text: /* Arduino SdFat Library
   * Copyright (C) 2009 by William Greiman
   *
   * This file is part of the Arduino SdFat Library
   *
   * This Library is free software: you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * This Library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with the Arduino SdFat Library.  If not, see
   * <http://www.gnu.org/licenses/>.
   */
  #include "SdFat.h"
  #ifdef __AVR__
  #include <avr/pgmspace.h>
  #endif
  #include <Arduino.h>
  //------------------------------------------------------------------------------
  // callback function for date/time
  void (*SdFile::dateTime_)(uint16_t* date, uint16_t* time) = NULL;
  
  #if ALLOW_DEPRECATED_FUNCTIONS
  // suppress cpplint warnings with NOLINT comment
  void (*SdFile::oldDateTime_)(uint16_t& date, uint16_t& time) = NULL;  // NOLINT
  #endif  // ALLOW_DEPRECATED_FUNCTIONS
  //------------------------------------------------------------------------------
  // add a cluster to a file
  uint8_t SdFile::addCluster() {
    if (!vol_->allocContiguous(1, &curCluster_)) return false;
  
    // if first cluster of file link to directory entry
    if (firstCluster_ == 0) {
      firstCluster_ = curCluster_;
      flags_ |= F_FILE_DIR_DIRTY;
    }
    return true;
  }
  //------------------------------------------------------------------------------
  // Add a cluster to a directory file and zero the cluster.
  // return with first block of cluster in the cache
  uint8_t SdFile::addDirCluster(void) {
    if (!addCluster()) return false;
  
    // zero data in cluster insure first cluster is in cache
    uint32_t block = vol_->clusterStartBlock(curCluster_);
    for (uint8_t i = vol_->blocksPerCluster_; i != 0; i--) {
      if (!SdVolume::cacheZeroBlock(block + i - 1)) return false;
    }
    // Increase directory file size by cluster size
    fileSize_ += 512UL << vol_->clusterSizeShift_;
    return true;
  }
  //------------------------------------------------------------------------------
  // cache a file's directory entry
  // return pointer to cached entry or null for failure
  dir_t* SdFile::cacheDirEntry(uint8_t action) {
    if (!SdVolume::cacheRawBlock(dirBlock_, action)) return NULL;
    return SdVolume::cacheBuffer_.dir + dirIndex_;
  }
  //------------------------------------------------------------------------------
  /**
   *  Close a file and force cached data and directory information
   *  to be written to the storage device.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include no file is open or an I/O error.
   */
  uint8_t SdFile::close(void) {
    if (!sync())return false;
    type_ = FAT_FILE_TYPE_CLOSED;
    return true;
  }
  //------------------------------------------------------------------------------
  /**
   * Check for contiguous file and return its raw block range.
   *
   * \param[out] bgnBlock the first block address for the file.
   * \param[out] endBlock the last  block address for the file.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include file is not contiguous, file has zero length
   * or an I/O error occurred.
   */
  uint8_t SdFile::contiguousRange(uint32_t* bgnBlock, uint32_t* endBlock) {
    // error if no blocks
    if (firstCluster_ == 0) return false;
  
    for (uint32_t c = firstCluster_; ; c++) {
      uint32_t next;
      if (!vol_->fatGet(c, &next)) return false;
  
      // check for contiguous
      if (next != (c + 1)) {
        // error if not end of chain
        if (!vol_->isEOC(next)) return false;
        *bgnBlock = vol_->clusterStartBlock(firstCluster_);
        *endBlock = vol_->clusterStartBlock(c)
                    + vol_->blocksPerCluster_ - 1;
        return true;
      }
    }
  }
  //------------------------------------------------------------------------------
  /**
   * Create and open a new contiguous file of a specified size.
   *
   * \note This function only supports short DOS 8.3 names.
   * See open() for more information.
   *
   * \param[in] dirFile The directory where the file will be created.
   * \param[in] fileName A valid DOS 8.3 file name.
   * \param[in] size The desired file size.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include \a fileName contains
   * an invalid DOS 8.3 file name, the FAT volume has not been initialized,
   * a file is already open, the file already exists, the root
   * directory is full or an I/O error.
   *
   */
  uint8_t SdFile::createContiguous(SdFile* dirFile,
          const char* fileName, uint32_t size) {
    // don't allow zero length file
    if (size == 0) return false;
    if (!open(dirFile, fileName, O_CREAT | O_EXCL | O_RDWR)) return false;
  
    // calculate number of clusters needed
    uint32_t count = ((size - 1) >> (vol_->clusterSizeShift_ + 9)) + 1;
  
    // allocate clusters
    if (!vol_->allocContiguous(count, &firstCluster_)) {
      remove();
      return false;
    }
    fileSize_ = size;
  
    // insure sync() will update dir entry
    flags_ |= F_FILE_DIR_DIRTY;
    return sync();
  }
  //------------------------------------------------------------------------------
  /**
   * Return a files directory entry
   *
   * \param[out] dir Location for return of the files directory entry.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   */
  uint8_t SdFile::dirEntry(dir_t* dir) {
    // make sure fields on SD are correct
    if (!sync()) return false;
  
    // read entry
    dir_t* p = cacheDirEntry(SdVolume::CACHE_FOR_READ);
    if (!p) return false;
  
