BaseTools: Don't Recurse NULL Includes Not Linked to Module

When collecting the required library instances for modules and
libraries, included libraries will be recursed to ensure the module is
built with all the libraries directly linked to it and indirectly
linked to it via included libraries.

Using the following scenario as an example:

[LibraryClasses.common.DXE_CORE]
NULL|Path/To/Library1.inf // Includes DebugLib

[LibraryClasses.common.DXE_DRIVER]
NULL|Path/To/Library2.inf // Includes DebugLib

[LibraryClasses.common.DXE_CORE, LibraryClasses.common.DXE_DRIVER]
DebugLib|MdePkg/Library/BaseDebugLibSerialPort/BaseDebugLibSerialPort.inf

[Components]
MdeModulePkg/Core/Dxe/DxeMain.inf // Includes DebugLib

The DXE_CORE NULL library will be assigned a fake library class like
NULL1 and the DXE_DRIVER will be assigned NULL2. The recursion logic
will see NULL1 as a directly linked and will add an instance of it to
the list of libraries which need to be included in the module. When
DebugLib is evaluated, the recursion logic will add the libraries
DebugLib depends on to the queue which includes both NULL1 and NULL2.
When NULL2 is unqueued, an instance of it will also be added to the
list of libraries needed to build DxeMain which now means that both
NULL1 and NULL2 have been linked.

NULL includes outside of module overrides are not supported according
to the spec, but we do it anyways so this seems like a case which
should be fixed. This change updates the recursion logic to skip
evaluating NULL libraries unless they are linked directly to the
module/library being evaluated.

Cc: Rebecca Cran <rebecca@bsdio.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Yuwei Chen <yuwei.chen@intel.com>

Signed-off-by: Taylor Beebe <taylor.d.beebe@gmail.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

1 files changed, 2 insertions, 0 deletions

diff --git a/BaseTools/Source/Python/Workspace/WorkspaceCommon.py b/BaseTools/Source/Python/Workspace/WorkspaceCommon.py
index 9e506fc646..8bb6553c6f 100644
--- a/BaseTools/Source/Python/Workspace/WorkspaceCommon.py
+++ b/BaseTools/Source/Python/Workspace/WorkspaceCommon.py
@@ -123,6 +123,8 @@ def GetModuleLibInstances(Module, Platform, BuildDatabase, Arch, Target, Toolcha
     while len(LibraryConsumerList) > 0:

         M = LibraryConsumerList.pop()

         for LibraryClassName in M.LibraryClasses:

+            if LibraryClassName.startswith("NULL") and bool(M.LibraryClass):

+                continue

             if LibraryClassName not in LibraryInstance:

                 # override library instance for this module

                 LibraryPath = Platform.Modules[str(Module)].LibraryClasses.get(LibraryClassName,Platform.LibraryClasses[LibraryClassName, ModuleType])