2 * This file is part of FFmpeg.
4 * FFmpeg 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.
9 * FFmpeg 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.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 #ifndef COMPAT_W32DLFCN_H
20 #define COMPAT_W32DLFCN_H
24 #if (_WIN32_WINNT < 0x0602) || HAVE_WINRT
25 #include "libavutil/wchar_filename.h"
28 * Safe function used to open dynamic libs. This attempts to improve program security
29 * by removing the current directory from the dll search path. Only dll's found in the
30 * executable or system directory are allowed to be loaded.
31 * @param name The dynamic lib name.
32 * @return A handle to the opened lib.
34 static inline HMODULE win32_dlopen(const char *name)
36 #if _WIN32_WINNT < 0x0602
37 // Need to check if KB2533623 is available
38 if (!GetProcAddress(GetModuleHandleW(L"kernel32.dll"), "SetDefaultDllDirectories")) {
39 HMODULE module = NULL;
40 wchar_t *path = NULL, *name_w = NULL;
42 if (utf8towchar(name, &name_w))
44 path = (wchar_t *)av_mallocz_array(MAX_PATH, sizeof(wchar_t));
45 // Try local directory first
46 pathlen = GetModuleFileNameW(NULL, path, MAX_PATH);
47 pathlen = wcsrchr(path, '\\') - path;
48 if (pathlen == 0 || pathlen + wcslen(name_w) + 2 > MAX_PATH)
51 wcscpy(path + pathlen + 1, name_w);
52 module = LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
54 // Next try System32 directory
55 pathlen = GetSystemDirectoryW(path, MAX_PATH);
56 if (pathlen == 0 || pathlen + wcslen(name_w) + 2 > MAX_PATH)
59 wcscpy(path + pathlen + 1, name_w);
60 module = LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
68 #ifndef LOAD_LIBRARY_SEARCH_APPLICATION_DIR
69 # define LOAD_LIBRARY_SEARCH_APPLICATION_DIR 0x00000200
71 #ifndef LOAD_LIBRARY_SEARCH_SYSTEM32
72 # define LOAD_LIBRARY_SEARCH_SYSTEM32 0x00000800
75 wchar_t *name_w = NULL;
77 if (utf8towchar(name, &name_w))
79 ret = LoadPackagedLibrary(name_w, 0);
83 return LoadLibraryExA(name, NULL, LOAD_LIBRARY_SEARCH_APPLICATION_DIR | LOAD_LIBRARY_SEARCH_SYSTEM32);
86 #define dlopen(name, flags) win32_dlopen(name)
87 #define dlclose FreeLibrary
88 #define dlsym GetProcAddress
93 #endif /* COMPAT_W32DLFCN_H */