    // copy to caller's struct
    memcpy(dir, p, sizeof(dir_t));
    return true;
  }
  //------------------------------------------------------------------------------
  /**
   * Format the name field of \a dir into the 13 byte array
   * \a name in standard 8.3 short name format.
   *
   * \param[in] dir The directory structure containing the name.
   * \param[out] name A 13 byte char array for the formatted name.
   */
  void SdFile::dirName(const dir_t& dir, char* name) {
    uint8_t j = 0;
    for (uint8_t i = 0; i < 11; i++) {
      if (dir.name[i] == ' ')continue;
      if (i == 8) name[j++] = '.';
      name[j++] = dir.name[i];
    }
    name[j] = 0;
  }
  //------------------------------------------------------------------------------
  /** List directory contents to Serial.
   *
   * \param[in] flags The inclusive OR of
   *
   * LS_DATE - %Print file modification date
   *
   * LS_SIZE - %Print file size.
   *
   * LS_R - Recursive list of subdirectories.
   *
   * \param[in] indent Amount of space before file name. Used for recursive
   * list to indicate subdirectory level.
   */
  void SdFile::ls(uint8_t flags, uint8_t indent) {
    dir_t* p;
  
    rewind();
    while ((p = readDirCache())) {
      // done if past last used entry
      if (p->name[0] == DIR_NAME_FREE) break;
  
      // skip deleted entry and entries for . and  ..
      if (p->name[0] == DIR_NAME_DELETED || p->name[0] == '.') continue;
  
      // only list subdirectories and files
      if (!DIR_IS_FILE_OR_SUBDIR(p)) continue;
  
      // print any indent spaces
      for (int8_t i = 0; i < indent; i++) Serial.print(' ');
  
      // print file name with possible blank fill
      printDirName(*p, flags & (LS_DATE | LS_SIZE) ? 14 : 0);
  
      // print modify date/time if requested
      if (flags & LS_DATE) {
         printFatDate(p->lastWriteDate);
         Serial.print(' ');
         printFatTime(p->lastWriteTime);
      }
      // print size if requested
      if (!DIR_IS_SUBDIR(p) && (flags & LS_SIZE)) {
        Serial.print(' ');
        Serial.print(p->fileSize);
      }
      Serial.println();
  
      // list subdirectory content if requested
      if ((flags & LS_R) && DIR_IS_SUBDIR(p)) {
        uint16_t index = curPosition()/32 - 1;
        SdFile s;
        if (s.open(this, index, O_READ)) s.ls(flags, indent + 2);
        seekSet(32 * (index + 1));
      }
    }
  }
  //------------------------------------------------------------------------------
  // format directory name field from a 8.3 name string
  uint8_t SdFile::make83Name(const char* str, uint8_t* name) {
    uint8_t c;
    uint8_t n = 7;  // max index for part before dot
    uint8_t i = 0;
    // blank fill name and extension
    while (i < 11) name[i++] = ' ';
    i = 0;
    while ((c = *str++) != '\0') {
      if (c == '.') {
        if (n == 10) return false;  // only one dot allowed
        n = 10;  // max index for full 8.3 name
        i = 8;   // place for extension
      } else {
        // illegal FAT characters
        uint8_t b;
  #if defined(__AVR__)
        PGM_P p = PSTR("|<>^+=?/[];,*\"\\");
        while ((b = pgm_read_byte(p++))) if (b == c) return false;
  #elif defined(__arm__)
        const uint8_t valid[] = "|<>^+=?/[];,*\"\\";
        const uint8_t *p = valid;
        while ((b = *p++)) if (b == c) return false;
  #endif
        // check size and only allow ASCII printable characters
        if (i > n || c < 0X21 || c > 0X7E)return false;
        // only upper case allowed in 8.3 names - convert lower to upper
        name[i++] = c < 'a' || c > 'z' ?  c : c + ('A' - 'a');
      }
    }
    // must have a file name, extension is optional
    return name[0] != ' ';
  }
  //------------------------------------------------------------------------------
  /** Make a new directory.
   *
   * \param[in] dir An open SdFat instance for the directory that will containing
   * the new directory.
   *
   * \param[in] dirName A valid 8.3 DOS name for the new directory.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include this SdFile is already open, \a dir is not a
   * directory, \a dirName is invalid or already exists in \a dir.
   */
  uint8_t SdFile::makeDir(SdFile* dir, const char* dirName) {
    dir_t d;
  
    // create a normal file
    if (!open(dir, dirName, O_CREAT | O_EXCL | O_RDWR)) return false;
  
    // convert SdFile to directory
    flags_ = O_READ;
    type_ = FAT_FILE_TYPE_SUBDIR;
  
    // allocate and zero first cluster
    if (!addDirCluster())return false;
  
    // force entry to SD
    if (!sync()) return false;
  
    // cache entry - should already be in cache due to sync() call
    dir_t* p = cacheDirEntry(SdVolume::CACHE_FOR_WRITE);
    if (!p) return false;
  
    // change directory entry  attribute
    p->attributes = DIR_ATT_DIRECTORY;
  
    // make entry for '.'
    memcpy(&d, p, sizeof(d));
    for (uint8_t i = 1; i < 11; i++) d.name[i] = ' ';
    d.name[0] = '.';
  
