[reactos] 01/01: [KERNEL32] Rewrite QueryDosDeviceW to handle global and local MS-DOS namespaces
5 May
2019
5 May
'19
12:19 p.m.
https://git.reactos.org/?p=reactos.git;a=commitdiff;h=5d20d512beed5b3bdd10f…
commit 5d20d512beed5b3bdd10f3d5af525d780cd0e7d9
Author: Pierre Schweitzer <pierre(a)reactos.org>
AuthorDate: Sun May 5 14:18:09 2019 +0200
Commit: Pierre Schweitzer <pierre(a)reactos.org>
CommitDate: Sun May 5 14:18:09 2019 +0200
[KERNEL32] Rewrite QueryDosDeviceW to handle global and local MS-DOS namespaces
It also comes with a small performance boost: instead of performing object
queries one after another, we query them all at once.
---
dll/win32/kernel32/client/dosdev.c | 653 +++++++++++++++++++++++++++++++------
1 file changed, 560 insertions(+), 93 deletions(-)
diff --git a/dll/win32/kernel32/client/dosdev.c b/dll/win32/kernel32/client/dosdev.c
index b32d434195..67fd60859d 100644
--- a/dll/win32/kernel32/client/dosdev.c
+++ b/dll/win32/kernel32/client/dosdev.c
@@ -4,6 +4,7 @@
* FILE: dll/win32/kernel32/client/dosdev.c
* PURPOSE: Dos device functions
* PROGRAMMER: Ariadne (ariadne(a)xs4all.nl)
+ * Pierre Schweitzer
* UPDATE HISTORY:
* Created 01/11/98
*/
@@ -19,6 +20,142 @@ DEBUG_CHANNEL(kernel32file);
/* FUNCTIONS *****************************************************************/
+/*
+ * @implemented
+ */
+NTSTATUS
+IsGlobalDeviceMap(
+ HANDLE DirectoryHandle,
+ PBOOLEAN IsGlobal)
+{
+ NTSTATUS Status;
+ DWORD ReturnLength;
+ UNICODE_STRING GlobalString;
+ OBJECT_NAME_INFORMATION NameInfo, *PNameInfo;
+
+ /* We need both parameters */
+ if (DirectoryHandle == 0 || IsGlobal == NULL)
+ {
+ return STATUS_INVALID_PARAMETER;
+ }
+
+ PNameInfo = NULL;
+ _SEH2_TRY
+ {
+ /* Query handle information */
+ Status = NtQueryObject(DirectoryHandle,
+ ObjectNameInformation,
+ &NameInfo,
+ 0,
+ &ReturnLength);
+ /* Only failure we tolerate is length mismatch */
+ if (NT_SUCCESS(Status) || Status == STATUS_INFO_LENGTH_MISMATCH)
+ {
+ /* Allocate big enough buffer */
+ PNameInfo = RtlAllocateHeap(RtlGetProcessHeap(), 0, ReturnLength);
+ if (PNameInfo == NULL)
+ {
+ Status = STATUS_NO_MEMORY;
+ _SEH2_LEAVE;
+ }
+
+ /* Query again handle information */
+ Status = NtQueryObject(DirectoryHandle,
+ ObjectNameInformation,
+ PNameInfo,
+ ReturnLength,
+ &ReturnLength);
+
+ /*
+ * If it succeed, check we have Global??
