Add helper functions for pipes (microsoft#17566)

lhecker · web-flow · commit d68c6a5e7a80 · 2024-07-16T22:24:16.000Z
Split off from microsoft#17510: * `HandleWantsOverlappedIo` can be used to check if a handle requires overlapped IO. This is important, as `ReadFile` and `WriteFile` are documented to not work correctly if an overlapped handle is used without overlapped IO and vice versa. In my tests with pipes, this appears to be true. * `CreatePipe` creates a synchronous, unidirectional pipe. * `CreateOverlappedPipe` does what it says on the tin, while allowing you to specify the direction of the pipe (in, out, duplex). * `GetOverlappedResultSameThread` is largely the same as `GetOverlappedResult`, but adds back a neat optimization from the time before Windows 7. I thought it was neat.
diff --git a/.github/actions/spelling/expect/expect.txt b/.github/actions/spelling/expect/expect.txt
@@ -1205,6 +1205,7 @@ nouicompat
 nounihan
 NOYIELD
 NOZORDER
+NPFS
 nrcs
 NSTATUS
 ntapi
diff --git a/src/types/inc/utils.hpp b/src/types/inc/utils.hpp
@@ -15,6 +15,12 @@ Author(s):
 
 namespace Microsoft::Console::Utils
 {
+    struct Pipe
+    {
+        wil::unique_hfile server;
+        wil::unique_hfile client;
+    };
+
     // Function Description:
     // - Returns -1, 0 or +1 to indicate the sign of the passed-in value.
     template<typename T>
@@ -24,6 +30,10 @@ namespace Microsoft::Console::Utils
     }
 
     bool IsValidHandle(const HANDLE handle) noexcept;
+    bool HandleWantsOverlappedIo(HANDLE handle) noexcept;
+    Pipe CreatePipe(DWORD bufferSize);
+    Pipe CreateOverlappedPipe(DWORD openMode, DWORD bufferSize);
+    HRESULT GetOverlappedResultSameThread(const OVERLAPPED* overlapped, DWORD* bytesTransferred) noexcept;
 
     // Function Description:
     // - Clamps a long in between `min` and `SHRT_MAX`
diff --git a/src/types/utils.cpp b/src/types/utils.cpp
@@ -4,13 +4,11 @@
 #include "precomp.h"
 #include "inc/utils.hpp"
 
-#include <propsys.h>
+#include <til/string.h>
+#include <wil/token_helpers.h>
 
 #include "inc/colorTable.hpp"
 
-#include <wil/token_helpers.h>
-#include <til/string.h>
-
 using namespace Microsoft::Console;
 
 // Routine Description:
@@ -631,6 +629,208 @@ bool Utils::IsValidHandle(const HANDLE handle) noexcept
     return handle != nullptr && handle != INVALID_HANDLE_VALUE;
 }
 
