/Python/dynload_win.c
http://unladen-swallow.googlecode.com/ · C · 274 lines · 170 code · 40 blank · 64 comment · 41 complexity · 43b5ff1e4f596d744b871de59cbf23ed MD5 · raw file
- /* Support for dynamic loading of extension modules */
- #include "Python.h"
- #ifdef HAVE_DIRECT_H
- #include <direct.h>
- #endif
- #include <ctype.h>
- #include "importdl.h"
- #include <windows.h>
- // "activation context" magic - see dl_nt.c...
- extern ULONG_PTR _Py_ActivateActCtx();
- void _Py_DeactivateActCtx(ULONG_PTR cookie);
- const struct filedescr _PyImport_DynLoadFiletab[] = {
- #ifdef _DEBUG
- {"_d.pyd", "rb", C_EXTENSION},
- #else
- {".pyd", "rb", C_EXTENSION},
- #endif
- {0, 0}
- };
- /* Case insensitive string compare, to avoid any dependencies on particular
- C RTL implementations */
- static int strcasecmp (char *string1, char *string2)
- {
- int first, second;
- do {
- first = tolower(*string1);
- second = tolower(*string2);
- string1++;
- string2++;
- } while (first && first == second);
- return (first - second);
- }
- /* Function to return the name of the "python" DLL that the supplied module
- directly imports. Looks through the list of imported modules and
- returns the first entry that starts with "python" (case sensitive) and
- is followed by nothing but numbers until the separator (period).
- Returns a pointer to the import name, or NULL if no matching name was
- located.
- This function parses through the PE header for the module as loaded in
- memory by the system loader. The PE header is accessed as documented by
- Microsoft in the MSDN PE and COFF specification (2/99), and handles
- both PE32 and PE32+. It only worries about the direct import table and
- not the delay load import table since it's unlikely an extension is
- going to be delay loading Python (after all, it's already loaded).
- If any magic values are not found (e.g., the PE header or optional
- header magic), then this function simply returns NULL. */
- #define DWORD_AT(mem) (*(DWORD *)(mem))
- #define WORD_AT(mem) (*(WORD *)(mem))
- static char *GetPythonImport (HINSTANCE hModule)
- {
- unsigned char *dllbase, *import_data, *import_name;
- DWORD pe_offset, opt_offset;
- WORD opt_magic;
- int num_dict_off, import_off;
- /* Safety check input */
- if (hModule == NULL) {
- return NULL;
- }
- /* Module instance is also the base load address. First portion of
- memory is the MS-DOS loader, which holds the offset to the PE
- header (from the load base) at 0x3C */
- dllbase = (unsigned char *)hModule;
- pe_offset = DWORD_AT(dllbase + 0x3C);
- /* The PE signature must be "PE\0\0" */
- if (memcmp(dllbase+pe_offset,"PE\0\0",4)) {
- return NULL;
- }
- /* Following the PE signature is the standard COFF header (20
- bytes) and then the optional header. The optional header starts
- with a magic value of 0x10B for PE32 or 0x20B for PE32+ (PE32+
- uses 64-bits for some fields). It might also be 0x107 for a ROM
- image, but we don't process that here.