+ * If so, return success
+ */
+ if (NT_SUCCESS(Status))
+ {
+ RtlInitUnicodeString(&GlobalString, L"\\GLOBAL??");
+ *IsGlobal = RtlEqualUnicodeString(&GlobalString,
&PNameInfo->Name, FALSE);
+ Status = STATUS_SUCCESS;
+ }
+
+
+ }
+ }
+ _SEH2_FINALLY
+ {
+ if (PNameInfo != NULL)
+ {
+ RtlFreeHeap(RtlGetProcessHeap(), 0, PNameInfo);
+ }
+ }
+ _SEH2_END;
+
+ return Status;
+}
+
+/*
+ * @implemented
+ */
+DWORD
+FindSymbolicLinkEntry(
+ PWSTR NameToFind,
+ PWSTR NamesList,
+ DWORD TotalEntries,
+ PBOOLEAN Found)
+{
+ WCHAR Current;
+ DWORD Entries;
+ PWSTR PartialNamesList;
+
+ /* We need all parameters to be set */
+ if (NameToFind == NULL || NamesList == NULL || Found == NULL)
+ {
+ return ERROR_INVALID_PARAMETER;
+ }
+
+ /* Assume failure */
+ *Found = FALSE;
+
+ /* If no entries, job done, nothing found */
+ if (TotalEntries == 0)
+ {
+ return ERROR_SUCCESS;
+ }
+
+ /* Start browsing the names list */
+ Entries = 0;
+ PartialNamesList = NamesList;
+ /* As long as we didn't find the name... */
+ while (wcscmp(NameToFind, PartialNamesList) != 0)
+ {
+ /* We chomped an entry! */
+ ++Entries;
+
+ /* We're out of entries, bail out not to overrun */
+ if (Entries > TotalEntries)
+ {
+ /*
+ * Even though we found nothing,
+ * the function ran fine
+ */
+ return ERROR_SUCCESS;
+ }
+
+ /* Jump to the next string */
+ do
+ {
+ Current = *PartialNamesList;
+ ++PartialNamesList;
+ } while (Current != UNICODE_NULL);
+ }
+
+ /*
+ * We're here because the loop stopped:
+ * it means we found the name in the list
+ */
+ *Found = TRUE;
+ return ERROR_SUCCESS;
+}
+
/*
* @implemented
*/
@@ -381,19 +518,17 @@ QueryDosDeviceW(
DWORD ucchMax
)
{
- POBJECT_DIRECTORY_INFORMATION DirInfo;
- OBJECT_ATTRIBUTES ObjectAttributes;
- UNICODE_STRING UnicodeString;
- HANDLE DirectoryHandle;
- HANDLE DeviceHandle;
- ULONG ReturnLength;
- ULONG NameLength;
- ULONG Length;
- ULONG Context;
- BOOLEAN RestartScan;
- NTSTATUS Status;
- UCHAR Buffer[512];
PWSTR Ptr;
+ PVOID Buffer;
+ NTSTATUS Status;
+ USHORT i, TotalEntries;
+ UNICODE_STRING UnicodeString;
+ OBJECT_ATTRIBUTES ObjectAttributes;
+ HANDLE DirectoryHandle, DeviceHandle;
+ BOOLEAN IsGlobal, GlobalNeeded, Found;
+ POBJECT_DIRECTORY_INFORMATION DirInfo;
+ OBJECT_DIRECTORY_INFORMATION NullEntry = {{0}};
+ ULONG ReturnLength, NameLength, Length, Context, BufferLength;
/* Open the '\??' directory */
RtlInitUnicodeString(&UnicodeString, L"\\??");
@@ -412,123 +547,455 @@ QueryDosDeviceW(
return 0;
}
- Length = 0;
-
- if (lpDeviceName != NULL)
+ Buffer = NULL;
+ _SEH2_TRY
{
- /* Open the lpDeviceName link object */
- RtlInitUnicodeString(&UnicodeString, (PWSTR)lpDeviceName);
- InitializeObjectAttributes(&ObjectAttributes,
- &UnicodeString,
- OBJ_CASE_INSENSITIVE,
- DirectoryHandle,
- NULL);
- Status = NtOpenSymbolicLinkObject(&DeviceHandle,
- SYMBOLIC_LINK_QUERY,