+#define FileModeInformation (FILE_INFORMATION_CLASS)16
+
+#define FILE_PIPE_BYTE_STREAM_TYPE 0x00000000
+#define FILE_PIPE_BYTE_STREAM_MODE 0x00000000
+#define FILE_PIPE_QUEUE_OPERATION 0x00000000
+
+typedef struct _FILE_MODE_INFORMATION
+{
+    ULONG Mode;
+} FILE_MODE_INFORMATION, *PFILE_MODE_INFORMATION;
+
+extern "C" NTSTATUS NTAPI NtQueryInformationFile(
+    HANDLE FileHandle,
+    PIO_STATUS_BLOCK IoStatusBlock,
+    PVOID FileInformation,
+    ULONG Length,
+    FILE_INFORMATION_CLASS FileInformationClass);
+
+extern "C" NTSTATUS NTAPI NtCreateNamedPipeFile(
+    PHANDLE FileHandle,
+    ULONG DesiredAccess,
+    POBJECT_ATTRIBUTES ObjectAttributes,
+    PIO_STATUS_BLOCK IoStatusBlock,
+    ULONG ShareAccess,
+    ULONG CreateDisposition,
+    ULONG CreateOptions,
+    ULONG NamedPipeType,
+    ULONG ReadMode,
+    ULONG CompletionMode,
+    ULONG MaximumInstances,
+    ULONG InboundQuota,
+    ULONG OutboundQuota,
+    PLARGE_INTEGER DefaultTimeout);
+
+bool Utils::HandleWantsOverlappedIo(HANDLE handle) noexcept
+{
+    IO_STATUS_BLOCK statusBlock;
+    FILE_MODE_INFORMATION modeInfo;
+    const auto status = NtQueryInformationFile(handle, &statusBlock, &modeInfo, sizeof(modeInfo), FileModeInformation);
+    return status == 0 && WI_AreAllFlagsClear(modeInfo.Mode, FILE_SYNCHRONOUS_IO_ALERT | FILE_SYNCHRONOUS_IO_NONALERT);
+}
+
+// Creates an anonymous pipe. Behaves like PIPE_ACCESS_INBOUND,
+// meaning the .server is for reading and the .client is for writing.
+Utils::Pipe Utils::CreatePipe(DWORD bufferSize)
+{
+    wil::unique_hfile rx, tx;
+    THROW_IF_WIN32_BOOL_FALSE(::CreatePipe(rx.addressof(), tx.addressof(), nullptr, bufferSize));
+    return { std::move(rx), std::move(tx) };
+}
+
+// Creates an overlapped anonymous pipe. openMode should be either:
+// * PIPE_ACCESS_INBOUND
+// * PIPE_ACCESS_OUTBOUND
+// * PIPE_ACCESS_DUPLEX
+//
+// I know, I know. MSDN infamously says
+// > Asynchronous (overlapped) read and write operations are not supported by anonymous pipes.
+// but that's a lie. The only reason they're not supported is because the Win32
+// API doesn't have a parameter where you could pass FILE_FLAG_OVERLAPPED!
+// So, we'll simply use the underlying NT APIs instead.
+//
+// Most code on the internet suggests creating named pipes with a random name,
+// but usually conveniently forgets to mention that named pipes require strict ACLs.
+// https://stackoverflow.com/q/60645 for instance contains a lot of poor advice.
+// Anonymous pipes also cannot be discovered via NtQueryDirectoryFile inside the NPFS driver,
+// whereas running a tool like Sysinternals' PipeList will return all those semi-named pipes.
+//
+// The code below contains comments to create unidirectional pipes.
+Utils::Pipe Utils::CreateOverlappedPipe(DWORD openMode, DWORD bufferSize)
+{
+    LARGE_INTEGER timeout = { .QuadPart = -10'0000'0000 }; // 1 second
+    UNICODE_STRING emptyPath{};
+    IO_STATUS_BLOCK statusBlock;
+    OBJECT_ATTRIBUTES objectAttributes{
+        .Length = sizeof(OBJECT_ATTRIBUTES),
+        .ObjectName = &emptyPath,
+        .Attributes = OBJ_CASE_INSENSITIVE,
+    };
+    DWORD serverDesiredAccess = 0;
+    DWORD clientDesiredAccess = 0;
+    DWORD serverShareAccess = 0;
+    DWORD clientShareAccess = 0;
+
+    switch (openMode)
+    {
+    case PIPE_ACCESS_INBOUND:
+        serverDesiredAccess = SYNCHRONIZE | GENERIC_READ | FILE_WRITE_ATTRIBUTES;
+        clientDesiredAccess = SYNCHRONIZE | GENERIC_WRITE | FILE_READ_ATTRIBUTES;
+        serverShareAccess = FILE_SHARE_WRITE;
+        clientShareAccess = FILE_SHARE_READ;
+        break;
+    case PIPE_ACCESS_OUTBOUND:
+        serverDesiredAccess = SYNCHRONIZE | GENERIC_WRITE | FILE_READ_ATTRIBUTES;
+        clientDesiredAccess = SYNCHRONIZE | GENERIC_READ | FILE_WRITE_ATTRIBUTES;
+        serverShareAccess = FILE_SHARE_READ;
+        clientShareAccess = FILE_SHARE_WRITE;
+        break;
+    case PIPE_ACCESS_DUPLEX:
+        serverDesiredAccess = SYNCHRONIZE | GENERIC_READ | GENERIC_WRITE;
+        clientDesiredAccess = SYNCHRONIZE | GENERIC_READ | GENERIC_WRITE;
+        serverShareAccess = FILE_SHARE_READ | FILE_SHARE_WRITE;
+        clientShareAccess = FILE_SHARE_READ | FILE_SHARE_WRITE;
+        break;
+    default:
+        THROW_HR(E_UNEXPECTED);
+    }
+
+    // Cache a handle to the pipe driver.
+    static const auto pipeDirectory = []() {
