/*++

Copyright (c) 1990  Microsoft Corporation

Module Name:

    atom.c

Abstract:

    This file contains the common code to implement atom tables.  It is called
    by both the user mode Win32 Atom API functions (Local/GlobalxxxAtom) and
    by the kernel mode window manager code to access global atoms.

Author:

    Steve Wood (stevewo) 26-Oct-1990

Revision History:

--*/

#include "ntrtlp.h"
#include "atom.h"

ULONG RtlpAtomAllocateTag;

PVOID
RtlpAllocateAtom(
    IN ULONG NumberOfBytes
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
    return ExAllocatePoolWithTag( PagedPool, NumberOfBytes, RtlpAtomAllocateTag );
#else
    return RtlAllocateHeap( RtlProcessHeap(), RtlpAtomAllocateTag, NumberOfBytes );
#endif
}


void
RtlpFreeAtom(
    IN PVOID p
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
    ExFreePool( p );
#else
    RtlFreeHeap( RtlProcessHeap(), 0, p );
#endif
    return;
}


void
RtlpInitializeLockAtomTable(
    IN OUT PRTL_ATOM_TABLE AtomTable
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
    ExInitializeFastMutex( &AtomTable->FastMutex );
#else
    RtlInitializeCriticalSection( &AtomTable->CriticalSection );
#endif
    return;
}

BOOLEAN
RtlpLockAtomTable(
    IN PRTL_ATOM_TABLE AtomTable
    )
{
    if (AtomTable == NULL || AtomTable->Signature != RTL_ATOM_TABLE_SIGNATURE) {
        return FALSE;
        }

#if defined(NTOS_KERNEL_RUNTIME)
    ExAcquireFastMutex( &AtomTable->FastMutex );
#else
    RtlEnterCriticalSection( &AtomTable->CriticalSection );
#endif

    return TRUE;
}

void
RtlpUnlockAtomTable(
    IN PRTL_ATOM_TABLE AtomTable
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
    ExReleaseFastMutex( &AtomTable->FastMutex );
#else
    RtlLeaveCriticalSection( &AtomTable->CriticalSection );
#endif
}


void
RtlpDestroyLockAtomTable(
    IN OUT PRTL_ATOM_TABLE AtomTable
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
#else
    RtlDeleteCriticalSection( &AtomTable->CriticalSection );
#endif
}


BOOLEAN
RtlpInitializeHandleTableForAtomTable(
    PRTL_ATOM_TABLE AtomTable
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
    AtomTable->ExHandleTable = ExCreateHandleTable( NULL, 64, 32 );
    if (AtomTable->ExHandleTable != NULL) {
        //
        // Make sure atom handle tables are NOT part of object handle enumeration
        //

        ExRemoveHandleTable( AtomTable->ExHandleTable );
        return TRUE;
        }
    else {
        return FALSE;
        }
#else
    RtlInitializeHandleTable( (ULONG)(USHORT)~RTL_ATOM_MAXIMUM_INTEGER_ATOM,
                              sizeof( RTL_ATOM_HANDLE_TABLE_ENTRY ),
                              &AtomTable->RtlHandleTable
                            );
    return TRUE;
#endif
}

void
RtlpDestroyHandleTableForAtomTable(
    PRTL_ATOM_TABLE AtomTable
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
    ExDestroyHandleTable( AtomTable->ExHandleTable, NULL );
#else
    RtlDestroyHandleTable( &AtomTable->RtlHandleTable );
#endif
    return;
}

PRTL_ATOM_TABLE_ENTRY
RtlpAtomMapAtomToHandleEntry(
    IN PRTL_ATOM_TABLE AtomTable,
    IN ULONG HandleIndex
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
    PHANDLE_ENTRY ExHandleEntry;
    PRTL_ATOM_TABLE_ENTRY a;

