EmbeddedPkg/Ebl/Main.c - SHIFTPHONES/android_bootable_bootloader_edk2 - Gitiles

 /** @file
   Basic command line parser for EBL (Embedded Boot Loader)

   Copyright (c) 2007, Intel Corporation. All rights reserved.<BR>
   Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>

   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
   http://opensource.org/licenses/bsd-license.php

   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.


 **/

 #include "Ebl.h"

 // Globals for command history processing
 INTN mCmdHistoryEnd     = -1;
 INTN mCmdHistoryStart   = -1;
 INTN mCmdHistoryCurrent = -1;
 CHAR8 mCmdHistory[MAX_CMD_HISTORY][MAX_CMD_LINE];
 CHAR8 *mCmdBlank = "";

 // Globals to remember current screen geometry
 UINTN gScreenColumns;
 UINTN gScreenRows;

 // Global to turn on/off breaking commands with prompts before they scroll the screen
 BOOLEAN gPageBreak = TRUE;

 VOID
 RingBufferIncrement (
   IN  INTN  *Value
   )
 {
   *Value = *Value + 1;

   if (*Value >= MAX_CMD_HISTORY) {
     *Value = 0;
   }
 }

 VOID
 RingBufferDecrement (
   IN  INTN  *Value
   )
 {
   *Value = *Value - 1;

   if (*Value < 0) {
     *Value = MAX_CMD_HISTORY - 1;
   }
 }

 /**
   Save this command in the circular history buffer. Older commands are
   overwritten with newer commands.

   @param  Cmd   Command line to archive the history of.

   @return None

 **/
 VOID
 SetCmdHistory (
   IN  CHAR8 *Cmd
   )
 {
   // Don't bother adding empty commands to the list
   if (AsciiStrLen(Cmd) != 0) {

     // First entry
     if (mCmdHistoryStart == -1) {
       mCmdHistoryStart   = 0;
       mCmdHistoryEnd     = 0;
     } else {
       // Record the new command at the next index
       RingBufferIncrement(&mCmdHistoryStart);

       // If the next index runs into the end index, shuffle end back by one
       if (mCmdHistoryStart == mCmdHistoryEnd) {
         RingBufferIncrement(&mCmdHistoryEnd);
       }
     }

     // Copy the new command line into the ring buffer
     AsciiStrnCpy(&mCmdHistory[mCmdHistoryStart][0], Cmd, MAX_CMD_LINE);
   }

   // Reset the command history for the next up arrow press
   mCmdHistoryCurrent = mCmdHistoryStart;
 }


 /**
   Retreave data from the Command History buffer. Direction maps into up arrow
   an down arrow on the command line

   @param  Direction  Command forward or back

   @return The Command history based on the Direction

 **/
 CHAR8 *
 GetCmdHistory (
   IN UINT16   Direction
   )
 {
   CHAR8 *HistoricalCommand = NULL;

   // No history yet?
   if (mCmdHistoryCurrent == -1) {
     HistoricalCommand = mCmdBlank;
     goto Exit;
   }

   if (Direction == SCAN_UP) {
     HistoricalCommand = &mCmdHistory[mCmdHistoryCurrent][0];

     // if we just echoed the last command, hang out there, don't wrap around
     if (mCmdHistoryCurrent == mCmdHistoryEnd) {
       goto Exit;
     }

     // otherwise, back up by one
     RingBufferDecrement(&mCmdHistoryCurrent);

   } else if (Direction == SCAN_DOWN) {

     // if we last echoed the start command, put a blank prompt out
     if (mCmdHistoryCurrent == mCmdHistoryStart) {
       HistoricalCommand = mCmdBlank;
       goto Exit;
     }

     // otherwise increment the current pointer and return that command
     RingBufferIncrement(&mCmdHistoryCurrent);
     RingBufferIncrement(&mCmdHistoryCurrent);

     HistoricalCommand = &mCmdHistory[mCmdHistoryCurrent][0];
     RingBufferDecrement(&mCmdHistoryCurrent);
   }

 Exit:
   return HistoricalCommand;
 }


 /**
   Parse the CmdLine and break it up into Argc (arg count) and Argv (array of
   pointers to each argument). The Cmd buffer is altered and separators are
   converted to string terminators. This allows Argv to point into CmdLine.
   A CmdLine can support multiple commands. The next command in the command line
   is returned if it exists.

   @param  CmdLine String to parse for a set of commands
   @param  Argc    Returns the number of arguments in the CmdLine current command
   @param  Argv    Argc pointers to each string in CmdLine

   @return Next Command in the command line or NULL if non exists
 **/
 CHAR8 *
 ParseArguments (
   IN  CHAR8  *CmdLine,
   OUT UINTN  *Argc,
   OUT CHAR8  **Argv
   )
 {
   UINTN   Arg;
   CHAR8   *Char;
   BOOLEAN LookingForArg;
   BOOLEAN InQuote;

   *Argc = 0;
   if (AsciiStrLen (CmdLine) == 0) {
     return NULL;
   }

   // Walk a single command line. A CMD_SEPARATOR allows multiple commands on a single line
   InQuote       = FALSE;
   LookingForArg = TRUE;
   for (Char = CmdLine, Arg = 0; *Char != '\0'; Char++) {
     if (!InQuote && *Char == CMD_SEPARATOR) {
       break;
     }

