PC/import_nt.c

   1 /********************************************************************
   2
   3  import_nt.c
   4
   5   Win32 specific import code.
   6
   7 */
   8
   9 #include "Python.h"
  10 #include "osdefs.h"
  11 #include <windows.h>
  12 #include "importdl.h"
  13 #include "malloc.h" /* for alloca */
  14
  15 /* a string loaded from the DLL at startup */
  16 extern const char *PyWin_DLLVersionString;
  17
  18 FILE *PyWin_FindRegisteredModule(const char *moduleName,
  19                                  struct filedescr **ppFileDesc,
  20                                  char *pathBuf,
  21                                  Py_ssize_t pathLen)
  22 {
  23         char *moduleKey;
  24         const char keyPrefix[] = "Software\\Python\\PythonCore\\";
  25         const char keySuffix[] = "\\Modules\\";
  26 #ifdef _DEBUG
  27         /* In debugging builds, we _must_ have the debug version
  28          * registered.
  29          */
  30         const char debugString[] = "\\Debug";
  31 #else
  32         const char debugString[] = "";
  33 #endif
  34         struct filedescr *fdp = NULL;
  35         FILE *fp;
  36         HKEY keyBase = HKEY_CURRENT_USER;
  37         int modNameSize;
  38         long regStat;
  39
  40         /* Calculate the size for the sprintf buffer.
  41          * Get the size of the chars only, plus 1 NULL.
  42          */
  43         size_t bufSize = sizeof(keyPrefix)-1 +
  44                          strlen(PyWin_DLLVersionString) +
  45                          sizeof(keySuffix) +
  46                          strlen(moduleName) +
  47                          sizeof(debugString) - 1;
  48         /* alloca == no free required, but memory only local to fn,
  49          * also no heap fragmentation!
  50          */
  51         moduleKey = alloca(bufSize);
  52         PyOS_snprintf(moduleKey, bufSize,
  53                       "Software\\Python\\PythonCore\\%s\\Modules\\%s%s",
  54                       PyWin_DLLVersionString, moduleName, debugString);
  55
  56         assert(pathLen < INT_MAX);
  57         modNameSize = (int)pathLen;
  58         regStat = RegQueryValue(keyBase, moduleKey, pathBuf, &modNameSize);
  59         if (regStat != ERROR_SUCCESS) {
  60                 /* No user setting - lookup in machine settings */
  61                 keyBase = HKEY_LOCAL_MACHINE;
  62                 /* be anal - failure may have reset size param */
  63                 modNameSize = (int)pathLen;
  64                 regStat = RegQueryValue(keyBase, moduleKey,
  65                                         pathBuf, &modNameSize);
  66
  67                 if (regStat != ERROR_SUCCESS)
  68                         return NULL;
  69         }
  70         /* use the file extension to locate the type entry. */
  71         for (fdp = _PyImport_Filetab; fdp->suffix != NULL; fdp++) {
  72                 size_t extLen = strlen(fdp->suffix);
  73                 assert(modNameSize >= 0); /* else cast to size_t is wrong */
  74                 if ((size_t)modNameSize > extLen &&
  75                     strnicmp(pathBuf + ((size_t)modNameSize-extLen-1),
  76                              fdp->suffix,
  77                              extLen) == 0)
  78                         break;
  79         }
  80         if (fdp->suffix == NULL)
  81                 return NULL;
  82         fp = fopen(pathBuf, fdp->mode);
  83         if (fp != NULL)
  84                 *ppFileDesc = fdp;
  85         return fp;
  86 }