Quadrotor

/*

 SD - a slightly more friendly wrapper for sdfatlib

 This library aims to expose a subset of SD card functionality

 in the form of a higher level "wrapper" object.

 License: GNU General Public License V3

          (Because sdfatlib is licensed with this.)

 (C) Copyright 2010 SparkFun Electronics

 This library provides four key benefits:

   * Including `SD.h` automatically creates a global

     `SD` object which can be interacted with in a similar

     manner to other standard global objects like `Serial` and `Ethernet`.

   * Boilerplate initialisation code is contained in one method named 

     `begin` and no further objects need to be created in order to access

     the SD card.

   * Calls to `open` can supply a full path name including parent 

     directories which simplifies interacting with files in subdirectories.

   * Utility methods are provided to determine whether a file exists

     and to create a directory heirarchy.

  Note however that not all functionality provided by the underlying

  sdfatlib library is exposed.

 */

/*

  Implementation Notes

  In order to handle multi-directory path traversal, functionality that 

  requires this ability is implemented as callback functions.

  Individual methods call the `walkPath` function which performs the actual

  directory traversal (swapping between two different directory/file handles

  along the way) and at each level calls the supplied callback function.

  Some types of functionality will take an action at each level (e.g. exists

  or make directory) which others will only take an action at the bottom

  level (e.g. open).

 */

#include "SD.h"

// Used by `getNextPathComponent`

#define MAX_COMPONENT_LEN 12 // What is max length?

#define PATH_COMPONENT_BUFFER_LEN MAX_COMPONENT_LEN+1

bool getNextPathComponent(char *path, unsigned int *p_offset,

                          char *buffer) {

  /*

    Parse individual path components from a path.

      e.g. after repeated calls '/foo/bar/baz' will be split

           into 'foo', 'bar', 'baz'.

    This is similar to `strtok()` but copies the component into the

    supplied buffer rather than modifying the original string.

    `buffer` needs to be PATH_COMPONENT_BUFFER_LEN in size.

    `p_offset` needs to point to an integer of the offset at

    which the previous path component finished.

    Returns `true` if more components remain.

    Returns `false` if this is the last component.

      (This means path ended with 'foo' or 'foo/'.)

   */

  // TODO: Have buffer local to this function, so we know it's the

  //       correct length?

  int bufferOffset = 0;

  int offset = *p_offset;

  // Skip root or other separator

  if (path[offset] == '/') {

    offset++;

  }

  // Copy the next next path segment

  while (bufferOffset < MAX_COMPONENT_LEN

         && (path[offset] != '/')

         && (path[offset] != '\0')) {

    buffer[bufferOffset++] = path[offset++];

  }

  buffer[bufferOffset] = '\0';

  // Skip trailing separator so we can determine if this

  // is the last component in the path or not.

  if (path[offset] == '/') {

    offset++;

  }

  *p_offset = offset;

  return (path[offset] != '\0');

}

boolean walkPath(char *filepath, SdFile& parentDir,

                 boolean (*callback)(SdFile& parentDir,

                                     char *filePathComponent,

                                     boolean isLastComponent,

                                     void *object),

                 void *object = NULL) {

  /*

     When given a file path (and parent directory--normally root),

     this function traverses the directories in the path and at each

     level calls the supplied callback function while also providing

     the supplied object for context if required.

       e.g. given the path '/foo/bar/baz'

            the callback would be called at the equivalent of

            '/foo', '/foo/bar' and '/foo/bar/baz'.

     The implementation swaps between two different directory/file

     handles as it traverses the directories and does not use recursion

     in an attempt to use memory efficiently.

     If a callback wishes to stop the directory traversal it should

     return false--in this case the function will stop the traversal,

     tidy up and return false.

     If a directory path doesn't exist at some point this function will

     also return false and not subsequently call the callback.

     If a directory path specified is complete, valid and the callback

     did not indicate the traversal should be interrupted then this

     function will return true.

   */

  SdFile subfile1;

  SdFile subfile2;

  char buffer[PATH_COMPONENT_BUFFER_LEN]; 

  unsigned int offset = 0;

  SdFile *p_parent;

  SdFile *p_child;

  SdFile *p_tmp_sdfile;  

  p_child = &subfile1;

  p_parent = &parentDir;

  while (true) {

    boolean moreComponents = getNextPathComponent(filepath, &offset, buffer);

    boolean shouldContinue = callback((*p_parent), buffer, !moreComponents, object);

    if (!shouldContinue) {

      // TODO: Don't repeat this code?