     // Perform any text conversion here
     if (*Char == '\t') {
       // TAB to space
       *Char = ' ';
     }

     if (LookingForArg) {
       // Look for the beginning of an Argv[] entry
       if (*Char == '"') {
         Argv[Arg++] = ++Char;
         LookingForArg = FALSE;
         InQuote = TRUE;
       } else if (*Char != ' ') {
         Argv[Arg++] = Char;
         LookingForArg = FALSE;
       }
     } else {
       // Looking for the terminator of an Argv[] entry
       if (!InQuote && (*Char == ' ')) {
         *Char = '\0';
         LookingForArg = TRUE;
       } else if (!InQuote && (*Char == '"') && (*(Char-1) != '\\')) {
         InQuote = TRUE;
       } else if (InQuote && (*Char == '"') && (*(Char-1) != '\\')) {
         *Char = '\0';
         InQuote = FALSE;
       }
     }
   }

   *Argc = Arg;

   if (*Char == CMD_SEPARATOR) {
     // Replace the command delimiter with null and return pointer to next command line
     *Char = '\0';
     return ++Char;
   }

   return NULL;
 }


 /**
   Return a keypress or optionally timeout if a timeout value was passed in.
   An optional callback function is called every second when waiting for a
   timeout.

   @param  Key           EFI Key information returned
   @param  TimeoutInSec  Number of seconds to wait to timeout
   @param  CallBack      Callback called every second during the timeout wait

   @return EFI_SUCCESS  Key was returned
   @return EFI_TIMEOUT  If the TimoutInSec expired

 **/
 EFI_STATUS
 EFIAPI
 EblGetCharKey (
   IN OUT EFI_INPUT_KEY            *Key,
   IN     UINTN                    TimeoutInSec,
   IN     EBL_GET_CHAR_CALL_BACK   CallBack   OPTIONAL
   )
 {
   EFI_STATUS    Status;
   UINTN         WaitCount;
   UINTN         WaitIndex;
   EFI_EVENT     WaitList[2];

   WaitCount   = 1;
   WaitList[0] = gST->ConIn->WaitForKey;
   if (TimeoutInSec != 0) {
     // Create a time event for 1 sec duration if we have a timeout
     gBS->CreateEvent (EVT_TIMER, 0, NULL, NULL, &WaitList[1]);
     gBS->SetTimer (WaitList[1], TimerPeriodic, EFI_SET_TIMER_TO_SECOND);
     WaitCount++;
   }

   for (;;) {
     Status = gBS->WaitForEvent (WaitCount, WaitList, &WaitIndex);
     ASSERT_EFI_ERROR (Status);

     switch (WaitIndex) {
     case 0:
       // Key event signaled
       Status = gST->ConIn->ReadKeyStroke (gST->ConIn, Key);
       if (!EFI_ERROR (Status)) {
         if (WaitCount == 2) {
           gBS->CloseEvent (WaitList[1]);
         }
         return EFI_SUCCESS;
       }
       break;

     case 1:
       // Periodic 1 sec timer signaled
       TimeoutInSec--;
       if (CallBack != NULL) {
         // Call the users callback function if registered
         CallBack (TimeoutInSec);
       }
       if (TimeoutInSec == 0) {
         gBS->CloseEvent (WaitList[1]);
         return EFI_TIMEOUT;
       }
       break;
     default:
       ASSERT (FALSE);
     }
   }
 }


 /**
   This routine is used prevent command output data from scrolling off the end
   of the screen. The global gPageBreak is used to turn on or off this feature.
   If the CurrentRow is near the end of the screen pause and print out a prompt
   If the use hits Q to quit return TRUE else for any other key return FALSE.
   PrefixNewline is used to figure out if a newline is needed before the prompt
   string. This depends on the last print done before calling this function.
   CurrentRow is updated by one on a call or set back to zero if a prompt is
   needed.

   @param  CurrentRow  Used to figure out if its the end of the page and updated
   @param  PrefixNewline  Did previous print issue a newline

   @return TRUE if Q was hit to quit, FALSE in all other cases.

 **/
 BOOLEAN
 EFIAPI
 EblAnyKeyToContinueQtoQuit (
   IN  UINTN   *CurrentRow,
   IN  BOOLEAN PrefixNewline
   )
 {
   EFI_INPUT_KEY     InputKey;

   if (!gPageBreak) {
     // global disable for this feature
     return FALSE;
   }

   if (*CurrentRow >= (gScreenRows - 2)) {
     if (PrefixNewline) {
       AsciiPrint ("\n");
     }
     AsciiPrint ("Any key to continue (Q to quit): ");
     EblGetCharKey (&InputKey, 0, NULL);
     AsciiPrint ("\n");

     // Time to promt to stop the screen. We have to leave space for the prompt string
     *CurrentRow = 0;
     if (InputKey.UnicodeChar == 'Q' || InputKey.UnicodeChar == 'q') {
       return TRUE;
     }
   } else {
     *CurrentRow += 1;
   }

   return FALSE;
 }


 /**
   Set the text color of the EFI Console. If a zero is passed in reset to
   default text/background color.

