ShellPkg/Library/UefiShellDebug1CommandsLib/Comp.c - third_party/edk2 - Git at Google

 /** @file
   Main file for Comp shell Debug1 function.

   (C) Copyright 2015 Hewlett-Packard Development Company, L.P.<BR>
   Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent

 **/

 #include "UefiShellDebug1CommandsLib.h"

 STATIC CONST SHELL_PARAM_ITEM  ParamList[] = {
   { L"-n", TypeValue },
   { L"-s", TypeValue },
   { NULL,  TypeMax   }
 };

 typedef enum {
   OutOfDiffPoint,
   InDiffPoint,
   InPrevDiffPoint
 } READ_STATUS;

 //
 // Buffer type, for reading both file operands in chunks.
 //
 typedef struct {
   UINT8    *Data;     // dynamically allocated buffer
   UINTN    Allocated; // the allocated size of Data
   UINTN    Next;      // next position in Data to fetch a byte at
   UINTN    Left;      // number of bytes left in Data for fetching at Next
 } FILE_BUFFER;

 /**
   Function to print differnt point data.

   @param[in]  FileName        File name.
   @param[in]  FileTag         File tag name.
   @param[in]  Buffer          Data buffer to be printed.
   @param[in]  BufferSize      Size of the data to be printed.
   @param[in]  Address         Address of the differnt point.
   @param[in]  DifferentBytes  Total size of the buffer.

 **/
 VOID
 PrintDifferentPoint (
   CONST CHAR16  *FileName,
   CHAR16        *FileTag,
   UINT8         *Buffer,
   UINT64        BufferSize,
   UINTN         Address,
   UINT64        DifferentBytes
   )
 {
   UINTN  Index;

   ShellPrintEx (-1, -1, L"%s: %s\r\n  %08x:", FileTag, FileName, Address);

   //
   // Print data in hex-format.
   //
   for (Index = 0; Index < BufferSize; Index++) {
     ShellPrintEx (-1, -1, L" %02x", Buffer[Index]);
   }

   if (BufferSize < DifferentBytes) {
     ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_COMP_END_OF_FILE), gShellDebug1HiiHandle);
   }

   ShellPrintEx (-1, -1, L"    *");

   //
   // Print data in char-format.
   //
   for (Index = 0; Index < BufferSize; Index++) {
     if ((Buffer[Index] >= 0x20) && (Buffer[Index] <= 0x7E)) {
       ShellPrintEx (-1, -1, L"%c", Buffer[Index]);
     } else {
       //
       // Print dots for control characters
       //
       ShellPrintEx (-1, -1, L".");
     }
   }

   ShellPrintEx (-1, -1, L"*\r\n");
 }

 /**
   Initialize a FILE_BUFFER.

   @param[out] FileBuffer  The FILE_BUFFER to initialize. On return, the caller
                           is responsible for checking FileBuffer->Data: if
                           FileBuffer->Data is NULL on output, then memory
                           allocation failed.
 **/
 STATIC
 VOID
 FileBufferInit (
   OUT FILE_BUFFER  *FileBuffer
   )
 {
   FileBuffer->Allocated = PcdGet32 (PcdShellFileOperationSize);
   FileBuffer->Data      = AllocatePool (FileBuffer->Allocated);
   FileBuffer->Left      = 0;
 }

 /**
   Uninitialize a FILE_BUFFER.

   @param[in,out] FileBuffer  The FILE_BUFFER to uninitialize. The caller is
                              responsible for making sure FileBuffer was first
                              initialized with FileBufferInit(), successfully or
                              unsuccessfully.
 **/
 STATIC
 VOID
 FileBufferUninit (
   IN OUT FILE_BUFFER  *FileBuffer
   )
 {
   SHELL_FREE_NON_NULL (FileBuffer->Data);
 }

 /**
   Read a byte from a SHELL_FILE_HANDLE, buffered with a FILE_BUFFER.

   @param[in] FileHandle      The SHELL_FILE_HANDLE to replenish FileBuffer
                              from, if needed.

   @param[in,out] FileBuffer  The FILE_BUFFER to read a byte from. If FileBuffer
                              is empty on entry, then FileBuffer is refilled
                              from FileHandle, before outputting a byte from
                              FileBuffer to Byte. The caller is responsible for
                              ensuring that FileBuffer was successfully
                              initialized with FileBufferInit().

   @param[out] BytesRead      On successful return, BytesRead is set to 1 if the
                              next byte from FileBuffer has been stored to Byte.
                              On successful return, BytesRead is set to 0 if
                              FileBuffer is empty, and FileHandle is at EOF.
                              When an error is returned, BytesRead is not set.

   @param[out] Byte           On output, the next byte from FileBuffer. Only set
                              if (a) EFI_SUCCESS is returned and (b) BytesRead
                              is set to 1 on output.