+        UNICODE_STRING path = RTL_CONSTANT_STRING(L"\\Device\\NamedPipe\\");
+
+        OBJECT_ATTRIBUTES objectAttributes{
+            .Length = sizeof(OBJECT_ATTRIBUTES),
+            .ObjectName = &path,
+        };
+
+        wil::unique_hfile dir;
+        IO_STATUS_BLOCK statusBlock;
+        THROW_IF_NTSTATUS_FAILED(NtCreateFile(
+            /* FileHandle        */ dir.addressof(),
+            /* DesiredAccess     */ SYNCHRONIZE | GENERIC_READ,
+            /* ObjectAttributes  */ &objectAttributes,
+            /* IoStatusBlock     */ &statusBlock,
+            /* AllocationSize    */ nullptr,
+            /* FileAttributes    */ 0,
+            /* ShareAccess       */ FILE_SHARE_READ | FILE_SHARE_WRITE,
+            /* CreateDisposition */ FILE_OPEN,
+            /* CreateOptions     */ FILE_SYNCHRONOUS_IO_NONALERT,
+            /* EaBuffer          */ nullptr,
+            /* EaLength          */ 0));
+
+        return dir;
+    }();
+
+    wil::unique_hfile server;
+    objectAttributes.RootDirectory = pipeDirectory.get();
+    THROW_IF_NTSTATUS_FAILED(NtCreateNamedPipeFile(
+        /* FileHandle        */ server.addressof(),
+        /* DesiredAccess     */ serverDesiredAccess,
+        /* ObjectAttributes  */ &objectAttributes,
+        /* IoStatusBlock     */ &statusBlock,
+        /* ShareAccess       */ serverShareAccess,
+        /* CreateDisposition */ FILE_CREATE,
+        /* CreateOptions     */ 0, // would be FILE_SYNCHRONOUS_IO_NONALERT for a synchronous pipe
+        /* NamedPipeType     */ FILE_PIPE_BYTE_STREAM_TYPE,
+        /* ReadMode          */ FILE_PIPE_BYTE_STREAM_MODE,
+        /* CompletionMode    */ FILE_PIPE_QUEUE_OPERATION, // would be FILE_PIPE_COMPLETE_OPERATION for PIPE_NOWAIT
+        /* MaximumInstances  */ 1,
+        /* InboundQuota      */ bufferSize,
+        /* OutboundQuota     */ bufferSize,
+        /* DefaultTimeout    */ &timeout));
+
+    wil::unique_hfile client;
+    objectAttributes.RootDirectory = server.get();
+    THROW_IF_NTSTATUS_FAILED(NtCreateFile(
+        /* FileHandle        */ client.addressof(),
+        /* DesiredAccess     */ clientDesiredAccess,
+        /* ObjectAttributes  */ &objectAttributes,
+        /* IoStatusBlock     */ &statusBlock,
+        /* AllocationSize    */ nullptr,
+        /* FileAttributes    */ 0,
+        /* ShareAccess       */ clientShareAccess,
+        /* CreateDisposition */ FILE_OPEN,
+        /* CreateOptions     */ FILE_NON_DIRECTORY_FILE, // would include FILE_SYNCHRONOUS_IO_NONALERT for a synchronous pipe
+        /* EaBuffer          */ nullptr,
+        /* EaLength          */ 0));
+
+    return { std::move(server), std::move(client) };
+}
+
+// GetOverlappedResult() for professionals! Only for single-threaded use.
+//
+// GetOverlappedResult() used to have a neat optimization where it would only call WaitForSingleObject() if the state was STATUS_PENDING.
+// That got removed in Windows 7, because people kept starting a read/write on one thread and called GetOverlappedResult() on another.
+// When the OS sets Internal from STATUS_PENDING to 0 (= done) and then flags the hEvent, that doesn't happen atomically.
+// This results in a race condition if a OVERLAPPED is used across threads.
+HRESULT Utils::GetOverlappedResultSameThread(const OVERLAPPED* overlapped, DWORD* bytesTransferred) noexcept
+{
+    assert(overlapped != nullptr);
+    assert(overlapped->hEvent != nullptr);
+    assert(bytesTransferred != nullptr);
+
+    __assume(overlapped != nullptr);
+    __assume(overlapped->hEvent != nullptr);
+    __assume(bytesTransferred != nullptr);
+
+    if (overlapped->Internal == STATUS_PENDING)
+    {
+        if (WaitForSingleObjectEx(overlapped->hEvent, INFINITE, FALSE) != WAIT_OBJECT_0)
+        {
+            return HRESULT_FROM_WIN32(GetLastError());
+        }
+    }
+
+    // Assuming no multi-threading as per the function contract and
+    // now that we ensured that hEvent is set (= read/write done),
+    // we can safely read whatever want because nothing will set these concurrently.
+    *bytesTransferred = gsl::narrow_cast<DWORD>(overlapped->InternalHigh);
+    return HRESULT_FROM_NT(overlapped->Internal);
+}
+
 // Function Description:
 // - Generate a Version 5 UUID (specified in RFC4122 4.3)
 //   v5 UUIDs are stable given the same namespace and "name".