    // cache block for '.'  and '..'
    uint32_t block = vol_->clusterStartBlock(firstCluster_);
    if (!SdVolume::cacheRawBlock(block, SdVolume::CACHE_FOR_WRITE)) return false;
  
    // copy '.' to block
    memcpy(&SdVolume::cacheBuffer_.dir[0], &d, sizeof(d));
  
    // make entry for '..'
    d.name[1] = '.';
    if (dir->isRoot()) {
      d.firstClusterLow = 0;
      d.firstClusterHigh = 0;
    } else {
      d.firstClusterLow = dir->firstCluster_ & 0XFFFF;
      d.firstClusterHigh = dir->firstCluster_ >> 16;
    }
    // copy '..' to block
    memcpy(&SdVolume::cacheBuffer_.dir[1], &d, sizeof(d));
  
    // set position after '..'
    curPosition_ = 2 * sizeof(d);
  
    // write first block
    return SdVolume::cacheFlush();
  }
  //------------------------------------------------------------------------------
  /**
   * Open a file or directory by name.
   *
   * \param[in] dirFile An open SdFat instance for the directory containing the
   * file to be opened.
   *
   * \param[in] fileName A valid 8.3 DOS name for a file to be opened.
   *
   * \param[in] oflag Values for \a oflag are constructed by a bitwise-inclusive
   * OR of flags from the following list
   *
   * O_READ - Open for reading.
   *
   * O_RDONLY - Same as O_READ.
   *
   * O_WRITE - Open for writing.
   *
   * O_WRONLY - Same as O_WRITE.
   *
   * O_RDWR - Open for reading and writing.
   *
   * O_APPEND - If set, the file offset shall be set to the end of the
   * file prior to each write.
   *
   * O_CREAT - If the file exists, this flag has no effect except as noted
   * under O_EXCL below. Otherwise, the file shall be created
   *
   * O_EXCL - If O_CREAT and O_EXCL are set, open() shall fail if the file exists.
   *
   * O_SYNC - Call sync() after each write.  This flag should not be used with
   * write(uint8_t), write_P(PGM_P), writeln_P(PGM_P), or the Arduino Print class.
   * These functions do character at a time writes so sync() will be called
   * after each byte.
   *
   * O_TRUNC - If the file exists and is a regular file, and the file is
   * successfully opened and is not read only, its length shall be truncated to 0.
   *
   * \note Directory files must be opened read only.  Write and truncation is
   * not allowed for directory files.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include this SdFile is already open, \a difFile is not
   * a directory, \a fileName is invalid, the file does not exist
   * or can't be opened in the access mode specified by oflag.
   */
  uint8_t SdFile::open(SdFile* dirFile, const char* fileName, uint8_t oflag) {
    uint8_t dname[11];
    dir_t* p;
  
    // error if already open
    if (isOpen())return false;
  
    if (!make83Name(fileName, dname)) return false;
    vol_ = dirFile->vol_;
    dirFile->rewind();
  
    // bool for empty entry found
    uint8_t emptyFound = false;
  
    // search for file
    while (dirFile->curPosition_ < dirFile->fileSize_) {
      uint8_t index = 0XF & (dirFile->curPosition_ >> 5);
      p = dirFile->readDirCache();
      if (p == NULL) return false;
  
      if (p->name[0] == DIR_NAME_FREE || p->name[0] == DIR_NAME_DELETED) {
        // remember first empty slot
        if (!emptyFound) {
          emptyFound = true;
          dirIndex_ = index;
          dirBlock_ = SdVolume::cacheBlockNumber_;
        }
        // done if no entries follow
        if (p->name[0] == DIR_NAME_FREE) break;
      } else if (!memcmp(dname, p->name, 11)) {
        // don't open existing file if O_CREAT and O_EXCL
        if ((oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) return false;
  
        // open found file
        return openCachedEntry(0XF & index, oflag);
      }
    }
    // only create file if O_CREAT and O_WRITE
    if ((oflag & (O_CREAT | O_WRITE)) != (O_CREAT | O_WRITE)) return false;
  
    // cache found slot or add cluster if end of file
    if (emptyFound) {
      p = cacheDirEntry(SdVolume::CACHE_FOR_WRITE);
      if (!p) return false;
    } else {
      if (dirFile->type_ == FAT_FILE_TYPE_ROOT16) return false;
  
      // add and zero cluster for dirFile - first cluster is in cache for write
      if (!dirFile->addDirCluster()) return false;
  
      // use first entry in cluster
      dirIndex_ = 0;
      p = SdVolume::cacheBuffer_.dir;
    }
    // initialize as empty file
    memset(p, 0, sizeof(dir_t));
    memcpy(p->name, dname, 11);
  
    // set timestamps
    if (dateTime_) {
      // call user function
      dateTime_(&p->creationDate, &p->creationTime);
    } else {
      // use default date/time
      p->creationDate = FAT_DEFAULT_DATE;
      p->creationTime = FAT_DEFAULT_TIME;
    }
    p->lastAccessDate = p->creationDate;
    p->lastWriteDate = p->creationDate;
    p->lastWriteTime = p->creationTime;
  
    // force write of entry to SD
    if (!SdVolume::cacheFlush()) return false;
  