   @retval EFI_SUCCESS  BytesRead has been set to 0 or 1. In the latter case,
                        Byte has been set as well.

   @return              Error codes propagated from
                        gEfiShellProtocol->ReadFile().
 **/
 STATIC
 EFI_STATUS
 FileBufferReadByte (
   IN     SHELL_FILE_HANDLE  FileHandle,
   IN OUT FILE_BUFFER        *FileBuffer,
   OUT UINTN                 *BytesRead,
   OUT UINT8                 *Byte
   )
 {
   UINTN       ReadSize;
   EFI_STATUS  Status;

   if (FileBuffer->Left == 0) {
     ReadSize = FileBuffer->Allocated;
     Status   = gEfiShellProtocol->ReadFile (
                                     FileHandle,
                                     &ReadSize,
                                     FileBuffer->Data
                                     );
     if (EFI_ERROR (Status)) {
       return Status;
     }

     if (ReadSize == 0) {
       *BytesRead = 0;
       return EFI_SUCCESS;
     }

     FileBuffer->Next = 0;
     FileBuffer->Left = ReadSize;
   }

   *BytesRead = 1;
   *Byte      = FileBuffer->Data[FileBuffer->Next];

   FileBuffer->Next++;
   FileBuffer->Left--;
   return EFI_SUCCESS;
 }

 /**
   Function for 'comp' command.

   @param[in] ImageHandle  Handle to the Image (NULL if Internal).
   @param[in] SystemTable  Pointer to the System Table (NULL if Internal).
 **/
 SHELL_STATUS
 EFIAPI
 ShellCommandRunComp (
   IN EFI_HANDLE        ImageHandle,
   IN EFI_SYSTEM_TABLE  *SystemTable
   )
 {
   EFI_STATUS         Status;
   LIST_ENTRY         *Package;
   CHAR16             *ProblemParam;
   CHAR16             *FileName1;
   CHAR16             *FileName2;
   CONST CHAR16       *TempParam;
   SHELL_STATUS       ShellStatus;
   SHELL_FILE_HANDLE  FileHandle1;
   SHELL_FILE_HANDLE  FileHandle2;
   UINT64             Size1;
   UINT64             Size2;
   UINT64             DifferentBytes;
   UINT64             DifferentCount;
   UINT8              DiffPointNumber;
   UINT8              OneByteFromFile1;
   UINT8              OneByteFromFile2;
   UINT8              *DataFromFile1;
   UINT8              *DataFromFile2;
   FILE_BUFFER        FileBuffer1;
   FILE_BUFFER        FileBuffer2;
   UINTN              InsertPosition1;
   UINTN              InsertPosition2;
   UINTN              DataSizeFromFile1;
   UINTN              DataSizeFromFile2;
   UINTN              TempAddress;
   UINTN              Index;
   UINTN              DiffPointAddress;
   READ_STATUS        ReadStatus;

   ShellStatus      = SHELL_SUCCESS;
   Status           = EFI_SUCCESS;
   FileName1        = NULL;
   FileName2        = NULL;
   FileHandle1      = NULL;
   FileHandle2      = NULL;
   DataFromFile1    = NULL;
   DataFromFile2    = NULL;
   ReadStatus       = OutOfDiffPoint;
   DifferentCount   = 10;
   DifferentBytes   = 4;
   DiffPointNumber  = 0;
   InsertPosition1  = 0;
   InsertPosition2  = 0;
   TempAddress      = 0;
   DiffPointAddress = 0;

   //
   // initialize the shell lib (we must be in non-auto-init...)
   //
   Status = ShellInitialize ();
   ASSERT_EFI_ERROR (Status);

   Status = CommandInit ();
   ASSERT_EFI_ERROR (Status);

   //
   // parse the command line
   //
   Status = ShellCommandLineParse (ParamList, &Package, &ProblemParam, TRUE);
   if (EFI_ERROR (Status)) {
     if ((Status == EFI_VOLUME_CORRUPTED) && (ProblemParam != NULL)) {
       ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_PROBLEM), gShellDebug1HiiHandle, L"comp", ProblemParam);
       FreePool (ProblemParam);
       ShellStatus = SHELL_INVALID_PARAMETER;
     } else {
       ASSERT (FALSE);
     }
   } else {
     if (ShellCommandLineGetCount (Package) > 3) {
       ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_TOO_MANY), gShellDebug1HiiHandle, L"comp");
       ShellStatus = SHELL_INVALID_PARAMETER;
     } else if (ShellCommandLineGetCount (Package) < 3) {
       ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_TOO_FEW), gShellDebug1HiiHandle, L"comp");
       ShellStatus = SHELL_INVALID_PARAMETER;
     } else {
       TempParam = ShellCommandLineGetRawValue (Package, 1);
       ASSERT (TempParam != NULL);
       FileName1 = ShellFindFilePath (TempParam);
       if (FileName1 == NULL) {
         ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_FILE_FIND_FAIL), gShellDebug1HiiHandle, L"comp", TempParam);
         ShellStatus = SHELL_NOT_FOUND;
       } else {
         Status = ShellOpenFileByName (FileName1, &FileHandle1, EFI_FILE_MODE_READ, 0);
         if (EFI_ERROR (Status)) {
           ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_FILE_OPEN_FAIL), gShellDebug1HiiHandle, L"comp", TempParam);
           ShellStatus = SHELL_NOT_FOUND;
         }
       }

