diff --git a/drivers/filesystems/udfs/CMakeLists.txt b/drivers/filesystems/udfs/CMakeLists.txt
index 1ae3d50d9b070..4c80d75da5aa4 100644
--- a/drivers/filesystems/udfs/CMakeLists.txt
+++ b/drivers/filesystems/udfs/CMakeLists.txt
@@ -2,55 +2,53 @@
 include_directories(Include)
 
 list(APPEND SOURCE
-    udf_info/alloc.cpp
-    udf_info/dirtree.cpp
-    udf_info/extent.cpp
-    udf_info/mount.cpp
-    udf_info/phys_eject.cpp
-    udf_info/physical.cpp
-    udf_info/remap.cpp
-    udf_info/udf_info.cpp
-    cleanup.cpp
-    close.cpp
-    create.cpp
-    devcntrl.cpp
-    dircntrl.cpp
-    env_spec.cpp
-    fastio.cpp
-    fileinfo.cpp
-    flush.cpp
-    fscntrl.cpp
-    lockctrl.cpp
-    mem.cpp
-    misc.cpp
-    namesup.cpp
-    prefxsup.cpp
-    pnp.cpp
-    read.cpp
-    secursup.cpp
-    shutdown.cpp
-    sys_spec.cpp
-    udf_dbg.cpp
-    udfinit.cpp
-    unload.cpp
-    verfysup.cpp
-    volinfo.cpp
-    write.cpp
-    strucsup.cpp
-    filobsup.cpp
-    udfdata.cpp
+    udf_info/alloc.c
+    udf_info/dirtree.c
+    udf_info/extent.c
+    udf_info/mount.c
+    udf_info/phys_eject.c
+    udf_info/physical.c
+    udf_info/remap.c
+    udf_info/udf_info.c
+    cleanup.c
+    close.c
+    create.c
+    devcntrl.c
+    dircntrl.c
+    env_spec.c
+    fastio.c
+    fileinfo.c
+    flush.c
+    fscntrl.c
+    lockctrl.c
+    mem.c
+    misc.c
+    namesup.c
+    prefxsup.c
+    pnp.c
+    read.c
+    secursup.c
+    shutdown.c
+    sys_spec.c
+    udf_dbg.c
+    udfinit.c
+    unload.c
+    verfysup.c
+    volinfo.c
+    write.c
+    strucsup.c
+    filobsup.c
+    udfdata.c
     udffs.h)
 
 add_library(udfs MODULE ${SOURCE} udffs.rc)
 
 if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
     target_compile_options(udfs PRIVATE -Wno-unused-but-set-variable)
-    target_compile_options(udfs PRIVATE -Wno-invalid-offsetof)
-    target_compile_options(udfs PRIVATE -Wno-error -fpermissive)
 endif()
 
 if(CMAKE_C_COMPILER_ID STREQUAL "Clang")
-    target_compile_options(udfs PRIVATE -Wno-extern-c-compat -Wno-unused-value)
+    target_compile_options(udfs PRIVATE -Wno-unused-value)
     target_compile_options(udfs PRIVATE -Wno-tautological-constant-out-of-range-compare)
     target_compile_options(udfs PRIVATE -Wno-tautological-unsigned-zero-compare -Wno-self-assign)
     target_compile_options(udfs PRIVATE -Wno-sometimes-uninitialized -Wno-parentheses-equality)
diff --git a/drivers/filesystems/udfs/Include/Sys_spec_lib.cpp b/drivers/filesystems/udfs/Include/Sys_spec_lib.c
similarity index 100%
rename from drivers/filesystems/udfs/Include/Sys_spec_lib.cpp
rename to drivers/filesystems/udfs/Include/Sys_spec_lib.c
diff --git a/drivers/filesystems/udfs/Include/Sys_spec_lib.h b/drivers/filesystems/udfs/Include/Sys_spec_lib.h
index 7187ab6e0371b..696022e2d2d4c 100644
--- a/drivers/filesystems/udfs/Include/Sys_spec_lib.h
+++ b/drivers/filesystems/udfs/Include/Sys_spec_lib.h
@@ -104,7 +104,7 @@ __inline LARGE_INTEGER UDFMakeLargeInteger(LONGLONG value) {
 
 #define UDFGetNTFileId(Vcb, fi) \
     UDFMakeLargeInteger((((fi)->Dloc->FELoc.Mapping[0].extLocation - UDFPartStart(Vcb, -2)) + \
-                      ((LONGLONG)Vcb<<32)))
+                      ((LONGLONG)(ULONG_PTR)Vcb<<32)))
 
 #define UnicodeIsPrint(a) RtlIsValidOemCharacter(&(a))
 
diff --git a/drivers/filesystems/udfs/Include/mem_tools.cpp b/drivers/filesystems/udfs/Include/mem_tools.c
similarity index 100%
rename from drivers/filesystems/udfs/Include/mem_tools.cpp
rename to drivers/filesystems/udfs/Include/mem_tools.c
diff --git a/drivers/filesystems/udfs/Include/mem_tools.h b/drivers/filesystems/udfs/Include/mem_tools.h
index fa06ad9708fb5..259d95e1a4dcc 100644
--- a/drivers/filesystems/udfs/Include/mem_tools.h
+++ b/drivers/filesystems/udfs/Include/mem_tools.h
@@ -46,6 +46,7 @@ extern ULONG MemTotalAllocated;
 #define MY_HEAP_MAX_FRAMES          512
 #define MY_HEAP_MAX_BLOCKS          4*1024  // blocks per frame
 
+#ifdef MY_USE_INTERNAL_MEMMANAGER
 // Mem
 BOOLEAN MyAllocInit(VOID);
 VOID MyAllocRelease(VOID);
@@ -66,6 +67,8 @@ ULONG __fastcall MyReallocPool( PCHAR addr, ULONG OldLength, PCHAR* NewBuff, ULO
 #endif
 VOID __fastcall MyFreePool(PCHAR addr);
 