    // open entry in cache
    return openCachedEntry(dirIndex_, oflag);
  }
  //------------------------------------------------------------------------------
  /**
   * Open a file by index.
   *
   * \param[in] dirFile An open SdFat instance for the directory.
   *
   * \param[in] index The \a index of the directory entry for the file to be
   * opened.  The value for \a index is (directory file position)/32.
   *
   * \param[in] oflag Values for \a oflag are constructed by a bitwise-inclusive
   * OR of flags O_READ, O_WRITE, O_TRUNC, and O_SYNC.
   *
   * See open() by fileName for definition of flags and return values.
   *
   */
  uint8_t SdFile::open(SdFile* dirFile, uint16_t index, uint8_t oflag) {
    // error if already open
    if (isOpen())return false;
  
    // don't open existing file if O_CREAT and O_EXCL - user call error
    if ((oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) return false;
  
    vol_ = dirFile->vol_;
  
    // seek to location of entry
    if (!dirFile->seekSet(32 * index)) return false;
  
    // read entry into cache
    dir_t* p = dirFile->readDirCache();
    if (p == NULL) return false;
  
    // error if empty slot or '.' or '..'
    if (p->name[0] == DIR_NAME_FREE ||
        p->name[0] == DIR_NAME_DELETED || p->name[0] == '.') {
      return false;
    }
    // open cached entry
    return openCachedEntry(index & 0XF, oflag);
  }
  //------------------------------------------------------------------------------
  // open a cached directory entry. Assumes vol_ is initializes
  uint8_t SdFile::openCachedEntry(uint8_t dirIndex, uint8_t oflag) {
    // location of entry in cache
    dir_t* p = SdVolume::cacheBuffer_.dir + dirIndex;
  
    // write or truncate is an error for a directory or read-only file
    if (p->attributes & (DIR_ATT_READ_ONLY | DIR_ATT_DIRECTORY)) {
      if (oflag & (O_WRITE | O_TRUNC)) return false;
    }
    // remember location of directory entry on SD
    dirIndex_ = dirIndex;
    dirBlock_ = SdVolume::cacheBlockNumber_;
  
    // copy first cluster number for directory fields
    firstCluster_ = (uint32_t)p->firstClusterHigh << 16;
    firstCluster_ |= p->firstClusterLow;
  
    // make sure it is a normal file or subdirectory
    if (DIR_IS_FILE(p)) {
      fileSize_ = p->fileSize;
      type_ = FAT_FILE_TYPE_NORMAL;
    } else if (DIR_IS_SUBDIR(p)) {
      if (!vol_->chainSize(firstCluster_, &fileSize_)) return false;
      type_ = FAT_FILE_TYPE_SUBDIR;
    } else {
      return false;
    }
    // save open flags for read/write
    flags_ = oflag & (O_ACCMODE | O_SYNC | O_APPEND);
  
    // set to start of file
    curCluster_ = 0;
    curPosition_ = 0;
  
    // truncate file to zero length if requested
    if (oflag & O_TRUNC) return truncate(0);
    return true;
  }
  //------------------------------------------------------------------------------
  /**
   * Open a volume's root directory.
   *
   * \param[in] vol The FAT volume containing the root directory to be opened.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include the FAT volume has not been initialized
   * or it a FAT12 volume.
   */
  uint8_t SdFile::openRoot(SdVolume* vol) {
    // error if file is already open
    if (isOpen()) return false;
  
    if (vol->fatType() == 16) {
      type_ = FAT_FILE_TYPE_ROOT16;
      firstCluster_ = 0;
      fileSize_ = 32 * vol->rootDirEntryCount();
    } else if (vol->fatType() == 32) {
      type_ = FAT_FILE_TYPE_ROOT32;
      firstCluster_ = vol->rootDirStart();
      if (!vol->chainSize(firstCluster_, &fileSize_)) return false;
    } else {
      // volume is not initialized or FAT12
      return false;
    }
    vol_ = vol;
    // read only
    flags_ = O_READ;
  
    // set to start of file
    curCluster_ = 0;
    curPosition_ = 0;
  
