src/lib/log/win32err.c

   1 /* Copyright (c) 2003-2004, Roger Dingledine
   2  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   3  * Copyright (c) 2007-2020, The Tor Project, Inc. */
   4 /* See LICENSE for licensing information */
   5
   6 /**
   7  * \file win32err.c
   8  * \brief Convert windows error codes to useful C strings.
   9  **/
  10
  11 #ifdef _WIN32
  12 #include "orconfig.h"
  13 #include "lib/log/win32err.h"
  14 #include "lib/malloc/malloc.h"
  15
  16 #include <tchar.h>
  17 #include <windows.h>
  18
  19 /** Return a newly allocated string describing the windows system error code
  20  * <b>err</b>.  Note that error codes are different from errno.  Error codes
  21  * come from GetLastError() when a winapi call fails.  errno is set only when
  22  * ANSI functions fail.  Whee. */
  23 char *
  24 format_win32_error(DWORD err)
  25 {
  26   TCHAR *str = NULL;
  27   char *result;
  28   DWORD n;
  29
  30   /* Somebody once decided that this interface was better than strerror(). */
  31   n = FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
  32                  FORMAT_MESSAGE_FROM_SYSTEM |
  33                  FORMAT_MESSAGE_IGNORE_INSERTS,
  34                  NULL, err,
  35                  MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
  36                  (LPVOID)&str,
  37                  0, NULL);
  38
  39   if (str && n) {
  40 #ifdef UNICODE
  41     size_t len;
  42     if (n > 128*1024)
  43       len = (128 * 1024) * 2 + 1; /* This shouldn't be possible, but let's
  44                                    * make sure. */
  45     else
  46       len = n * 2 + 1;
  47     result = tor_malloc(len);
  48     wcstombs(result,str,len);
  49     result[len-1] = '\0';
  50 #else /* !defined(UNICODE) */
  51     result = tor_strdup(str);
  52 #endif /* defined(UNICODE) */
  53   } else {
  54     result = tor_strdup("<unformattable error>");
  55   }
  56   if (str) {
  57     LocalFree(str); /* LocalFree != free() */
  58   }
  59   return result;
  60 }
  61 #endif /* defined(_WIN32) */