+#endif // MY_USE_INTERNAL_MEMMANAGER
+
 #ifdef MY_HEAP_CHECK_BOUNDS
   #define MY_HEAP_ALIGN             63
 #else
@@ -130,7 +133,7 @@ MyFindMemBaseByAddr(
 #define MyAlignSize__(size) (size)
 #endif
 
-BOOLEAN inline MyAllocInit(VOID) {return TRUE;}
+static inline BOOLEAN MyAllocInit(VOID) {return TRUE;}
 #define MyAllocRelease()
 
 #ifndef MY_MEM_BOUNDS_CHECK
@@ -176,7 +179,7 @@ PVOID inline MyAllocatePool__(ULONG type, ULONG len) {
 }
 */
 
-PVOID inline MyAllocatePoolTag__(ULONG type, ULONG len, /*PCHAR*/ULONG tag) {
+static inline PVOID MyAllocatePoolTag__(ULONG type, ULONG len, /*PCHAR*/ULONG tag) {
     PCHAR newaddr;
     ULONG i;
 //    newaddr = (PCHAR)MyAllocatePoolTag_(type, len+MY_HEAP_ALIGN+1, tag);
@@ -193,7 +196,7 @@ PVOID inline MyAllocatePoolTag__(ULONG type, ULONG len, /*PCHAR*/ULONG tag) {
     return newaddr;
 }
 
-VOID inline MyFreePool__(PVOID addr) {
+static inline VOID MyFreePool__(PVOID addr) {
     PCHAR newaddr;
 //    ULONG i;
     newaddr = (PCHAR)addr;
@@ -220,7 +223,7 @@ VOID inline MyFreePool__(PVOID addr) {
 #pragma GCC diagnostic ignored "-Wstringop-overflow"
 #endif
 
-ULONG inline MyReallocPool__(PCHAR addr, ULONG len, PCHAR *pnewaddr, ULONG newlen) {
+static inline ULONG MyReallocPool__(PCHAR addr, ULONG len, PCHAR *pnewaddr, ULONG newlen) {
     ULONG _len, _newlen;
     _newlen = MyAlignSize__(newlen);
     _len = MyAlignSize__(len);
diff --git a/drivers/filesystems/udfs/Include/phys_lib.cpp b/drivers/filesystems/udfs/Include/phys_lib.c
similarity index 99%
rename from drivers/filesystems/udfs/Include/phys_lib.cpp
rename to drivers/filesystems/udfs/Include/phys_lib.c
index bba91e86d1c06..b8da310d2e039 100644
--- a/drivers/filesystems/udfs/Include/phys_lib.cpp
+++ b/drivers/filesystems/udfs/Include/phys_lib.c
@@ -796,14 +796,14 @@ UDFGetBlockSize(
     if (UDFGetDevType(DeviceObject) == FILE_DEVICE_DISK) {
         UDFPrint(("UDFGetBlockSize: HDD\n"));
         RC = UDFPhSendIOCTL(IOCTL_DISK_GET_DRIVE_GEOMETRY_EX,DeviceObject,
-            0,NULL,
+            NULL,0,
             &DiskGeometryEx,sizeof(DISK_GEOMETRY_EX),
             TRUE,NULL );
 
         if (!NT_SUCCESS(RC))
             try_return(RC);
         RC = UDFPhSendIOCTL(IOCTL_DISK_GET_PARTITION_INFO,DeviceObject,
-            0,NULL,
+            NULL,0,
             &PartitionInfo,sizeof(PARTITION_INFORMATION),
             TRUE,NULL );
         if (!NT_SUCCESS(RC)) {
@@ -1002,7 +1002,6 @@ UDFPrepareForReadOperation(
         Vcb->VcbState &= ~UDF_VCB_LAST_WRITE;
         return STATUS_SUCCESS;
     }
-    uint32 i = Vcb->LastReadTrack;
 
 #ifdef _UDF_STRUCTURES_H_
     if (Vcb->BSBM_Bitmap) {
@@ -1036,7 +1035,7 @@ UDFReadSectors(
     OUT PULONG ReadBytes
     )
 {
-    return UDFTRead(IrpContext, Vcb, Buffer, BCount*Vcb->SectorSize, Lba, ReadBytes);
+    return UDFTRead(IrpContext, Vcb, Buffer, BCount*Vcb->SectorSize, Lba, ReadBytes, 0);
 } // end UDFReadSectors()
 
 /*
@@ -1167,7 +1166,7 @@ UDFWriteSectors(
             Vcb->LastLBA = Lba+BCount-1;
     }
 
-    status = UDFTWrite(IrpContext, Vcb, Buffer, BCount<<Vcb->SectorShift, Lba, WrittenBytes);
+    status = UDFTWrite(IrpContext, Vcb, Buffer, BCount<<Vcb->SectorShift, Lba, WrittenBytes, 0);
     ASSERT(NT_SUCCESS(status));
 
     return status;
diff --git a/drivers/filesystems/udfs/Include/phys_lib.h b/drivers/filesystems/udfs/Include/phys_lib.h
index 747b95450acf7..19203d202daa5 100644
--- a/drivers/filesystems/udfs/Include/phys_lib.h
+++ b/drivers/filesystems/udfs/Include/phys_lib.h
@@ -15,7 +15,7 @@ UDFTRead(
     SIZE_T Length,
     ULONG LBA,
     PULONG ReadBytes,
-    ULONG Flags = 0
+    ULONG Flags
     );
 
 NTSTATUS
@@ -26,7 +26,7 @@ UDFTWrite(
     IN SIZE_T Length,
     IN ULONG LBA,
     OUT PSIZE_T WrittenBytes,
-    IN ULONG Flags = 0
+    IN ULONG Flags
     );
 