       TempParam = ShellCommandLineGetRawValue (Package, 2);
       ASSERT (TempParam != NULL);
       FileName2 = ShellFindFilePath (TempParam);
       if (FileName2 == NULL) {
         ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_FILE_FIND_FAIL), gShellDebug1HiiHandle, L"comp", TempParam);
         ShellStatus = SHELL_NOT_FOUND;
       } else {
         Status = ShellOpenFileByName (FileName2, &FileHandle2, EFI_FILE_MODE_READ, 0);
         if (EFI_ERROR (Status)) {
           ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_FILE_OPEN_FAIL), gShellDebug1HiiHandle, L"comp", TempParam);
           ShellStatus = SHELL_NOT_FOUND;
         }
       }

       if (ShellStatus == SHELL_SUCCESS) {
         Status = gEfiShellProtocol->GetFileSize (FileHandle1, &Size1);
         ASSERT_EFI_ERROR (Status);
         Status = gEfiShellProtocol->GetFileSize (FileHandle2, &Size2);
         ASSERT_EFI_ERROR (Status);

         if (ShellCommandLineGetFlag (Package, L"-n")) {
           TempParam = ShellCommandLineGetValue (Package, L"-n");
           if (TempParam == NULL) {
             ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_NO_VALUE), gShellDebug1HiiHandle, L"comp", L"-n");
             ShellStatus = SHELL_INVALID_PARAMETER;
           } else {
             if (gUnicodeCollation->StriColl (gUnicodeCollation, (CHAR16 *)TempParam, L"all") == 0) {
               DifferentCount = MAX_UINTN;
             } else {
               Status = ShellConvertStringToUint64 (TempParam, &DifferentCount, FALSE, TRUE);
               if (EFI_ERROR (Status) || (DifferentCount == 0)) {
                 ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_PROBLEM_VAL), gShellDebug1HiiHandle, L"comp", TempParam, L"-n");
                 ShellStatus = SHELL_INVALID_PARAMETER;
               }
             }
           }
         }

         if (ShellCommandLineGetFlag (Package, L"-s")) {
           TempParam = ShellCommandLineGetValue (Package, L"-s");
           if (TempParam == NULL) {
             ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_NO_VALUE), gShellDebug1HiiHandle, L"comp", L"-s");
             ShellStatus = SHELL_INVALID_PARAMETER;
           } else {
             Status = ShellConvertStringToUint64 (TempParam, &DifferentBytes, FALSE, TRUE);
             if (EFI_ERROR (Status) || (DifferentBytes == 0)) {
               ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_PROBLEM_VAL), gShellDebug1HiiHandle, L"comp", TempParam, L"-s");
               ShellStatus = SHELL_INVALID_PARAMETER;
             } else {
               if (DifferentBytes > MAX (Size1, Size2)) {
                 DifferentBytes = MAX (Size1, Size2);
               }
             }
           }
         }
       }

       if (ShellStatus == SHELL_SUCCESS) {
         DataFromFile1 = AllocateZeroPool ((UINTN)DifferentBytes);
         DataFromFile2 = AllocateZeroPool ((UINTN)DifferentBytes);
         FileBufferInit (&FileBuffer1);
         FileBufferInit (&FileBuffer2);
         if ((DataFromFile1 == NULL) || (DataFromFile2 == NULL) ||
             (FileBuffer1.Data == NULL) || (FileBuffer2.Data == NULL))
         {
           ShellStatus = SHELL_OUT_OF_RESOURCES;
           SHELL_FREE_NON_NULL (DataFromFile1);
           SHELL_FREE_NON_NULL (DataFromFile2);
           FileBufferUninit (&FileBuffer1);
           FileBufferUninit (&FileBuffer2);
         }
       }

       if (ShellStatus == SHELL_SUCCESS) {
         while (DiffPointNumber < DifferentCount) {
           DataSizeFromFile1 = 1;
           DataSizeFromFile2 = 1;
           OneByteFromFile1  = 0;
           OneByteFromFile2  = 0;
           Status            = FileBufferReadByte (
                                 FileHandle1,
                                 &FileBuffer1,
                                 &DataSizeFromFile1,
                                 &OneByteFromFile1
                                 );
           ASSERT_EFI_ERROR (Status);
           Status = FileBufferReadByte (
                      FileHandle2,
                      &FileBuffer2,
                      &DataSizeFromFile2,
                      &OneByteFromFile2
                      );
           ASSERT_EFI_ERROR (Status);