- &ObjectAttributes);
- if (!NT_SUCCESS(Status))
+ if (lpDeviceName != NULL)
{
- WARN("NtOpenSymbolicLinkObject() failed (Status %lx)\n", Status);
- NtClose(DirectoryHandle);
- BaseSetLastNTError(Status);
- return 0;
- }
+ /* Open the lpDeviceName link object */
+ RtlInitUnicodeString(&UnicodeString, lpDeviceName);
+ InitializeObjectAttributes(&ObjectAttributes,
+ &UnicodeString,
+ OBJ_CASE_INSENSITIVE,
+ DirectoryHandle,
+ NULL);
+ Status = NtOpenSymbolicLinkObject(&DeviceHandle,
+ SYMBOLIC_LINK_QUERY,
+ &ObjectAttributes);
+ if (!NT_SUCCESS(Status))
+ {
+ WARN("NtOpenSymbolicLinkObject() failed (Status %lx)\n",
Status);
+ _SEH2_LEAVE;
+ }
- /* Query link target */
- UnicodeString.Length = 0;
- UnicodeString.MaximumLength = (USHORT)ucchMax * sizeof(WCHAR);
- UnicodeString.Buffer = lpTargetPath;
-
- ReturnLength = 0;
- Status = NtQuerySymbolicLinkObject(DeviceHandle,
- &UnicodeString,
- &ReturnLength);
- NtClose(DeviceHandle);
- NtClose(DirectoryHandle);
- if (!NT_SUCCESS(Status))
- {
- WARN("NtQuerySymbolicLinkObject() failed (Status %lx)\n", Status);
- BaseSetLastNTError(Status);
- return 0;
- }
+ /*
+ * Make sure we don't overrun the output buffer, so convert our DWORD
+ * size to USHORT size properly
+ */
+ Length = (ucchMax <= MAXULONG / sizeof(WCHAR)) ? (ucchMax * sizeof(WCHAR))
: MAXULONG;
+
+ /* Query link target */
+ UnicodeString.Length = 0;
+ UnicodeString.MaximumLength = Length <= MAXUSHORT ? Length : MAXUSHORT;
+ UnicodeString.Buffer = lpTargetPath;
+
+ ReturnLength = 0;
+ Status = NtQuerySymbolicLinkObject(DeviceHandle,
+ &UnicodeString,
+ &ReturnLength);
+ NtClose(DeviceHandle);
+ if (!NT_SUCCESS(Status))
+ {
+ WARN("NtQuerySymbolicLinkObject() failed (Status %lx)\n",
Status);
+ _SEH2_LEAVE;
+ }
- TRACE("ReturnLength: %lu\n", ReturnLength);
- TRACE("TargetLength: %hu\n", UnicodeString.Length);
- TRACE("Target: '%wZ'\n", &UnicodeString);
+ TRACE("ReturnLength: %lu\n", ReturnLength);
+ TRACE("TargetLength: %hu\n", UnicodeString.Length);
+ TRACE("Target: '%wZ'\n", &UnicodeString);
- Length = UnicodeString.Length / sizeof(WCHAR);
- if (Length < ucchMax)
- {
- /* Append null-character */
- lpTargetPath[Length] = UNICODE_NULL;
- Length++;
+ Length = ReturnLength / sizeof(WCHAR);
+ /* Make sure we null terminate output buffer */
+ if (Length == 0 || lpTargetPath[Length - 1] != UNICODE_NULL)
+ {
+ if (Length >= ucchMax)
+ {
+ TRACE("Buffer is too small\n");
+ Status = STATUS_BUFFER_TOO_SMALL;
+ _SEH2_LEAVE;
+ }
+
+ /* Append null-character */
+ lpTargetPath[Length] = UNICODE_NULL;
+ Length++;
+ }
+
+ if (Length < ucchMax)
+ {
+ /* Append null-character */
+ lpTargetPath[Length] = UNICODE_NULL;
+ Length++;
+ }
+
+ _SEH2_LEAVE;
}
- else
+
+ /*
+ * If LUID device maps are enabled,
+ * ?? may not point to BaseNamedObjects
+ * It may only be local DOS namespace.
