1 /*
2 * ====================================================================
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 * ====================================================================
20 */
21
22 #include <apr_thread_mutex.h>
23 #include <apr_hash.h>
24
25 #include "svn_hash.h"
26 #include "svn_dso.h"
27 #include "svn_pools.h"
28 #include "svn_private_config.h"
29
30 #include "private/svn_mutex.h"
31 #include "private/svn_atomic.h"
32 #include "private/svn_subr_private.h"
33
34 /* A mutex to protect our global pool and cache. */
35 static svn_mutex__t *dso_mutex = NULL;
36
37 /* Global pool to allocate DSOs in. */
38 static apr_pool_t *dso_pool;
39
40 /* Global cache for storing DSO objects. */
41 static apr_hash_t *dso_cache;
42
43 /* Just an arbitrary location in memory... */
44 static int not_there_sentinel;
45
46 static volatile svn_atomic_t atomic_init_status = 0;
47
48 /* A specific value we store in the dso_cache to indicate that the
49 library wasn't found. This keeps us from allocating extra memory
50 from dso_pool when trying to find libraries we already know aren't
51 there. */
52 #define NOT_THERE ((void *) ¬_there_sentinel)
53
54 static svn_error_t *
atomic_init_func(void * baton,apr_pool_t * pool)55 atomic_init_func(void *baton,
56 apr_pool_t *pool)
57 {
58 dso_pool = svn_pool_create(NULL);
59
60 SVN_ERR(svn_mutex__init(&dso_mutex, TRUE, dso_pool));
61
62 dso_cache = apr_hash_make(dso_pool);
63 return SVN_NO_ERROR;
64 }
65
66 svn_error_t *
svn_dso_initialize2(void)67 svn_dso_initialize2(void)
68 {
69 SVN_ERR(svn_atomic__init_once(&atomic_init_status, atomic_init_func,
70 NULL, NULL));
71
72 return SVN_NO_ERROR;
73 }
74
75 #if APR_HAS_DSO
76 static svn_error_t *
svn_dso_load_internal(apr_dso_handle_t ** dso,const char * fname)77 svn_dso_load_internal(apr_dso_handle_t **dso, const char *fname)
78 {
79 *dso = svn_hash_gets(dso_cache, fname);
80
81 /* First check to see if we've been through this before... We do this
82 to avoid calling apr_dso_load multiple times for a given library,
83 which would result in wasting small amounts of memory each time. */
84 if (*dso == NOT_THERE)
85 {
86 *dso = NULL;
87 return SVN_NO_ERROR;
88 }
89
90 /* If we got nothing back from the cache, try and load the library. */
91 if (! *dso)
92 {
93 apr_status_t status = apr_dso_load(dso, fname, dso_pool);
94 if (status)
95 {
96 #ifdef SVN_DEBUG_DSO
97 char buf[1024];
98 fprintf(stderr,
99 "Dynamic loading of '%s' failed with the following error:\n%s\n",
100 fname,
101 apr_dso_error(*dso, buf, 1024));
102 #endif
103 *dso = NULL;
104
105 /* It wasn't found, so set the special "we didn't find it" value. */
106 svn_hash_sets(dso_cache, apr_pstrdup(dso_pool, fname), NOT_THERE);
107
108 return SVN_NO_ERROR;
109 }
110
111 /* Stash the dso so we can use it next time. */
112 svn_hash_sets(dso_cache, apr_pstrdup(dso_pool, fname), *dso);
113 }
114
115 return SVN_NO_ERROR;
116 }
117
118 svn_error_t *
svn_dso_load(apr_dso_handle_t ** dso,const char * fname)119 svn_dso_load(apr_dso_handle_t **dso, const char *fname)
120 {
121 SVN_ERR(svn_dso_initialize2());
122
123 SVN_MUTEX__WITH_LOCK(dso_mutex, svn_dso_load_internal(dso, fname));
124
125 return SVN_NO_ERROR;
126 }
127
128 apr_pool_t *
svn_dso__pool(void)129 svn_dso__pool(void)
130 {
131 return dso_pool;
132 }
133
134 #endif /* APR_HAS_DSO */
135