   @param  Attribute   For text and background color

 **/
 VOID
 EblSetTextColor (
   UINTN   Attribute
   )
 {
   if (Attribute == 0) {
     // Set the text color back to default
     Attribute = (UINTN)PcdGet32 (PcdEmbeddedDefaultTextColor);
   }

   gST->ConOut->SetAttribute (gST->ConOut, Attribute);
 }


 /**
   Collect the keyboard input for a cmd line. Carriage Return, New Line, or ESC
   terminates the command line. You can edit the command line via left arrow,
   delete and backspace and they all back up and erase the command line.
   No edit of command line is possible without deletion at this time!
   The up arrow and down arrow fill Cmd with information from the history
   buffer.

   @param  Cmd         Command line to return
   @param  CmdMaxSize  Maximum size of Cmd

   @return The Status of EblGetCharKey()

 **/
 EFI_STATUS
 GetCmd (
   IN OUT  CHAR8   *Cmd,
   IN      UINTN   CmdMaxSize
   )
 {
   EFI_STATUS    Status;
   UINTN         Index;
   UINTN         Index2;
   CHAR8         Char;
   CHAR8         *History;
   EFI_INPUT_KEY Key;

   for (Index = 0; Index < CmdMaxSize - 1;) {
     Status = EblGetCharKey (&Key, 0, NULL);
     if (EFI_ERROR (Status)) {
       Cmd[Index] = '\0';
       AsciiPrint ("\n");
       return Status;
     }

     Char = (CHAR8)Key.UnicodeChar;
     if ((Char == '\n') || (Char == '\r') || (Char == 0x7f)) {
       Cmd[Index] = '\0';
       if (FixedPcdGetBool(PcdEmbeddedShellCharacterEcho) == TRUE) {
         AsciiPrint ("\n\r");
       }
       return EFI_SUCCESS;
     } else if ((Char == '\b') || (Key.ScanCode == SCAN_LEFT) || (Key.ScanCode == SCAN_DELETE)){
       if (Index != 0) {
         Index--;
         //
         // Update the display
         //
         AsciiPrint ("\b \b");
       }
     } else if ((Key.ScanCode == SCAN_UP) || Key.ScanCode == SCAN_DOWN) {
       History = GetCmdHistory (Key.ScanCode);
       //
       // Clear display line
       //
       for (Index2 = 0; Index2 < Index; Index2++) {
         AsciiPrint ("\b \b");
       }
       AsciiPrint (History);
       Index = AsciiStrLen (History);
       AsciiStrnCpy (Cmd, History, CmdMaxSize);
     } else {
       Cmd[Index++] = Char;
       if (FixedPcdGetBool(PcdEmbeddedShellCharacterEcho) == TRUE) {
         AsciiPrint ("%c", Char);
       }
     }
   }

   return EFI_SUCCESS;
 }


 /**
   Print the boot up banner for the EBL.
 **/
 VOID
 EblPrintStartupBanner (
   VOID
   )
 {
   AsciiPrint ("Embedded Boot Loader (");
   EblSetTextColor (EFI_YELLOW);
   AsciiPrint ("EBL");
   EblSetTextColor (0);
   AsciiPrint (") prototype. Built at %a on %a\n",__TIME__, __DATE__);
   AsciiPrint ("THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN 'AS IS' BASIS,\nWITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\n");
   AsciiPrint ("Please send feedback to edk2-devel@lists.sourceforge.net\n");
 }


 /**
   Send null requests to all removable media block IO devices so the a media add/remove/change
   can be detected in real before we execute a command.

   This is mainly due to the fact that the FAT driver does not do this today so you can get stale
   dir commands after an SD Card has been removed.
 **/
 VOID
 EblProbeRemovableMedia (
   VOID
   )
 {
   UINTN         Index;
   UINTN         Max;
   EFI_OPEN_FILE *File;

   //
   // Probe for media insertion/removal in removable media devices
   //
   Max = EfiGetDeviceCounts (EfiOpenBlockIo);
   if (Max != 0) {
     for (Index = 0; Index < Max; Index++) {
       File = EfiDeviceOpenByType (EfiOpenBlockIo, Index);
       if (File != NULL) {
         if (File->FsBlockIoMedia->RemovableMedia) {
           // Probe to see if media is present (or not) or media changed
           //  this causes the ReinstallProtocolInterface() to fire in the
           //  block io driver to update the system about media change events
           File->FsBlockIo->ReadBlocks (File->FsBlockIo, File->FsBlockIo->Media->MediaId, (EFI_LBA)0, 0, NULL);
         }
         EfiClose (File);
       }
     }
   }
 }


 /**
   Print the prompt for the EBL.
 **/
 VOID
 EblPrompt (
   VOID
   )
 {
   EblSetTextColor (EFI_YELLOW);
   AsciiPrint ("%a %a",(CHAR8 *)PcdGetPtr (PcdEmbeddedPrompt), EfiGetCwd ());
   EblSetTextColor (0);
   AsciiPrint ("%a", ">");
 }


 /**
   Parse a command line and execute the commands. The ; separator allows
   multiple commands for each command line. Stop processing if one of the
   commands returns an error.

