Source code of Windows XP (NT5)
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/*++
Copyright (c) 1991 Microsoft Corporation
Module Name:
Regnccls.c
Abstract:
This file contains functions needed for handling
change notifications in the classes portion of the registry
Author:
Adam P. Edwards (adamed) 14-Nov-1997
Key Functions:
BaseRegNotifyClassKey
Notes:
--*/
#ifdef LOCAL
#include <rpc.h>
#include <string.h>
#include <wchar.h>
#include "regrpc.h"
#include "localreg.h"
#include "regclass.h"
#include "regnccls.h"
#include <malloc.h>
NTSTATUS BaseRegNotifyClassKey(
IN HKEY hKey,
IN HANDLE hEvent,
IN PIO_STATUS_BLOCK pLocalIoStatusBlock,
IN DWORD dwNotifyFilter,
IN BOOLEAN fWatchSubtree,
IN BOOLEAN fAsynchronous)
{
NTSTATUS Status;
HKEY hkUser;
HKEY hkMachine;
SKeySemantics KeyInfo;
UNICODE_STRING EmptyString = {0, 0, 0};
BYTE rgNameBuf[REG_MAX_CLASSKEY_LEN + REG_CHAR_SIZE + sizeof(OBJECT_NAME_INFORMATION)];
OBJECT_ATTRIBUTES Obja;
BOOL fAllocatedPath;
//
// Set buffer to store info about this key
//
KeyInfo._pFullPath = (PKEY_NAME_INFORMATION) rgNameBuf;
KeyInfo._cbFullPath = sizeof(rgNameBuf);
KeyInfo._fAllocedNameBuf = FALSE;
//
// get information about this key
//
Status = BaseRegGetKeySemantics(hKey, &EmptyString, &KeyInfo);
if (!NT_SUCCESS(Status)) {
return Status;
}
//
// Initialize conditionally freed resources
//
hkUser = NULL;
hkMachine = NULL;
fAllocatedPath = FALSE;
Obja.ObjectName = NULL;
//
// Now get handles for both user and machine versions of the key
//
Status = BaseRegGetUserAndMachineClass(
&KeyInfo,
hKey,
KEY_NOTIFY,
&hkUser,
&hkMachine);
if (!NT_SUCCESS(Status)) {
goto cleanup;
}
if (fWatchSubtree || (hkUser && hkMachine)) {
//
// This will return the closest ancestor to the
// nonexistent translated key -- note that it allocates memory
// to the Obja.ObjectName member, so we need to free that on
// success
//
Status = BaseRegGetBestAncestor(
&KeyInfo,
hkUser,
hkMachine,
&Obja);
fAllocatedPath = Obja.ObjectName != NULL;
if (!NT_SUCCESS(Status)) {
goto cleanup;
}
//
// Ask for the notify on both user and machine keys (or
// the closest approximation). Note that we pass a full path --
// if we used an relative path with an object handle instead, we
// would never have an opportunity to close the object, so we would
// leak objects
//
//
Status = NtNotifyChangeMultipleKeys(
hKey,
1,
&Obja,
hEvent,
NULL,
NULL,
pLocalIoStatusBlock,
dwNotifyFilter,
fWatchSubtree,
NULL,
0,
fAsynchronous
);
} else {
Status = NtNotifyChangeKey(
hkUser ? hkUser : hkMachine,
hEvent,
NULL,
NULL,
pLocalIoStatusBlock,
dwNotifyFilter,
fWatchSubtree,
NULL,
0,
fAsynchronous
);
}
cleanup:
//if (!NT_SUCCESS(Status)) {
if (hkUser && (hkUser != hKey)) {
NtClose(hkUser);
}
if (hkMachine && (hkMachine != hKey)) {
NtClose(hkMachine);
}
//}
if (fAllocatedPath) {
RegClassHeapFree(Obja.ObjectName);
}
return Status;
}
NTSTATUS BaseRegGetBestAncestor(
IN SKeySemantics* pKeySemantics,
IN HKEY hkUser,
IN HKEY hkMachine,
IN POBJECT_ATTRIBUTES pObja)
/*++
Routine Description:
Finds a full object path for the closest ancestor for a key
described by a key semantics structure
Arguments:
pKeySemantics - contains information about a registry key
hkUser - handle to a user class version of the key above
hkMachine - handle to a machine class version of the key above
pObja - Object Attributes structure to initialize with a full
object path for the closest ancestor -- not that memory
is allocated for the ObjectName member of the structure
which must be freed by the caller -- caller should
check this member to see if it's non-NULL, regardless
of success code returned by function
Return Value:
Returns ERROR_SUCCESS (0) for success; error-code for failure.