 #define PH_TMP_BUFFER          1
diff --git a/drivers/filesystems/udfs/Include/regtools.cpp b/drivers/filesystems/udfs/Include/regtools.c
similarity index 100%
rename from drivers/filesystems/udfs/Include/regtools.cpp
rename to drivers/filesystems/udfs/Include/regtools.c
diff --git a/drivers/filesystems/udfs/Include/string_lib.cpp b/drivers/filesystems/udfs/Include/string_lib.c
similarity index 98%
rename from drivers/filesystems/udfs/Include/string_lib.cpp
rename to drivers/filesystems/udfs/Include/string_lib.c
index 1750feb27ff16..37bd1d894879a 100644
--- a/drivers/filesystems/udfs/Include/string_lib.cpp
+++ b/drivers/filesystems/udfs/Include/string_lib.c
@@ -4,7 +4,6 @@
 // This file was released under the GPLv2 on June 2015.
 ////////////////////////////////////////////////////////////////////
 
-extern "C"
 ULONG
 MyRtlCompareMemory(
     PVOID s1,
@@ -26,7 +25,6 @@ MyRtlCompareMemory(
 
 #ifndef NT_NATIVE_MODE
 
-extern "C"
 ULONG
 RtlCompareUnicodeString(
     PUNICODE_STRING s1,
@@ -41,7 +39,6 @@ RtlCompareUnicodeString(
     return i;
 }
 
-extern "C"
 NTSTATUS
 RtlUpcaseUnicodeString(
     PUNICODE_STRING dst,
@@ -57,7 +54,6 @@ RtlUpcaseUnicodeString(
     return STATUS_SUCCESS;
 }
 
-extern "C"
 NTSTATUS
 RtlAppendUnicodeToString(
     IN PUNICODE_STRING Str1,
diff --git a/drivers/filesystems/udfs/cleanup.cpp b/drivers/filesystems/udfs/cleanup.c
similarity index 100%
rename from drivers/filesystems/udfs/cleanup.cpp
rename to drivers/filesystems/udfs/cleanup.c
diff --git a/drivers/filesystems/udfs/close.cpp b/drivers/filesystems/udfs/close.c
similarity index 100%
rename from drivers/filesystems/udfs/close.cpp
rename to drivers/filesystems/udfs/close.c
diff --git a/drivers/filesystems/udfs/create.cpp b/drivers/filesystems/udfs/create.c
similarity index 100%
rename from drivers/filesystems/udfs/create.cpp
rename to drivers/filesystems/udfs/create.c
diff --git a/drivers/filesystems/udfs/devcntrl.cpp b/drivers/filesystems/udfs/devcntrl.c
similarity index 100%
rename from drivers/filesystems/udfs/devcntrl.cpp
rename to drivers/filesystems/udfs/devcntrl.c
diff --git a/drivers/filesystems/udfs/dircntrl.cpp b/drivers/filesystems/udfs/dircntrl.c
similarity index 100%
rename from drivers/filesystems/udfs/dircntrl.cpp
rename to drivers/filesystems/udfs/dircntrl.c
diff --git a/drivers/filesystems/udfs/env_spec.cpp b/drivers/filesystems/udfs/env_spec.c
similarity index 99%
rename from drivers/filesystems/udfs/env_spec.cpp
rename to drivers/filesystems/udfs/env_spec.c
index 52e1cb5382576..6872a86d9924f 100644
--- a/drivers/filesystems/udfs/env_spec.cpp
+++ b/drivers/filesystems/udfs/env_spec.c
@@ -134,7 +134,6 @@ UDFPhReadSynchronous(
     PIO_STACK_LOCATION IrpSp;
     KIRQL               CurIrql = KeGetCurrentIrql();
     PVOID               IoBuf = NULL;
-    PVCB Vcb = NULL;
 
     ROffset.QuadPart = Offset;
     (*ReadBytes) = 0;
@@ -252,8 +251,6 @@ UDFPhWriteSynchronous(
     KIRQL               CurIrql = KeGetCurrentIrql();
     PVOID               IoBuf = NULL;
 
-    PVCB Vcb = NULL;
-
 #ifdef DBG
     if (UDF_SIMULATE_WRITES) {
 /* FIXME ReactOS
diff --git a/drivers/filesystems/udfs/fastio.cpp b/drivers/filesystems/udfs/fastio.c
similarity index 100%
rename from drivers/filesystems/udfs/fastio.cpp
rename to drivers/filesystems/udfs/fastio.c
diff --git a/drivers/filesystems/udfs/fileinfo.cpp b/drivers/filesystems/udfs/fileinfo.c
similarity index 100%
rename from drivers/filesystems/udfs/fileinfo.cpp
rename to drivers/filesystems/udfs/fileinfo.c
diff --git a/drivers/filesystems/udfs/filobsup.cpp b/drivers/filesystems/udfs/filobsup.c
similarity index 100%
rename from drivers/filesystems/udfs/filobsup.cpp
rename to drivers/filesystems/udfs/filobsup.c
diff --git a/drivers/filesystems/udfs/flush.cpp b/drivers/filesystems/udfs/flush.c
similarity index 100%
rename from drivers/filesystems/udfs/flush.cpp
rename to drivers/filesystems/udfs/flush.c
diff --git a/drivers/filesystems/udfs/fscntrl.cpp b/drivers/filesystems/udfs/fscntrl.c
similarity index 99%
rename from drivers/filesystems/udfs/fscntrl.cpp
rename to drivers/filesystems/udfs/fscntrl.c
index 74982610e6a43..9eb4cec14ce27 100644
--- a/drivers/filesystems/udfs/fscntrl.cpp
+++ b/drivers/filesystems/udfs/fscntrl.c
@@ -296,7 +296,7 @@ UDFMountVolume(
     ASSERT(IrpSp);
     UDFPrint(("\n !!! UDFMountVolume\n"));
 
-    auto RealDevice = Vpb->RealDevice;
+    PDEVICE_OBJECT RealDevice = Vpb->RealDevice;
     
     SetDoVerifyOnFail = UDFRealDevNeedsVerify(RealDevice);
 