    // root has no directory entry
    dirBlock_ = 0;
    dirIndex_ = 0;
    return true;
  }
  //------------------------------------------------------------------------------
  /** %Print the name field of a directory entry in 8.3 format to Serial.
   *
   * \param[in] dir The directory structure containing the name.
   * \param[in] width Blank fill name if length is less than \a width.
   */
  void SdFile::printDirName(const dir_t& dir, uint8_t width) {
    uint8_t w = 0;
    for (uint8_t i = 0; i < 11; i++) {
      if (dir.name[i] == ' ')continue;
      if (i == 8) {
        Serial.print('.');
        w++;
      }
      Serial.write(dir.name[i]);
      w++;
    }
    if (DIR_IS_SUBDIR(&dir)) {
      Serial.print('/');
      w++;
    }
    while (w < width) {
      Serial.print(' ');
      w++;
    }
  }
  //------------------------------------------------------------------------------
  /** %Print a directory date field to Serial.
   *
   *  Format is yyyy-mm-dd.
   *
   * \param[in] fatDate The date field from a directory entry.
   */
  void SdFile::printFatDate(uint16_t fatDate) {
    Serial.print(FAT_YEAR(fatDate));
    Serial.print('-');
    printTwoDigits(FAT_MONTH(fatDate));
    Serial.print('-');
    printTwoDigits(FAT_DAY(fatDate));
  }
  //------------------------------------------------------------------------------
  /** %Print a directory time field to Serial.
   *
   * Format is hh:mm:ss.
   *
   * \param[in] fatTime The time field from a directory entry.
   */
  void SdFile::printFatTime(uint16_t fatTime) {
    printTwoDigits(FAT_HOUR(fatTime));
    Serial.print(':');
    printTwoDigits(FAT_MINUTE(fatTime));
    Serial.print(':');
    printTwoDigits(FAT_SECOND(fatTime));
  }
  //------------------------------------------------------------------------------
  /** %Print a value as two digits to Serial.
   *
   * \param[in] v Value to be printed, 0 <= \a v <= 99
   */
  void SdFile::printTwoDigits(uint8_t v) {
    char str[3];
    str[0] = '0' + v/10;
    str[1] = '0' + v % 10;
    str[2] = 0;
    Serial.print(str);
  }
  //------------------------------------------------------------------------------
  /**
   * Read data from a file starting at the current position.
   *
   * \param[out] buf Pointer to the location that will receive the data.
   *
   * \param[in] nbyte Maximum number of bytes to read.
   *
   * \return For success read() returns the number of bytes read.
   * A value less than \a nbyte, including zero, will be returned
   * if end of file is reached.
   * If an error occurs, read() returns -1.  Possible errors include
   * read() called before a file has been opened, corrupt file system
   * or an I/O error occurred.
   */
  int16_t SdFile::read(void* buf, uint16_t nbyte) {
    uint8_t* dst = reinterpret_cast<uint8_t*>(buf);
  
    // error if not open or write only
    if (!isOpen() || !(flags_ & O_READ)) return -1;
  
    // max bytes left in file
    if (nbyte > (fileSize_ - curPosition_)) nbyte = fileSize_ - curPosition_;
  
    // amount left to read
    uint16_t toRead = nbyte;
    while (toRead > 0) {
      uint32_t block;  // raw device block number
      uint16_t offset = curPosition_ & 0X1FF;  // offset in block
      if (type_ == FAT_FILE_TYPE_ROOT16) {
        block = vol_->rootDirStart() + (curPosition_ >> 9);
      } else {
        uint8_t blockOfCluster = vol_->blockOfCluster(curPosition_);
        if (offset == 0 && blockOfCluster == 0) {
          // start of new cluster
          if (curPosition_ == 0) {
            // use first cluster in file
            curCluster_ = firstCluster_;
          } else {
            // get next cluster from FAT
            if (!vol_->fatGet(curCluster_, &curCluster_)) return -1;
          }
        }
        block = vol_->clusterStartBlock(curCluster_) + blockOfCluster;
      }
      uint16_t n = toRead;
  
      // amount to be read from current block
      if (n > (512 - offset)) n = 512 - offset;
  
      // no buffering needed if n == 512 or user requests no buffering
      if ((unbufferedRead() || n == 512) &&
        block != SdVolume::cacheBlockNumber_) {
        if (!vol_->readData(block, offset, n, dst)) return -1;
        dst += n;
      } else {
        // read block to cache and copy data to caller
        if (!SdVolume::cacheRawBlock(block, SdVolume::CACHE_FOR_READ)) return -1;
        uint8_t* src = SdVolume::cacheBuffer_.data + offset;
        uint8_t* end = src + n;
        while (src != end) *dst++ = *src++;
      }
      curPosition_ += n;
      toRead -= n;
    }
    return nbyte;
  }
  //------------------------------------------------------------------------------
  /**
   * Read the next directory entry from a directory file.
   *
   * \param[out] dir The dir_t struct that will receive the data.
   *
   * \return For success readDir() returns the number of bytes read.
   * A value of zero will be returned if end of file is reached.
   * If an error occurs, readDir() returns -1.  Possible errors include
   * readDir() called before a directory has been opened, this is not
   * a directory file or an I/O error occurred.
   */
  int8_t SdFile::readDir(dir_t* dir) {
    int8_t n;
    // if not a directory file or miss-positioned return an error
    if (!isDir() || (0X1F & curPosition_)) return -1;
  
    while ((n = read(dir, sizeof(dir_t))) == sizeof(dir_t)) {
      // last entry if DIR_NAME_FREE
      if (dir->name[0] == DIR_NAME_FREE) break;
      // skip empty entries and entry for .  and ..
      if (dir->name[0] == DIR_NAME_DELETED || dir->name[0] == '.') continue;
      // return if normal file or subdirectory
      if (DIR_IS_FILE_OR_SUBDIR(dir)) return n;
    }
    // error, end of file, or past last entry
    return n < 0 ? -1 : 0;
  }
  //------------------------------------------------------------------------------
  // Read next directory entry into the cache
  // Assumes file is correctly positioned
  dir_t* SdFile::readDirCache(void) {
    // error if not directory
    if (!isDir()) return NULL;
  
    // index of entry in cache
    uint8_t i = (curPosition_ >> 5) & 0XF;
  
    // use read to locate and cache block
    if (read() < 0) return NULL;
  
    // advance to next entry
    curPosition_ += 31;
  