+ * And thus, it might be required to browse
+ * Global?? for global devices
+ */
+ GlobalNeeded = FALSE;
+ if (BaseStaticServerData->LUIDDeviceMapsEnabled)
{
- TRACE("Buffer is too small\n");
- BaseSetLastNTError(STATUS_BUFFER_TOO_SMALL);
- return 0;
+ /* Assume ?? == Global?? */
+ IsGlobal = TRUE;
+ /* Check if it's the case */
+ Status = IsGlobalDeviceMap(DirectoryHandle, &IsGlobal);
+ if (NT_SUCCESS(Status) && !IsGlobal)
+ {
+ /* It's not, we'll have to browse Global?? too! */
+ GlobalNeeded = TRUE;
+ }
}
- }
- else
- {
- RestartScan = TRUE;
- Context = 0;
+
+ /*
+ * Make sure we don't overrun the output buffer, so convert our DWORD
+ * size to USHORT size properly
+ */
+ BufferLength = (ucchMax <= MAXULONG / sizeof(WCHAR)) ? (ucchMax *
sizeof(WCHAR)) : MAXULONG;
+ Length = 0;
Ptr = lpTargetPath;
- DirInfo = (POBJECT_DIRECTORY_INFORMATION)Buffer;
- while (TRUE)
+ Context = 0;
+ TotalEntries = 0;
+
+ /*
+ * We'll query all entries at once, with a rather big buffer
+ * If it's too small, we'll grow it by 2.
+ * Limit the number of attempts to 3.
+ */
+ for (i = 0; i < 3; ++i)
{
+ /* Allocate the query buffer */
+ Buffer = RtlAllocateHeap(RtlGetProcessHeap(), 0, BufferLength);
+ if (Buffer == NULL)
+ {
+ Status = STATUS_INSUFFICIENT_RESOURCES;
+ _SEH2_LEAVE;
+ }
+
+ /* Perform the query */
Status = NtQueryDirectoryObject(DirectoryHandle,
Buffer,
- sizeof(Buffer),
+ BufferLength,
+ FALSE,
TRUE,
- RestartScan,
&Context,
&ReturnLength);
+ /* Only failure accepted is: no more entries */
if (!NT_SUCCESS(Status))
{
- if (Status == STATUS_NO_MORE_ENTRIES)
+ if (Status != STATUS_NO_MORE_ENTRIES)
{
- /* Terminate the buffer */
- *Ptr = UNICODE_NULL;
- Length++;
-
- Status = STATUS_SUCCESS;
+ _SEH2_LEAVE;
}
- else
+
+ /*
+ * Which is a success! But break out,
+ * it means our query returned no results
+ * so, nothing to parse.
+ */
+ Status = STATUS_SUCCESS;
+ break;
+ }
+
+ /* In case we had them all, start browsing for devices */
+ if (Status != STATUS_MORE_ENTRIES)
+ {
+ DirInfo = Buffer;
+
+ /* Loop until we find the nul entry (terminating entry) */
+ while (TRUE)
{
- Length = 0;
+ /* It's an entry full of zeroes */
+ if (RtlCompareMemory(&NullEntry, DirInfo, sizeof(NullEntry)) ==
sizeof(NullEntry))
+ {
+ break;
+ }
+
+ /* Only handle symlinks */
+ if (!wcscmp(DirInfo->TypeName.Buffer, L"SymbolicLink"))
+ {
+ TRACE("Name: '%wZ'\n", &DirInfo->Name);
+
+ /* Get name length in chars to only comparisons */
+ NameLength = DirInfo->Name.Length / sizeof(WCHAR);
+
+ /* Make sure we don't overrun output buffer */
+ if (Length > ucchMax ||
+ NameLength > ucchMax - Length ||
+ ucchMax - NameLength - Length < sizeof(WCHAR))
+ {
+ Status = STATUS_BUFFER_TOO_SMALL;
+ _SEH2_LEAVE;
+ }
+
+ /* Copy and NULL terminate string */
+ memcpy(Ptr, DirInfo->Name.Buffer, DirInfo->Name.Length);
+ Ptr[NameLength] = UNICODE_NULL;
+
+ Ptr += (NameLength + 1);
+ Length += (NameLength + 1);
+
+ /*
+ * Keep the entries count, in case we would have to
+ * handle GLOBAL?? too
+ */
+ ++TotalEntries;
+ }
+
+ /* Move to the next entry */
+ ++DirInfo;
}
- BaseSetLastNTError(Status);
+
+ /*
+ * No need to loop again here, we got all the entries
+ * Note: we don't free the buffer here, because we may
+ * need it for GLOBAL??, so we save a few cycles here.
