1 /*
2 * Copyright (C) 2019 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "src/android_internal/lazy_library_loader.h"
18
19 #include <dlfcn.h>
20 #include <stdlib.h>
21
22 #include "perfetto/base/build_config.h"
23 #include "perfetto/base/logging.h"
24
25 namespace perfetto {
26 namespace android_internal {
27
28 namespace {
29
30 const char kLibName[] = "libperfetto_android_internal.so";
31
LoadLibraryOnce()32 void* LoadLibraryOnce() {
33 #if !PERFETTO_BUILDFLAG(PERFETTO_ANDROID_BUILD)
34 // For testing only. Allows to use the version of the .so shipped in the
35 // system (if any) with the standalone builds of perfetto. This is really
36 // crash-prone and should not be used in production. The .so doesn't have a
37 // stable ABI, hence the version of the library in the system and the code in
38 // ToT can diverge.
39 const char* env_var = getenv("PERFETTO_ENABLE_ANDROID_INTERNAL_LIB");
40 if (!env_var || strcmp(env_var, "1")) {
41 PERFETTO_ELOG(
42 "android_internal functions can be used only with in-tree builds of "
43 "perfetto.");
44 return nullptr;
45 }
46 #endif
47 void* handle = dlopen(kLibName, RTLD_NOW);
48 if (!handle)
49 PERFETTO_PLOG("dlopen(%s) failed", kLibName);
50 return handle;
51 }
52
53 } // namespace
54
LazyLoadFunction(const char * name)55 void* LazyLoadFunction(const char* name) {
56 // Strip the namespace qualification from the full symbol name.
57 const char* sep = strrchr(name, ':');
58 const char* function_name = sep ? sep + 1 : name;
59 static void* handle = LoadLibraryOnce();
60 if (!handle)
61 return nullptr;
62 void* fn = dlsym(handle, function_name);
63 if (!fn)
64 PERFETTO_PLOG("dlsym(%s) failed", function_name);
65 return fn;
66 }
67
68 } // namespace android_internal
69 } // namespace perfetto
70