           TempAddress++;

           //
           // 1.When end of file and no chars in DataFromFile buffer, then break while.
           // 2.If no more char in File1 or File2, The ReadStatus is InPrevDiffPoint forever.
           //   So the previous different point is the last one, then break the while block.
           //
           if (((DataSizeFromFile1 == 0) && (InsertPosition1 == 0) && (DataSizeFromFile2 == 0) && (InsertPosition2 == 0)) ||
               ((ReadStatus == InPrevDiffPoint) && ((DataSizeFromFile1 == 0) || (DataSizeFromFile2 == 0)))
               )
           {
             break;
           }

           if (ReadStatus == OutOfDiffPoint) {
             if (OneByteFromFile1 != OneByteFromFile2) {
               ReadStatus       = InDiffPoint;
               DiffPointAddress = TempAddress;
               if (DataSizeFromFile1 == 1) {
                 DataFromFile1[InsertPosition1++] = OneByteFromFile1;
               }

               if (DataSizeFromFile2 == 1) {
                 DataFromFile2[InsertPosition2++] = OneByteFromFile2;
               }
             }
           } else if (ReadStatus == InDiffPoint) {
             if (DataSizeFromFile1 == 1) {
               DataFromFile1[InsertPosition1++] = OneByteFromFile1;
             }

             if (DataSizeFromFile2 == 1) {
               DataFromFile2[InsertPosition2++] = OneByteFromFile2;
             }
           } else if (ReadStatus == InPrevDiffPoint) {
             if (OneByteFromFile1 == OneByteFromFile2) {
               ReadStatus = OutOfDiffPoint;
             }
           }

           //
           // ReadStatus should be always equal InDiffPoint.
           //
           if ((InsertPosition1 == DifferentBytes) ||
               (InsertPosition2 == DifferentBytes) ||
               ((DataSizeFromFile1 == 0) && (DataSizeFromFile2 == 0))
               )
           {
             ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_COMP_DIFFERENCE_POINT), gShellDebug1HiiHandle, ++DiffPointNumber);
             PrintDifferentPoint (FileName1, L"File1", DataFromFile1, InsertPosition1, DiffPointAddress, DifferentBytes);
             PrintDifferentPoint (FileName2, L"File2", DataFromFile2, InsertPosition2, DiffPointAddress, DifferentBytes);

             //
             // One of two buffuers is empty, it means this is the last different point.
             //
             if ((InsertPosition1 == 0) || (InsertPosition2 == 0)) {
               break;
             }

             for (Index = 1; Index < InsertPosition1 && Index < InsertPosition2; Index++) {
               if (DataFromFile1[Index] == DataFromFile2[Index]) {
                 ReadStatus = OutOfDiffPoint;
                 break;
               }
             }

             if (ReadStatus == OutOfDiffPoint) {
               //
               // Try to find a new different point in the rest of DataFromFile.
               //
               for ( ; Index < MAX (InsertPosition1, InsertPosition2); Index++) {
                 if (DataFromFile1[Index] != DataFromFile2[Index]) {
                   ReadStatus        = InDiffPoint;
                   DiffPointAddress += Index;
                   break;
                 }
               }
             } else {
               //
               // Doesn't find a new different point, still in the same different point.
               //
               ReadStatus = InPrevDiffPoint;
             }

             CopyMem (DataFromFile1, DataFromFile1 + Index, InsertPosition1 - Index);
             CopyMem (DataFromFile2, DataFromFile2 + Index, InsertPosition2 - Index);

             SetMem (DataFromFile1 + InsertPosition1 - Index, (UINTN)DifferentBytes - InsertPosition1 + Index, 0);
             SetMem (DataFromFile2 + InsertPosition2 - Index, (UINTN)DifferentBytes - InsertPosition2 + Index, 0);

             InsertPosition1 -= Index;
             InsertPosition2 -= Index;
           }
         }

         SHELL_FREE_NON_NULL (DataFromFile1);
         SHELL_FREE_NON_NULL (DataFromFile2);
         FileBufferUninit (&FileBuffer1);
         FileBufferUninit (&FileBuffer2);

         if (DiffPointNumber == 0) {
           ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_COMP_FOOTER_PASS), gShellDebug1HiiHandle);
         } else {
           ShellStatus = SHELL_NOT_EQUAL;
           ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_COMP_FOOTER_FAIL), gShellDebug1HiiHandle);
         }
       }
     }

     ShellCommandLineFreeVarList (Package);
   }

   SHELL_FREE_NON_NULL (FileName1);
   SHELL_FREE_NON_NULL (FileName2);

   if (FileHandle1 != NULL) {
     gEfiShellProtocol->CloseFile (FileHandle1);
   }

   if (FileHandle2 != NULL) {
     gEfiShellProtocol->CloseFile (FileHandle2);
   }

   return (ShellStatus);
 }
	/** @file
	Main file for Comp shell Debug1 function.