+ */
+ break;
+ }
+
+ /* Failure path here, we'll need bigger buffer */
+ RtlFreeHeap(RtlGetProcessHeap(), 0, Buffer);
+ Buffer = NULL;
+
+ /* We can't have bigger than that one, so leave */
+ if (BufferLength == MAXULONG)
+ {
break;
}
- if (!wcscmp(DirInfo->TypeName.Buffer, L"SymbolicLink"))
+ /* Prevent any overflow while computing new size */
+ if (MAXULONG - BufferLength < BufferLength)
{
- TRACE("Name: '%wZ'\n", &DirInfo->Name);
+ BufferLength = MAXULONG;
+ }
+ else
+ {
+ BufferLength *= 2;
+ }
+ }
+
+ /*
+ * Out of the hot loop, but with more entries left?
+ * that's an error case, leave here!
+ */
+ if (Status == STATUS_MORE_ENTRIES)
+ {
+ Status = STATUS_BUFFER_TOO_SMALL;
+ _SEH2_LEAVE;
+ }
+
+ /* Now, if we had to handle GLOBAL??, go for it! */
+ if (BaseStaticServerData->LUIDDeviceMapsEnabled && NT_SUCCESS(Status)
&& GlobalNeeded)
+ {
+ NtClose(DirectoryHandle);
+ DirectoryHandle = 0;
+
+ RtlInitUnicodeString(&UnicodeString, L"\\GLOBAL??");
+ InitializeObjectAttributes(&ObjectAttributes,
+ &UnicodeString,
+ OBJ_CASE_INSENSITIVE,
+ NULL,
+ NULL);
+ Status = NtOpenDirectoryObject(&DirectoryHandle,
+ DIRECTORY_QUERY,
+ &ObjectAttributes);
+ if (!NT_SUCCESS(Status))
+ {
+ WARN("NtOpenDirectoryObject() failed (Status %lx)\n", Status);
+ _SEH2_LEAVE;
+ }
+
+ /*
+ * We'll query all entries at once, with a rather big buffer
+ * If it's too small, we'll grow it by 2.
+ * Limit the number of attempts to 3.
+ */
+ for (i = 0; i < 3; ++i)
+ {
+ /* If we had no buffer from previous attempt, allocate one */
+ if (Buffer == NULL)
+ {
+ Buffer = RtlAllocateHeap(RtlGetProcessHeap(), 0, BufferLength);
+ if (Buffer == NULL)
+ {
+ Status = STATUS_INSUFFICIENT_RESOURCES;
+ _SEH2_LEAVE;
+ }
+ }
+
+ /* Perform the query */
+ Status = NtQueryDirectoryObject(DirectoryHandle,
+ Buffer,
+ BufferLength,
+ FALSE,
+ TRUE,
+ &Context,
+ &ReturnLength);
+ /* Only failure accepted is: no more entries */
+ if (!NT_SUCCESS(Status))
+ {
+ if (Status != STATUS_NO_MORE_ENTRIES)
+ {
+ _SEH2_LEAVE;
+ }
- NameLength = DirInfo->Name.Length / sizeof(WCHAR);
- if (Length + NameLength + 1 >= ucchMax)
+ /*
+ * Which is a success! But break out,
+ * it means our query returned no results
+ * so, nothing to parse.
+ */
+ Status = STATUS_SUCCESS;
+ break;
+ }
+
+ /* In case we had them all, start browsing for devices */
+ if (Status != STATUS_MORE_ENTRIES)
+ {
+ DirInfo = Buffer;
+
+ /* Loop until we find the nul entry (terminating entry) */
+ while (TRUE)
+ {
+ /* It's an entry full of zeroes */
+ if (RtlCompareMemory(&NullEntry, DirInfo, sizeof(NullEntry))
== sizeof(NullEntry))
+ {
+ break;
+ }
+
+ /* Only handle symlinks */
+ if (!wcscmp(DirInfo->TypeName.Buffer,
L"SymbolicLink"))
+ {
+ TRACE("Name: '%wZ'\n",
&DirInfo->Name);
+
+ /*
+ * Now, we previously already browsed ??, and we
+ * don't want to devices twice, so we'll check
+ * the output buffer for duplicates.
+ * We'll add our entry only if we don't have already
+ * returned it.