    // return pointer to entry
    return (SdVolume::cacheBuffer_.dir + i);
  }
  //------------------------------------------------------------------------------
  /**
   * Remove a file.
   *
   * The directory entry and all data for the file are deleted.
   *
   * \note This function should not be used to delete the 8.3 version of a
   * file that has a long name. For example if a file has the long name
   * "New Text Document.txt" you should not delete the 8.3 name "NEWTEX~1.TXT".
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include the file read-only, is a directory,
   * or an I/O error occurred.
   */
  uint8_t SdFile::remove(void) {
    // free any clusters - will fail if read-only or directory
    if (!truncate(0)) return false;
  
    // cache directory entry
    dir_t* d = cacheDirEntry(SdVolume::CACHE_FOR_WRITE);
    if (!d) return false;
  
    // mark entry deleted
    d->name[0] = DIR_NAME_DELETED;
  
    // set this SdFile closed
    type_ = FAT_FILE_TYPE_CLOSED;
  
    // write entry to SD
    return SdVolume::cacheFlush();
  }
  //------------------------------------------------------------------------------
  /**
   * Remove a file.
   *
   * The directory entry and all data for the file are deleted.
   *
   * \param[in] dirFile The directory that contains the file.
   * \param[in] fileName The name of the file to be removed.
   *
   * \note This function should not be used to delete the 8.3 version of a
   * file that has a long name. For example if a file has the long name
   * "New Text Document.txt" you should not delete the 8.3 name "NEWTEX~1.TXT".
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include the file is a directory, is read only,
   * \a dirFile is not a directory, \a fileName is not found
   * or an I/O error occurred.
   */
  uint8_t SdFile::remove(SdFile* dirFile, const char* fileName) {
    SdFile file;
    if (!file.open(dirFile, fileName, O_WRITE)) return false;
    return file.remove();
  }
  //------------------------------------------------------------------------------
  /** Remove a directory file.
   *
   * The directory file will be removed only if it is empty and is not the
   * root directory.  rmDir() follows DOS and Windows and ignores the
   * read-only attribute for the directory.
   *
   * \note This function should not be used to delete the 8.3 version of a
   * directory that has a long name. For example if a directory has the
   * long name "New folder" you should not delete the 8.3 name "NEWFOL~1".
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include the file is not a directory, is the root
   * directory, is not empty, or an I/O error occurred.
   */
  uint8_t SdFile::rmDir(void) {
    // must be open subdirectory
    if (!isSubDir()) return false;
  
    rewind();
  
    // make sure directory is empty
    while (curPosition_ < fileSize_) {
      dir_t* p = readDirCache();
      if (p == NULL) return false;
      // done if past last used entry
      if (p->name[0] == DIR_NAME_FREE) break;
      // skip empty slot or '.' or '..'
      if (p->name[0] == DIR_NAME_DELETED || p->name[0] == '.') continue;
      // error not empty
      if (DIR_IS_FILE_OR_SUBDIR(p)) return false;
    }
    // convert empty directory to normal file for remove
    type_ = FAT_FILE_TYPE_NORMAL;
    flags_ |= O_WRITE;
    return remove();
  }
  //------------------------------------------------------------------------------
  /** Recursively delete a directory and all contained files.
   *
   * This is like the Unix/Linux 'rm -rf *' if called with the root directory
   * hence the name.
   *
   * Warning - This will remove all contents of the directory including
   * subdirectories.  The directory will then be removed if it is not root.
   * The read-only attribute for files will be ignored.
   *
   * \note This function should not be used to delete the 8.3 version of
   * a directory that has a long name.  See remove() and rmDir().
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   */
  uint8_t SdFile::rmRfStar(void) {
    rewind();
    while (curPosition_ < fileSize_) {
      SdFile f;
  
      // remember position
      uint16_t index = curPosition_/32;
  
      dir_t* p = readDirCache();
      if (!p) return false;
  
      // done if past last entry
      if (p->name[0] == DIR_NAME_FREE) break;
  
      // skip empty slot or '.' or '..'
      if (p->name[0] == DIR_NAME_DELETED || p->name[0] == '.') continue;
  
      // skip if part of long file name or volume label in root
      if (!DIR_IS_FILE_OR_SUBDIR(p)) continue;
  
      if (!f.open(this, index, O_READ)) return false;
      if (f.isSubDir()) {
        // recursively delete
        if (!f.rmRfStar()) return false;
      } else {
        // ignore read-only
        f.flags_ |= O_WRITE;
        if (!f.remove()) return false;
      }
      // position to next entry if required
      if (curPosition_ != (32*(index + 1))) {
        if (!seekSet(32*(index + 1))) return false;
      }
    }
    // don't try to delete root
    if (isRoot()) return true;
    return rmDir();
  }
  //------------------------------------------------------------------------------
  /**
   * Sets a file's position.
   *
   * \param[in] pos The new position in bytes from the beginning of the file.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   */
  uint8_t SdFile::seekSet(uint32_t pos) {
    // error if file not open or seek past end of file
    if (!isOpen() || pos > fileSize_) return false;
  
    if (type_ == FAT_FILE_TYPE_ROOT16) {
      curPosition_ = pos;
      return true;
    }
    if (pos == 0) {
      // set position to start of file
      curCluster_ = 0;
      curPosition_ = 0;
      return true;
    }
    // calculate cluster index for cur and new position
    uint32_t nCur = (curPosition_ - 1) >> (vol_->clusterSizeShift_ + 9);
    uint32_t nNew = (pos - 1) >> (vol_->clusterSizeShift_ + 9);
  
