msvc/missing.c

   1 /*
   2  * Source file for missing WinCE functionality
   3  * Copyright © 2012 RealVNC Ltd.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 #include "missing.h"
  21
  22 #include <config.h>
  23 #include <libusbi.h>
  24
  25 #include <windows.h>
  26
  27 // The registry path to store environment variables
  28 #define ENVIRONMENT_REG_PATH _T("Software\\libusb\\environment")
  29
  30 /* Workaround getenv not being available on WinCE.
  31  * Instead look in HKLM\Software\libusb\environment */
  32 char *getenv(const char *name)
  33 {
  34         static char value[MAX_PATH];
  35         TCHAR wValue[MAX_PATH];
  36         WCHAR wName[MAX_PATH];
  37         DWORD dwType, dwData;
  38         HKEY hkey;
  39         LONG rc;
  40
  41         if (!name)
  42                 return NULL;
  43
  44         if (MultiByteToWideChar(CP_UTF8, 0, name, -1, wName, MAX_PATH) <= 0) {
  45                 usbi_dbg("Failed to convert environment variable name to wide string");
  46                 return NULL;
  47         }
  48         wName[MAX_PATH - 1] = 0; // Be sure it's NUL terminated
  49
  50         rc = RegOpenKeyEx(HKEY_LOCAL_MACHINE, ENVIRONMENT_REG_PATH, 0, KEY_QUERY_VALUE, &hkey);
  51         if (rc != ERROR_SUCCESS) {
  52                 usbi_dbg("Failed to open registry key for getenv with error %d", rc);
  53                 return NULL;
  54         }
  55
  56         // Attempt to read the key
  57         dwData = sizeof(wValue);
  58         rc = RegQueryValueEx(hkey, wName, NULL, &dwType,
  59                 (LPBYTE)&wValue, &dwData);
  60         RegCloseKey(hkey);
  61         if (rc != ERROR_SUCCESS) {
  62                 usbi_dbg("Failed to read registry key value for getenv with error %d", rc);
  63                 return NULL;
  64         }
  65         if (dwType != REG_SZ) {
  66                 usbi_dbg("Registry value was of type %d instead of REG_SZ", dwType);
  67                 return NULL;
  68         }
  69
  70         // Success in reading the key, convert from WCHAR to char
  71         if (WideCharToMultiByte(CP_UTF8, 0,
  72                         wValue, dwData / sizeof(*wValue),
  73                         value, MAX_PATH,
  74                         NULL, NULL) <= 0) {
  75                 usbi_dbg("Failed to convert environment variable value to narrow string");
  76                 return NULL;
  77         }
  78         value[MAX_PATH - 1] = 0; // Be sure it's NUL terminated
  79         return value;
  80 }