+ */
+ if (FindSymbolicLinkEntry(DirInfo->Name.Buffer,
+ lpTargetPath,
+ TotalEntries,
+ &Found) == ERROR_SUCCESS
&&
+ !Found)
+ {
+ /* Get name length in chars to only comparisons */
+ NameLength = DirInfo->Name.Length / sizeof(WCHAR);
+
+ /* Make sure we don't overrun output buffer */
+ if (Length > ucchMax ||
+ NameLength > ucchMax - Length ||
+ ucchMax - NameLength - Length < sizeof(WCHAR))
+ {
+ RtlFreeHeap(RtlGetProcessHeap(), 0, Buffer);
+ NtClose(DirectoryHandle);
+ BaseSetLastNTError(STATUS_BUFFER_TOO_SMALL);
+ return 0;
+ }
+
+ /* Copy and NULL terminate string */
+ memcpy(Ptr, DirInfo->Name.Buffer,
DirInfo->Name.Length);
+ Ptr[NameLength] = UNICODE_NULL;
+
+ Ptr += (NameLength + 1);
+ Length += (NameLength + 1);
+ }
+ }
+
+ /* Move to the next entry */
+ ++DirInfo;
+ }
+
+ /* No need to loop again here, we got all the entries */
+ break;
+ }
+
+ /* Failure path here, we'll need bigger buffer */
+ RtlFreeHeap(RtlGetProcessHeap(), 0, Buffer);
+ Buffer = NULL;
+
+ /* We can't have bigger than that one, so leave */
+ if (BufferLength == MAXULONG)
{
- Length = 0;
- BaseSetLastNTError(STATUS_BUFFER_TOO_SMALL);
break;
}
- memcpy(Ptr, DirInfo->Name.Buffer, DirInfo->Name.Length);
- Ptr += NameLength;
- Length += NameLength;
- *Ptr = UNICODE_NULL;
- Ptr++;
- Length++;
+ /* Prevent any overflow while computing new size */
+ if (MAXULONG - BufferLength < BufferLength)
+ {
+ BufferLength = MAXULONG;
+ }
+ else
+ {
+ BufferLength *= 2;
+ }
+ }
+
+ /*
+ * Out of the hot loop, but with more entries left?
+ * that's an error case, leave here!
+ */
+ if (Status == STATUS_MORE_ENTRIES)
+ {
+ Status = STATUS_BUFFER_TOO_SMALL;
+ _SEH2_LEAVE;
+ }
+ }
+
+ /* If we failed somewhere, just leave */
+ if (!NT_SUCCESS(Status))
+ {
+ _SEH2_LEAVE;
+ }
+
+ /* If we returned no entries, time to write the empty string */
+ if (Length == 0)
+ {
+ /* Unless output buffer is too small! */
+ if (ucchMax <= 0)
+ {
+ Status = STATUS_BUFFER_TOO_SMALL;
+ _SEH2_LEAVE;
}
- RestartScan = FALSE;
+ /* Emptry string is one char (terminator!) */
+ *Ptr = UNICODE_NULL;
+ ++Ptr;
+ Length = 1;
}
- NtClose(DirectoryHandle);
+ /*
+ * If we have enough room, we need to double terminate the buffer:
+ * that's a MULTI_SZ buffer, its end is marked by double NULL.
+ * One was already added during the "copy string" process.
+ * If we don't have enough room: that's a failure case.
+ */
+ if (Length < ucchMax)
+ {
+ *Ptr = UNICODE_NULL;
+ ++Ptr;
+ }
+ else
+ {
+ Status = STATUS_BUFFER_TOO_SMALL;
+ }
+ }
+ _SEH2_FINALLY
+ {
+ if (DirectoryHandle != 0)
+ {
+ NtClose(DirectoryHandle);
+ }
+
+ if (Buffer != NULL)
+ {
+ RtlFreeHeap(RtlGetProcessHeap(), 0, Buffer);
+ }
+
+ if (!NT_SUCCESS(Status))
+ {
+ Length = 0;
+ BaseSetLastNTError(Status);
+ }
}
+ _SEH2_END;
return Length;
}
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Pierre Schweitzer