@@ -1339,7 +1339,7 @@ UDFGetVolumeBitmap(
 
         // Fill in the fixed part of the output buffer
 
-        __try {
+        _SEH2_TRY {
 
             // StartingLcn in output = aligned starting block
 
@@ -1349,10 +1349,10 @@ UDFGetVolumeBitmap(
 
             OutputBuffer->BitmapSize.QuadPart = DesiredClusters;
 
-        } __except (EXCEPTION_EXECUTE_HANDLER) {
+        } _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER) {
 
             try_return(Status = STATUS_INVALID_USER_BUFFER);
-        }
+        } _SEH2_END
 
         OutputBufferLength -= FIELD_OFFSET(VOLUME_BITMAP_BUFFER, Buffer);
 
diff --git a/drivers/filesystems/udfs/lockctrl.cpp b/drivers/filesystems/udfs/lockctrl.c
similarity index 100%
rename from drivers/filesystems/udfs/lockctrl.cpp
rename to drivers/filesystems/udfs/lockctrl.c
diff --git a/drivers/filesystems/udfs/mem.cpp b/drivers/filesystems/udfs/mem.c
similarity index 93%
rename from drivers/filesystems/udfs/mem.cpp
rename to drivers/filesystems/udfs/mem.c
index 072602c852327..301ead0d8ba72 100644
--- a/drivers/filesystems/udfs/mem.cpp
+++ b/drivers/filesystems/udfs/mem.c
@@ -8,4 +8,4 @@
 // define the file specific bug-check id
 #define         UDF_BUG_CHECK_ID                UDF_FILE_MEM
 
-#include "Include/mem_tools.cpp"
+#include "Include/mem_tools.c"
diff --git a/drivers/filesystems/udfs/misc.cpp b/drivers/filesystems/udfs/misc.c
similarity index 99%
rename from drivers/filesystems/udfs/misc.cpp
rename to drivers/filesystems/udfs/misc.c
index 75765fe90ce48..3607dc774a31d 100644
--- a/drivers/filesystems/udfs/misc.cpp
+++ b/drivers/filesystems/udfs/misc.c
@@ -501,7 +501,7 @@ UDFCreateIrpContext(
     }
 
     // TODO: fix
-    if (false && IrpSp->FileObject != NULL) {
+    if (FALSE && IrpSp->FileObject != NULL) {
 
         PFILE_OBJECT FileObject = IrpSp->FileObject;
 
@@ -1867,5 +1867,5 @@ UDFWaitForIoAtEof(
     return TRUE;
 }
 
-#include "Include/regtools.cpp"
+#include "Include/regtools.c"
 
diff --git a/drivers/filesystems/udfs/namesup.cpp b/drivers/filesystems/udfs/namesup.c
similarity index 100%
rename from drivers/filesystems/udfs/namesup.cpp
rename to drivers/filesystems/udfs/namesup.c
diff --git a/drivers/filesystems/udfs/pnp.cpp b/drivers/filesystems/udfs/pnp.c
similarity index 100%
rename from drivers/filesystems/udfs/pnp.cpp
rename to drivers/filesystems/udfs/pnp.c
diff --git a/drivers/filesystems/udfs/prefxsup.cpp b/drivers/filesystems/udfs/prefxsup.c
similarity index 100%
rename from drivers/filesystems/udfs/prefxsup.cpp
rename to drivers/filesystems/udfs/prefxsup.c
diff --git a/drivers/filesystems/udfs/protos.h b/drivers/filesystems/udfs/protos.h
index acaa3cd52b8b4..e40e55610e1dd 100644
--- a/drivers/filesystems/udfs/protos.h
+++ b/drivers/filesystems/udfs/protos.h
@@ -1047,7 +1047,7 @@ UDFCommonShutdown(
 /*************************************************************************
 * Prototypes for the file UDFinit.cpp
 *************************************************************************/
-extern "C" NTSTATUS NTAPI DriverEntry(
+NTSTATUS NTAPI DriverEntry(
 PDRIVER_OBJECT              DriverObject,       // created by the I/O sub-system
 PUNICODE_STRING             RegistryPath);      // path to the registry key
 
@@ -1337,6 +1337,8 @@ enum TYPE_OF_ACQUIRE {
 
 };
 
+typedef enum TYPE_OF_ACQUIRE TYPE_OF_ACQUIRE;
+
 _Requires_lock_held_(_Global_critical_region_)
 _When_(Type == AcquireExclusive && return != FALSE, _Acquires_exclusive_lock_(*Resource))
 _When_(Type == AcquireShared && return != FALSE, _Acquires_shared_lock_(*Resource))
@@ -1383,7 +1385,7 @@ UDFAcquireResource(
 #define UDFReleasePagingIo(IC,F)                                                        \
     ExReleaseResourceLite((F)->Header.PagingIoResource)
 
-inline
+static inline
 ULONG
 UDFHighBit(
     ULONG Word
@@ -1407,7 +1409,7 @@ UDFHighBit(
 
 #define SectorSize(V) ((V)->SectorSize)
 
-inline
+static inline
 ULONG
 SectorAlign(
     PVCB Vcb,
@@ -1417,7 +1419,7 @@ SectorAlign(
     return (Length + (Vcb->SectorSize - 1)) & ~(Vcb->SectorSize - 1);
 }
 
-inline
+static inline
 ULONGLONG
 LlSectorAlign( 
     PVCB Vcb, 
@@ -1439,7 +1441,7 @@ UDFSetThreadContext(
     (IC)->ThreadContext = NULL
 
 
-inline
+static inline
 BOOLEAN UdfIsExtendedFESupported(
     _In_ PVCB Vcb
 )
@@ -1447,7 +1449,7 @@ BOOLEAN UdfIsExtendedFESupported(
     return Vcb->NSRDesc == VRS_NSR03_FOUND;
 }
 