	(C) Copyright 2015 Hewlett-Packard Development Company, L.P.<BR>
	Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
	SPDX-License-Identifier: BSD-2-Clause-Patent

	**/

	#include "UefiShellDebug1CommandsLib.h"

	STATIC CONST SHELL_PARAM_ITEM ParamList[] = {
	{ L"-n", TypeValue },
	{ L"-s", TypeValue },
	{ NULL, TypeMax }
	};

	typedef enum {
	OutOfDiffPoint,
	InDiffPoint,
	InPrevDiffPoint
	} READ_STATUS;

	//
	// Buffer type, for reading both file operands in chunks.
	//
	typedef struct {
	UINT8 *Data; // dynamically allocated buffer
	UINTN Allocated; // the allocated size of Data
	UINTN Next; // next position in Data to fetch a byte at
	UINTN Left; // number of bytes left in Data for fetching at Next
	} FILE_BUFFER;

	/**
	Function to print differnt point data.

	@param[in] FileName File name.
	@param[in] FileTag File tag name.
	@param[in] Buffer Data buffer to be printed.
	@param[in] BufferSize Size of the data to be printed.
	@param[in] Address Address of the differnt point.
	@param[in] DifferentBytes Total size of the buffer.

	**/
	VOID
	PrintDifferentPoint (
	CONST CHAR16 *FileName,
	CHAR16 *FileTag,
	UINT8 *Buffer,
	UINT64 BufferSize,
	UINTN Address,
	UINT64 DifferentBytes
	)
	{
	UINTN Index;

	ShellPrintEx (-1, -1, L"%s: %s\r\n %08x:", FileTag, FileName, Address);

	//
	// Print data in hex-format.
	//
	for (Index = 0; Index < BufferSize; Index++) {
	ShellPrintEx (-1, -1, L" %02x", Buffer[Index]);
	}

	if (BufferSize < DifferentBytes) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_COMP_END_OF_FILE), gShellDebug1HiiHandle);
	}

	ShellPrintEx (-1, -1, L" *");

	//
	// Print data in char-format.
	//
	for (Index = 0; Index < BufferSize; Index++) {
	if ((Buffer[Index] >= 0x20) && (Buffer[Index] <= 0x7E)) {
	ShellPrintEx (-1, -1, L"%c", Buffer[Index]);
	} else {
	//
	// Print dots for control characters
	//
	ShellPrintEx (-1, -1, L".");
	}
	}

	ShellPrintEx (-1, -1, L"*\r\n");
	}

	/**
	Initialize a FILE_BUFFER.

	@param[out] FileBuffer The FILE_BUFFER to initialize. On return, the caller
	is responsible for checking FileBuffer->Data: if
	FileBuffer->Data is NULL on output, then memory
	allocation failed.
	**/
	STATIC
	VOID
	FileBufferInit (
	OUT FILE_BUFFER *FileBuffer
	)
	{
	FileBuffer->Allocated = PcdGet32 (PcdShellFileOperationSize);
	FileBuffer->Data = AllocatePool (FileBuffer->Allocated);
	FileBuffer->Left = 0;
	}

	/**
	Uninitialize a FILE_BUFFER.

	@param[in,out] FileBuffer The FILE_BUFFER to uninitialize. The caller is
	responsible for making sure FileBuffer was first
	initialized with FileBufferInit(), successfully or
	unsuccessfully.
	**/
	STATIC
	VOID
	FileBufferUninit (
	IN OUT FILE_BUFFER *FileBuffer
	)
	{
	SHELL_FREE_NON_NULL (FileBuffer->Data);
	}

	/**
	Read a byte from a SHELL_FILE_HANDLE, buffered with a FILE_BUFFER.

	@param[in] FileHandle The SHELL_FILE_HANDLE to replenish FileBuffer
	from, if needed.

	@param[in,out] FileBuffer The FILE_BUFFER to read a byte from. If FileBuffer
	is empty on entry, then FileBuffer is refilled
	from FileHandle, before outputting a byte from
	FileBuffer to Byte. The caller is responsible for
	ensuring that FileBuffer was successfully
	initialized with FileBufferInit().

	@param[out] BytesRead On successful return, BytesRead is set to 1 if the
	next byte from FileBuffer has been stored to Byte.
	On successful return, BytesRead is set to 0 if
	FileBuffer is empty, and FileHandle is at EOF.
	When an error is returned, BytesRead is not set.

	@param[out] Byte On output, the next byte from FileBuffer. Only set
	if (a) EFI_SUCCESS is returned and (b) BytesRead
	is set to 1 on output.

