1 files changed, 142 insertions, 0 deletions
diff --git a/src/nt_path_converter/nt2dos.c b/src/nt_path_converter/nt2dos.c
new file mode 100644
index 0000000..fb0fd80
--- /dev/null
+++ b/src/nt_path_converter/nt2dos.c
@@ -0,0 +1,142 @@
+/**
+ * \file
+ * \author Egor Tensin <Egor.Tensin@gmail.com>
+ * \copyright This file is licensed under the terms of the MIT License.
+ *            See LICENSE.txt for details.
+ */
+
+#include <ntifs.h>
+
+#include "nt2dos.h"
+
+static NTSTATUS get_object_name_info(
+    void *object,
+    OBJECT_NAME_INFORMATION **object_name_info)
+{
+    unsigned long nbneeded;
+    NTSTATUS status = STATUS_SUCCESS;
+
+    status = ObQueryNameString(object, NULL, 0, &nbneeded);
+    if (status != STATUS_INFO_LENGTH_MISMATCH)
+        return status;
+    *object_name_info = ExAllocatePoolWithTag(PagedPool, nbneeded, '1l');
+    if (*object_name_info == NULL)
+        return STATUS_INSUFFICIENT_RESOURCES;
+    status = ObQueryNameString(object, *object_name_info, nbneeded, &nbneeded);
+    if (!NT_SUCCESS(status))
+        goto free_object_name_info;
+    return status;
+
+free_object_name_info:
+    ExFreePool(*object_name_info);
+
+    return status;
+}
+
+NTSTATUS nt2dos(UNICODE_STRING *u_resolved, UNICODE_STRING *u_unresolved)
+{
+    IO_STATUS_BLOCK io_status_block;
+    DEVICE_OBJECT *volume_object;
+    FILE_OBJECT *file_object;
+    HANDLE file;
+    OBJECT_ATTRIBUTES file_attrs;
+    OBJECT_NAME_INFORMATION *file_name_info, *volume_name_info;
+    UNICODE_STRING u_dos_name;
+    USHORT u_resolved_size;
+    NTSTATUS status = STATUS_SUCCESS;
+
+    InitializeObjectAttributes(&file_attrs,
+                               u_unresolved,
+                               OBJ_CASE_INSENSITIVE | OBJ_OPENIF,
+                               NULL,
+                               NULL);
+
+    status = ZwCreateFile(&file,
+                          FILE_READ_ATTRIBUTES,
+                          &file_attrs,
+                          &io_status_block,
+                          NULL,
+                          FILE_ATTRIBUTE_NORMAL,
+                          FILE_SHARE_READ | FILE_SHARE_WRITE,
+                          FILE_OPEN,
+                          FILE_SYNCHRONOUS_IO_NONALERT,
+                          NULL, 0);
+
+    if (!NT_SUCCESS(status))
+        return status;
+
+    status = ObReferenceObjectByHandle(file,
+                                       FILE_READ_ATTRIBUTES,
+                                       *IoFileObjectType,
+                                       KernelMode,
+                                       &file_object,
+                                       NULL);
+    if (!NT_SUCCESS(status))
+        goto close_file;
+
+    status = get_object_name_info(file_object, &file_name_info);
+    if (!NT_SUCCESS(status))
+        goto close_file;
+
+    if (file_object->Vpb == NULL)
+    {
+        u_resolved->Buffer = ExAllocatePoolWithTag(
+            PagedPool, file_name_info->Name.Length, '1l');
+        if (u_resolved->Buffer == NULL)
+        {
+            status = STATUS_INSUFFICIENT_RESOURCES;
+            goto free_file_name_info;
+        }
+
+        RtlInitEmptyUnicodeString(u_resolved,
+                                  u_resolved->Buffer,
+                                  file_name_info->Name.Length);
+        RtlCopyUnicodeString(u_resolved, &file_name_info->Name);
+        goto free_file_name_info;
+    }
+
+    volume_object = file_object->Vpb->RealDevice;
+    status = get_object_name_info(volume_object, &volume_name_info);
+
+    if (!NT_SUCCESS(status))
+        goto free_file_name_info;
+
+    status = IoVolumeDeviceToDosName(volume_object, &u_dos_name);
+    if (!NT_SUCCESS(status))
+        goto free_volume_name_info;
+
+    u_resolved_size = file_name_info->Name.Length
+        - volume_name_info->Name.Length
+        + u_dos_name.Length;
+
+    u_resolved->Buffer = ExAllocatePoolWithTag(
+        PagedPool, u_resolved_size, '1l');
+    if (u_resolved->Buffer == NULL)
+    {
+        status = STATUS_INSUFFICIENT_RESOURCES;
+        goto free_dos_name;
+    }
+
+    RtlInitEmptyUnicodeString(u_resolved, u_resolved->Buffer, u_resolved_size);
+
+    RtlCopyUnicodeString(u_resolved, &u_dos_name);
+    file_name_info->Name.Buffer +=
+        volume_name_info->Name.Length / sizeof(wchar_t);
+    file_name_info->Name.Length -=
+        volume_name_info->Name.Length;
+    RtlUnicodeStringCat(u_resolved, &file_name_info->Name);
+
+free_dos_name:
+    ExFreePool(u_dos_name.Buffer);
+
+free_volume_name_info:
+    ExFreePool(volume_name_info);
+
+free_file_name_info:
+    ExFreePool(file_name_info);
+
+close_file:
+    ZwClose(file);
+
+    return status;
+}