      // If it's one we've created then we

      // don't need the parent handle anymore.

      if (p_parent != &parentDir) {

        (*p_parent).close();

      }

      return false;

    }

    if (!moreComponents) {

      break;

    }

    boolean exists = (*p_child).open(*p_parent, buffer, O_RDONLY);

    // If it's one we've created then we

    // don't need the parent handle anymore.

    if (p_parent != &parentDir) {

      (*p_parent).close();

    }

    // Handle case when it doesn't exist and we can't continue...

    if (exists) {

      // We alternate between two file handles as we go down

      // the path.

      if (p_parent == &parentDir) {

        p_parent = &subfile2;

      }

      p_tmp_sdfile = p_parent;

      p_parent = p_child;

      p_child = p_tmp_sdfile;

    } else {

      return false;

    }

  }

  if (p_parent != &parentDir) {

    (*p_parent).close(); // TODO: Return/ handle different?

  }

  return true;

}

/*

   The callbacks used to implement various functionality follow.

   Each callback is supplied with a parent directory handle,

   character string with the name of the current file path component,

   a flag indicating if this component is the last in the path and

   a pointer to an arbitrary object used for context.

 */

boolean callback_pathExists(SdFile& parentDir, char *filePathComponent, 

                            boolean isLastComponent, void *object) {

  /*

    Callback used to determine if a file/directory exists in parent

    directory.

    Returns true if file path exists.

  */

  SdFile child;

  boolean exists = child.open(parentDir, filePathComponent, O_RDONLY);

  if (exists) {

     child.close(); 

  }

  return exists;

}

boolean callback_makeDirPath(SdFile& parentDir, char *filePathComponent, 

                             boolean isLastComponent, void *object) {

  /*

    Callback used to create a directory in the parent directory if

    it does not already exist.

    Returns true if a directory was created or it already existed.

  */

  boolean result = false;

  SdFile child;

  result = callback_pathExists(parentDir, filePathComponent, isLastComponent, object);

  if (!result) {

    result = child.makeDir(parentDir, filePathComponent);

  } 

  return result;

}

  /*

boolean callback_openPath(SdFile& parentDir, char *filePathComponent, 

                          boolean isLastComponent, void *object) {

    Callback used to open a file specified by a filepath that may

    specify one or more directories above it.

    Expects the context object to be an instance of `SDClass` and

    will use the `file` property of the instance to open the requested

    file/directory with the associated file open mode property.

    Always returns true if the directory traversal hasn't reached the

    bottom of the directory heirarchy.

    Returns false once the file has been opened--to prevent the traversal

    from descending further. (This may be unnecessary.)

  if (isLastComponent) {

    SDClass *p_SD = static_cast<SDClass*>(object);

    p_SD->file.open(parentDir, filePathComponent, p_SD->fileOpenMode);

    if (p_SD->fileOpenMode == FILE_WRITE) {

      p_SD->file.seekSet(p_SD->file.fileSize());

    }

    // TODO: Return file open result?

    return false;

  }

  return true;

}

  */

boolean callback_remove(SdFile& parentDir, char *filePathComponent, 

                        boolean isLastComponent, void *object) {

  if (isLastComponent) {

    return SdFile::remove(parentDir, filePathComponent);

  }

  return true;

}

boolean callback_rmdir(SdFile& parentDir, char *filePathComponent, 

                        boolean isLastComponent, void *object) {

  if (isLastComponent) {

    SdFile f;

    if (!f.open(parentDir, filePathComponent, O_READ)) return false;

    return f.rmDir();

  }

  return true;

}

/* Implementation of class used to create `SDCard` object. */

boolean SDClass::begin(uint8_t csPin) {

  /*

    Performs the initialisation required by the sdfatlib library.

    Return true if initialization succeeds, false otherwise.

   */

  return card.init(SPI_HALF_SPEED, csPin) &&

         volume.init(card) &&

         root.openRoot(volume);

}

// this little helper is used to traverse paths

SdFile SDClass::getParentDir(const char *filepath, int *index) {

  // get parent directory

  SdFile d1 = root; // start with the mostparent, root!

  SdFile d2;

  // we'll use the pointers to swap between the two objects

  SdFile *parent = &d1;

  SdFile *subdir = &d2;

  const char *origpath = filepath;

  while (strchr(filepath, '/')) {

    // get rid of leading /'s

    if (filepath[0] == '/') {

      filepath++;

      continue;

    }

    if (! strchr(filepath, '/')) {

      // it was in the root directory, so leave now

      break;

    }

    // extract just the name of the next subdirectory

    uint8_t idx = strchr(filepath, '/') - filepath;

    if (idx > 12)

      idx = 12;    // dont let them specify long names

    char subdirname[13];

    strncpy(subdirname, filepath, idx);

    subdirname[idx] = 0;

    // close the subdir (we reuse them) if open

    subdir->close();

    if (! subdir->open(parent, subdirname, O_READ)) {

      // failed to open one of the subdirectories

      return SdFile();

    }

    // move forward to the next subdirectory

    filepath += idx;

    // we reuse the objects, close it.

    parent->close();

    // swap the pointers

    SdFile *t = parent;

    parent = subdir;

    subdir = t;

  }

  *index = (int)(filepath - origpath);

  // parent is now the parent diretory of the file!

  return *parent;

}

File SDClass::open(const char *filepath, uint8_t mode) {

  /*

     Open the supplied file path for reading or writing.

