[RFC 5/5] EmbeddedPkg/PrePiLib: break section extraction info into helper function

["Leif Lindholm" <leif@nuviainc.com>]

Create a new helper function FfsGetExtractionInfo, which handles figuring
out the buffer sizes needed for extracting UefiCompressed or
GuidedSection sections, and also hides away some of the differences
between the two, getting rid of a bunch of local variables.

Signed-off-by: Leif Lindholm <leif@nuviainc.com>
---
 EmbeddedPkg/Library/PrePiLib/FwVol.c | 90 +++++++++++++++++-----------
 1 file changed, 55 insertions(+), 35 deletions(-)

diff --git a/EmbeddedPkg/Library/PrePiLib/FwVol.c b/EmbeddedPkg/Library/PrePiLib/FwVol.c
index 083bc27efead..d0f91efa77a1 100644
--- a/EmbeddedPkg/Library/PrePiLib/FwVol.c
+++ b/EmbeddedPkg/Library/PrePiLib/FwVol.c
@@ -318,6 +318,50 @@ FfsCompressionSectionHeaderSize (
   return sizeof (EFI_COMPRESSION_SECTION);
 }
 
+STATIC
+EFI_STATUS
+FfsGetExtractionInfo (
+  IN      EFI_COMMON_SECTION_HEADER               *Section,
+  OUT     UINT32                                  *SectionLength,
+  IN OUT  VOID                                    **SrcBuffer,
+  OUT     UINT32                                  *DstBufferSize,
+  OUT     UINT32                                  *ScratchBufferSize
+  )
+{
+  EFI_STATUS  Status;
+
+  if (Section->Type == EFI_SECTION_COMPRESSION) {
+    *SectionLength = FfsSectionLength (Section);
+
+    if (FfsSectionCompressionType (Section) != EFI_STANDARD_COMPRESSION) {
+      return EFI_UNSUPPORTED;
+    }
+
+    *SrcBuffer = (VOID *)((UINTN)Section + FfsCompressionSectionHeaderSize (Section));
+    Status = UefiDecompressGetInfo (
+               *SrcBuffer,
+               *SectionLength - FfsCompressionSectionHeaderSize (Section),
+               DstBufferSize,
+               ScratchBufferSize
+               );
+  } else if (Section->Type == EFI_SECTION_GUID_DEFINED) {
+    UINT16 Ignored;
+
+    *SrcBuffer = Section;
+
+    Status = ExtractGuidedSectionGetInfo (
+               *SrcBuffer,
+               DstBufferSize,
+               ScratchBufferSize,
+               &Ignored      // SectionAttribute not used by this library
+               );
+  } else {
+    Status = EFI_UNSUPPORTED;
+  }
+
+  return Status;
+}
+
 /**
   Go through the file to search SectionType section,
   when meeting an encapsuled section.
@@ -344,15 +388,11 @@ FfsProcessSection (
   VOID                                    *ScratchBuffer;
   UINT32                                  ScratchBufferSize;
   VOID                                    *DstBuffer;
-  UINT16                                  SectionAttribute;
-  UINT32                                  AuthenticationStatus;
-  CHAR8                                   *CompressedData;
-  UINTN                                   CompressedDataLength;
-
+  VOID                                    *SrcBuffer;
 
   *OutputBuffer = NULL;
   ParsedLength  = 0;
-  Status        = EFI_NOT_FOUND;
+
   while (ParsedLength < SectionSize) {
     if (IS_SECTION2 (Section)) {
       ASSERT (SECTION2_SIZE (Section) > 0x00FFFFFF);
@@ -364,32 +404,11 @@ FfsProcessSection (
       return EFI_SUCCESS;
     }
 
+    SectionLength = FfsSectionLength (Section);
+
     if ((Section->Type == EFI_SECTION_COMPRESSION) || (Section->Type == EFI_SECTION_GUID_DEFINED)) {
-      if (Section->Type == EFI_SECTION_COMPRESSION) {
-        SectionLength = FfsSectionLength (Section);
-
-        if (FfsSectionCompressionType (Section) != EFI_STANDARD_COMPRESSION) {
-          return EFI_UNSUPPORTED;
-        }
-
-        CompressedData = (VOID *)((UINTN)Section + FfsCompressionSectionHeaderSize (Section));
-        CompressedDataLength = SectionLength - FfsCompressionSectionHeaderSize (Section);
-
-        Status = UefiDecompressGetInfo (
-                   CompressedData,
-                   CompressedDataLength,
-                   &DstBufferSize,
-                   &ScratchBufferSize
-                   );
-      } else if (Section->Type == EFI_SECTION_GUID_DEFINED) {
-        Status = ExtractGuidedSectionGetInfo (
-                   Section,
-                   &DstBufferSize,
-                   &ScratchBufferSize,
-                   &SectionAttribute
-                   );
-      }
-
+      Status = FfsGetExtractionInfo (Section, &SectionLength, &SrcBuffer,
+                                     &DstBufferSize, &ScratchBufferSize);
       if (EFI_ERROR (Status)) {
         //
         // GetInfo failed
@@ -421,16 +440,18 @@ FfsProcessSection (
       //
       if (Section->Type == EFI_SECTION_COMPRESSION) {
         Status = UefiDecompress (
-                   CompressedData,
+                   SrcBuffer,
                    DstBuffer,
                    ScratchBuffer
                    );
       } else if (Section->Type == EFI_SECTION_GUID_DEFINED) {
+        UINT32  Ignored;
+
         Status = ExtractGuidedSectionDecode (
-                   Section,
+                   SrcBuffer,
                    &DstBuffer,
                    ScratchBuffer,
-                   &AuthenticationStatus
+                   &Ignored  // AuthenticationStatus not used by this library
                    );
       }
 
@@ -450,7 +471,6 @@ FfsProcessSection (
        }
     }
 
-    SectionLength = FfsSectionLength (Section);
     //
     // SectionLength is adjusted it is 4 byte aligned.
     // Go to the next section
-- 
2.20.1