    ExHandleEntry = ExMapHandleToPointer( AtomTable->ExHandleTable,
                                          INDEX_TO_HANDLE( HandleIndex ),
                                          TRUE
                                        );
    if (ExHandleEntry != NULL) {
        a = ExHandleEntry->Object;
        ExUnlockHandleTableShared( AtomTable->ExHandleTable );
        return a;
        }
#else
    PRTL_ATOM_HANDLE_TABLE_ENTRY HandleEntry;

    if (RtlIsValidIndexHandle( &AtomTable->RtlHandleTable,
                               HandleIndex,
                               (PRTL_HANDLE_TABLE_ENTRY *)&HandleEntry
                             )
       ) {
        return HandleEntry->Atom;
        }
#endif
    return NULL;
}

BOOLEAN
RtlpCreateHandleForAtom(
    PRTL_ATOM_TABLE p,
    PRTL_ATOM_TABLE_ENTRY a
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
    HANDLE ExHandle;
    HANDLE_ENTRY ExHandleEntry;

    ExHandleEntry.Object = a;
    ExHandleEntry.Attributes = 0;
    ExHandle = ExCreateHandle( p->ExHandleTable, &ExHandleEntry );
    if (ExHandle != NULL) {
        a->HandleIndex = (USHORT)HANDLE_TO_INDEX( ExHandle );
        a->Atom = (RTL_ATOM)((USHORT)a->HandleIndex | RTL_ATOM_MAXIMUM_INTEGER_ATOM);
        return TRUE;
        }
#else
    PRTL_ATOM_HANDLE_TABLE_ENTRY HandleEntry;
    ULONG HandleIndex;

    HandleEntry = (PRTL_ATOM_HANDLE_TABLE_ENTRY)RtlAllocateHandle( &p->RtlHandleTable,
                                                                   &HandleIndex
                                                                 );
    if (HandleEntry != NULL) {
        if (HandleIndex < RTL_ATOM_MAXIMUM_INTEGER_ATOM) {
            a->HandleIndex = (USHORT)HandleIndex;
            a->Atom = (RTL_ATOM)((USHORT)HandleIndex | RTL_ATOM_MAXIMUM_INTEGER_ATOM);
            HandleEntry->Atom = a;
            HandleEntry->LockCount = 0;
            HandleEntry->Flags = RTL_HANDLE_ALLOCATED;
            return TRUE;
            }

        RtlFreeHandle( &p->RtlHandleTable, (PRTL_HANDLE_TABLE_ENTRY)HandleEntry );
        }
#endif
    return FALSE;
}

void
RtlpFreeHandleForAtom(
    PRTL_ATOM_TABLE p,
    PRTL_ATOM_TABLE_ENTRY a
    )
{
#if defined(NTOS_KERNEL_RUNTIME)
    ExDestroyHandle( p->ExHandleTable, INDEX_TO_HANDLE( a->HandleIndex ), FALSE );
#else
    PRTL_ATOM_HANDLE_TABLE_ENTRY HandleEntry;

    if (RtlIsValidIndexHandle( &p->RtlHandleTable,
                               a->HandleIndex,
                               (PRTL_HANDLE_TABLE_ENTRY *)&HandleEntry
                             )
       ) {
        RtlFreeHandle( &p->RtlHandleTable, (PRTL_HANDLE_TABLE_ENTRY)HandleEntry );
        }
#endif
    return;
}

NTSTATUS
RtlInitializeAtomPackage(
    IN ULONG AllocationTag
    )
{
    RtlpAtomAllocateTag = AllocationTag;
    return STATUS_SUCCESS;
}

NTSTATUS
RtlCreateAtomTable(
    IN ULONG NumberOfBuckets,
    OUT PVOID *AtomTableHandle
    )
{
    NTSTATUS Status;
    PRTL_ATOM_TABLE p;
    ULONG Size;

    Status = STATUS_SUCCESS;
    if (*AtomTableHandle == NULL) {
        if (NumberOfBuckets <= 1) {
            NumberOfBuckets = RTL_ATOM_TABLE_DEFAULT_NUMBER_OF_BUCKETS;
            }

