system76-edk2/FatPkg/EnhancedFatDxe/FileName.c

/*++

Copyright (c) 2005 - 2015, Intel Corporation. All rights reserved.<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.


Module Name:

  FileName.c

Abstract:

  Functions for manipulating file names

Revision History

--*/

#include "Fat.h"

BOOLEAN
FatCheckIs8Dot3Name (
  IN  CHAR16    *FileName,
  OUT CHAR8     *File8Dot3Name
  )
/*++

Routine Description:

  This function checks whether the input FileName is a valid 8.3 short name.
  If the input FileName is a valid 8.3, the output is the 8.3 short name;
  otherwise, the output is the base tag of 8.3 short name.

Arguments:

  FileName              - The input unicode filename.
  File8Dot3Name         - The output ascii 8.3 short name or base tag of 8.3 short name.

Returns:

  TRUE                  - The input unicode filename is a valid 8.3 short name.
  FALSE                 - The input unicode filename is not a valid 8.3 short name.

--*/
{
  BOOLEAN PossibleShortName;
  CHAR16  *TempName;
  CHAR16  *ExtendName;
  CHAR16  *SeparateDot;
  UINTN   MainNameLen;
  UINTN   ExtendNameLen;

  PossibleShortName = TRUE;
  SeparateDot       = NULL;
  SetMem (File8Dot3Name, FAT_NAME_LEN, ' ');
  for (TempName = FileName; *TempName; TempName++) {
    if (*TempName == L'.') {
      SeparateDot = TempName;
    }
  }

  if (SeparateDot == NULL) {
    //
    // Extended filename is not detected
    //
    MainNameLen   = TempName - FileName;
    ExtendName    = TempName;
    ExtendNameLen = 0;
  } else {
    //
    // Extended filename is detected
    //
    MainNameLen   = SeparateDot - FileName;
    ExtendName    = SeparateDot + 1;
    ExtendNameLen = TempName - ExtendName;
  }
  //
  // We scan the filename for the second time
  // to check if there exists any extra blanks and dots
  //
  while (--TempName >= FileName) {
    if ((*TempName == L'.' || *TempName == L' ') && (TempName != SeparateDot)) {
      //
      // There exist extra blanks and dots
      //
      PossibleShortName = FALSE;
    }
  }

  if (MainNameLen == 0) {
    PossibleShortName = FALSE;
  }

  if (MainNameLen > FAT_MAIN_NAME_LEN) {
    PossibleShortName = FALSE;
    MainNameLen       = FAT_MAIN_NAME_LEN;
  }

  if (ExtendNameLen > FAT_EXTEND_NAME_LEN) {
    PossibleShortName = FALSE;
    ExtendNameLen     = FAT_EXTEND_NAME_LEN;
  }

  if (FatStrToFat (FileName, MainNameLen, File8Dot3Name)) {
    PossibleShortName = FALSE;
  }

  if (FatStrToFat (ExtendName, ExtendNameLen, File8Dot3Name + FAT_MAIN_NAME_LEN)) {
    PossibleShortName = FALSE;
  }

  return PossibleShortName;
}

STATIC
UINTN
FatTrimAsciiTrailingBlanks (
  IN CHAR8        *Name,
  IN UINTN        Len
  )
/*++

Routine Description:

  Trim the trailing blanks of fat name.

Arguments:

  Name                  - The Char8 string needs to be trimed.
  Len                   - The length of the fat name.

Returns:

  The real length of the fat name after the trailing blanks are trimmed.

--*/
{
  while (Len > 0 && Name[Len - 1] == ' ') {
    Len--;
  }

  return Len;
}

VOID
FatNameToStr (
  IN  CHAR8            *FatName,
  IN  UINTN            Len,
  IN  UINTN            LowerCase,
  OUT CHAR16           *Str
  )
/*++

Routine Description:

  Convert the ascii fat name to the unicode string and strip trailing spaces,
  and if necessary, convert the unicode string to lower case.

Arguments:

  FatName               - The Char8 string needs to be converted.
  Len                   - The length of the fat name.
  LowerCase             - Indicate whether to convert the string to lower case.
  Str                   - The result of the convertion.

Returns:

  None.

--*/
{
  //
  // First, trim the trailing blanks
  //
  Len = FatTrimAsciiTrailingBlanks (FatName, Len);
  //
  // Convert fat string to unicode string
  //
  FatFatToStr (Len, FatName, Str);

  //
  // If the name is to be lower cased, do it now
  //
  if (LowerCase != 0) {
    FatStrLwr (Str);
  }
}

VOID
FatCreate8Dot3Name (
  IN FAT_OFILE    *Parent,
  IN FAT_DIRENT   *DirEnt
  )
/*++

Routine Description:

  This function generates 8Dot3 name from user specified name for a newly created file.

Arguments:

  Parent                - The parent directory.
  DirEnt                - The directory entry whose 8Dot3Name needs to be generated.

Returns:

  None.