   @param  CmdLine          Command Line to process.
   @param  MaxCmdLineSize   MaxSize of the Command line

   @return EFI status of the Command

 **/
 EFI_STATUS
 ProcessCmdLine (
   IN CHAR8      *CmdLine,
   IN UINTN      MaxCmdLineSize
   )
 {
   EFI_STATUS          Status;
   EBL_COMMAND_TABLE   *Cmd;
   CHAR8               *Ptr;
   UINTN               Argc;
   CHAR8               *Argv[MAX_ARGS];

   // Parse the command line. The loop processes commands separated by ;
   for (Ptr = CmdLine, Status = EFI_SUCCESS; Ptr != NULL;) {
     Ptr = ParseArguments (Ptr, &Argc, Argv);
     if (Argc != 0) {
       Cmd = EblGetCommand (Argv[0]);
       if (Cmd != NULL) {
         // Execute the Command!
         Status = Cmd->Command (Argc, Argv);
         if (Status == EFI_ABORTED) {
           // exit command so lets exit
           break;
         } else if (Status == EFI_TIMEOUT) {
           // pause command got input so don't process any more cmd on this cmd line
           break;
         } else if (EFI_ERROR (Status)) {
           AsciiPrint ("%a returned %r error\n", Cmd->Name, Status);
           // if any command fails stop processing CmdLine
           break;
         }
       } else {
         AsciiPrint ("The command '%a' is not supported.\n", Argv[0]);
       }
     }
   }

   return Status;
 }


 /**
   Embedded Boot Loader (EBL) - A simple EFI command line application for embedded
   devices. PcdEmbeddedAutomaticBootCommand is a complied in command line that
   gets executed automatically. The ; separator allows multiple commands
   for each command line.

   @param  ImageHandle   EFI ImageHandle for this application.
   @param  SystemTable   EFI system table

   @return EFI status of the application

 **/
 EFI_STATUS
 EFIAPI
 EdkBootLoaderEntry (
   IN EFI_HANDLE                            ImageHandle,
   IN EFI_SYSTEM_TABLE                      *SystemTable
   )
 {
   EFI_STATUS  Status;
   CHAR8       CmdLine[MAX_CMD_LINE];
   CHAR16      *CommandLineVariable = NULL;
   CHAR16      *CommandLineVariableName = L"default-cmdline";
   UINTN       CommandLineVariableSize = 0;
   EFI_GUID    VendorGuid;

   // Initialize tables of commands
   EblInitializeCmdTable ();
   EblInitializeDeviceCmd ();
   EblInitializemdHwDebugCmds ();
   EblInitializemdHwIoDebugCmds ();
   EblInitializeDirCmd ();
   EblInitializeHobCmd ();
   EblInitializeScriptCmd ();
   EblInitializeExternalCmd ();
   EblInitializeNetworkCmd();
   EblInitializeVariableCmds ();

   if (gST->ConOut == NULL) {
     DEBUG((EFI_D_ERROR,"Error: No Console Output\n"));
     return EFI_NOT_READY;
   }

   // Disable the 5 minute EFI watchdog time so we don't get automatically reset
   gBS->SetWatchdogTimer (0, 0, 0, NULL);

   if (FeaturePcdGet (PcdEmbeddedMacBoot)) {
     // A MAC will boot in graphics mode, so turn it back to text here
     // This protocol was removed from edk2. It is only an edk thing. We need to make our own copy.
     // DisableQuietBoot ();

     // Enable the biggest output screen size possible
     gST->ConOut->SetMode (gST->ConOut, (UINTN)gST->ConOut->Mode->MaxMode - 1);

   }

   // Save current screen mode
   gST->ConOut->QueryMode (gST->ConOut, gST->ConOut->Mode->Mode, &gScreenColumns, &gScreenRows);

   EblPrintStartupBanner ();

   // Parse command line and handle commands separated by ;
   // The loop prints the prompt gets user input and saves history

   // Look for a variable with a default command line, otherwise use the Pcd
   ZeroMem(&VendorGuid, sizeof(EFI_GUID));

   Status = gRT->GetVariable(CommandLineVariableName, &VendorGuid, NULL, &CommandLineVariableSize, CommandLineVariable);
   if (Status == EFI_BUFFER_TOO_SMALL) {
     CommandLineVariable = AllocatePool(CommandLineVariableSize);

     Status = gRT->GetVariable(CommandLineVariableName, &VendorGuid, NULL, &CommandLineVariableSize, CommandLineVariable);
     if (!EFI_ERROR(Status)) {
       UnicodeStrToAsciiStr(CommandLineVariable, CmdLine);
     }

     FreePool(CommandLineVariable);
   }

   if (EFI_ERROR(Status)) {
     AsciiStrCpy (CmdLine, (CHAR8 *)PcdGetPtr (PcdEmbeddedAutomaticBootCommand));
   }

   for (;;) {
     Status = ProcessCmdLine (CmdLine, MAX_CMD_LINE);
     if (Status == EFI_ABORTED) {
       // if a command returns EFI_ABORTED then exit the EBL
       EblShutdownExternalCmdTable ();
       return EFI_SUCCESS;
     }

     // get the command line from the user
     EblPrompt ();
     GetCmd (CmdLine, MAX_CMD_LINE);
     SetCmdHistory (CmdLine);

     if (FeaturePcdGet (PcdEmbeddedProbeRemovable)) {
       // Probe removable media devices to see if media has been inserted or removed.
       EblProbeRemovableMedia ();
     }
   }
 }
	/** @file
	Basic command line parser for EBL (Embedded Boot Loader)

	Copyright (c) 2007, Intel Corporation. All rights reserved.<BR>
	Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
	(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>

	This program and the accompanying materials
	are licensed and made available under the terms and conditions of the BSD License
	which accompanies this distribution. The full text of the license may be found at
	http://opensource.org/licenses/bsd-license.php

	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.


