mirror of https://github.com/python/cpython
329 lines
11 KiB
C
329 lines
11 KiB
C
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/* Support for dynamic loading of extension modules */
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#include "Python.h"
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#include "pycore_fileutils.h" // _Py_add_relfile()
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#include "pycore_pystate.h" // _PyInterpreterState_GET()
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#include "pycore_importdl.h" // dl_funcptr
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#include "patchlevel.h" // PY_MAJOR_VERSION
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#include <windows.h>
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const char *_PyImport_DynLoadFiletab[] = {
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PYD_TAGGED_SUFFIX,
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PYD_UNTAGGED_SUFFIX,
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NULL
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};
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/* Function to return the name of the "python" DLL that the supplied module
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directly imports. Looks through the list of imported modules and
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returns the first entry that starts with "python" (case sensitive) and
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is followed by nothing but numbers until the separator (period).
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Returns a pointer to the import name, or NULL if no matching name was
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located.
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This function parses through the PE header for the module as loaded in
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memory by the system loader. The PE header is accessed as documented by
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Microsoft in the MSDN PE and COFF specification (2/99), and handles
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both PE32 and PE32+. It only worries about the direct import table and
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not the delay load import table since it's unlikely an extension is
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going to be delay loading Python (after all, it's already loaded).
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If any magic values are not found (e.g., the PE header or optional
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header magic), then this function simply returns NULL. */
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#define DWORD_AT(mem) (*(DWORD *)(mem))
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#define WORD_AT(mem) (*(WORD *)(mem))
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static char *GetPythonImport (HINSTANCE hModule)
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{
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unsigned char *dllbase, *import_data, *import_name;
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DWORD pe_offset, opt_offset;
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WORD opt_magic;
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int num_dict_off, import_off;
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/* Safety check input */
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if (hModule == NULL) {
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return NULL;
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}
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/* Module instance is also the base load address. First portion of
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memory is the MS-DOS loader, which holds the offset to the PE
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header (from the load base) at 0x3C */
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dllbase = (unsigned char *)hModule;
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pe_offset = DWORD_AT(dllbase + 0x3C);
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/* The PE signature must be "PE\0\0" */
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if (memcmp(dllbase+pe_offset,"PE\0\0",4)) {
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return NULL;
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}
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/* Following the PE signature is the standard COFF header (20
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bytes) and then the optional header. The optional header starts
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with a magic value of 0x10B for PE32 or 0x20B for PE32+ (PE32+
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uses 64-bits for some fields). It might also be 0x107 for a ROM
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image, but we don't process that here.
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The optional header ends with a data dictionary that directly
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points to certain types of data, among them the import entries
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(in the second table entry). Based on the header type, we
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determine offsets for the data dictionary count and the entry
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within the dictionary pointing to the imports. */
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opt_offset = pe_offset + 4 + 20;
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opt_magic = WORD_AT(dllbase+opt_offset);
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if (opt_magic == 0x10B) {
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/* PE32 */
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num_dict_off = 92;
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import_off = 104;
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} else if (opt_magic == 0x20B) {
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/* PE32+ */
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num_dict_off = 108;
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import_off = 120;
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} else {
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/* Unsupported */
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return NULL;
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}
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/* Now if an import table exists, offset to it and walk the list of
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imports. The import table is an array (ending when an entry has
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empty values) of structures (20 bytes each), which contains (at
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offset 12) a relative address (to the module base) at which a
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string constant holding the import name is located. */
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if (DWORD_AT(dllbase + opt_offset + num_dict_off) >= 2) {
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/* We have at least 2 tables - the import table is the second
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one. But still it may be that the table size is zero */
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if (0 == DWORD_AT(dllbase + opt_offset + import_off + sizeof(DWORD)))
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return NULL;
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import_data = dllbase + DWORD_AT(dllbase +
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opt_offset +
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import_off);
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while (DWORD_AT(import_data)) {
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import_name = dllbase + DWORD_AT(import_data+12);
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if (strlen(import_name) >= 6 &&
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!strncmp(import_name,"python",6)) {
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char *pch;
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/* Don't claim that python3.dll is a Python DLL. */
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#ifdef _DEBUG
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if (strcmp(import_name, "python3_d.dll") == 0) {
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#else
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if (strcmp(import_name, "python3.dll") == 0) {
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#endif
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import_data += 20;
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continue;
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}
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/* Ensure python prefix is followed only
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by numbers to the end of the basename */
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pch = import_name + 6;
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#ifdef _DEBUG
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while (*pch && pch[0] != '_' && pch[1] != 'd' && pch[2] != '.') {
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#else
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while (*pch && *pch != '.') {
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#endif
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if (*pch >= '0' && *pch <= '9') {
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pch++;
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} else {
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pch = NULL;
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break;
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}
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}
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if (pch) {
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/* Found it - return the name */
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return import_name;
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}
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}
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import_data += 20;
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}
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}
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return NULL;
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}
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#ifdef Py_ENABLE_SHARED
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/* Load python3.dll before loading any extension module that might refer
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to it. That way, we can be sure that always the python3.dll corresponding
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to this python DLL is loaded, not a python3.dll that might be on the path
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by chance.
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Return whether the DLL was found.