--*/
{
  CHAR8 *ShortName;
  CHAR8 *ShortNameChar;
  UINTN BaseTagLen;
  UINTN Index;
  UINTN Retry;
  UINT8 Segment;
  union {
    UINT32  Crc;
    struct HEX_DATA {
      UINT8 Segment : HASH_VALUE_TAG_LEN;
    } Hex[HASH_VALUE_TAG_LEN];
  } HashValue;
  //
  // Make sure the whole directory has been loaded
  //
  ASSERT (Parent->ODir->EndOfDir);
  ShortName = DirEnt->Entry.FileName;

  //
  // Trim trailing blanks of 8.3 name
  //
  BaseTagLen = FatTrimAsciiTrailingBlanks (ShortName, FAT_MAIN_NAME_LEN);
  if (BaseTagLen > SPEC_BASE_TAG_LEN) {
    BaseTagLen = SPEC_BASE_TAG_LEN;
  }
  //
  // We first use the algorithm described by spec.
  //
  ShortNameChar     = ShortName + BaseTagLen;
  *ShortNameChar++  = '~';
  *ShortNameChar    = '1';
  Retry = 0;
  while (*FatShortNameHashSearch (Parent->ODir, ShortName) != NULL) {
    *ShortNameChar = (CHAR8)(*ShortNameChar + 1);
    if (++Retry == MAX_SPEC_RETRY) {
      //
      // We use new algorithm to generate 8.3 name
      //
      ASSERT (DirEnt->FileString != NULL);
      gBS->CalculateCrc32 (DirEnt->FileString, StrSize (DirEnt->FileString), &HashValue.Crc);

      if (BaseTagLen > HASH_BASE_TAG_LEN) {
        BaseTagLen = HASH_BASE_TAG_LEN;
      }

      ShortNameChar = ShortName + BaseTagLen;
      for (Index = 0; Index < HASH_VALUE_TAG_LEN; Index++) {
        Segment = HashValue.Hex[Index].Segment;
        if (Segment > 9) {
          *ShortNameChar++ = (CHAR8)(Segment - 10 + 'A');
        } else {
          *ShortNameChar++ = (CHAR8)(Segment + '0');
        }
      }

      *ShortNameChar++  = '~';
      *ShortNameChar    = '1';
    }
  }
}

STATIC
UINT8
FatCheckNameCase (
  IN CHAR16           *Str,
  IN UINT8            InCaseFlag
  )
/*++

Routine Description:

  Check the string is lower case or upper case
  and it is used by fatname to dir entry count

Arguments:

  Str                   - The string which needs to be checked.
  InCaseFlag            - The input case flag which is returned when the string is lower case.

Returns:

  OutCaseFlag           - The output case flag.

--*/
{
  CHAR16  Buffer[FAT_MAIN_NAME_LEN + 1 + FAT_EXTEND_NAME_LEN + 1];
  UINT8   OutCaseFlag;

  //
  // Assume the case of input string is mixed
  //
  OutCaseFlag = FAT_CASE_MIXED;
  //
  // Lower case a copy of the string, if it matches the
  // original then the string is lower case
  //
  StrCpyS (Buffer, sizeof (Buffer) / sizeof (Buffer[0]), Str);
  FatStrLwr (Buffer);
  if (StrCmp (Str, Buffer) == 0) {
    OutCaseFlag = InCaseFlag;
  }
  //
  // Upper case a copy of the string, if it matches the
  // original then the string is upper case
  //
  StrCpyS (Buffer, sizeof (Buffer) / sizeof (Buffer[0]), Str);
  FatStrUpr (Buffer);
  if (StrCmp (Str, Buffer) == 0) {
    OutCaseFlag = 0;
  }

  return OutCaseFlag;
}

VOID
FatSetCaseFlag (
  IN FAT_DIRENT   *DirEnt
  )
/*++

Routine Description:

  Set the caseflag value for the directory entry.

Arguments:

  DirEnt                - The logical directory entry whose caseflag value is to be set.

Returns:

  None.

--*/
{
  CHAR16  LfnBuffer[FAT_MAIN_NAME_LEN + 1 + FAT_EXTEND_NAME_LEN + 1];
  CHAR16  *TempCharPtr;
  CHAR16  *ExtendName;
  CHAR16  *FileNameCharPtr;
  UINT8   CaseFlag;

  ExtendName      = NULL;
  TempCharPtr     = LfnBuffer;
  FileNameCharPtr = DirEnt->FileString;
  ASSERT (StrSize (DirEnt->FileString) <= sizeof (LfnBuffer));
  while ((*TempCharPtr = *FileNameCharPtr) != 0) {
    if (*TempCharPtr == L'.') {
      ExtendName = TempCharPtr;
    }

    TempCharPtr++;
    FileNameCharPtr++;
  }

  CaseFlag = 0;
  if (ExtendName != NULL) {
    *ExtendName = 0;
    ExtendName++;
    CaseFlag = (UINT8)(CaseFlag | FatCheckNameCase (ExtendName, FAT_CASE_EXT_LOWER));
  }

  CaseFlag = (UINT8)(CaseFlag | FatCheckNameCase (LfnBuffer, FAT_CASE_NAME_LOWER));
  if ((CaseFlag & FAT_CASE_MIXED) == 0) {
    //
    // We just need one directory entry to store this file name entry
    //
    DirEnt->Entry.CaseFlag = CaseFlag;
  } else {
    //
    // We need one extra directory entry to store the mixed case entry
    //
    DirEnt->Entry.CaseFlag = 0;
    DirEnt->EntryCount++;
  }
}

VOID
FatGetFileNameViaCaseFlag (
  IN     FAT_DIRENT   *DirEnt,
  IN OUT CHAR16       *FileString,
  IN     UINTN        FileStringMax
  )
/*++

Routine Description:

  Convert the 8.3 ASCII fat name to cased Unicode string according to case flag.