	**/

	#include "Ebl.h"

	// Globals for command history processing
	INTN mCmdHistoryEnd = -1;
	INTN mCmdHistoryStart = -1;
	INTN mCmdHistoryCurrent = -1;
	CHAR8 mCmdHistory[MAX_CMD_HISTORY][MAX_CMD_LINE];
	CHAR8 *mCmdBlank = "";

	// Globals to remember current screen geometry
	UINTN gScreenColumns;
	UINTN gScreenRows;

	// Global to turn on/off breaking commands with prompts before they scroll the screen
	BOOLEAN gPageBreak = TRUE;

	VOID
	RingBufferIncrement (
	IN INTN *Value
	)
	{
	Value = Value + 1;

	if (*Value >= MAX_CMD_HISTORY) {
	*Value = 0;
	}
	}

	VOID
	RingBufferDecrement (
	IN INTN *Value
	)
	{
	Value = Value - 1;

	if (*Value < 0) {
	*Value = MAX_CMD_HISTORY - 1;
	}
	}

	/**
	Save this command in the circular history buffer. Older commands are
	overwritten with newer commands.

	@param Cmd Command line to archive the history of.

	@return None

	**/
	VOID
	SetCmdHistory (
	IN CHAR8 *Cmd
	)
	{
	// Don't bother adding empty commands to the list
	if (AsciiStrLen(Cmd) != 0) {

	// First entry
	if (mCmdHistoryStart == -1) {
	mCmdHistoryStart = 0;
	mCmdHistoryEnd = 0;
	} else {
	// Record the new command at the next index
	RingBufferIncrement(&mCmdHistoryStart);

	// If the next index runs into the end index, shuffle end back by one
	if (mCmdHistoryStart == mCmdHistoryEnd) {
	RingBufferIncrement(&mCmdHistoryEnd);
	}
	}

	// Copy the new command line into the ring buffer
	AsciiStrnCpy(&mCmdHistory[mCmdHistoryStart][0], Cmd, MAX_CMD_LINE);
	}

	// Reset the command history for the next up arrow press
	mCmdHistoryCurrent = mCmdHistoryStart;
	}


	/**
	Retreave data from the Command History buffer. Direction maps into up arrow
	an down arrow on the command line

	@param Direction Command forward or back

	@return The Command history based on the Direction

	**/
	CHAR8 *
	GetCmdHistory (
	IN UINT16 Direction
	)
	{
	CHAR8 *HistoricalCommand = NULL;

	// No history yet?
	if (mCmdHistoryCurrent == -1) {
	HistoricalCommand = mCmdBlank;
	goto Exit;
	}

	if (Direction == SCAN_UP) {
	HistoricalCommand = &mCmdHistory[mCmdHistoryCurrent][0];

	// if we just echoed the last command, hang out there, don't wrap around
	if (mCmdHistoryCurrent == mCmdHistoryEnd) {
	goto Exit;
	}

	// otherwise, back up by one
	RingBufferDecrement(&mCmdHistoryCurrent);

	} else if (Direction == SCAN_DOWN) {

	// if we last echoed the start command, put a blank prompt out
	if (mCmdHistoryCurrent == mCmdHistoryStart) {
	HistoricalCommand = mCmdBlank;
	goto Exit;
	}

	// otherwise increment the current pointer and return that command
	RingBufferIncrement(&mCmdHistoryCurrent);
	RingBufferIncrement(&mCmdHistoryCurrent);

	HistoricalCommand = &mCmdHistory[mCmdHistoryCurrent][0];
	RingBufferDecrement(&mCmdHistoryCurrent);
	}

	Exit:
	return HistoricalCommand;
	}


	/**
	Parse the CmdLine and break it up into Argc (arg count) and Argv (array of
	pointers to each argument). The Cmd buffer is altered and separators are
	converted to string terminators. This allows Argv to point into CmdLine.
	A CmdLine can support multiple commands. The next command in the command line
	is returned if it exists.

	@param CmdLine String to parse for a set of commands
	@param Argc Returns the number of arguments in the CmdLine current command
	@param Argv Argc pointers to each string in CmdLine

	@return Next Command in the command line or NULL if non exists
	**/
	CHAR8 *
	ParseArguments (
	IN CHAR8 *CmdLine,
	OUT UINTN *Argc,
	OUT CHAR8 **Argv
	)
	{
	UINTN Arg;
	CHAR8 *Char;
	BOOLEAN LookingForArg;
	BOOLEAN InQuote;

	*Argc = 0;
	if (AsciiStrLen (CmdLine) == 0) {
	return NULL;
	}

	// Walk a single command line. A CMD_SEPARATOR allows multiple commands on a single line
	InQuote = FALSE;
	LookingForArg = TRUE;
	for (Char = CmdLine, Arg = 0; *Char != '\0'; Char++) {
	if (!InQuote && *Char == CMD_SEPARATOR) {
	break;
	}