	@retval EFI_SUCCESS BytesRead has been set to 0 or 1. In the latter case,
	Byte has been set as well.

	@return Error codes propagated from
	gEfiShellProtocol->ReadFile().
	**/
	STATIC
	EFI_STATUS
	FileBufferReadByte (
	IN SHELL_FILE_HANDLE FileHandle,
	IN OUT FILE_BUFFER *FileBuffer,
	OUT UINTN *BytesRead,
	OUT UINT8 *Byte
	)
	{
	UINTN ReadSize;
	EFI_STATUS Status;

	if (FileBuffer->Left == 0) {
	ReadSize = FileBuffer->Allocated;
	Status = gEfiShellProtocol->ReadFile (
	FileHandle,
	&ReadSize,
	FileBuffer->Data
	);
	if (EFI_ERROR (Status)) {
	return Status;
	}

	if (ReadSize == 0) {
	*BytesRead = 0;
	return EFI_SUCCESS;
	}

	FileBuffer->Next = 0;
	FileBuffer->Left = ReadSize;
	}

	*BytesRead = 1;
	*Byte = FileBuffer->Data[FileBuffer->Next];

	FileBuffer->Next++;
	FileBuffer->Left--;
	return EFI_SUCCESS;
	}

	/**
	Function for 'comp' command.

	@param[in] ImageHandle Handle to the Image (NULL if Internal).
	@param[in] SystemTable Pointer to the System Table (NULL if Internal).
	**/
	SHELL_STATUS
	EFIAPI
	ShellCommandRunComp (
	IN EFI_HANDLE ImageHandle,
	IN EFI_SYSTEM_TABLE *SystemTable
	)
	{
	EFI_STATUS Status;
	LIST_ENTRY *Package;
	CHAR16 *ProblemParam;
	CHAR16 *FileName1;
	CHAR16 *FileName2;
	CONST CHAR16 *TempParam;
	SHELL_STATUS ShellStatus;
	SHELL_FILE_HANDLE FileHandle1;
	SHELL_FILE_HANDLE FileHandle2;
	UINT64 Size1;
	UINT64 Size2;
	UINT64 DifferentBytes;
	UINT64 DifferentCount;
	UINT8 DiffPointNumber;
	UINT8 OneByteFromFile1;
	UINT8 OneByteFromFile2;
	UINT8 *DataFromFile1;
	UINT8 *DataFromFile2;
	FILE_BUFFER FileBuffer1;
	FILE_BUFFER FileBuffer2;
	UINTN InsertPosition1;
	UINTN InsertPosition2;
	UINTN DataSizeFromFile1;
	UINTN DataSizeFromFile2;
	UINTN TempAddress;
	UINTN Index;
	UINTN DiffPointAddress;
	READ_STATUS ReadStatus;

	ShellStatus = SHELL_SUCCESS;
	Status = EFI_SUCCESS;
	FileName1 = NULL;
	FileName2 = NULL;
	FileHandle1 = NULL;
	FileHandle2 = NULL;
	DataFromFile1 = NULL;
	DataFromFile2 = NULL;
	ReadStatus = OutOfDiffPoint;
	DifferentCount = 10;
	DifferentBytes = 4;
	DiffPointNumber = 0;
	InsertPosition1 = 0;
	InsertPosition2 = 0;
	TempAddress = 0;
	DiffPointAddress = 0;

	//
	// initialize the shell lib (we must be in non-auto-init...)
	//
	Status = ShellInitialize ();
	ASSERT_EFI_ERROR (Status);

	Status = CommandInit ();
	ASSERT_EFI_ERROR (Status);

	//
	// parse the command line
	//
	Status = ShellCommandLineParse (ParamList, &Package, &ProblemParam, TRUE);
	if (EFI_ERROR (Status)) {
	if ((Status == EFI_VOLUME_CORRUPTED) && (ProblemParam != NULL)) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_PROBLEM), gShellDebug1HiiHandle, L"comp", ProblemParam);
	FreePool (ProblemParam);
	ShellStatus = SHELL_INVALID_PARAMETER;
	} else {
	ASSERT (FALSE);
	}
	} else {
	if (ShellCommandLineGetCount (Package) > 3) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_TOO_MANY), gShellDebug1HiiHandle, L"comp");
	ShellStatus = SHELL_INVALID_PARAMETER;
	} else if (ShellCommandLineGetCount (Package) < 3) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_TOO_FEW), gShellDebug1HiiHandle, L"comp");
	ShellStatus = SHELL_INVALID_PARAMETER;
	} else {
	TempParam = ShellCommandLineGetRawValue (Package, 1);
	ASSERT (TempParam != NULL);
	FileName1 = ShellFindFilePath (TempParam);
	if (FileName1 == NULL) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_FILE_FIND_FAIL), gShellDebug1HiiHandle, L"comp", TempParam);
	ShellStatus = SHELL_NOT_FOUND;
	} else {
	Status = ShellOpenFileByName (FileName1, &FileHandle1, EFI_FILE_MODE_READ, 0);
	if (EFI_ERROR (Status)) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_FILE_OPEN_FAIL), gShellDebug1HiiHandle, L"comp", TempParam);
	ShellStatus = SHELL_NOT_FOUND;
	}
	}

