xref: /illumos-gate/usr/src/lib/gss_mechs/mech_krb5/krb5/os/lock_file.c (revision 55fea89dcaa64928bed4327112404dcb3e07b79f)
1 /*
2  * lib/krb5/os/lock_file.c
3  *
4  * Copyright 1990, 1998 by the Massachusetts Institute of Technology.
5  * All Rights Reserved.
6  *
7  * Export of this software from the United States of America may
8  *   require a specific license from the United States Government.
9  *   It is the responsibility of any person or organization contemplating
10  *   export to obtain such a license before exporting.
11  *
12  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
13  * distribute this software and its documentation for any purpose and
14  * without fee is hereby granted, provided that the above copyright
15  * notice appear in all copies and that both that copyright notice and
16  * this permission notice appear in supporting documentation, and that
17  * the name of M.I.T. not be used in advertising or publicity pertaining
18  * to distribution of the software without specific, written prior
19  * permission.  Furthermore if you modify this software you must label
20  * your software as modified software and not distribute it in such a
21  * fashion that it might be confused with the original M.I.T. software.
22  * M.I.T. makes no representations about the suitability of
23  * this software for any purpose.  It is provided "as is" without express
24  * or implied warranty.
25  *
26  *
27  * libos: krb5_lock_file routine
28  */
29 
30 #include "k5-int.h"
31 #include <stdio.h>
32 
33 #if !defined(_WIN32)
34 
35 /* Unix version...  */
36 
37 #if HAVE_UNISTD_H
38 #include <unistd.h>
39 #endif
40 
41 #include <errno.h>
42 
43 #ifdef HAVE_FCNTL_H
44 #include <fcntl.h>
45 #endif
46 
47 #if defined(HAVE_FCNTL_H) && defined(F_SETLKW) && defined(F_RDLCK)
48 #define POSIX_FILE_LOCKS
49 #endif
50 
51 #ifdef HAVE_FLOCK
52 #ifndef sysvimp
53 #include <sys/file.h>
54 #endif
55 #else
56 #ifndef LOCK_SH
57 #define LOCK_SH 0
58 #define LOCK_EX 0
59 #define LOCK_UN 0
60 #endif
61 #endif
62 
63 /*ARGSUSED*/
64 krb5_error_code
krb5_lock_file(krb5_context context,int fd,int mode)65 krb5_lock_file(krb5_context context, int fd, int mode)
66 {
67     int 		lock_flag = -1;
68     krb5_error_code	retval = 0;
69 #ifdef POSIX_FILE_LOCKS
70     int lock_cmd = F_SETLKW;
71     struct flock lock_arg = { 0 };
72 #endif
73 
74     switch (mode & ~KRB5_LOCKMODE_DONTBLOCK) {
75     case KRB5_LOCKMODE_SHARED:
76 #ifdef POSIX_FILE_LOCKS
77 	lock_arg.l_type = F_RDLCK;
78 #endif
79 	lock_flag = LOCK_SH;
80 	break;
81     case KRB5_LOCKMODE_EXCLUSIVE:
82 #ifdef POSIX_FILE_LOCKS
83 	lock_arg.l_type = F_WRLCK;
84 #endif
85 	lock_flag = LOCK_EX;
86 	break;
87     case KRB5_LOCKMODE_UNLOCK:
88 #ifdef POSIX_FILE_LOCKS
89 	lock_arg.l_type = F_UNLCK;
90 #endif
91 	lock_flag = LOCK_UN;
92 	break;
93     }
94 
95     if (lock_flag == -1)
96 	return(KRB5_LIBOS_BADLOCKFLAG);
97 
98     if (mode & KRB5_LOCKMODE_DONTBLOCK) {
99 #ifdef POSIX_FILE_LOCKS
100 	lock_cmd = F_SETLK;
101 #endif
102 #ifdef HAVE_FLOCK
103 	lock_flag |= LOCK_NB;
104 #endif
105     }
106 
107 #ifdef POSIX_FILE_LOCKS
108     lock_arg.l_whence = 0;
109     lock_arg.l_start = 0;
110     lock_arg.l_len = 0;
111     if (fcntl(fd, lock_cmd, &lock_arg) == -1) {
112 	if (errno == EACCES || errno == EAGAIN)	/* see POSIX/IEEE 1003.1-1988,
113 						   6.5.2.4 */
114 	    return(EAGAIN);
115 	if (errno != EINVAL)	/* Fall back to flock if we get EINVAL */
116 	    return(errno);
117 	retval = errno;
118     } else
119 	    return 0;		/* We succeeded.  Yay. */
120 #endif
121 
122 #ifdef HAVE_FLOCK
123     if (flock(fd, lock_flag) == -1)
124 	retval = errno;
125 #endif
126 
127     return retval;
128 }
129 #else   /* Windows or Macintosh */
130 
131 krb5_error_code
krb5_lock_file(context,fd,mode)132 krb5_lock_file(context, fd, mode)
133     krb5_context context;
134     int fd;
135     int mode;
136 {
137     return 0;
138 }
139 #endif
140