mirror of
https://github.com/python/cpython
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![Steve Dower](/assets/img/avatar_default.png)
The getpath.py file is frozen at build time and executed as code over a namespace. It is never imported, nor is it meant to be importable or reusable. However, it should be easier to read, modify, and patch than the previous code. This commit attempts to preserve every previously tested quirk, but these may be changed in the future to better align platforms.
346 lines
12 KiB
C
346 lines
12 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_pathconfig.h" // _PyPathConfig_ComputeSysPath0()
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#include "pycore_pystate.h" // _PyInterpreterState_GET()
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#ifdef HAVE_DIRECT_H
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#include <direct.h>
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#endif
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#include <ctype.h>
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#include "importdl.h"
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#include "patchlevel.h"
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#include <windows.h>
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#ifdef _DEBUG
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#define PYD_DEBUG_SUFFIX "_d"
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#else
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#define PYD_DEBUG_SUFFIX ""
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#endif
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#ifdef PYD_PLATFORM_TAG
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#define PYD_TAGGED_SUFFIX PYD_DEBUG_SUFFIX ".cp" Py_STRINGIFY(PY_MAJOR_VERSION) Py_STRINGIFY(PY_MINOR_VERSION) "-" PYD_PLATFORM_TAG ".pyd"
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#else
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#define PYD_TAGGED_SUFFIX PYD_DEBUG_SUFFIX ".cp" Py_STRINGIFY(PY_MAJOR_VERSION) Py_STRINGIFY(PY_MINOR_VERSION) ".pyd"
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#endif
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#define PYD_UNTAGGED_SUFFIX PYD_DEBUG_SUFFIX ".pyd"
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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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#ifndef _DEBUG
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/* In a release version, don't claim that python3.dll is
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a Python DLL. */
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if (strcmp(import_name, "python3.dll") == 0) {
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import_data += 20;
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continue;
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}
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#endif
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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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/* 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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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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_Py_CheckPython3();
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#if USE_UNICODE_WCHAR_CACHE
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const wchar_t *wpathname = _PyUnicode_AsUnicode(pathname);
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#else /* USE_UNICODE_WCHAR_CACHE */
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wchar_t *wpathname = PyUnicode_AsWideCharString(pathname, NULL);
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#endif /* USE_UNICODE_WCHAR_CACHE */
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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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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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/* 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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#if !USE_UNICODE_WCHAR_CACHE
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PyMem_Free(wpathname);
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#endif /* USE_UNICODE_WCHAR_CACHE */
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/* restore old error mode settings */
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SetErrorMode(old_mode);
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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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