-inline
+static inline
 BOOLEAN UDFIsStreamsSupported(
     _In_ PVCB Vcb
 )
diff --git a/drivers/filesystems/udfs/read.cpp b/drivers/filesystems/udfs/read.c
similarity index 100%
rename from drivers/filesystems/udfs/read.cpp
rename to drivers/filesystems/udfs/read.c
diff --git a/drivers/filesystems/udfs/secursup.cpp b/drivers/filesystems/udfs/secursup.c
similarity index 100%
rename from drivers/filesystems/udfs/secursup.cpp
rename to drivers/filesystems/udfs/secursup.c
diff --git a/drivers/filesystems/udfs/shutdown.cpp b/drivers/filesystems/udfs/shutdown.c
similarity index 100%
rename from drivers/filesystems/udfs/shutdown.cpp
rename to drivers/filesystems/udfs/shutdown.c
diff --git a/drivers/filesystems/udfs/strucsup.cpp b/drivers/filesystems/udfs/strucsup.c
similarity index 99%
rename from drivers/filesystems/udfs/strucsup.cpp
rename to drivers/filesystems/udfs/strucsup.c
index 6e746f30fc8a4..84ad29f046bf0 100644
--- a/drivers/filesystems/udfs/strucsup.cpp
+++ b/drivers/filesystems/udfs/strucsup.c
@@ -46,7 +46,7 @@ UDFInsertFcbIntoTable(
     SetFlag(Fcb->FcbState, FCB_STATE_IN_FCB_TABLE);
 }
 
-inline
+static inline
 PFCB_NONPAGED
 UDFAllocateFcbNonpaged(
 )
@@ -54,7 +54,7 @@ UDFAllocateFcbNonpaged(
     return (PFCB_NONPAGED)ExAllocateFromNPagedLookasideList(&UdfData.UDFNonPagedFcbLookasideList);
 }
 
-inline
+static inline
 PFCB
 UDFAllocateFcbIndex(
 )
@@ -62,7 +62,7 @@ UDFAllocateFcbIndex(
     return (PFCB)ExAllocateFromPagedLookasideList(&UdfData.UDFFcbIndexLookasideList);
 }
 
-inline
+static inline
 PFCB
 UDFAllocateFcbData(
 )
@@ -70,7 +70,7 @@ UDFAllocateFcbData(
     return (PFCB)ExAllocateFromPagedLookasideList(&UdfData.UDFFcbDataLookasideList);
 }
 
-inline
+static inline
 PFCB
 UDFAllocateFcb(
 )
@@ -78,7 +78,7 @@ UDFAllocateFcb(
     return (PFCB)ExAllocatePoolWithTag(NonPagedPool, sizeof(FCB), TAG_FCB);
 }
 
-inline
+static inline
 VOID
 UDFDeallocateFcbNonpaged(
     PFCB_NONPAGED FcbNonpaged
@@ -87,7 +87,7 @@ UDFDeallocateFcbNonpaged(
     ExFreeToNPagedLookasideList(&UdfData.UDFNonPagedFcbLookasideList, FcbNonpaged);
 }
 
-inline
+static inline
 VOID
 UDFDeallocateFcbIndex(
     PFCB Fcb
@@ -96,7 +96,7 @@ UDFDeallocateFcbIndex(
     ExFreeToPagedLookasideList(&UdfData.UDFFcbIndexLookasideList, Fcb);
 }
 
-inline
+static inline
 VOID
 UDFDeallocateFcbData(
     PFCB Fcb
@@ -1185,7 +1185,7 @@ UDFCompleteMount(
     UNICODE_STRING LocalPath;
     ULONG LastSector = 0;
     BOOLEAN UnlockVcb = FALSE;
-    FILE_ID FileId{};
+    FILE_ID FileId = {0};
 
     PAGED_CODE();
 
@@ -1305,7 +1305,7 @@ UDFCompleteMount(
         // Open Unallocatable space stream
         // Generally, it should be placed in SystemStreamDirectory, but some
         // stupid apps think that RootDirectory is much better place.... :((
-        LocalPath = RTL_CONSTANT_STRING(UDF_FN_NON_ALLOCATABLE);
+        RtlInitUnicodeString(&LocalPath, UDF_FN_NON_ALLOCATABLE);
         Status = UDFOpenFile__(IrpContext, Vcb, FALSE, TRUE, &LocalPath, Vcb->RootIndexFcb->FileInfo, &Vcb->NonAllocFileInfo, NULL);
 
         if (!NT_SUCCESS(Status) && (Status != STATUS_OBJECT_NAME_NOT_FOUND)) {
@@ -1328,7 +1328,7 @@ UDFCompleteMount(
             UDFDirIndex(UDFGetDirIndexByFileInfo(Vcb->NonAllocFileInfo), Vcb->NonAllocFileInfo->Index)->FI_Flags |= UDF_FI_FLAG_FI_INTERNAL;
         } else {
             /* try to read Non-allocatable from alternate locations */
-            LocalPath = RTL_CONSTANT_STRING(UDF_FN_NON_ALLOCATABLE_2);
+            RtlInitUnicodeString(&LocalPath, UDF_FN_NON_ALLOCATABLE_2);
             Status = UDFOpenFile__(IrpContext, Vcb, FALSE, TRUE, &LocalPath, Vcb->RootIndexFcb->FileInfo, &(Vcb->NonAllocFileInfo), NULL);
             if (!NT_SUCCESS(Status) && (Status != STATUS_OBJECT_NAME_NOT_FOUND)) {
                 goto unwind_1;
@@ -1338,7 +1338,7 @@ UDFCompleteMount(
                 UDFDirIndex(UDFGetDirIndexByFileInfo(Vcb->NonAllocFileInfo), Vcb->NonAllocFileInfo->Index)->FI_Flags |= UDF_FI_FLAG_FI_INTERNAL;
             } else
             if (Vcb->SysSDirFileInfo) {
-                LocalPath = RTL_CONSTANT_STRING(UDF_SN_NON_ALLOCATABLE);
+                RtlInitUnicodeString(&LocalPath, UDF_SN_NON_ALLOCATABLE);
                 Status = UDFOpenFile__(IrpContext, Vcb, FALSE, TRUE, &LocalPath, Vcb->SysSDirFileInfo , &(Vcb->NonAllocFileInfo), NULL);
                 if (!NT_SUCCESS(Status) && (Status != STATUS_OBJECT_NAME_NOT_FOUND)) {
                     goto unwind_1;
@@ -1357,7 +1357,7 @@ UDFCompleteMount(
         /* Read SN UID mapping */
         if (Vcb->SysSDirFileInfo) {
 
