private static string GetEnvironmentVariableCore(string variable)
{
if (AppDomain.IsAppXModel() && !AppDomain.IsAppXDesignMode())
{
// Environment variable accessors are not approved modern API.
// Behave as if the variable was not found in this case.
return(null);
}
StringBuilder sb = StringBuilderCache.Acquire(128); // A somewhat reasonable default size
int requiredSize = Win32Native.GetEnvironmentVariable(variable, sb, sb.Capacity);
if (requiredSize == 0 && Marshal.GetLastWin32Error() == Win32Native.ERROR_ENVVAR_NOT_FOUND)
{
StringBuilderCache.Release(sb);
return(null);
}
while (requiredSize > sb.Capacity)
{
sb.Capacity = requiredSize;
sb.Length = 0;
requiredSize = Win32Native.GetEnvironmentVariable(variable, sb, sb.Capacity);
}
return(StringBuilderCache.GetStringAndRelease(sb));
}
private static void SetEnvironmentVariableCore(string variable, string value)
{
// explicitly null out value if is the empty string.
if (string.IsNullOrEmpty(value) || value[0] == '\0')
{
value = null;
}
if (AppDomain.IsAppXModel() && !AppDomain.IsAppXDesignMode())
{
// Environment variable accessors are not approved modern API.
// so we throw PlatformNotSupportedException.
throw new PlatformNotSupportedException();
}
if (!Win32Native.SetEnvironmentVariable(variable, value))
{
int errorCode = Marshal.GetLastWin32Error();
switch (errorCode)
{
case Win32Native.ERROR_ENVVAR_NOT_FOUND:
// Allow user to try to clear a environment variable
return;
case Win32Native.ERROR_FILENAME_EXCED_RANGE:
// The error message from Win32 is "The filename or extension is too long",
// which is not accurate.
throw new ArgumentException(GetResourceString("Argument_LongEnvVarValue"));
default:
throw new ArgumentException(Win32Native.GetMessage(errorCode));
}
}
}
private static IDictionary GetEnvironmentVariablesCore()
{
if (AppDomain.IsAppXModel() && !AppDomain.IsAppXDesignMode())
{
// Environment variable accessors are not approved modern API.
// Behave as if no environment variables are defined in this case.
return(new Dictionary <string, string>(0));
}
return(GetRawEnvironmentVariables());
}
public static String ExpandEnvironmentVariables(String name)
{
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
Contract.EndContractBlock();
if (name.Length == 0)
{
return(name);
}
if (AppDomain.IsAppXModel() && !AppDomain.IsAppXDesignMode())
{
// Environment variable accessors are not approved modern API.
// Behave as if no variables are defined in this case.
return(name);
}
int currentSize = 100;
StringBuilder blob = new StringBuilder(currentSize); // A somewhat reasonable default size
#if PLATFORM_UNIX // Win32Native.ExpandEnvironmentStrings isn't available
int lastPos = 0, pos;
while (lastPos < name.Length && (pos = name.IndexOf('%', lastPos + 1)) >= 0)
{
if (name[lastPos] == '%')
{
string key = name.Substring(lastPos + 1, pos - lastPos - 1);
string value = Environment.GetEnvironmentVariable(key);
if (value != null)
{
blob.Append(value);
lastPos = pos + 1;
continue;
}
}
blob.Append(name.Substring(lastPos, pos - lastPos));
lastPos = pos;
}
blob.Append(name.Substring(lastPos));
#else
int size;
blob.Length = 0;
size = Win32Native.ExpandEnvironmentStrings(name, blob, currentSize);
if (size == 0)
{
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}
while (size > currentSize)
{
currentSize = size;
blob.Capacity = currentSize;
blob.Length = 0;
size = Win32Native.ExpandEnvironmentStrings(name, blob, currentSize);
if (size == 0)
{
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}
}
#endif // PLATFORM_UNIX
return(blob.ToString());
}
