lock_file(context, filep, pathname, mode)
krb5_context context;
FILE *filep;
char *pathname;
int mode;
{
#ifdef POSIX_FILE_LOCKS
int lock_cmd = F_SETLKW;
struct flock lock_arg;
#define lock_flag lock_arg.l_type
lock_flag = -1;
#else
int lock_flag = -1;
#endif
switch (mode & ~KRB5_LOCKMODE_DONTBLOCK) {
case KRB5_LOCKMODE_SHARED:
lock_flag = SHARED_LOCK;
break;
case KRB5_LOCKMODE_EXCLUSIVE:
lock_flag = EXCLUSIVE_LOCK;
break;
case KRB5_LOCKMODE_UNLOCK:
lock_flag = UNLOCK_LOCK;
break;
}
if (lock_flag == -1)
return(KRB5_LIBOS_BADLOCKFLAG);
if (mode & KRB5_LOCKMODE_DONTBLOCK) {
#ifdef POSIX_FILE_LOCKS
lock_cmd = F_SETLK;
#else
lock_flag |= LOCK_NB;
#endif
}
#ifdef POSIX_FILE_LOCKS
lock_arg.l_whence = 0;
lock_arg.l_start = 0;
lock_arg.l_len = 0;
if (fcntl(fileno(filep), lock_cmd, &lock_arg) == -1) {
if (errno == EACCES || errno == EAGAIN) /* see POSIX/IEEE 1003.1-1988,
6.5.2.4 */
return(EAGAIN);
return(errno);
}
#else
if (flock(fileno(filep), lock_flag) == -1)
return(errno);
#endif
return 0;
}
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