        Size = sizeof( RTL_ATOM_TABLE ) +
               (sizeof( RTL_ATOM_TABLE_ENTRY ) * (NumberOfBuckets-1));

        p = (PRTL_ATOM_TABLE)RtlpAllocateAtom( Size );
        if (p == NULL) {
            Status = STATUS_NO_MEMORY;
            }
        else {
            RtlZeroMemory( p, Size );
            p->NumberOfBuckets = NumberOfBuckets;
            if (RtlpInitializeHandleTableForAtomTable( p )) {
                RtlpInitializeLockAtomTable( p );
                p->Signature = RTL_ATOM_TABLE_SIGNATURE;
                *AtomTableHandle = p;
                }
            else {
                Status = STATUS_NO_MEMORY;
                RtlpFreeAtom( p );
                }
            }
        }

    return Status;
}


NTSTATUS
RtlDestroyAtomTable(
    IN PVOID AtomTableHandle
    )
{
    NTSTATUS Status;
    PRTL_ATOM_TABLE p = (PRTL_ATOM_TABLE)AtomTableHandle;
    PRTL_ATOM_TABLE_ENTRY a, aNext, *pa;
    ULONG i;

    Status = STATUS_SUCCESS;
    if (!RtlpLockAtomTable( p )) {
        return STATUS_INVALID_PARAMETER;
        }
    try {
        pa = &p->Buckets[ 0 ];
        for (i=0; i<p->NumberOfBuckets; i++) {
            aNext = *pa;
            *pa++ = NULL;
            while ((a = aNext) != NULL) {
                aNext = a->HashLink;
                a->HashLink = NULL;
                RtlpFreeAtom( a );
                }
            }
        p->Signature = 0;
        RtlpUnlockAtomTable( p );

        RtlpDestroyHandleTableForAtomTable( p );
        RtlpDestroyLockAtomTable( p );
        RtlZeroMemory( p, sizeof( RTL_ATOM_TABLE ) );
        RtlpFreeAtom( p );
        }
    except (EXCEPTION_EXECUTE_HANDLER) {
        Status = GetExceptionCode();
        }

    return Status;
}

NTSTATUS
RtlEmptyAtomTable(
    IN PVOID AtomTableHandle,
    IN BOOLEAN IncludePinnedAtoms
    )
{
    NTSTATUS Status;
    PRTL_ATOM_TABLE p = (PRTL_ATOM_TABLE)AtomTableHandle;
    PRTL_ATOM_TABLE_ENTRY a, aNext, *pa, *pa1;
    ULONG i;

    Status = STATUS_SUCCESS;
    if (!RtlpLockAtomTable( p )) {
        return STATUS_INVALID_PARAMETER;
        }
    try {
        pa = &p->Buckets[ 0 ];
        for (i=0; i<p->NumberOfBuckets; i++) {
            pa1 = pa++;
            while ((a = *pa1) != NULL) {
                if (IncludePinnedAtoms || !(a->Flags & RTL_ATOM_PINNED)) {
                    *pa1 = a->HashLink;
                    a->HashLink = NULL;
                    RtlpFreeHandleForAtom( p, a );
                    RtlpFreeAtom( a );
                    }
                else {
                    pa1 = &a->HashLink;
                    }
                }
            }

        RtlpUnlockAtomTable( p );
        }
    except (EXCEPTION_EXECUTE_HANDLER) {
        Status = GetExceptionCode();
        }

    return Status;
}

BOOLEAN
RtlpGetIntegerAtom(
    PWSTR Name,
    PRTL_ATOM Atom OPTIONAL
    )
{
    NTSTATUS Status;
    UNICODE_STRING UnicodeString;
    PWSTR s;
    ULONG n;
    RTL_ATOM Temp;

    if (((ULONG)Name & 0xFFFF0000) == 0) {
        Temp = (RTL_ATOM)(USHORT)Name;
        if (Temp >= RTL_ATOM_MAXIMUM_INTEGER_ATOM) {
            return FALSE;
            }
        else {
            if (Temp == RTL_ATOM_INVALID_ATOM) {
                Temp = RTL_ATOM_MAXIMUM_INTEGER_ATOM;
                }

            if (ARGUMENT_PRESENT( Atom )) {
                *Atom = Temp;
                }

            return TRUE;
            }
        }
    else
    if (*Name != L'#') {
        return FALSE;
        }

    s = ++Name;
    while (*s != UNICODE_NULL) {
        if (*s < L'0' || *s > L'9') {
            return FALSE;
            }
        else {
            s++;
            }
        }

