1 /*
2  * Copyright (C) 2020 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 "DlHelp.h"
18 
19 #include <stdbool.h>
20 
21 #ifdef WIN32_LEAN_AND_MEAN
22 #include <stdio.h>
23 #include <windows.h>
24 #else
25 #include <dlfcn.h>
26 #endif
27 
28 DlLibrary DlOpenLibrary(const char* filename) {
29 #ifdef _WIN32
30   return LoadLibrary(filename);
31 #else
32   // Load with RTLD_NODELETE in order to ensure that libart.so is not unmapped when it is closed.
33   // This is due to the fact that it is possible that some threads might have yet to finish
34   // exiting even after JNI_DeleteJavaVM returns, which can lead to segfaults if the library is
35   // unloaded.
36   return dlopen(filename, RTLD_NOW | RTLD_NODELETE);
37 #endif
38 }
39 
40 bool DlCloseLibrary(DlLibrary library) {
41 #ifdef _WIN32
42   return (FreeLibrary(library) == TRUE);
43 #else
44   return (dlclose(library) == 0);
45 #endif
46 }
47 
48 DlSymbol DlGetSymbol(DlLibrary handle, const char* symbol) {
49 #ifdef _WIN32
50   return (DlSymbol) GetProcAddress(handle, symbol);
51 #else
52   return dlsym(handle, symbol);
53 #endif
54 }
55 
56 const char* DlGetError() {
57 #ifdef _WIN32
58   static char buffer[256];
59 
60   DWORD cause = GetLastError();
61   DWORD flags = FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS;
62   DWORD length = FormatMessageA(flags, NULL, cause, 0, buffer, sizeof(buffer), NULL);
63   if (length == 0) {
64     snprintf(buffer, sizeof(buffer),
65              "Error %lu while retrieving message for error %lu",
66              GetLastError(), cause);
67     length = strlen(buffer);
68   }
69 
70   // Trim trailing whitespace.
71   for (DWORD i = length - 1; i > 0; --i) {
72     if (!isspace(buffer[i])) {
73       break;
74     }
75     buffer[i] = '\0';
76   }
77 
78   return buffer;
79 #else
80   return dlerror();
81 #endif
82 }
83