src/windows/native/java/io/io_util_md.c

*** 27,36 ****
--- 27,37 ----
  #include "jni_util.h"
  #include "jvm.h"
  #include "io_util.h"
  #include "io_util_md.h"
  #include <stdio.h>
+ #include <windows.h>
  
  #include <wchar.h>
  #include <io.h>
  #include <fcntl.h>
  #include <errno.h>
*** 587,591 ****
--- 588,666 ----
      if (SetFilePointerEx(h, distance, &pos, op) == 0) {
          return -1;
      }
      return long_to_jlong(pos.QuadPart);
  }
+ 
+ size_t
+ getLastErrorString(char *utf8_jvmErrorMsg, size_t cbErrorMsg)
+ {
+     size_t n = 0;
+     if (cbErrorMsg > 0) {
+         BOOLEAN noError = FALSE;
+         WCHAR *utf16_osErrorMsg = (WCHAR *)malloc(cbErrorMsg*sizeof(WCHAR));
+         if (utf16_osErrorMsg == NULL) {
+             // OOM accident
+             strncpy(utf8_jvmErrorMsg, "Out of memory", cbErrorMsg);
+             // truncate if too long
+             utf8_jvmErrorMsg[cbErrorMsg - 1] = '\0';
+             n = strlen(utf8_jvmErrorMsg);
+         } else {
+             DWORD errval = GetLastError();
+             if (errval != 0) {
+                 // WIN32 error
+                 n = (size_t)FormatMessageW(
+                     FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
+                     NULL,
+                     errval,
+                     0,
+                     utf16_osErrorMsg,
+                     (DWORD)cbErrorMsg,
+                     NULL);
+                 if (n > 3) {
+                     // Drop final '.', CR, LF
+                     if (utf16_osErrorMsg[n - 1] == L'\n') --n;
+                     if (utf16_osErrorMsg[n - 1] == L'\r') --n;
+                     if (utf16_osErrorMsg[n - 1] == L'.') --n;
+                     utf16_osErrorMsg[n] = L'\0';
+                 }
+             } else if (errno != 0) {
+                 // C runtime error that has no corresponding WIN32 error code
+                 const WCHAR *rtError = _wcserror(errno);
+                 if (rtError != NULL) {
+                     wcsncpy(utf16_osErrorMsg, rtError, cbErrorMsg);
+                     // truncate if too long
+                     utf16_osErrorMsg[cbErrorMsg - 1] = L'\0';
+                     n = wcslen(utf16_osErrorMsg);
+                 }
+             } else
+                 noError = TRUE; //OS has no error to report
+ 
+             if (!noError) {
+                 if (n > 0) {
+                     n = WideCharToMultiByte(
+                         CP_UTF8,
+                         0,
+                         utf16_osErrorMsg,
+                         n,
+                         utf8_jvmErrorMsg,
+                         cbErrorMsg,
+                         NULL,
+                         NULL);
+ 
+                     // no way to die
+                     if (n > 0)
+                         utf8_jvmErrorMsg[min(cbErrorMsg - 1, n)] = '\0';
+                 }
+ 
+                 if (n <= 0) {
+                     strncpy(utf8_jvmErrorMsg, "Secondary error while OS message extraction", cbErrorMsg);
+                     // truncate if too long
+                     utf8_jvmErrorMsg[cbErrorMsg - 1] = '\0';
+                     n = strlen(utf8_jvmErrorMsg);
+                 }
+             }
+             free(utf16_osErrorMsg);
+         }
+     }
+     return n;
+ }