	TempParam = ShellCommandLineGetRawValue (Package, 2);
	ASSERT (TempParam != NULL);
	FileName2 = ShellFindFilePath (TempParam);
	if (FileName2 == NULL) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_FILE_FIND_FAIL), gShellDebug1HiiHandle, L"comp", TempParam);
	ShellStatus = SHELL_NOT_FOUND;
	} else {
	Status = ShellOpenFileByName (FileName2, &FileHandle2, EFI_FILE_MODE_READ, 0);
	if (EFI_ERROR (Status)) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_FILE_OPEN_FAIL), gShellDebug1HiiHandle, L"comp", TempParam);
	ShellStatus = SHELL_NOT_FOUND;
	}
	}

	if (ShellStatus == SHELL_SUCCESS) {
	Status = gEfiShellProtocol->GetFileSize (FileHandle1, &Size1);
	ASSERT_EFI_ERROR (Status);
	Status = gEfiShellProtocol->GetFileSize (FileHandle2, &Size2);
	ASSERT_EFI_ERROR (Status);

	if (ShellCommandLineGetFlag (Package, L"-n")) {
	TempParam = ShellCommandLineGetValue (Package, L"-n");
	if (TempParam == NULL) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_NO_VALUE), gShellDebug1HiiHandle, L"comp", L"-n");
	ShellStatus = SHELL_INVALID_PARAMETER;
	} else {
	if (gUnicodeCollation->StriColl (gUnicodeCollation, (CHAR16 *)TempParam, L"all") == 0) {
	DifferentCount = MAX_UINTN;
	} else {
	Status = ShellConvertStringToUint64 (TempParam, &DifferentCount, FALSE, TRUE);
	if (EFI_ERROR (Status) \|\| (DifferentCount == 0)) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_PROBLEM_VAL), gShellDebug1HiiHandle, L"comp", TempParam, L"-n");
	ShellStatus = SHELL_INVALID_PARAMETER;
	}
	}
	}
	}

	if (ShellCommandLineGetFlag (Package, L"-s")) {
	TempParam = ShellCommandLineGetValue (Package, L"-s");
	if (TempParam == NULL) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_NO_VALUE), gShellDebug1HiiHandle, L"comp", L"-s");
	ShellStatus = SHELL_INVALID_PARAMETER;
	} else {
	Status = ShellConvertStringToUint64 (TempParam, &DifferentBytes, FALSE, TRUE);
	if (EFI_ERROR (Status) \|\| (DifferentBytes == 0)) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_PROBLEM_VAL), gShellDebug1HiiHandle, L"comp", TempParam, L"-s");
	ShellStatus = SHELL_INVALID_PARAMETER;
	} else {
	if (DifferentBytes > MAX (Size1, Size2)) {
	DifferentBytes = MAX (Size1, Size2);
	}
	}
	}
	}
	}

	if (ShellStatus == SHELL_SUCCESS) {
	DataFromFile1 = AllocateZeroPool ((UINTN)DifferentBytes);
	DataFromFile2 = AllocateZeroPool ((UINTN)DifferentBytes);
	FileBufferInit (&FileBuffer1);
	FileBufferInit (&FileBuffer2);
	if ((DataFromFile1 == NULL) \|\| (DataFromFile2 == NULL) \|\|
	(FileBuffer1.Data == NULL) \|\| (FileBuffer2.Data == NULL))
	{
	ShellStatus = SHELL_OUT_OF_RESOURCES;
	SHELL_FREE_NON_NULL (DataFromFile1);
	SHELL_FREE_NON_NULL (DataFromFile2);
	FileBufferUninit (&FileBuffer1);
	FileBufferUninit (&FileBuffer2);
	}
	}

	if (ShellStatus == SHELL_SUCCESS) {
	while (DiffPointNumber < DifferentCount) {
	DataSizeFromFile1 = 1;
	DataSizeFromFile2 = 1;
	OneByteFromFile1 = 0;
	OneByteFromFile2 = 0;
	Status = FileBufferReadByte (
	FileHandle1,
	&FileBuffer1,
	&DataSizeFromFile1,
	&OneByteFromFile1
	);
	ASSERT_EFI_ERROR (Status);
	Status = FileBufferReadByte (
	FileHandle2,
	&FileBuffer2,
	&DataSizeFromFile2,
	&OneByteFromFile2
	);
	ASSERT_EFI_ERROR (Status);