	// Perform any text conversion here
	if (*Char == '\t') {
	// TAB to space
	*Char = ' ';
	}

	if (LookingForArg) {
	// Look for the beginning of an Argv[] entry
	if (*Char == '"') {
	Argv[Arg++] = ++Char;
	LookingForArg = FALSE;
	InQuote = TRUE;
	} else if (*Char != ' ') {
	Argv[Arg++] = Char;
	LookingForArg = FALSE;
	}
	} else {
	// Looking for the terminator of an Argv[] entry
	if (!InQuote && (*Char == ' ')) {
	*Char = '\0';
	LookingForArg = TRUE;
	} else if (!InQuote && (Char == '"') && ((Char-1) != '\\')) {
	InQuote = TRUE;
	} else if (InQuote && (Char == '"') && ((Char-1) != '\\')) {
	*Char = '\0';
	InQuote = FALSE;
	}
	}
	}

	*Argc = Arg;

	if (*Char == CMD_SEPARATOR) {
	// Replace the command delimiter with null and return pointer to next command line
	*Char = '\0';
	return ++Char;
	}

	return NULL;
	}


	/**
	Return a keypress or optionally timeout if a timeout value was passed in.
	An optional callback function is called every second when waiting for a
	timeout.

	@param Key EFI Key information returned
	@param TimeoutInSec Number of seconds to wait to timeout
	@param CallBack Callback called every second during the timeout wait

	@return EFI_SUCCESS Key was returned
	@return EFI_TIMEOUT If the TimoutInSec expired

	**/
	EFI_STATUS
	EFIAPI
	EblGetCharKey (
	IN OUT EFI_INPUT_KEY *Key,
	IN UINTN TimeoutInSec,
	IN EBL_GET_CHAR_CALL_BACK CallBack OPTIONAL
	)
	{
	EFI_STATUS Status;
	UINTN WaitCount;
	UINTN WaitIndex;
	EFI_EVENT WaitList[2];

	WaitCount = 1;
	WaitList[0] = gST->ConIn->WaitForKey;
	if (TimeoutInSec != 0) {
	// Create a time event for 1 sec duration if we have a timeout
	gBS->CreateEvent (EVT_TIMER, 0, NULL, NULL, &WaitList[1]);
	gBS->SetTimer (WaitList[1], TimerPeriodic, EFI_SET_TIMER_TO_SECOND);
	WaitCount++;
	}

	for (;;) {
	Status = gBS->WaitForEvent (WaitCount, WaitList, &WaitIndex);
	ASSERT_EFI_ERROR (Status);

	switch (WaitIndex) {
	case 0:
	// Key event signaled
	Status = gST->ConIn->ReadKeyStroke (gST->ConIn, Key);
	if (!EFI_ERROR (Status)) {
	if (WaitCount == 2) {
	gBS->CloseEvent (WaitList[1]);
	}
	return EFI_SUCCESS;
	}
	break;

	case 1:
	// Periodic 1 sec timer signaled
	TimeoutInSec--;
	if (CallBack != NULL) {
	// Call the users callback function if registered
	CallBack (TimeoutInSec);
	}
	if (TimeoutInSec == 0) {
	gBS->CloseEvent (WaitList[1]);
	return EFI_TIMEOUT;
	}
	break;
	default:
	ASSERT (FALSE);
	}
	}
	}


	/**
	This routine is used prevent command output data from scrolling off the end
	of the screen. The global gPageBreak is used to turn on or off this feature.
	If the CurrentRow is near the end of the screen pause and print out a prompt
	If the use hits Q to quit return TRUE else for any other key return FALSE.
	PrefixNewline is used to figure out if a newline is needed before the prompt
	string. This depends on the last print done before calling this function.
	CurrentRow is updated by one on a call or set back to zero if a prompt is
	needed.

	@param CurrentRow Used to figure out if its the end of the page and updated
	@param PrefixNewline Did previous print issue a newline

	@return TRUE if Q was hit to quit, FALSE in all other cases.

	**/
	BOOLEAN
	EFIAPI
	EblAnyKeyToContinueQtoQuit (
	IN UINTN *CurrentRow,
	IN BOOLEAN PrefixNewline
	)
	{
	EFI_INPUT_KEY InputKey;

	if (!gPageBreak) {
	// global disable for this feature
	return FALSE;
	}

	if (*CurrentRow >= (gScreenRows - 2)) {
	if (PrefixNewline) {
	AsciiPrint ("\n");
	}
	AsciiPrint ("Any key to continue (Q to quit): ");
	EblGetCharKey (&InputKey, 0, NULL);
	AsciiPrint ("\n");

	// Time to promt to stop the screen. We have to leave space for the prompt string
	*CurrentRow = 0;
	if (InputKey.UnicodeChar == 'Q' \|\| InputKey.UnicodeChar == 'q') {
	return TRUE;
	}
	} else {
	*CurrentRow += 1;
	}

	return FALSE;
	}


	/**
	Set the text color of the EFI Console. If a zero is passed in reset to
	default text/background color.

