xref: /reactos/sdk/lib/crt/misc/lock.c (revision c2c66aff)
1 /*
2  * Copyright (c) 2002, TransGaming Technologies Inc.
3  *
4  * This library is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * This library is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with this library; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
17  */
18 
19 #include <precomp.h>
20 
21 
22 typedef struct
23 {
24   BOOL             bInit;
25   CRITICAL_SECTION crit;
26 } LOCKTABLEENTRY;
27 
28 static LOCKTABLEENTRY lock_table[ _TOTAL_LOCKS ];
29 
msvcrt_mlock_set_entry_initialized(int locknum,BOOL initialized)30 static __inline void msvcrt_mlock_set_entry_initialized( int locknum, BOOL initialized )
31 {
32   lock_table[ locknum ].bInit = initialized;
33 }
34 
msvcrt_initialize_mlock(int locknum)35 static __inline void msvcrt_initialize_mlock( int locknum )
36 {
37   InitializeCriticalSection( &(lock_table[ locknum ].crit) );
38   msvcrt_mlock_set_entry_initialized( locknum, TRUE );
39 }
40 
msvcrt_uninitialize_mlock(int locknum)41 static __inline void msvcrt_uninitialize_mlock( int locknum )
42 {
43   DeleteCriticalSection( &(lock_table[ locknum ].crit) );
44   msvcrt_mlock_set_entry_initialized( locknum, FALSE );
45 }
46 
47 /**********************************************************************
48  *     msvcrt_init_mt_locks (internal)
49  *
50  * Initialize the table lock. All other locks will be initialized
51  * upon first use.
52  *
53  */
msvcrt_init_mt_locks(void)54 void msvcrt_init_mt_locks(void)
55 {
56   int i;
57 
58   TRACE( "initializing mtlocks\n" );
59 
60   /* Initialize the table */
61   for( i=0; i < _TOTAL_LOCKS; i++ )
62   {
63     msvcrt_mlock_set_entry_initialized( i, FALSE );
64   }
65 
66   /* Initialize our lock table lock */
67   msvcrt_initialize_mlock( _LOCKTAB_LOCK );
68 }
69 
70 /**********************************************************************
71  *     msvcrt_free_mt_locks (internal)
72  *
73  * Uninitialize all mt locks. Assume that neither _lock or _unlock will
74  * be called once we're calling this routine (ie _LOCKTAB_LOCK can be deleted)
75  *
76  */
msvcrt_free_mt_locks(void)77 void msvcrt_free_mt_locks(void)
78 {
79   int i;
80 
81   TRACE(": uninitializing all mtlocks\n" );
82 
83   /* Uninitialize the table */
84   for( i=0; i < _TOTAL_LOCKS; i++ )
85   {
86     if( lock_table[ i ].bInit )
87     {
88       msvcrt_uninitialize_mlock( i );
89     }
90   }
91 }
92 
93 
94 /**********************************************************************
95  *              _lock (MSVCRT.@)
96  */
_lock(int locknum)97 void _lock( int locknum )
98 {
99   TRACE( "(%d)\n", locknum );
100 
101   /* If the lock doesn't exist yet, create it */
102   if( lock_table[ locknum ].bInit == FALSE )
103   {
104     /* Lock while we're changing the lock table */
105     _lock( _LOCKTAB_LOCK );
106 
107     /* Check again if we've got a bit of a race on lock creation */
108     if( lock_table[ locknum ].bInit == FALSE )
109     {
110       TRACE( ": creating lock #%d\n", locknum );
111       msvcrt_initialize_mlock( locknum );
112     }
113 
114     /* Unlock ourselves */
115     _unlock( _LOCKTAB_LOCK );
116   }
117 
118   EnterCriticalSection( &(lock_table[ locknum ].crit) );
119 }
120 
121 /**********************************************************************
122  *              _unlock (MSVCRT.@)
123  *
124  * NOTE: There is no error detection to make sure the lock exists and is acquired.
125  */
_unlock(int locknum)126 void _unlock( int locknum )
127 {
128   TRACE( "(%d)\n", locknum );
129 
130   LeaveCriticalSection( &(lock_table[ locknum ].crit) );
131 }
132 
133 
134