Arguments:

  DirEnt                - The corresponding directory entry.
  FileString            - The output Unicode file name.

Returns:

  None.

--*/
{
  UINT8   CaseFlag;
  CHAR8   *File8Dot3Name;
  CHAR16  TempExt[1 + FAT_EXTEND_NAME_LEN + 1];
  //
  // Store file extension like ".txt"
  //
  CaseFlag      = DirEnt->Entry.CaseFlag;
  File8Dot3Name = DirEnt->Entry.FileName;

  FatNameToStr (File8Dot3Name, FAT_MAIN_NAME_LEN, CaseFlag & FAT_CASE_NAME_LOWER, FileString);
  FatNameToStr (File8Dot3Name + FAT_MAIN_NAME_LEN, FAT_EXTEND_NAME_LEN, CaseFlag & FAT_CASE_EXT_LOWER, &TempExt[1]);
  if (TempExt[1] != 0) {
    TempExt[0] = L'.';
    StrCatS (FileString, FileStringMax, TempExt);
  }
}

UINT8
FatCheckSum (
  IN CHAR8  *ShortNameString
  )
/*++

Routine Description:

  Get the Check sum for a short name.

Arguments:

  ShortNameString       - The short name for a file.

Returns:

  Sum                   - UINT8 checksum.

--*/
{
  UINTN ShortNameLen;
  UINT8 Sum;
  Sum = 0;
  for (ShortNameLen = FAT_NAME_LEN; ShortNameLen != 0; ShortNameLen--) {
    Sum = (UINT8)(((Sum & 1) ? 0x80 : 0) + (Sum >> 1) + *ShortNameString++);
  }

  return Sum;
}

CHAR16 *
FatGetNextNameComponent (
  IN  CHAR16      *Path,
  OUT CHAR16      *Name
  )
/*++

Routine Description:

  Takes Path as input, returns the next name component
  in Name, and returns the position after Name (e.g., the
  start of the next name component)

Arguments:

  Path                  - The path of one file.
  Name                  - The next name component in Path.

Returns:

  The position after Name in the Path

--*/
{
  while (*Path != 0 && *Path != PATH_NAME_SEPARATOR) {
    *Name++ = *Path++;
  }
  *Name = 0;
  //
  // Get off of trailing path name separator
  //
  while (*Path == PATH_NAME_SEPARATOR) {
    Path++;
  }

  return Path;
}

BOOLEAN
FatFileNameIsValid (
  IN  CHAR16  *InputFileName,
  OUT CHAR16  *OutputFileName
  )
/*++

Routine Description:

  Check whether the IFileName is valid long file name. If the IFileName is a valid
  long file name, then we trim the possible leading blanks and leading/trailing dots.
  the trimmed filename is stored in OutputFileName

Arguments:

  InputFileName         - The input file name.
  OutputFileName        - The output file name.


Returns:

  TRUE                  - The InputFileName is a valid long file name.
  FALSE                 - The InputFileName is not a valid long file name.

--*/
{
  CHAR16  *TempNamePointer;
  CHAR16  TempChar;
  //
  // Trim Leading blanks
  //
  while (*InputFileName == L' ') {
    InputFileName++;
  }

  TempNamePointer = OutputFileName;
  while (*InputFileName != 0) {
    *TempNamePointer++ = *InputFileName++;
  }
  //
  // Trim Trailing blanks and dots
  //
  while (TempNamePointer > OutputFileName) {
    TempChar = *(TempNamePointer - 1);
    if (TempChar != L' ' && TempChar != L'.') {
      break;
    }

    TempNamePointer--;
  }

  *TempNamePointer = 0;

  //
  // Per FAT Spec the file name should meet the following criteria:
  //   C1. Length (FileLongName) <= 255
  //   C2. Length (X:FileFullPath<NUL>) <= 260
  // Here we check C1.
  //
  if (TempNamePointer - OutputFileName > EFI_FILE_STRING_LENGTH) {
    return FALSE;
  }
  //
  // See if there is any illegal characters within the name
  //
  do {
    if (*OutputFileName < 0x20 ||
        *OutputFileName == '\"' ||
        *OutputFileName == '*' ||
        *OutputFileName == '/' ||
        *OutputFileName == ':' ||
        *OutputFileName == '<' ||
        *OutputFileName == '>' ||
        *OutputFileName == '?' ||
        *OutputFileName == '\\' ||
        *OutputFileName == '|'
        ) {
      return FALSE;
    }

    OutputFileName++;
  } while (*OutputFileName != 0);
  return TRUE;
}