    n = 0;
    UnicodeString.Buffer = Name;
    UnicodeString.Length = (USHORT)((PCHAR)s - (PCHAR)Name);
    UnicodeString.MaximumLength = UnicodeString.Length;
    Status = RtlUnicodeStringToInteger( &UnicodeString, 10, &n );
    if (NT_SUCCESS( Status )) {
        if (ARGUMENT_PRESENT( Atom )) {
            if (n == 0 || n > RTL_ATOM_MAXIMUM_INTEGER_ATOM) {
                *Atom = RTL_ATOM_MAXIMUM_INTEGER_ATOM;
                }
            else {
                *Atom = (RTL_ATOM)n;
                }
            }

        return TRUE;
        }
    else {
        return FALSE;
        }
}

PRTL_ATOM_TABLE_ENTRY
RtlpHashStringToAtom(
    IN PRTL_ATOM_TABLE p,
    IN PWSTR Name,
    OUT PRTL_ATOM_TABLE_ENTRY **PreviousAtom OPTIONAL,
    OUT PULONG NameLength
    )
{
    ULONG Length, Hash;
    WCHAR c;
    PWCH s;
    RTL_ATOM Atom;
    PRTL_ATOM_TABLE_ENTRY *pa, a;

    if (((ULONG)Name & 0xFFFF0000) == 0) {
        Atom = (RTL_ATOM)(USHORT)Name;
        a = NULL;
        if (Atom >= RTL_ATOM_MAXIMUM_INTEGER_ATOM) {
            a = RtlpAtomMapAtomToHandleEntry( p,
                                              (ULONG)(Atom & (USHORT)~RTL_ATOM_MAXIMUM_INTEGER_ATOM)
                                            );
            }

        if (ARGUMENT_PRESENT( PreviousAtom )) {
            *PreviousAtom = NULL;
            }

        return a;
        }

    s = Name;
    Hash = 0;
    while (*s != UNICODE_NULL) {
        c = RtlUpcaseUnicodeChar( *s++ );
        Hash = Hash + (c << 1) + (c >> 1) + c;
        }
    Length = s - Name;
    if (Length > RTL_ATOM_MAXIMUM_NAME_LENGTH) {
        pa = NULL;
        }
    else {
        pa = &p->Buckets[ Hash % p->NumberOfBuckets ];
        while (a = *pa) {
            if (a->NameLength == Length && !_wcsicmp( a->Name, Name )) {
                break;
                }
            else {
                pa = &a->HashLink;
                }
            }
        }

    if (ARGUMENT_PRESENT( PreviousAtom )) {
        *PreviousAtom = pa;
        }

    if (a == NULL && ARGUMENT_PRESENT( NameLength )) {
        *NameLength = Length * sizeof( WCHAR );
        }

    return a;
}


NTSTATUS
RtlAddAtomToAtomTable(
    IN PVOID AtomTableHandle,
    IN PWSTR AtomName OPTIONAL,
    IN OUT PRTL_ATOM Atom OPTIONAL
    )
{
    NTSTATUS Status;
    PRTL_ATOM_TABLE p = (PRTL_ATOM_TABLE)AtomTableHandle;
    PRTL_ATOM_TABLE_ENTRY a, *pa;
    ULONG NameLength;
    RTL_ATOM Temp;

    if (!RtlpLockAtomTable( p )) {
        return STATUS_INVALID_PARAMETER;
        }
    try {
        if (RtlpGetIntegerAtom( AtomName, &Temp )) {
            if (Temp >= RTL_ATOM_MAXIMUM_INTEGER_ATOM) {
                Temp = RTL_ATOM_INVALID_ATOM;
                Status = STATUS_INVALID_PARAMETER;
                }
            else {
                Status = STATUS_SUCCESS;
                }