-            LocalPath = RTL_CONSTANT_STRING(UDF_SN_UID_MAPPING);
+            RtlInitUnicodeString(&LocalPath, UDF_SN_UID_MAPPING);
 
             Status = UDFOpenFile__(IrpContext, Vcb, FALSE, TRUE, &LocalPath, Vcb->SysSDirFileInfo , &Vcb->UniqueIDMapFileInfo, NULL);
 
diff --git a/drivers/filesystems/udfs/struct.h b/drivers/filesystems/udfs/struct.h
index 74c032224266d..895fa13c767f8 100644
--- a/drivers/filesystems/udfs/struct.h
+++ b/drivers/filesystems/udfs/struct.h
@@ -38,6 +38,22 @@ struct IO_CONTEXT;
 struct IRP_CONTEXT;
 struct LCB;
 
+/* C typedef aliases – allow plain name usage without the 'struct' keyword */
+typedef struct IRP_CONTEXT_LITE IRP_CONTEXT_LITE;
+typedef struct IO_CONTEXT IO_CONTEXT;
+typedef struct IRP_CONTEXT IRP_CONTEXT;
+typedef struct LCB LCB;
+typedef struct UDFIdentifier UDFIdentifier;
+typedef struct UDFObjectName UDFObjectName;
+typedef struct CCB CCB;
+typedef struct FCB_NONPAGED FCB_NONPAGED;
+typedef struct FCB_DATA FCB_DATA;
+typedef struct FCB_INDEX FCB_INDEX;
+typedef struct FCB FCB;
+typedef struct VCB VCB;
+typedef struct VOLUME_DEVICE_OBJECT VOLUME_DEVICE_OBJECT;
+typedef struct THREAD_CONTEXT THREAD_CONTEXT;
+
 /**************************************************************************
     every structure has a node type, and a node size associated with it.
     The node type serves as a signature field. The size is used for
@@ -48,8 +64,7 @@ struct UDFIdentifier {
     NODE_BYTE_SIZE NodeByteSize;           // computed as sizeof(structure)
 };
 
-static_assert(sizeof(UDFIdentifier) == offsetof(FSRTL_ADVANCED_FCB_HEADER, Flags),
-    "UDFIdentifier size mismatch with NodeTypeCode and NodeByteSize in FSRTL_ADVANCED_FCB_HEADER");
+C_ASSERT(sizeof(UDFIdentifier) == offsetof(FSRTL_ADVANCED_FCB_HEADER, Flags));
 
 /**************************************************************************
     Every open on-disk object must have a name associated with it
@@ -68,7 +83,7 @@ struct UDFObjectName {
     // an absolute pathname of the object is stored below
     UNICODE_STRING                      ObjectName;
 };
-using PtrUDFObjectName = UDFObjectName*;
+typedef UDFObjectName* PtrUDFObjectName;
 
 /**************************************************************************
     Each file open instance is represented by a context control block.
@@ -107,7 +122,7 @@ struct CCB {
     PUNICODE_STRING                     DirectorySearchPattern;
     HASH_ENTRY                          hashes;
 };
-using PCCB = CCB*;
+typedef CCB* PCCB;
 
 #define CCB_FLAG_IGNORE_CASE                    (0x00000004)
 // the CCB has had an IRP_MJ_CLEANUP issued on it. we must
@@ -165,7 +180,7 @@ struct FCB_NONPAGED {
     FAST_MUTEX FcbFastMutex;
 
 };
-using PFCB_NONPAGED = FCB_NONPAGED*;
+typedef FCB_NONPAGED* PFCB_NONPAGED;
 
 /**************************************************************************
     each open file/directory/volume is represented by a file control block.
@@ -206,11 +221,11 @@ using PFCB_NONPAGED = FCB_NONPAGED*;
 /***************************************************/
 
 struct FCB_DATA {
-
+    UCHAR Placeholder;
 };
 
 struct FCB_INDEX {
-
+    UCHAR Placeholder;
 };
 
 struct FCB {
@@ -312,7 +327,7 @@ struct FCB {
         FCB_INDEX FcbIndex;
     };
 };
-using PFCB = FCB*;
+typedef FCB* PFCB;
 
 #define SIZEOF_FCB_DATA     \
     (FIELD_OFFSET(FCB, FcbType) + sizeof(FCB_DATA))
@@ -355,7 +370,7 @@ using PFCB = FCB*;
 
 **************************************************************************/
 
-enum UDFFSD_MEDIA_TYPE {
+typedef enum UDFFSD_MEDIA_TYPE {
     MediaUnknown = 0,
     MediaHdd,
     MediaCdr,
@@ -365,7 +380,7 @@ enum UDFFSD_MEDIA_TYPE {
     MediaFloppy,
     MediaDvdr,
     MediaDvdrw
-};
+} UDFFSD_MEDIA_TYPE;
 
 //***************************************************************************
 //                      LCB (Link Control Block)
@@ -439,7 +454,7 @@ struct LCB {
     UNICODE_STRING FileName;           // +0xE8 File name
 };
 
-using PLCB = LCB*;
+typedef LCB* PLCB;
 