--*/
{
USHORT PrefixLen;
NTSTATUS Status;
PUNICODE_STRING pKeyPath;
USHORT uMaxLen;
//
// Allocate memory for the Obja's ObjectName member
//
uMaxLen = (USHORT) pKeySemantics->_pFullPath->NameLength + REG_CLASSES_SUBTREE_PADDING;
pKeyPath = RegClassHeapAlloc(uMaxLen + sizeof(*pKeyPath));
if (!(pKeyPath)) {
return STATUS_NO_MEMORY;
}
//
// Now initialize the structure
//
pKeyPath->MaximumLength = uMaxLen;
pKeyPath->Buffer = (WCHAR*) (((PBYTE) pKeyPath) + sizeof(*pKeyPath));
//
// Now form a version of this key path in the opposite tree
//
if (pKeySemantics->_fUser) {
Status = BaseRegTranslateToMachineClassKey(
pKeySemantics,
pKeyPath,
&PrefixLen);
} else {
Status = BaseRegTranslateToUserClassKey(
pKeySemantics,
pKeyPath,
&PrefixLen);
}
//
// Make sure the caller has a reference to allocated memory
//
pObja->ObjectName = pKeyPath;
if (!NT_SUCCESS(Status)) {
goto cleanup;
}
//
// Set up the object attributes with this translated key so
// we can use the structure to notify keys
//
InitializeObjectAttributes(
pObja,
pKeyPath,
OBJ_CASE_INSENSITIVE,
NULL, // using absolute path, no hkey
NULL);
//
// If we were supplied both keys, then they both exist,
// so we can simply use the translated path above
//
if (hkUser && hkMachine) {
goto cleanup;
}
//
// At this point, we know the translated path doesn't exist,
// since we only have a handle for one of the paths. Therefore
// we will attempt to find an approximation. Note that the
// manipulation of KeyPath below affects the Obja passed in since
// the Obja struct references KeyPath
//
do
{
WCHAR* pBufferEnd;
HKEY hkExistingKey;
//
// Find the last pathsep in the current key path
//
pBufferEnd = wcsrchr(pKeyPath->Buffer, L'\\');
//
// We should never get NULL here, because all keys
// have the ancestory \Registry\User or \Registry\Machine,
// each which have two pathseps to spare -- the loop
// terminates once that path is shorter than those prefixes,
// so we should never encounter this situation
//
ASSERT(pBufferEnd);
//
// Now truncate the string
//
*pBufferEnd = L'\0';
//
// Adjust the unicode string structure to conform
// to the truncated string
//
RtlInitUnicodeString(pKeyPath, pKeyPath->Buffer);
//
// Now attempt to open with this truncated path
//
Status = NtOpenKey(
&hkExistingKey,
KEY_NOTIFY,
pObja);
//
// If we do open it, we will close it and not pass this object
// since we want our obja to use a full path and not a relative
// path off a kernel object
//
if (NT_SUCCESS(Status)) {
NtClose(hkExistingKey);
break;
}
//
// If we get any error besides a key not found error, then our reason
// for failing the open is not because the key did not exist, but because
// of some other error, most likely access denied.
//
if (STATUS_OBJECT_NAME_NOT_FOUND != Status) {
break;
}
} while (pKeyPath->Length > PrefixLen);
cleanup:
return Status;
}
#endif // defined ( LOCAL )