            if (ARGUMENT_PRESENT( Atom )) {
                *Atom = Temp;
                }
            }
        else
        if (*AtomName == UNICODE_NULL) {
            Status = STATUS_OBJECT_NAME_INVALID;
            }
        else {
            a = RtlpHashStringToAtom( p, AtomName, &pa, &NameLength );
            if (a == NULL) {
                if (pa != NULL) {
                    Status = STATUS_NO_MEMORY;
                    a = RtlpAllocateAtom( FIELD_OFFSET( RTL_ATOM_TABLE_ENTRY, Name ) +
                                          NameLength + sizeof( UNICODE_NULL )
                                        );
                    if (a != NULL) {
                        a->HashLink = NULL;
                        a->ReferenceCount = 1;
                        a->Flags = 0;
                        RtlMoveMemory( a->Name, AtomName, NameLength );
                        a->NameLength = (UCHAR)(NameLength / sizeof( WCHAR ));
                        a->Name[ a->NameLength ] = UNICODE_NULL;
                        if (RtlpCreateHandleForAtom( p, a )) {
                            a->Atom = (RTL_ATOM)a->HandleIndex | RTL_ATOM_MAXIMUM_INTEGER_ATOM;
                            *pa = a;
                            if (ARGUMENT_PRESENT( Atom )) {
                                *Atom = a->Atom;
                                }

                            Status = STATUS_SUCCESS;
                            }
                        else {
                            RtlpFreeAtom( a );
                            }
                        }
                    }
                else {
                    Status = STATUS_INVALID_PARAMETER;
                    }
                }
            else {
                if (!(a->Flags & RTL_ATOM_PINNED)) {
                    if (a->ReferenceCount == 0xFFFF) {
                        KdPrint(( "RTL: Pinning atom (%x) as reference count about to wrap\n", Atom ));
                        a->Flags |= RTL_ATOM_PINNED;
                        }
                    else {
                        a->ReferenceCount += 1;
                        }
                    }

                if (ARGUMENT_PRESENT( Atom )) {
                    *Atom = a->Atom;
                    }

                Status = STATUS_SUCCESS;
                }
            }
        }
    except (EXCEPTION_EXECUTE_HANDLER) {
        Status = GetExceptionCode();
        }

    RtlpUnlockAtomTable( p );

    return Status;
}

NTSTATUS
RtlLookupAtomInAtomTable(
    IN PVOID AtomTableHandle,
    IN PWSTR AtomName,
    OUT PRTL_ATOM Atom OPTIONAL
    )
{
    NTSTATUS Status;
    PRTL_ATOM_TABLE p = (PRTL_ATOM_TABLE)AtomTableHandle;
    PRTL_ATOM_TABLE_ENTRY a;
    RTL_ATOM Temp;

    if (!RtlpLockAtomTable( p )) {
        return STATUS_INVALID_PARAMETER;
        }
    try {
        if (RtlpGetIntegerAtom( AtomName, &Temp )) {
            if (Temp >= RTL_ATOM_MAXIMUM_INTEGER_ATOM) {
                Temp = RTL_ATOM_INVALID_ATOM;
                Status = STATUS_INVALID_PARAMETER;
                }
            else {
                Status = STATUS_SUCCESS;
                }

            if (ARGUMENT_PRESENT( Atom )) {
                *Atom = Temp;
                }
            }
        else
        if (*AtomName == UNICODE_NULL) {
            Status = STATUS_OBJECT_NAME_INVALID;
            }
        else {
            a = RtlpHashStringToAtom( p, AtomName, NULL, NULL );
            if (a == NULL) {
                Status = STATUS_OBJECT_NAME_NOT_FOUND;
                }
            else {
                if (RtlpAtomMapAtomToHandleEntry( p, (ULONG)a->HandleIndex ) != NULL) {
                    Status = STATUS_SUCCESS;
                    if (ARGUMENT_PRESENT( Atom )) {
                        *Atom = a->Atom;
                        }
                    }
                else {
                    Status = STATUS_INVALID_HANDLE;
                    }
                }
            }
        }
    except (EXCEPTION_EXECUTE_HANDLER) {
        Status = GetExceptionCode();
        }

