ThreadDescription.c

Go to the documentation of this file.

/*
 * PROJECT:     ReactOS Win32 Base API
 * LICENSE:     GPL-2.0-or-later (https://spdx.org/licenses/GPL-2.0-or-later)
 * PURPOSE:     NT10+ Thread Description helpers
 * COPYRIGHT:   Copyright 2025-2026 Hermès Bélusca-Maïto <hermes.belusca-maito@reactos.org>
 */
 
#include "k32_vista.h"
 
HRESULT
WINAPI
DECLSPEC_HOTPATCH
GetThreadDescription(
    _In_ HANDLE hThread,
    _Outptr_result_z_ PWSTR* ppszThreadDescription)
{
    PTHREAD_NAME_INFORMATION NameInfo = NULL;
    PVOID ptr;
    NTSTATUS Status;
    ULONG Length;
 
    *ppszThreadDescription = NULL;
 
    /* Since there may be concurrent SetThreadDescription() invocations being
     * executed, we need to loop over the buffer allocation size until we can
     * successfully capture the thread name. */
    Length = 0;
    Status = NtQueryInformationThread(hThread, ThreadNameInformation, NULL, 0, &Length);
    if (Status != STATUS_BUFFER_TOO_SMALL)
        return HRESULT_FROM_NT(Status);
 
    /* Loop again only if we get buffer-too-small types of errors;
     * otherwise, break the loop: any error will be handled below. */
    while (Status == STATUS_INFO_LENGTH_MISMATCH ||
           Status == STATUS_BUFFER_TOO_SMALL)
    {
        /* (Re-)allocate the information buffer */
        ptr = (NameInfo ? LocalReAlloc(NameInfo, Length, LMEM_MOVEABLE)
                        : LocalAlloc(LMEM_FIXED, Length));
        if (!ptr)
        {
            Status = STATUS_NO_MEMORY;
            break;
        }
        NameInfo = ptr;
        Status = NtQueryInformationThread(hThread, ThreadNameInformation,
                                          NameInfo, Length, &Length);
    }
    if (!NT_SUCCESS(Status))
    {
        LocalFree(NameInfo);
        return HRESULT_FROM_NT(Status);
    }
 
    /*
     * We already have a suitable memory buffer, containing a UNICODE_STRING
     * followed by the actual string data. Just move the string back to the
     * beginning of the buffer and resize it down. Since sizeof(UNICODE_STRING)
     * is larger than sizeof(WCHAR), we also have space for the NUL-terminator.
     */
    *ppszThreadDescription = (PWSTR)NameInfo;
    Length = NameInfo->ThreadName.Length;
    if (Length)
        RtlMoveMemory(*ppszThreadDescription, NameInfo->ThreadName.Buffer, Length);
    (*ppszThreadDescription)[Length / sizeof(WCHAR)] = UNICODE_NULL;
 
    /* Resize down the buffer. If the call fails, the old buffer
     * is still valid, but is larger than what is necessary. */
    ptr = LocalReAlloc(*ppszThreadDescription, Length + sizeof(WCHAR), LMEM_FIXED);
    if (ptr)
        *ppszThreadDescription = ptr;
 
    return HRESULT_FROM_NT(Status);
}
 
HRESULT
WINAPI
DECLSPEC_HOTPATCH
SetThreadDescription(
    _In_ HANDLE hThread,
    _In_ PCWSTR lpThreadDescription)
{
    THREAD_NAME_INFORMATION NameInfo;
    NTSTATUS Status;
 
    Status = RtlInitUnicodeStringEx(&NameInfo.ThreadName, lpThreadDescription);
    if (NT_SUCCESS(Status))
    {
        Status = NtSetInformationThread(hThread, ThreadNameInformation,
                                        &NameInfo, sizeof(NameInfo));
    }
    return HRESULT_FROM_NT(Status);
}