 // LCB Flags
 #define UDF_LCB_FLAG_POOL_ALLOCATED         0x00000001  // Allocated from pool (not lookaside)
@@ -465,14 +480,14 @@ using PLCB = LCB*;
 //                      VCB (Volume Control Block)
 //***************************************************************************
 
-enum VCB_CONDITION {
+typedef enum VCB_CONDITION {
 
     VcbNotMounted = 0,
     VcbMountInProgress,
     VcbMounted,
     VcbInvalid,
     VcbDismountInProgress
-};
+} VCB_CONDITION;
 
 struct VCB {
 
@@ -736,7 +751,7 @@ struct VCB {
     PVPB SwapVpb;
 };
 
-using PVCB = VCB*;
+typedef VCB* PVCB;
 
 // One for root
 #define UDFS_BASE_RESIDUAL_REFERENCE                (4)//(6)
@@ -810,7 +825,7 @@ struct THREAD_CONTEXT {
     //  will store the IrpContext for the request in this stack location.
     IRP_CONTEXT* TopLevelIrpContext;
 };
-using PTHREAD_CONTEXT = THREAD_CONTEXT*;
+typedef THREAD_CONTEXT* PTHREAD_CONTEXT;
 
 /**************************************************************************
     The IRP context encapsulates the current request. This structure is
@@ -854,7 +869,7 @@ struct IRP_CONTEXT {
 
     VCB*      Vcb;
 };
-using PIRP_CONTEXT = IRP_CONTEXT*;
+typedef IRP_CONTEXT* PIRP_CONTEXT;
 
 #define IRP_CONTEXT_FLAG_ON_STACK               (0x00000001)
 #define IRP_CONTEXT_FLAG_MORE_PROCESSING        (0x00000002)
@@ -919,7 +934,7 @@ struct IRP_CONTEXT_LITE {
     //  Real device object.  This represents the physical device closest to the media.
     PDEVICE_OBJECT                  RealDevice;
 };
-using PIRP_CONTEXT_LITE = IRP_CONTEXT_LITE*;
+typedef IRP_CONTEXT_LITE* PIRP_CONTEXT_LITE;
 
 /**************************************************************************
     we will store all of our global variables in one structure.
diff --git a/drivers/filesystems/udfs/sys_spec.cpp b/drivers/filesystems/udfs/sys_spec.c
similarity index 95%
rename from drivers/filesystems/udfs/sys_spec.cpp
rename to drivers/filesystems/udfs/sys_spec.c
index e9a11ab152817..df66b8c66f22e 100644
--- a/drivers/filesystems/udfs/sys_spec.cpp
+++ b/drivers/filesystems/udfs/sys_spec.c
@@ -20,6 +20,6 @@
 // define the file specific bug-check id
 #define         UDF_BUG_CHECK_ID        UDF_FILE_SYS_SPEC
 
-#include "Include/Sys_spec_lib.cpp"
+#include "Include/Sys_spec_lib.c"
 
 //#include "Include/tools.cpp"
diff --git a/drivers/filesystems/udfs/udf_dbg.cpp b/drivers/filesystems/udfs/udf_dbg.c
similarity index 100%
rename from drivers/filesystems/udfs/udf_dbg.cpp
rename to drivers/filesystems/udfs/udf_dbg.c
diff --git a/drivers/filesystems/udfs/udf_info/alloc.cpp b/drivers/filesystems/udfs/udf_info/alloc.c
similarity index 100%
rename from drivers/filesystems/udfs/udf_info/alloc.cpp
rename to drivers/filesystems/udfs/udf_info/alloc.c
diff --git a/drivers/filesystems/udfs/udf_info/dirtree.cpp b/drivers/filesystems/udfs/udf_info/dirtree.c
similarity index 100%
rename from drivers/filesystems/udfs/udf_info/dirtree.cpp
rename to drivers/filesystems/udfs/udf_info/dirtree.c
diff --git a/drivers/filesystems/udfs/udf_info/ecma_167.h b/drivers/filesystems/udfs/udf_info/ecma_167.h
index 6ca06a7c47fc2..7e4ebc9c9f064 100644
--- a/drivers/filesystems/udfs/udf_info/ecma_167.h
+++ b/drivers/filesystems/udfs/udf_info/ecma_167.h
@@ -772,5 +772,12 @@ typedef EXTENDED_FILE_ENTRY ExtendedFileEntry;
 
 #pragma pack(pop)
 
+typedef struct VolStructDesc VolStructDesc;
+typedef struct BeginningExtendedAreaDesc BeginningExtendedAreaDesc;
+typedef struct TerminatingExtendedAreaDesc TerminatingExtendedAreaDesc;
+typedef struct PrimaryVolDesc PrimaryVolDesc;
+typedef struct AnchorVolDescPtr AnchorVolDescPtr;
+typedef struct VolDescPtr VolDescPtr;
+
 #endif /* __ECMA_167_H__ */
 
diff --git a/drivers/filesystems/udfs/udf_info/extent.cpp b/drivers/filesystems/udfs/udf_info/extent.c
similarity index 100%
rename from drivers/filesystems/udfs/udf_info/extent.cpp
rename to drivers/filesystems/udfs/udf_info/extent.c
diff --git a/drivers/filesystems/udfs/udf_info/mount.cpp b/drivers/filesystems/udfs/udf_info/mount.c
similarity index 100%
rename from drivers/filesystems/udfs/udf_info/mount.cpp
rename to drivers/filesystems/udfs/udf_info/mount.c
diff --git a/drivers/filesystems/udfs/udf_info/phys_eject.cpp b/drivers/filesystems/udfs/udf_info/phys_eject.c
similarity index 100%
rename from drivers/filesystems/udfs/udf_info/phys_eject.cpp
rename to drivers/filesystems/udfs/udf_info/phys_eject.c
diff --git a/drivers/filesystems/udfs/udf_info/physical.cpp b/drivers/filesystems/udfs/udf_info/physical.c
similarity index 95%
rename from drivers/filesystems/udfs/udf_info/physical.cpp
rename to drivers/filesystems/udfs/udf_info/physical.c
index 1ba8a147f02f1..9468996cacd37 100644
--- a/drivers/filesystems/udfs/udf_info/physical.cpp
+++ b/drivers/filesystems/udfs/udf_info/physical.c
@@ -17,5 +17,5 @@
 // define the file specific bug-check id
 #define         UDF_BUG_CHECK_ID        UDF_FILE_PHYSICAL
 