- The optional header ends with a data dictionary that directly
- points to certain types of data, among them the import entries
- (in the second table entry). Based on the header type, we
- determine offsets for the data dictionary count and the entry
- within the dictionary pointing to the imports. */
- opt_offset = pe_offset + 4 + 20;
- opt_magic = WORD_AT(dllbase+opt_offset);
- if (opt_magic == 0x10B) {
- /* PE32 */
- num_dict_off = 92;
- import_off = 104;
- } else if (opt_magic == 0x20B) {
- /* PE32+ */
- num_dict_off = 108;
- import_off = 120;
- } else {
- /* Unsupported */
- return NULL;
- }
- /* Now if an import table exists, offset to it and walk the list of
- imports. The import table is an array (ending when an entry has
- empty values) of structures (20 bytes each), which contains (at
- offset 12) a relative address (to the module base) at which a
- string constant holding the import name is located. */
- if (DWORD_AT(dllbase + opt_offset + num_dict_off) >= 2) {
- /* We have at least 2 tables - the import table is the second
- one. But still it may be that the table size is zero */
- if (0 == DWORD_AT(dllbase + opt_offset + import_off + sizeof(DWORD)))
- return NULL;
- import_data = dllbase + DWORD_AT(dllbase +
- opt_offset +
- import_off);
- while (DWORD_AT(import_data)) {
- import_name = dllbase + DWORD_AT(import_data+12);
- if (strlen(import_name) >= 6 &&
- !strncmp(import_name,"python",6)) {
- char *pch;
- /* Ensure python prefix is followed only
- by numbers to the end of the basename */
- pch = import_name + 6;
- #ifdef _DEBUG
- while (*pch && pch[0] != '_' && pch[1] != 'd' && pch[2] != '.') {
- #else
- while (*pch && *pch != '.') {
- #endif
- if (*pch >= '0' && *pch <= '9') {
- pch++;
- } else {
- pch = NULL;
- break;
- }
- }
-
- if (pch) {
- /* Found it - return the name */
- return import_name;
- }
- }
- import_data += 20;
- }
- }
- return NULL;
- }
- dl_funcptr _PyImport_GetDynLoadFunc(const char *fqname, const char *shortname,
- const char *pathname, FILE *fp)
- {
- dl_funcptr p;
- char funcname[258], *import_python;
- PyOS_snprintf(funcname, sizeof(funcname), "init%.200s", shortname);
- {
- HINSTANCE hDLL = NULL;
- char pathbuf[260];
- LPTSTR dummy;
- unsigned int old_mode;
- ULONG_PTR cookie = 0;
- /* We use LoadLibraryEx so Windows looks for dependent DLLs
- in directory of pathname first. However, Windows95
- can sometimes not work correctly unless the absolute
- path is used. If GetFullPathName() fails, the LoadLibrary
- will certainly fail too, so use its error code */
- /* Don't display a message box when Python can't load a DLL */
- old_mode = SetErrorMode(SEM_FAILCRITICALERRORS);
- if (GetFullPathName(pathname,
- sizeof(pathbuf),
- pathbuf,
- &dummy)) {
- ULONG_PTR cookie = _Py_ActivateActCtx();
- /* XXX This call doesn't exist in Windows CE */
- hDLL = LoadLibraryEx(pathname, NULL,
- LOAD_WITH_ALTERED_SEARCH_PATH);
- _Py_DeactivateActCtx(cookie);
- }
- /* restore old error mode settings */
- SetErrorMode(old_mode);
- if (hDLL==NULL){
- char errBuf[256];
- unsigned int errorCode;
- /* Get an error string from Win32 error code */
- char theInfo[256]; /* Pointer to error text
- from system */
- int theLength; /* Length of error text */
- errorCode = GetLastError();
- theLength = FormatMessage(
- FORMAT_MESSAGE_FROM_SYSTEM |
- FORMAT_MESSAGE_IGNORE_INSERTS, /* flags */
- NULL, /* message source */
- errorCode, /* the message (error) ID */
- 0, /* default language environment */
- (LPTSTR) theInfo, /* the buffer */
- sizeof(theInfo), /* the buffer size */
- NULL); /* no additional format args. */
- /* Problem: could not get the error message.
- This should not happen if called correctly. */
- if (theLength == 0) {
- PyOS_snprintf(errBuf, sizeof(errBuf),
- "DLL load failed with error code %d",
- errorCode);
- } else {
- size_t len;
- /* For some reason a \r\n
- is appended to the text */
- if (theLength >= 2 &&
- theInfo[theLength-2] == '\r' &&
- theInfo[theLength-1] == '\n') {
- theLength -= 2;
- theInfo[theLength] = '\0';
- }
- strcpy(errBuf, "DLL load failed: ");
- len = strlen(errBuf);
- strncpy(errBuf+len, theInfo,
- sizeof(errBuf)-len);
- errBuf[sizeof(errBuf)-1] = '\0';
- }
- PyErr_SetString(PyExc_ImportError, errBuf);
- return NULL;
- } else {
- char buffer[256];
- #ifdef _DEBUG
- PyOS_snprintf(buffer, sizeof(buffer), "python%d%d_d.dll",
- #else
- PyOS_snprintf(buffer, sizeof(buffer), "python%d%d.dll",
- #endif
- PY_MAJOR_VERSION,PY_MINOR_VERSION);
- import_python = GetPythonImport(hDLL);
- if (import_python &&
- strcasecmp(buffer,import_python)) {
- PyOS_snprintf(buffer, sizeof(buffer),
- "Module use of %.150s conflicts "
- "with this version of Python.",
- import_python);
- PyErr_SetString(PyExc_ImportError,buffer);
- FreeLibrary(hDLL);
- return NULL;
- }
- }
- p = GetProcAddress(hDLL, funcname);
- }
- return p;
- }