Quadrotor

/* 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>

#include <avr/pgmspace.h>

#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

      PGM_P p = PSTR("|<>^+=?/[];,*\"\\");

      uint8_t b;

      while ((b = pgm_read_byte(p++))) if (b == c) return false;

      // 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.

 *