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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef COMPAT_W32DLFCN_H
#define COMPAT_W32DLFCN_H
#ifdef _WIN32
#include <stdint.h>
#include <windows.h>
#include "config.h"
#include "libavutil/macros.h"
#include "libavutil/wchar_filename.h"
static inline wchar_t *get_module_filename(HMODULE module)
{
wchar_t *path = NULL, *new_path;
DWORD path_size = 0, path_len;
do {
path_size = path_size ? FFMIN(2 * path_size, INT16_MAX + 1) : MAX_PATH;
new_path = av_realloc_array(path, path_size, sizeof *path);
if (!new_path) {
av_free(path);
return NULL;
}
path = new_path;
// Returns path_size in case of insufficient buffer.
// Whether the error is set or not and whether the output
// is null-terminated or not depends on the version of Windows.
path_len = GetModuleFileNameW(module, path, path_size);
} while (path_len && path_size <= INT16_MAX && path_size <= path_len);
if (!path_len) {
av_free(path);
return NULL;
}
return path;
}
/**
* Safe function used to open dynamic libs. This attempts to improve program security
* by removing the current directory from the dll search path. Only dll's found in the
* executable or system directory are allowed to be loaded.
* @param name The dynamic lib name.
* @return A handle to the opened lib.
*/
static inline HMODULE win32_dlopen(const char *name)
{
wchar_t *name_w;
HMODULE module = NULL;
if (utf8towchar(name, &name_w))
name_w = NULL;
#if _WIN32_WINNT < 0x0602
// On Win7 and earlier we check if KB2533623 is available
if (!GetProcAddress(GetModuleHandleW(L"kernel32.dll"), "SetDefaultDllDirectories")) {
wchar_t *path = NULL, *new_path;
DWORD pathlen, pathsize, namelen;
if (!name_w)
goto exit;
namelen = wcslen(name_w);
// Try local directory first
path = get_module_filename(NULL);
if (!path)
goto exit;
new_path = wcsrchr(path, '\\');
if (!new_path)
goto exit;
pathlen = new_path - path;
pathsize = pathlen + namelen + 2;
new_path = av_realloc_array(path, pathsize, sizeof *path);
if (!new_path)
goto exit;
path = new_path;
wcscpy(path + pathlen + 1, name_w);
module = LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
if (module == NULL) {
// Next try System32 directory
pathlen = GetSystemDirectoryW(path, pathsize);
if (!pathlen)
goto exit;
// Buffer is not enough in two cases:
// 1. system directory + \ + module name
// 2. system directory even without the module name.
if (pathlen + namelen + 2 > pathsize) {
pathsize = pathlen + namelen + 2;
new_path = av_realloc_array(path, pathsize, sizeof *path);
if (!new_path)
goto exit;
path = new_path;
// Query again to handle the case #2.
pathlen = GetSystemDirectoryW(path, pathsize);
if (!pathlen)
goto exit;
}
path[pathlen] = L'\\';
wcscpy(path + pathlen + 1, name_w);
module = LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
}
exit:
av_free(path);
av_free(name_w);
return module;
}
#endif
#ifndef LOAD_LIBRARY_SEARCH_APPLICATION_DIR
# define LOAD_LIBRARY_SEARCH_APPLICATION_DIR 0x00000200
#endif
#ifndef LOAD_LIBRARY_SEARCH_SYSTEM32
# define LOAD_LIBRARY_SEARCH_SYSTEM32 0x00000800
#endif
#if HAVE_WINRT
if (!name_w)
return NULL;
module = LoadPackagedLibrary(name_w, 0);
#else
#define LOAD_FLAGS (LOAD_LIBRARY_SEARCH_APPLICATION_DIR | LOAD_LIBRARY_SEARCH_SYSTEM32)
/* filename may be be in CP_ACP */
if (!name_w)
return LoadLibraryExA(name, NULL, LOAD_FLAGS);
module = LoadLibraryExW(name_w, NULL, LOAD_FLAGS);
#undef LOAD_FLAGS
#endif
av_free(name_w);
return module;
}
#define dlopen(name, flags) win32_dlopen(name)
#define dlclose FreeLibrary
#define dlsym GetProcAddress
#else
#include <dlfcn.h>
#endif
#endif /* COMPAT_W32DLFCN_H */
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