    RtlpUnlockAtomTable( p );

    return Status;
}


NTSTATUS
RtlDeleteAtomFromAtomTable(
    IN PVOID AtomTableHandle,
    IN RTL_ATOM Atom
    )
{
    NTSTATUS Status;
    PRTL_ATOM_TABLE p = (PRTL_ATOM_TABLE)AtomTableHandle;
    PRTL_ATOM_TABLE_ENTRY a, *pa;

    if (!RtlpLockAtomTable( p )) {
        return STATUS_INVALID_PARAMETER;
        }
    try {
        Status = STATUS_INVALID_HANDLE;
        if (Atom >= RTL_ATOM_MAXIMUM_INTEGER_ATOM) {
            a = RtlpAtomMapAtomToHandleEntry( p,
                                              (ULONG)(Atom & (USHORT)~RTL_ATOM_MAXIMUM_INTEGER_ATOM)
                                            );
            if (a != NULL && a->Atom == Atom) {
                Status = STATUS_SUCCESS;
                if (a->Flags & RTL_ATOM_PINNED) {
                    KdPrint(( "RTL: Ignoring attempt to delete a pinned atom (%x)\n", Atom ));
                    Status = STATUS_WAS_LOCKED;        // This is a success status code!
                    }
                else
                if (--a->ReferenceCount == 0) {
                    a = RtlpHashStringToAtom( p, a->Name, &pa, NULL );
                    if (a != NULL) {
                        *pa = a->HashLink;
                        RtlpFreeHandleForAtom( p, a );
                        RtlpFreeAtom( a );
                        }
                    }
                }
            }
        else
        if (Atom != RTL_ATOM_INVALID_ATOM) {
            Status = STATUS_SUCCESS;
            }
        }
    except (EXCEPTION_EXECUTE_HANDLER) {
        Status = GetExceptionCode();
        }

    RtlpUnlockAtomTable( p );

    return Status;
}

NTSTATUS
RtlPinAtomInAtomTable(
    IN PVOID AtomTableHandle,
    IN RTL_ATOM Atom
    )
{
    NTSTATUS Status;
    PRTL_ATOM_TABLE p = (PRTL_ATOM_TABLE)AtomTableHandle;
    PRTL_ATOM_TABLE_ENTRY a, *pa;

    if (!RtlpLockAtomTable( p )) {
        return STATUS_INVALID_PARAMETER;
        }
    try {
        Status = STATUS_INVALID_HANDLE;
        if (Atom >= RTL_ATOM_MAXIMUM_INTEGER_ATOM) {
            a = RtlpAtomMapAtomToHandleEntry( p,
                                              (ULONG)(Atom & (USHORT)~RTL_ATOM_MAXIMUM_INTEGER_ATOM)
                                            );
            if (a != NULL && a->Atom == Atom) {
                Status = STATUS_SUCCESS;
                a->Flags |= RTL_ATOM_PINNED;
                }
            }
        else
        if (Atom != RTL_ATOM_INVALID_ATOM) {
            Status = STATUS_SUCCESS;
            }
        }
    except (EXCEPTION_EXECUTE_HANDLER) {
        Status = GetExceptionCode();
        }

    RtlpUnlockAtomTable( p );

    return Status;
}

NTSTATUS
RtlQueryAtomInAtomTable(
    IN PVOID AtomTableHandle,
    IN RTL_ATOM Atom,
    OUT PULONG AtomUsage OPTIONAL,
    OUT PULONG AtomFlags OPTIONAL,
    IN OUT PWSTR AtomName OPTIONAL,
    IN OUT PULONG AtomNameLength OPTIONAL
    )
{
    NTSTATUS Status;
    PRTL_ATOM_TABLE p = (PRTL_ATOM_TABLE)AtomTableHandle;
    PRTL_ATOM_TABLE_ENTRY a;
    WCHAR AtomNameBuffer[ 16 ];
    ULONG CopyLength;

    if (!RtlpLockAtomTable( p )) {
        return STATUS_INVALID_PARAMETER;
        }
    try {
        if (Atom < RTL_ATOM_MAXIMUM_INTEGER_ATOM) {
            if (Atom == RTL_ATOM_INVALID_ATOM) {
                Status = STATUS_INVALID_PARAMETER;
                }
            else {
                Status = STATUS_SUCCESS;
                if (ARGUMENT_PRESENT( AtomUsage )) {
                    *AtomUsage = 1;
                    }

                if (ARGUMENT_PRESENT( AtomFlags )) {
                    *AtomFlags = RTL_ATOM_PINNED;
                    }