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*/
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extern HMODULE PyWin_DLLhModule;
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static int
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_Py_CheckPython3(void)
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{
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static int python3_checked = 0;
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static HANDLE hPython3;
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#define MAXPATHLEN 512
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wchar_t py3path[MAXPATHLEN+1];
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if (python3_checked) {
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return hPython3 != NULL;
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}
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python3_checked = 1;
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/* If there is a python3.dll next to the python3y.dll,
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use that DLL */
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if (PyWin_DLLhModule && GetModuleFileNameW(PyWin_DLLhModule, py3path, MAXPATHLEN)) {
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wchar_t *p = wcsrchr(py3path, L'\\');
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if (p) {
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wcscpy(p + 1, PY3_DLLNAME);
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hPython3 = LoadLibraryExW(py3path, NULL, LOAD_LIBRARY_SEARCH_DEFAULT_DIRS);
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if (hPython3 != NULL) {
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return 1;
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}
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}
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}
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/* If we can locate python3.dll in our application dir,
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use that DLL */
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hPython3 = LoadLibraryExW(PY3_DLLNAME, NULL, LOAD_LIBRARY_SEARCH_APPLICATION_DIR);
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if (hPython3 != NULL) {
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return 1;
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}
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/* For back-compat, also search {sys.prefix}\DLLs, though
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that has not been a normal install layout for a while */
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PyInterpreterState *interp = _PyInterpreterState_GET();
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PyConfig *config = (PyConfig*)_PyInterpreterState_GetConfig(interp);
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assert(config->prefix);
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if (config->prefix) {
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wcscpy_s(py3path, MAXPATHLEN, config->prefix);
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if (py3path[0] && _Py_add_relfile(py3path, L"DLLs\\" PY3_DLLNAME, MAXPATHLEN) >= 0) {
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hPython3 = LoadLibraryExW(py3path, NULL, LOAD_LIBRARY_SEARCH_DEFAULT_DIRS);
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}
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}
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return hPython3 != NULL;
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#undef MAXPATHLEN
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}
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#endif /* Py_ENABLE_SHARED */
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dl_funcptr _PyImport_FindSharedFuncptrWindows(const char *prefix,
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const char *shortname,
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PyObject *pathname, FILE *fp)
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{
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dl_funcptr p;
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char funcname[258], *import_python;
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#ifdef Py_ENABLE_SHARED
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_Py_CheckPython3();
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#endif /* Py_ENABLE_SHARED */
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wchar_t *wpathname = PyUnicode_AsWideCharString(pathname, NULL);
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if (wpathname == NULL)
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return NULL;
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PyOS_snprintf(funcname, sizeof(funcname), "%.20s_%.200s", prefix, shortname);
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{
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HINSTANCE hDLL = NULL;
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#ifdef MS_WINDOWS_DESKTOP
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unsigned int old_mode;
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/* Don't display a message box when Python can't load a DLL */
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old_mode = SetErrorMode(SEM_FAILCRITICALERRORS);
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#endif
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/* bpo-36085: We use LoadLibraryEx with restricted search paths
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to avoid DLL preloading attacks and enable use of the
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AddDllDirectory function. We add SEARCH_DLL_LOAD_DIR to
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ensure DLLs adjacent to the PYD are preferred. */
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Py_BEGIN_ALLOW_THREADS
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hDLL = LoadLibraryExW(wpathname, NULL,
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LOAD_LIBRARY_SEARCH_DEFAULT_DIRS |
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LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR);
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Py_END_ALLOW_THREADS
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PyMem_Free(wpathname);
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#ifdef MS_WINDOWS_DESKTOP
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/* restore old error mode settings */
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SetErrorMode(old_mode);
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#endif
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if (hDLL==NULL){
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PyObject *message;
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unsigned int errorCode;
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/* Get an error string from Win32 error code */
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wchar_t theInfo[256]; /* Pointer to error text
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from system */
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int theLength; /* Length of error text */
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errorCode = GetLastError();
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theLength = FormatMessageW(
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FORMAT_MESSAGE_FROM_SYSTEM |
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FORMAT_MESSAGE_IGNORE_INSERTS, /* flags */
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NULL, /* message source */
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errorCode, /* the message (error) ID */
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MAKELANGID(LANG_NEUTRAL,
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SUBLANG_DEFAULT),
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/* Default language */
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theInfo, /* the buffer */
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sizeof(theInfo) / sizeof(wchar_t), /* size in wchars */
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NULL); /* no additional format args. */
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/* Problem: could not get the error message.
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This should not happen if called correctly. */
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if (theLength == 0) {
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message = PyUnicode_FromFormat(
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"DLL load failed with error code %u while importing %s",
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errorCode, shortname);
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} else {
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/* For some reason a \r\n
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is appended to the text */
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if (theLength >= 2 &&
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theInfo[theLength-2] == '\r' &&
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theInfo[theLength-1] == '\n') {
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theLength -= 2;
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theInfo[theLength] = '\0';
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}
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message = PyUnicode_FromFormat(
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"DLL load failed while importing %s: ", shortname);
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PyUnicode_AppendAndDel(&message,
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PyUnicode_FromWideChar(
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theInfo,
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theLength));
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}
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if (message != NULL) {
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PyObject *shortname_obj = PyUnicode_FromString(shortname);
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PyErr_SetImportError(message, shortname_obj, pathname);
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Py_XDECREF(shortname_obj);
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Py_DECREF(message);
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}
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return NULL;
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} else {
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char buffer[256];
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PyOS_snprintf(buffer, sizeof(buffer),
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#ifdef _DEBUG
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"python%d%d_d.dll",
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#else
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"python%d%d.dll",
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#endif
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PY_MAJOR_VERSION,PY_MINOR_VERSION);
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import_python = GetPythonImport(hDLL);
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if (import_python &&
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_stricmp(buffer,import_python)) {
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PyErr_Format(PyExc_ImportError,
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"Module use of %.150s conflicts "
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"with this version of Python.",
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import_python);
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Py_BEGIN_ALLOW_THREADS
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FreeLibrary(hDLL);
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Py_END_ALLOW_THREADS
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return NULL;
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}
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}
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Py_BEGIN_ALLOW_THREADS
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p = GetProcAddress(hDLL, funcname);
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Py_END_ALLOW_THREADS
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}
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return p;
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}
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