	TempAddress++;

	//
	// 1.When end of file and no chars in DataFromFile buffer, then break while.
	// 2.If no more char in File1 or File2, The ReadStatus is InPrevDiffPoint forever.
	// So the previous different point is the last one, then break the while block.
	//
	if (((DataSizeFromFile1 == 0) && (InsertPosition1 == 0) && (DataSizeFromFile2 == 0) && (InsertPosition2 == 0)) \|\|
	((ReadStatus == InPrevDiffPoint) && ((DataSizeFromFile1 == 0) \|\| (DataSizeFromFile2 == 0)))
	)
	{
	break;
	}

	if (ReadStatus == OutOfDiffPoint) {
	if (OneByteFromFile1 != OneByteFromFile2) {
	ReadStatus = InDiffPoint;
	DiffPointAddress = TempAddress;
	if (DataSizeFromFile1 == 1) {
	DataFromFile1[InsertPosition1++] = OneByteFromFile1;
	}

	if (DataSizeFromFile2 == 1) {
	DataFromFile2[InsertPosition2++] = OneByteFromFile2;
	}
	}
	} else if (ReadStatus == InDiffPoint) {
	if (DataSizeFromFile1 == 1) {
	DataFromFile1[InsertPosition1++] = OneByteFromFile1;
	}

	if (DataSizeFromFile2 == 1) {
	DataFromFile2[InsertPosition2++] = OneByteFromFile2;
	}
	} else if (ReadStatus == InPrevDiffPoint) {
	if (OneByteFromFile1 == OneByteFromFile2) {
	ReadStatus = OutOfDiffPoint;
	}
	}

	//
	// ReadStatus should be always equal InDiffPoint.
	//
	if ((InsertPosition1 == DifferentBytes) \|\|
	(InsertPosition2 == DifferentBytes) \|\|
	((DataSizeFromFile1 == 0) && (DataSizeFromFile2 == 0))
	)
	{
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_COMP_DIFFERENCE_POINT), gShellDebug1HiiHandle, ++DiffPointNumber);
	PrintDifferentPoint (FileName1, L"File1", DataFromFile1, InsertPosition1, DiffPointAddress, DifferentBytes);
	PrintDifferentPoint (FileName2, L"File2", DataFromFile2, InsertPosition2, DiffPointAddress, DifferentBytes);

	//
	// One of two buffuers is empty, it means this is the last different point.
	//
	if ((InsertPosition1 == 0) \|\| (InsertPosition2 == 0)) {
	break;
	}

	for (Index = 1; Index < InsertPosition1 && Index < InsertPosition2; Index++) {
	if (DataFromFile1[Index] == DataFromFile2[Index]) {
	ReadStatus = OutOfDiffPoint;
	break;
	}
	}

	if (ReadStatus == OutOfDiffPoint) {
	//
	// Try to find a new different point in the rest of DataFromFile.
	//
	for ( ; Index < MAX (InsertPosition1, InsertPosition2); Index++) {
	if (DataFromFile1[Index] != DataFromFile2[Index]) {
	ReadStatus = InDiffPoint;
	DiffPointAddress += Index;
	break;
	}
	}
	} else {
	//
	// Doesn't find a new different point, still in the same different point.
	//
	ReadStatus = InPrevDiffPoint;
	}

	CopyMem (DataFromFile1, DataFromFile1 + Index, InsertPosition1 - Index);
	CopyMem (DataFromFile2, DataFromFile2 + Index, InsertPosition2 - Index);

	SetMem (DataFromFile1 + InsertPosition1 - Index, (UINTN)DifferentBytes - InsertPosition1 + Index, 0);
	SetMem (DataFromFile2 + InsertPosition2 - Index, (UINTN)DifferentBytes - InsertPosition2 + Index, 0);

	InsertPosition1 -= Index;
	InsertPosition2 -= Index;
	}
	}

	SHELL_FREE_NON_NULL (DataFromFile1);
	SHELL_FREE_NON_NULL (DataFromFile2);
	FileBufferUninit (&FileBuffer1);
	FileBufferUninit (&FileBuffer2);

	if (DiffPointNumber == 0) {
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_COMP_FOOTER_PASS), gShellDebug1HiiHandle);
	} else {
	ShellStatus = SHELL_NOT_EQUAL;
	ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_COMP_FOOTER_FAIL), gShellDebug1HiiHandle);
	}
	}
	}

	ShellCommandLineFreeVarList (Package);
	}

	SHELL_FREE_NON_NULL (FileName1);
	SHELL_FREE_NON_NULL (FileName2);

	if (FileHandle1 != NULL) {
	gEfiShellProtocol->CloseFile (FileHandle1);
	}

	if (FileHandle2 != NULL) {
	gEfiShellProtocol->CloseFile (FileHandle2);
	}

	return (ShellStatus);
	}