internal unsafe bool TryExpandShortFileName()
{
if (doNotTryExpandShortFileName)
{
return(false);
}
if (useStackAlloc)
{
NullTerminate();
char *buffer = UnsafeGetArrayPtr();
char *shortFileNameBuffer = stackalloc char[Path.MaxPath + 1];
int r = Interop.mincore.GetLongPathNameW(buffer, shortFileNameBuffer, Path.MaxPath);
// If success, the return buffer length does not account for the terminating null character.
// If in-sufficient buffer, the return buffer length does account for the path + the terminating null character.
// If failure, the return buffer length is zero
if (r >= Path.MaxPath)
{
throw new PathTooLongException(SR.IO_PathTooLong);
}
if (r == 0)
{
// Note: GetLongPathName will return ERROR_INVALID_FUNCTION on a
// path like \\.\PHYSICALDEVICE0 - some device driver doesn't
// support GetLongPathName on that string. This behavior is
// by design, according to the Core File Services team.
// We also get ERROR_NOT_ENOUGH_QUOTA in SQL_CLR_STRESS runs
// intermittently on paths like D:\DOCUME~1\user\LOCALS~1\Temp\
// We do not need to call GetLongPathName if we know it will fail becasue the path does not exist:
int lastErr = Marshal.GetLastWin32Error();
if (lastErr == Interop.mincore.Errors.ERROR_FILE_NOT_FOUND || lastErr == Interop.mincore.Errors.ERROR_PATH_NOT_FOUND)
{
doNotTryExpandShortFileName = true;
}
return(false);
}
// Safe to copy as we have already done Path.MaxPath bound checking
Wstrcpy(buffer, shortFileNameBuffer, r);
Length = r;
// We should explicitly null terminate as in some cases the long version of the path
// might actually be shorter than what we started with because of Win32's normalization
// Safe to write directly as bufferLength is guaranteed to be < Path.MaxPath
NullTerminate();
return(true);
}
else
{
StringBuilder sb = GetStringBuilder();
String origName = sb.ToString();
String tempName = origName;
bool addedPrefix = false;
if (tempName.Length > Path.MaxPath)
{
tempName = PathInternal.AddExtendedPathPrefix(tempName);
addedPrefix = true;
}
sb.Capacity = m_capacity;
sb.Length = 0;
int r = Interop.mincore.GetLongPathNameW(tempName, sb, m_capacity);
if (r == 0)
{
// Note: GetLongPathName will return ERROR_INVALID_FUNCTION on a
// path like \\.\PHYSICALDEVICE0 - some device driver doesn't
// support GetLongPathName on that string. This behavior is
// by design, according to the Core File Services team.
// We also get ERROR_NOT_ENOUGH_QUOTA in SQL_CLR_STRESS runs
// intermittently on paths like D:\DOCUME~1\user\LOCALS~1\Temp\
// We do not need to call GetLongPathName if we know it will fail becasue the path does not exist:
int lastErr = Marshal.GetLastWin32Error();
if (Interop.mincore.Errors.ERROR_FILE_NOT_FOUND == lastErr || Interop.mincore.Errors.ERROR_PATH_NOT_FOUND == lastErr)
{
doNotTryExpandShortFileName = true;
}
sb.Length = 0;
sb.Append(origName);
return(false);
}
if (addedPrefix)
{
r -= 4;
}
// If success, the return buffer length does not account for the terminating null character.
// If in-sufficient buffer, the return buffer length does account for the path + the terminating null character.
// If failure, the return buffer length is zero
if (r >= m_maxPath)
{
throw new PathTooLongException(SR.IO_PathTooLong);
}
sb = PathInternal.RemoveExtendedPathPrefix(sb);
Length = sb.Length;
return(true);
}
}