	@param Attribute For text and background color

	**/
	VOID
	EblSetTextColor (
	UINTN Attribute
	)
	{
	if (Attribute == 0) {
	// Set the text color back to default
	Attribute = (UINTN)PcdGet32 (PcdEmbeddedDefaultTextColor);
	}

	gST->ConOut->SetAttribute (gST->ConOut, Attribute);
	}


	/**
	Collect the keyboard input for a cmd line. Carriage Return, New Line, or ESC
	terminates the command line. You can edit the command line via left arrow,
	delete and backspace and they all back up and erase the command line.
	No edit of command line is possible without deletion at this time!
	The up arrow and down arrow fill Cmd with information from the history
	buffer.

	@param Cmd Command line to return
	@param CmdMaxSize Maximum size of Cmd

	@return The Status of EblGetCharKey()

	**/
	EFI_STATUS
	GetCmd (
	IN OUT CHAR8 *Cmd,
	IN UINTN CmdMaxSize
	)
	{
	EFI_STATUS Status;
	UINTN Index;
	UINTN Index2;
	CHAR8 Char;
	CHAR8 *History;
	EFI_INPUT_KEY Key;

	for (Index = 0; Index < CmdMaxSize - 1;) {
	Status = EblGetCharKey (&Key, 0, NULL);
	if (EFI_ERROR (Status)) {
	Cmd[Index] = '\0';
	AsciiPrint ("\n");
	return Status;
	}

	Char = (CHAR8)Key.UnicodeChar;
	if ((Char == '\n') \|\| (Char == '\r') \|\| (Char == 0x7f)) {
	Cmd[Index] = '\0';
	if (FixedPcdGetBool(PcdEmbeddedShellCharacterEcho) == TRUE) {
	AsciiPrint ("\n\r");
	}
	return EFI_SUCCESS;
	} else if ((Char == '\b') \|\| (Key.ScanCode == SCAN_LEFT) \|\| (Key.ScanCode == SCAN_DELETE)){
	if (Index != 0) {
	Index--;
	//
	// Update the display
	//
	AsciiPrint ("\b \b");
	}
	} else if ((Key.ScanCode == SCAN_UP) \|\| Key.ScanCode == SCAN_DOWN) {
	History = GetCmdHistory (Key.ScanCode);
	//
	// Clear display line
	//
	for (Index2 = 0; Index2 < Index; Index2++) {
	AsciiPrint ("\b \b");
	}
	AsciiPrint (History);
	Index = AsciiStrLen (History);
	AsciiStrnCpy (Cmd, History, CmdMaxSize);
	} else {
	Cmd[Index++] = Char;
	if (FixedPcdGetBool(PcdEmbeddedShellCharacterEcho) == TRUE) {
	AsciiPrint ("%c", Char);
	}
	}
	}

	return EFI_SUCCESS;
	}


	/**
	Print the boot up banner for the EBL.
	**/
	VOID
	EblPrintStartupBanner (
	VOID
	)
	{
	AsciiPrint ("Embedded Boot Loader (");
	EblSetTextColor (EFI_YELLOW);
	AsciiPrint ("EBL");
	EblSetTextColor (0);
	AsciiPrint (") prototype. Built at %a on %a\n",__TIME__, __DATE__);
	AsciiPrint ("THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN 'AS IS' BASIS,\nWITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\n");
	AsciiPrint ("Please send feedback to edk2-devel@lists.sourceforge.net\n");
	}


	/**
	Send null requests to all removable media block IO devices so the a media add/remove/change
	can be detected in real before we execute a command.

	This is mainly due to the fact that the FAT driver does not do this today so you can get stale
	dir commands after an SD Card has been removed.
	**/
	VOID
	EblProbeRemovableMedia (
	VOID
	)
	{
	UINTN Index;
	UINTN Max;
	EFI_OPEN_FILE *File;

	//
	// Probe for media insertion/removal in removable media devices
	//
	Max = EfiGetDeviceCounts (EfiOpenBlockIo);
	if (Max != 0) {
	for (Index = 0; Index < Max; Index++) {
	File = EfiDeviceOpenByType (EfiOpenBlockIo, Index);
	if (File != NULL) {
	if (File->FsBlockIoMedia->RemovableMedia) {
	// Probe to see if media is present (or not) or media changed
	// this causes the ReinstallProtocolInterface() to fire in the
	// block io driver to update the system about media change events
	File->FsBlockIo->ReadBlocks (File->FsBlockIo, File->FsBlockIo->Media->MediaId, (EFI_LBA)0, 0, NULL);
	}
	EfiClose (File);
	}
	}
	}
	}




	/**
	Print the prompt for the EBL.
	**/
	VOID
	EblPrompt (
	VOID
	)
	{
	EblSetTextColor (EFI_YELLOW);
	AsciiPrint ("%a %a",(CHAR8 *)PcdGetPtr (PcdEmbeddedPrompt), EfiGetCwd ());
	EblSetTextColor (0);
	AsciiPrint ("%a", ">");
	}



	/**
	Parse a command line and execute the commands. The ; separator allows
	multiple commands for each command line. Stop processing if one of the
	commands returns an error.