                if (ARGUMENT_PRESENT( AtomName )) {
                    CopyLength = _snwprintf( AtomNameBuffer,
                                             sizeof( AtomNameBuffer ) / sizeof( WCHAR ),
                                             L"#%u",
                                             Atom
                                           ) * sizeof( WCHAR );
                    if (CopyLength >= *AtomNameLength) {
                        if (*AtomNameLength >= sizeof( UNICODE_NULL )) {
                            CopyLength = *AtomNameLength - sizeof( UNICODE_NULL );
                            }
                        else {
                            CopyLength = 0;
                            }
                        }

                    if (CopyLength != 0) {
                        RtlMoveMemory( AtomName, AtomNameBuffer, CopyLength );
                        AtomName[ CopyLength / sizeof( WCHAR ) ] = UNICODE_NULL;
                        *AtomNameLength = CopyLength;
                        }
                    else {
                        Status = STATUS_BUFFER_TOO_SMALL;
                        }
                    }
                }
            }
        else {
            a = RtlpAtomMapAtomToHandleEntry( p,
                                              (ULONG)(Atom & (USHORT)~RTL_ATOM_MAXIMUM_INTEGER_ATOM)
                                            );
            if (a != NULL && a->Atom == Atom) {
                Status = STATUS_SUCCESS;
                if (ARGUMENT_PRESENT( AtomUsage )) {
                    *AtomUsage = a->ReferenceCount;
                    }

                if (ARGUMENT_PRESENT( AtomFlags )) {
                    *AtomFlags = a->Flags;
                    }

                if (ARGUMENT_PRESENT( AtomName )) {
                    //
                    // Fill in as much of the atom string as possible, and
                    // always zero terminate. This is what win3.1 does.
                    //

                    CopyLength = a->NameLength * sizeof( WCHAR );
                    if (CopyLength >= *AtomNameLength) {
                        if (*AtomNameLength >= sizeof( UNICODE_NULL )) {
                            CopyLength = *AtomNameLength - sizeof( UNICODE_NULL );
                            }
                        else {
                            CopyLength = 0;
                            }
                        }
                    if (CopyLength != 0) {
                        RtlMoveMemory( AtomName, a->Name, CopyLength );
                        AtomName[ CopyLength / sizeof( WCHAR ) ] = UNICODE_NULL;
                        *AtomNameLength = CopyLength;
                        }
                    else {
                        Status = STATUS_BUFFER_TOO_SMALL;
                        }
                    }
                }
            else {
                Status = STATUS_INVALID_HANDLE;
                }
            }
        }
    except (EXCEPTION_EXECUTE_HANDLER) {
        Status = GetExceptionCode();
        }

    RtlpUnlockAtomTable( p );

    return Status;
}

NTSTATUS
RtlQueryAtomsInAtomTable(
    IN PVOID AtomTableHandle,
    IN ULONG MaximumNumberOfAtoms,
    OUT PULONG NumberOfAtoms,
    OUT PRTL_ATOM Atoms
    )
{
    NTSTATUS Status;
    PRTL_ATOM_TABLE p = (PRTL_ATOM_TABLE)AtomTableHandle;
    PRTL_ATOM_TABLE_ENTRY a;
    ULONG i;
    ULONG CurrentAtomIndex;

    if (!RtlpLockAtomTable( p )) {
        return STATUS_INVALID_PARAMETER;
        }

    Status = STATUS_SUCCESS;
    try {
        CurrentAtomIndex = 0;
        for (i=0; i<p->NumberOfBuckets; i++) {
            a = p->Buckets[ i ];
            while (a) {
                if (CurrentAtomIndex < MaximumNumberOfAtoms) {
                    Atoms[ CurrentAtomIndex ] = a->Atom;
                    }
                else {
                    Status = STATUS_INFO_LENGTH_MISMATCH;
                    }

                CurrentAtomIndex += 1;
                a = a->HashLink;
                }
            }

        *NumberOfAtoms = CurrentAtomIndex;
        }
    except (EXCEPTION_EXECUTE_HANDLER) {
        Status = GetExceptionCode();
        }

    RtlpUnlockAtomTable( p );

    return Status;
}