    if (nNew < nCur || curPosition_ == 0) {
      // must follow chain from first cluster
      curCluster_ = firstCluster_;
    } else {
      // advance from curPosition
      nNew -= nCur;
    }
    while (nNew--) {
      if (!vol_->fatGet(curCluster_, &curCluster_)) return false;
    }
    curPosition_ = pos;
    return true;
  }
  //------------------------------------------------------------------------------
  /**
   * The sync() call causes all modified data and directory fields
   * to be written to the storage device.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include a call to sync() before a file has been
   * opened or an I/O error.
   */
  uint8_t SdFile::sync(void) {
    // only allow open files and directories
    if (!isOpen()) return false;
  
    if (flags_ & F_FILE_DIR_DIRTY) {
      dir_t* d = cacheDirEntry(SdVolume::CACHE_FOR_WRITE);
      if (!d) return false;
  
      // do not set filesize for dir files
      if (!isDir()) d->fileSize = fileSize_;
  
      // update first cluster fields
      d->firstClusterLow = firstCluster_ & 0XFFFF;
      d->firstClusterHigh = firstCluster_ >> 16;
  
      // set modify time if user supplied a callback date/time function
      if (dateTime_) {
        dateTime_(&d->lastWriteDate, &d->lastWriteTime);
        d->lastAccessDate = d->lastWriteDate;
      }
      // clear directory dirty
      flags_ &= ~F_FILE_DIR_DIRTY;
    }
    return SdVolume::cacheFlush();
  }
  //------------------------------------------------------------------------------
  /**
   * Set a file's timestamps in its directory entry.
   *
   * \param[in] flags Values for \a flags are constructed by a bitwise-inclusive
   * OR of flags from the following list
   *
   * T_ACCESS - Set the file's last access date.
   *
   * T_CREATE - Set the file's creation date and time.
   *
   * T_WRITE - Set the file's last write/modification date and time.
   *
   * \param[in] year Valid range 1980 - 2107 inclusive.
   *
   * \param[in] month Valid range 1 - 12 inclusive.
   *
   * \param[in] day Valid range 1 - 31 inclusive.
   *
   * \param[in] hour Valid range 0 - 23 inclusive.
   *
   * \param[in] minute Valid range 0 - 59 inclusive.
   *
   * \param[in] second Valid range 0 - 59 inclusive
   *
   * \note It is possible to set an invalid date since there is no check for
   * the number of days in a month.
   *
   * \note
   * Modify and access timestamps may be overwritten if a date time callback
   * function has been set by dateTimeCallback().
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   */
  uint8_t SdFile::timestamp(uint8_t flags, uint16_t year, uint8_t month,
           uint8_t day, uint8_t hour, uint8_t minute, uint8_t second) {
    if (!isOpen()
      || year < 1980
      || year > 2107
      || month < 1
      || month > 12
      || day < 1
      || day > 31
      || hour > 23
      || minute > 59
      || second > 59) {
        return false;
    }
    dir_t* d = cacheDirEntry(SdVolume::CACHE_FOR_WRITE);
    if (!d) return false;
  
    uint16_t dirDate = FAT_DATE(year, month, day);
    uint16_t dirTime = FAT_TIME(hour, minute, second);
    if (flags & T_ACCESS) {
      d->lastAccessDate = dirDate;
    }
    if (flags & T_CREATE) {
      d->creationDate = dirDate;
      d->creationTime = dirTime;
      // seems to be units of 1/100 second not 1/10 as Microsoft states
      d->creationTimeTenths = second & 1 ? 100 : 0;
    }
    if (flags & T_WRITE) {
      d->lastWriteDate = dirDate;
      d->lastWriteTime = dirTime;
    }
    SdVolume::cacheSetDirty();
    return sync();
  }
  //------------------------------------------------------------------------------
  /**
   * Truncate a file to a specified length.  The current file position
   * will be maintained if it is less than or equal to \a length otherwise
   * it will be set to end of file.
   *
   * \param[in] length The desired length for the file.
   *
   * \return The value one, true, is returned for success and
   * the value zero, false, is returned for failure.
   * Reasons for failure include file is read only, file is a directory,
   * \a length is greater than the current file size or an I/O error occurs.
   */
  uint8_t SdFile::truncate(uint32_t length) {
  // error if not a normal file or read-only
    if (!isFile() || !(flags_ & O_WRITE)) return false;
  
    // error if length is greater than current size
    if (length > fileSize_) return false;
  
    // fileSize and length are zero - nothing to do
    if (fileSize_ == 0) return true;
  
    // remember position for seek after truncation
    uint32_t newPos = curPosition_ > length ? length : curPosition_;
  
    // position to last cluster in truncated file
    if (!seekSet(length)) return false;
  
    if (length == 0) {
      // free all clusters
      if (!vol_->freeChain(firstCluster_)) return false;
      firstCluster_ = 0;
    } else {
      uint32_t toFree;
      if (!vol_->fatGet(curCluster_, &toFree)) return false;
  
      if (!vol_->isEOC(toFree)) {
        // free extra clusters
        if (!vol_->freeChain(toFree)) return false;
  
        // current cluster is end of chain
        if (!vol_->fatPutEOC(curCluster_)) return false;
      }
    }
    fileSize_ = length;
  