-#include "Include/phys_lib.cpp"
+#include "Include/phys_lib.c"
 
diff --git a/drivers/filesystems/udfs/udf_info/remap.cpp b/drivers/filesystems/udfs/udf_info/remap.c
similarity index 100%
rename from drivers/filesystems/udfs/udf_info/remap.cpp
rename to drivers/filesystems/udfs/udf_info/remap.c
diff --git a/drivers/filesystems/udfs/udf_info/udf_info.cpp b/drivers/filesystems/udfs/udf_info/udf_info.c
similarity index 99%
rename from drivers/filesystems/udfs/udf_info/udf_info.cpp
rename to drivers/filesystems/udfs/udf_info/udf_info.c
index e9556aa93de31..fe3dde19cd202 100644
--- a/drivers/filesystems/udfs/udf_info/udf_info.cpp
+++ b/drivers/filesystems/udfs/udf_info/udf_info.c
@@ -4589,7 +4589,7 @@ UDFReadTagged(
 
     // Read the block
     if (Block == 0xFFFFFFFF)
-        return NULL;
+        return STATUS_UNSUCCESSFUL;
 
     _SEH2_TRY {
         RC = UDFReadSectors(IrpContext, Vcb, FALSE, Block, 1, FALSE, Buf, &ReadBytes);
diff --git a/drivers/filesystems/udfs/udfdata.cpp b/drivers/filesystems/udfs/udfdata.c
similarity index 100%
rename from drivers/filesystems/udfs/udfdata.cpp
rename to drivers/filesystems/udfs/udfdata.c
diff --git a/drivers/filesystems/udfs/udffs.h b/drivers/filesystems/udfs/udffs.h
index 272046b907e62..2aae42ef2fa5f 100644
--- a/drivers/filesystems/udfs/udffs.h
+++ b/drivers/filesystems/udfs/udffs.h
@@ -133,7 +133,7 @@ extern UDFData              UdfData;
 
 //  Encapsulate safe pool freeing
 
-inline
+static inline
 VOID
 UDFFreePool(
     _Inout_ _At_(*Pool, __drv_freesMem(Mem) _Post_null_) PVOID *Pool
@@ -152,7 +152,7 @@ UDFFreePool(
 
 // small check for illegal open mode (desired access) if volume is
 // read only (on standard CD-ROM device or another like this)
-inline
+static inline
 BOOLEAN
 UDFIllegalFcbAccess(
     IN PVCB Vcb,
@@ -398,7 +398,7 @@ UDFIllegalFcbAccess(
 
 #define FID_DIR_MASK  0x80000000            // high order bit means directory.
 
-inline
+static inline
 FILE_ID
 UdfGetFidFromLbAddr(lb_addr lbAddr)
 {
diff --git a/drivers/filesystems/udfs/udfinit.cpp b/drivers/filesystems/udfs/udfinit.c
similarity index 100%
rename from drivers/filesystems/udfs/udfinit.cpp
rename to drivers/filesystems/udfs/udfinit.c
diff --git a/drivers/filesystems/udfs/unload.cpp b/drivers/filesystems/udfs/unload.c
similarity index 100%
rename from drivers/filesystems/udfs/unload.cpp
rename to drivers/filesystems/udfs/unload.c
diff --git a/drivers/filesystems/udfs/verfysup.cpp b/drivers/filesystems/udfs/verfysup.c
similarity index 99%
rename from drivers/filesystems/udfs/verfysup.cpp
rename to drivers/filesystems/udfs/verfysup.c
index 015af5a6b423b..aad0057c6650c 100644
--- a/drivers/filesystems/udfs/verfysup.cpp
+++ b/drivers/filesystems/udfs/verfysup.c
@@ -234,6 +234,9 @@ UDFVerifyVcb(
             UDFRaiseStatus(IrpContext, STATUS_FILE_INVALID);
         }
         break;
+
+    default:
+        break;
     }
 } // end UDFVerifyVcb()
 
diff --git a/drivers/filesystems/udfs/volinfo.cpp b/drivers/filesystems/udfs/volinfo.c
similarity index 100%
rename from drivers/filesystems/udfs/volinfo.cpp
rename to drivers/filesystems/udfs/volinfo.c
diff --git a/drivers/filesystems/udfs/write.cpp b/drivers/filesystems/udfs/write.c
similarity index 99%
rename from drivers/filesystems/udfs/write.cpp
rename to drivers/filesystems/udfs/write.c
index 076e5a6cbe305..7adf7b952c3a8 100644
--- a/drivers/filesystems/udfs/write.cpp
+++ b/drivers/filesystems/udfs/write.c
@@ -243,7 +243,7 @@ UDFCommonWrite(
             // Perform actual Write
             Status = UDFTWrite(IrpContext, Vcb, SystemBuffer, ByteCount,
                            (ULONG)(StartingOffset >> Vcb->SectorShift),
-                           &NumberBytesWritten);
+                           &NumberBytesWritten, 0);
             UDFUnlockCallersBuffer(IrpContext, Irp, SystemBuffer);
             try_return(Status);
         }
@@ -894,8 +894,8 @@ UDFZeroData (
 
 --*/
 {
-    LARGE_INTEGER ZeroStart = {0,0};
-    LARGE_INTEGER BeyondZeroEnd = {0,0};
+    LARGE_INTEGER ZeroStart = {{0, 0}};
+    LARGE_INTEGER BeyondZeroEnd = {{0, 0}};
 
     BOOLEAN Finished;