     The file content can be accessed via the `file` property of

     the `SDClass` object--this property is currently

     a standard `SdFile` object from `sdfatlib`.

     Defaults to read only.

     If `write` is true, default action (when `append` is true) is to

     append data to the end of the file.

     If `append` is false then the file will be truncated first.

     If the file does not exist and it is opened for writing the file

     will be created.

     An attempt to open a file for reading that does not exist is an

     error.

   */

  int pathidx;

  // do the interative search

  SdFile parentdir = getParentDir(filepath, &pathidx);

  // no more subdirs!

  filepath += pathidx;

  if (! filepath[0]) {

    // it was the directory itself!

    return File(parentdir, "/");

  }

  // Open the file itself

  SdFile file;

  // failed to open a subdir!

  if (!parentdir.isOpen())

    return File();

  // there is a special case for the Root directory since its a static dir

  if (parentdir.isRoot()) {

    if ( ! file.open(SD.root, filepath, mode)) {

      // failed to open the file :(

      return File();

    }

    // dont close the root!

  } else {

    if ( ! file.open(parentdir, filepath, mode)) {

      return File();

    }

    // close the parent

    parentdir.close();

  }

  if (mode & (O_APPEND | O_WRITE)) 

    file.seekSet(file.fileSize());

  return File(file, filepath);

}

/*

File SDClass::open(char *filepath, uint8_t mode) {

  //

     Open the supplied file path for reading or writing.

     The file content can be accessed via the `file` property of

     the `SDClass` object--this property is currently

     a standard `SdFile` object from `sdfatlib`.

     Defaults to read only.

     If `write` is true, default action (when `append` is true) is to

     append data to the end of the file.

     If `append` is false then the file will be truncated first.

     If the file does not exist and it is opened for writing the file

     will be created.

     An attempt to open a file for reading that does not exist is an

     error.

   //

  // TODO: Allow for read&write? (Possibly not, as it requires seek.)

  fileOpenMode = mode;

  walkPath(filepath, root, callback_openPath, this);

  return File();

}

*/

//boolean SDClass::close() {

//  /*

//

//    Closes the file opened by the `open` method.

//

//   */

//  file.close();

//}

boolean SDClass::exists(char *filepath) {

  /*

     Returns true if the supplied file path exists.

   */

  return walkPath(filepath, root, callback_pathExists);

}

//boolean SDClass::exists(char *filepath, SdFile& parentDir) {

//  /*

//

//     Returns true if the supplied file path rooted at `parentDir`

//     exists.

//

//   */

//  return walkPath(filepath, parentDir, callback_pathExists);

//}

boolean SDClass::mkdir(char *filepath) {

  /*

    Makes a single directory or a heirarchy of directories.

    A rough equivalent to `mkdir -p`.

   */

  return walkPath(filepath, root, callback_makeDirPath);

}

boolean SDClass::rmdir(char *filepath) {

  /*

    Makes a single directory or a heirarchy of directories.

    A rough equivalent to `mkdir -p`.

   */

  return walkPath(filepath, root, callback_rmdir);

}

boolean SDClass::remove(char *filepath) {

  return walkPath(filepath, root, callback_remove);

}

// allows you to recurse into a directory

File File::openNextFile(uint8_t mode) {

  dir_t p;

  //Serial.print("\t\treading dir...");

  while (_file->readDir(&p) > 0) {

    // done if past last used entry

    if (p.name[0] == DIR_NAME_FREE) {

      //Serial.println("end");

      return File();

    }

    // skip deleted entry and entries for . and  ..

    if (p.name[0] == DIR_NAME_DELETED || p.name[0] == '.') {

      //Serial.println("dots");

      continue;

    }

    // only list subdirectories and files

    if (!DIR_IS_FILE_OR_SUBDIR(&p)) {

      //Serial.println("notafile");

      continue;

    }

    // print file name with possible blank fill

    SdFile f;

    char name[13];

    _file->dirName(p, name);

    //Serial.print("try to open file ");

    //Serial.println(name);

    if (f.open(_file, name, mode)) {

      //Serial.println("OK!");

      return File(f, name);    

    } else {

      //Serial.println("ugh");

      return File();

    }

  }

  //Serial.println("nothing");

  return File();

}

void File::rewindDirectory(void) {  

  if (isDirectory())

    _file->rewind();

}

SDClass SD;