using System;
using System.Runtime.InteropServices;
namespace Vanara.PInvoke
{
public static partial class Kernel32
{
/// Waits forever for a message.
public const uint MAILSLOT_WAIT_FOREVER = unchecked((uint)-1);
///
/// Creates a mailslot with the specified name and returns a handle that a mailslot server can use to perform operations on the
/// mailslot. The mailslot is local to the computer that creates it. An error occurs if a mailslot with the specified name already exists.
///
///
/// The name of the mailslot. This name must have the following form:
/// \\.\mailslot\[path]name
///
/// The name field must be unique. The name may include multiple levels of pseudo directories separated by backslashes. For example,
/// both \\.\mailslot\example_mailslot_name and \\.\mailslot\abc\def\ghi are valid names.
///
///
///
/// The maximum size of a single message that can be written to the mailslot, in bytes. To specify that the message can be of any
/// size, set this value to zero.
///
///
///
/// The time a read operation can wait for a message to be written to the mailslot before a time-out occurs, in milliseconds. The
/// following values have special meanings.
///
///
///
///
/// Value
/// Meaning
///
/// -
/// 0
/// Returns immediately if no message is present. (The system does not treat an immediate return as an error.)
///
/// -
/// MAILSLOT_WAIT_FOREVER((DWORD)-1)
/// Waits forever for a message.
///
///
///
/// This time-out value applies to all subsequent read operations and all inherited mailslot handles.
///
///
/// A pointer to a SECURITY_ATTRIBUTES structure. The bInheritHandle member of the structure determines whether the
/// returned handle can be inherited by child processes. If lpSecurityAttributes is NULL, the handle cannot be inherited.
///
///
///
/// If the function succeeds, the return value is a handle to the mailslot, for use in server mailslot operations. The handle
/// returned by this function is asynchronous, or overlapped.
///
/// If the function fails, the return value is INVALID_HANDLE_VALUE. To get extended error information, call GetLastError.
///
// HANDLE WINAPI CreateMailslot( _In_ LPCTSTR lpName, _In_ DWORD nMaxMessageSize, _In_ DWORD lReadTimeout, _In_opt_
// LPSECURITY_ATTRIBUTES lpSecurityAttributes); https://msdn.microsoft.com/en-us/library/windows/desktop/aa365147(v=vs.85).aspx
[DllImport(Lib.Kernel32, SetLastError = true, CharSet = CharSet.Auto)]
[PInvokeData("Winbase.h", MSDNShortId = "aa365147")]
public static extern SafeMailslotHandle CreateMailslot(string lpName, uint nMaxMessageSize, uint lReadTimeout, [In, Optional] SECURITY_ATTRIBUTES lpSecurityAttributes);
/// Retrieves information about the specified mailslot.
/// A handle to a mailslot. The CreateMailslot function must create this handle.
///
/// The maximum message size, in bytes, allowed for this mailslot. This value can be greater than or equal to the value specified in
/// the cbMaxMsg parameter of the CreateMailslot function that created the mailslot. This parameter can be NULL.
///
///
/// The size of the next message, in bytes. The following value has special meaning.
///
///
///
/// Value
/// Meaning
///
/// -
/// MAILSLOT_NO_MESSAGE((DWORD)-1)
/// There is no next message.
///
///
///
/// This parameter can be NULL.
///
///
/// The total number of messages waiting to be read, when the function returns. This parameter can be NULL.
///
///
/// The amount of time, in milliseconds, a read operation can wait for a message to be written to the mailslot before a time-out
/// occurs. This parameter is filled in when the function returns. This parameter can be NULL.
///
///
/// If the function succeeds, the return value is nonzero.
/// If the function fails, the return value is zero. To get extended error information, call GetLastError.
///
// BOOL WINAPI GetMailslotInfo( _In_ HANDLE hMailslot, _Out_opt_ LPDWORD lpMaxMessageSize, _Out_opt_ LPDWORD lpNextSize, _Out_opt_
// LPDWORD lpMessageCount, _Out_opt_ LPDWORD lpReadTimeout); https://msdn.microsoft.com/en-us/library/windows/desktop/aa365435(v=vs.85).aspx
[DllImport(Lib.Kernel32, SetLastError = true, ExactSpelling = true)]
[PInvokeData("Winbase.h", MSDNShortId = "aa365435")]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool GetMailslotInfo([In] SafeMailslotHandle hMailslot, out uint lpMaxMessageSize, out uint lpNextSize, out uint lpMessageCount, out uint lpReadTimeout);
/// Sets the time-out value used by the specified mailslot for a read operation.
/// A handle to a mailslot. The CreateMailslot function must create this handle.
///
///
/// The time a read operation can wait for a message to be written to the mailslot before a time-out occurs, in milliseconds. The
/// following values have special meanings.
///
///
///
///
/// Value
/// Meaning
///
/// -
/// 0
/// Returns immediately if no message is present. (The system does not treat an immediate return as an error.)
///
/// -
/// MAILSLOT_WAIT_FOREVER((DWORD)-1)
/// Waits forever for a message.
///
///
///
/// This time-out value applies to all subsequent read operations and to all inherited mailslot handles.
///
///
/// If the function succeeds, the return value is nonzero.
/// If the function fails, the return value is zero. To get extended error information, call GetLastError.
///
// BOOL WINAPI SetMailslotInfo( _In_ HANDLE hMailslot, _In_ DWORD lReadTimeout); https://msdn.microsoft.com/en-us/library/windows/desktop/aa365786(v=vs.85).aspx
[DllImport(Lib.Kernel32, SetLastError = true, ExactSpelling = true)]
[PInvokeData("Winbase.h", MSDNShortId = "aa365786")]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool SetMailslotInfo([In] SafeMailslotHandle hMailslot, uint lReadTimeout);
///
/// Provides a to a mailslot that releases a created MailslotHandle instance at disposal using CloseHandle.
///
public class SafeMailslotHandle : SafeKernelHandle
{
/// Initializes a new instance of the class and assigns an existing handle.
/// An object that represents the pre-existing handle to use.
///
/// to reliably release the handle during the finalization phase; otherwise, (not recommended).
///
public SafeMailslotHandle(IntPtr preexistingHandle, bool ownsHandle = true) : base(preexistingHandle, ownsHandle) { }
/// Initializes a new instance of the class.
private SafeMailslotHandle() : base() { }
}
}
}