    // need to update directory entry
    flags_ |= F_FILE_DIR_DIRTY;
  
    if (!sync()) return false;
  
    // set file to correct position
    return seekSet(newPos);
  }
  //------------------------------------------------------------------------------
  /**
   * Write data to an open file.
   *
   * \note Data is moved to the cache but may not be written to the
   * storage device until sync() is called.
   *
   * \param[in] buf Pointer to the location of the data to be written.
   *
   * \param[in] nbyte Number of bytes to write.
   *
   * \return For success write() returns the number of bytes written, always
   * \a nbyte.  If an error occurs, write() returns -1.  Possible errors
   * include write() is called before a file has been opened, write is called
   * for a read-only file, device is full, a corrupt file system or an I/O error.
   *
   */
  size_t SdFile::write(const void* buf, uint16_t nbyte) {
    // convert void* to uint8_t*  -  must be before goto statements
    const uint8_t* src = reinterpret_cast<const uint8_t*>(buf);
  
    // number of bytes left to write  -  must be before goto statements
    uint16_t nToWrite = nbyte;
  
    // error if not a normal file or is read-only
    if (!isFile() || !(flags_ & O_WRITE)) goto writeErrorReturn;
  
    // seek to end of file if append flag
    if ((flags_ & O_APPEND) && curPosition_ != fileSize_) {
      if (!seekEnd()) goto writeErrorReturn;
    }
  
    while (nToWrite > 0) {
      uint8_t blockOfCluster = vol_->blockOfCluster(curPosition_);
      uint16_t blockOffset = curPosition_ & 0X1FF;
      if (blockOfCluster == 0 && blockOffset == 0) {
        // start of new cluster
        if (curCluster_ == 0) {
          if (firstCluster_ == 0) {
            // allocate first cluster of file
            if (!addCluster()) goto writeErrorReturn;
          } else {
            curCluster_ = firstCluster_;
          }
        } else {
          uint32_t next;
          if (!vol_->fatGet(curCluster_, &next)) return false;
          if (vol_->isEOC(next)) {
            // add cluster if at end of chain
            if (!addCluster()) goto writeErrorReturn;
          } else {
            curCluster_ = next;
          }
        }
      }
      // max space in block
      uint16_t n = 512 - blockOffset;
  
      // lesser of space and amount to write
      if (n > nToWrite) n = nToWrite;
  
      // block for data write
      uint32_t block = vol_->clusterStartBlock(curCluster_) + blockOfCluster;
      if (n == 512) {
        // full block - don't need to use cache
        // invalidate cache if block is in cache
        if (SdVolume::cacheBlockNumber_ == block) {
          SdVolume::cacheBlockNumber_ = 0XFFFFFFFF;
        }
        if (!vol_->writeBlock(block, src)) goto writeErrorReturn;
        src += 512;
      } else {
        if (blockOffset == 0 && curPosition_ >= fileSize_) {
          // start of new block don't need to read into cache
          if (!SdVolume::cacheFlush()) goto writeErrorReturn;
          SdVolume::cacheBlockNumber_ = block;
          SdVolume::cacheSetDirty();
        } else {
          // rewrite part of block
          if (!SdVolume::cacheRawBlock(block, SdVolume::CACHE_FOR_WRITE)) {
            goto writeErrorReturn;
          }
        }
        uint8_t* dst = SdVolume::cacheBuffer_.data + blockOffset;
        uint8_t* end = dst + n;
        while (dst != end) *dst++ = *src++;
      }
      nToWrite -= n;
      curPosition_ += n;
    }
    if (curPosition_ > fileSize_) {
      // update fileSize and insure sync will update dir entry
      fileSize_ = curPosition_;
      flags_ |= F_FILE_DIR_DIRTY;
    } else if (dateTime_ && nbyte) {
      // insure sync will update modified date and time
      flags_ |= F_FILE_DIR_DIRTY;
    }
  
    if (flags_ & O_SYNC) {
      if (!sync()) goto writeErrorReturn;
    }
    return nbyte;
  
   writeErrorReturn:
    // return for write error
    //writeError = true;
    setWriteError();
    return 0;
  }
  //------------------------------------------------------------------------------
  /**
   * Write a byte to a file. Required by the Arduino Print class.
   *
   * Use SdFile::writeError to check for errors.
   */
  size_t SdFile::write(uint8_t b) {
    return write(&b, 1);
  }
  //------------------------------------------------------------------------------
  /**
   * Write a string to a file. Used by the Arduino Print class.
   *
   * Use SdFile::writeError to check for errors.
   */
  size_t SdFile::write(const char* str) {
    return write(str, strlen(str));
  }
  #ifdef __AVR__
  //------------------------------------------------------------------------------
  /**
   * Write a PROGMEM string to a file.
   *
   * Use SdFile::writeError to check for errors.
   */
  void SdFile::write_P(PGM_P str) {
    for (uint8_t c; (c = pgm_read_byte(str)); str++) write(c);
  }
  //------------------------------------------------------------------------------
  /**
   * Write a PROGMEM string followed by CR/LF to a file.
   *
   * Use SdFile::writeError to check for errors.
   */
  void SdFile::writeln_P(PGM_P str) {
    write_P(str);
    println();
  }
  #endif
  