	@param CmdLine Command Line to process.
	@param MaxCmdLineSize MaxSize of the Command line

	@return EFI status of the Command

	**/
	EFI_STATUS
	ProcessCmdLine (
	IN CHAR8 *CmdLine,
	IN UINTN MaxCmdLineSize
	)
	{
	EFI_STATUS Status;
	EBL_COMMAND_TABLE *Cmd;
	CHAR8 *Ptr;
	UINTN Argc;
	CHAR8 *Argv[MAX_ARGS];

	// Parse the command line. The loop processes commands separated by ;
	for (Ptr = CmdLine, Status = EFI_SUCCESS; Ptr != NULL;) {
	Ptr = ParseArguments (Ptr, &Argc, Argv);
	if (Argc != 0) {
	Cmd = EblGetCommand (Argv[0]);
	if (Cmd != NULL) {
	// Execute the Command!
	Status = Cmd->Command (Argc, Argv);
	if (Status == EFI_ABORTED) {
	// exit command so lets exit
	break;
	} else if (Status == EFI_TIMEOUT) {
	// pause command got input so don't process any more cmd on this cmd line
	break;
	} else if (EFI_ERROR (Status)) {
	AsciiPrint ("%a returned %r error\n", Cmd->Name, Status);
	// if any command fails stop processing CmdLine
	break;
	}
	} else {
	AsciiPrint ("The command '%a' is not supported.\n", Argv[0]);
	}
	}
	}

	return Status;
	}



	/**
	Embedded Boot Loader (EBL) - A simple EFI command line application for embedded
	devices. PcdEmbeddedAutomaticBootCommand is a complied in command line that
	gets executed automatically. The ; separator allows multiple commands
	for each command line.

	@param ImageHandle EFI ImageHandle for this application.
	@param SystemTable EFI system table

	@return EFI status of the application

	**/
	EFI_STATUS
	EFIAPI
	EdkBootLoaderEntry (
	IN EFI_HANDLE ImageHandle,
	IN EFI_SYSTEM_TABLE *SystemTable
	)
	{
	EFI_STATUS Status;
	CHAR8 CmdLine[MAX_CMD_LINE];
	CHAR16 *CommandLineVariable = NULL;
	CHAR16 *CommandLineVariableName = L"default-cmdline";
	UINTN CommandLineVariableSize = 0;
	EFI_GUID VendorGuid;

	// Initialize tables of commands
	EblInitializeCmdTable ();
	EblInitializeDeviceCmd ();
	EblInitializemdHwDebugCmds ();
	EblInitializemdHwIoDebugCmds ();
	EblInitializeDirCmd ();
	EblInitializeHobCmd ();
	EblInitializeScriptCmd ();
	EblInitializeExternalCmd ();
	EblInitializeNetworkCmd();
	EblInitializeVariableCmds ();

	if (gST->ConOut == NULL) {
	DEBUG((EFI_D_ERROR,"Error: No Console Output\n"));
	return EFI_NOT_READY;
	}

	// Disable the 5 minute EFI watchdog time so we don't get automatically reset
	gBS->SetWatchdogTimer (0, 0, 0, NULL);

	if (FeaturePcdGet (PcdEmbeddedMacBoot)) {
	// A MAC will boot in graphics mode, so turn it back to text here
	// This protocol was removed from edk2. It is only an edk thing. We need to make our own copy.
	// DisableQuietBoot ();

	// Enable the biggest output screen size possible
	gST->ConOut->SetMode (gST->ConOut, (UINTN)gST->ConOut->Mode->MaxMode - 1);

	}

	// Save current screen mode
	gST->ConOut->QueryMode (gST->ConOut, gST->ConOut->Mode->Mode, &gScreenColumns, &gScreenRows);

	EblPrintStartupBanner ();

	// Parse command line and handle commands separated by ;
	// The loop prints the prompt gets user input and saves history

	// Look for a variable with a default command line, otherwise use the Pcd
	ZeroMem(&VendorGuid, sizeof(EFI_GUID));

	Status = gRT->GetVariable(CommandLineVariableName, &VendorGuid, NULL, &CommandLineVariableSize, CommandLineVariable);
	if (Status == EFI_BUFFER_TOO_SMALL) {
	CommandLineVariable = AllocatePool(CommandLineVariableSize);

	Status = gRT->GetVariable(CommandLineVariableName, &VendorGuid, NULL, &CommandLineVariableSize, CommandLineVariable);
	if (!EFI_ERROR(Status)) {
	UnicodeStrToAsciiStr(CommandLineVariable, CmdLine);
	}

	FreePool(CommandLineVariable);
	}

	if (EFI_ERROR(Status)) {
	AsciiStrCpy (CmdLine, (CHAR8 *)PcdGetPtr (PcdEmbeddedAutomaticBootCommand));
	}

	for (;;) {
	Status = ProcessCmdLine (CmdLine, MAX_CMD_LINE);
	if (Status == EFI_ABORTED) {
	// if a command returns EFI_ABORTED then exit the EBL
	EblShutdownExternalCmdTable ();
	return EFI_SUCCESS;
	}

	// get the command line from the user
	EblPrompt ();
	GetCmd (CmdLine, MAX_CMD_LINE);
	SetCmdHistory (CmdLine);

	if (FeaturePcdGet (PcdEmbeddedProbeRemovable)) {
	// Probe removable media devices to see if media has been inserted or removed.
	EblProbeRemovableMedia ();
	}
	}
	}