ACE/ace/MQX_Filesystem.h

   1 /**
   2  * @file MQX_Filesystem.h
   3  *
   4  * @author Frederick Hornsey <hornseyf@objectcomputing.com>
   5  */
   6
   7 #ifndef MQX_FILESYSTEM_HEADER
   8 #define MQX_FILESYSTEM_HEADER
   9
  10 #include "ace/config-all.h"
  11
  12 #ifdef ACE_MQX
  13
  14 #include <mqx.h>
  15 #include <fio.h>
  16
  17 #if !defined (FOPEN_MAX)
  18 # define FOPEN_MAX 20
  19 #endif
  20
  21 #if !defined (ACE_MQX_DLIB_FULL)
  22 # undef read
  23 # undef write
  24 #endif
  25
  26 struct stat;
  27 typedef struct stat ACE_stat;
  28
  29 #define ACE_MQX_ABS_PATH_SIZE (IOCFG_FS_MAX_DEVLEN + FS_FILENAME_SIZE - 1)
  30
  31 /**
  32  * Since MQX has an unusual filesystem API, this class is provided to try to
  33  * normalize it by managing the current working directory on a global context
  34  * instead of a device by device context provided by MQX. It also tries to make
  35  * these functions act more like their UNIX counterparts to some extent.
  36  *
  37  * This class is also the interface between the DLib IO functions and MQX file
  38  * IO. It does this by implementing the classic UNIX IO functions below.
  39  *
  40  * WARNING: This is already being done in the ACE_TMAIN macro, but
  41  * complete_initialization() should be called before using DLib or ACE file IO
  42  * functions, but after MQX has been initialized. Either way, standard streams
  43  * will not work properly, or some other behavior depending on the what
  44  * functions are called in what order.
  45  */
  46 class MQX_Filesystem {
  47 public:
  48   /// Get the singleton instance of the class
  49   inline static MQX_Filesystem &inst() {
  50     return instance_;
  51   }
  52
  53   /**
  54    * Initialize the Standard Streams and the Current Filesystem
  55    *
  56    * This must be done after MQX has been initialized. See warning in class
  57    * documenting comment.
  58    */
  59   void complete_initialization ();
  60
  61   /**
  62    * Attempt to reset the cwd state by asking MQX for the first valid filesystem
  63    * and "cd-ing" into the root of it.
  64    */
  65   bool reset_state ();
  66
  67   /**
  68    * @name Unix-like File Functions
  69    *
  70    * Classic UNIX-like Operations Implemented for for DLib
  71    */
  72   ///@{
  73   /**
  74    * Open a file and return the file descriptor.
  75    *
  76    * Returns the file descriptor if successful, -1 otherwise.
  77    *
  78    * Known Limitations:
  79    *  - Mode is being converted from DLib Unix-like mode to MQX cstdlib mode.
  80    *    This is not perfected yet and is limited by the common denominator of
  81    *    what is supported by both systems.
  82    */
  83   int open (const char *path, int mode);
  84   int close (int fd);
  85   size_t read (int fd, unsigned char *buffer, size_t size);
  86   size_t write (int fd, const unsigned char *buffer, size_t size);
  87   long lseek (int fd, long offset, int whence);
  88   ///@}
  89
  90   /**
  91    * @name Unix-like Filesystem Functions
  92    */
  93   ///@{
  94   /**
  95    * Put the current directory path in buf of size.
  96    *
  97    * Returns NULL if an error occurred, otherwise buf.
  98    */
  99   char *getcwd (char *buf, size_t size);
 100
 101   /**
 102    * Create a directory at path.
 103    *
 104    * Returns -1 if an error occurred, otherwise 0.
 105    */
 106   int mkdir (const char *path);
 107
 108   /**
 109    * Change to the directory at path.
 110    *
 111    * Returns -1 if an error occurred, otherwise 0.
 112    */
 113   int chdir (const char *path);
 114
 115   /**
 116    * Remove the empty directory at path.
 117    *
 118    * Returns -1 if an error occurred, otherwise 0.
 119    */
 120   int rmdir (const char *path);
 121
 122   /**
 123    * Unlink the file at path.
 124    *
 125    * Returns -1 if an error occurred, otherwise 0.
 126    */
 127   int unlink (const char *path);
 128
 129   /**
 130    * Rename or move the file or rename the directory from newpath to oldpath.
 131    *
 132    * Returns -1 if an error occurred, otherwise 0.
 133    *
 134    * As standard rename does, this sets errno to EXDEV if you try to move a
 135    * file across filesystems. It also overwrites regular files that occupy the
 136    * new path.
 137    *
 138    * Known Limitations:
 139    *   - Can only rename directories, will refuse to move them. This is MFS's
 140    *     IO_IOCTL_RENAME_FILE refusing to do this. This could be implemented by
 141    *     the function, but would involve either manually copying the file tree
 142    *     or refusing to move nonempty directories.
 143    */
 144   int rename (const char *oldpath, const char *newpath);
 145
 146   /**
 147    * Get status of file given by path.
 148    *
 149    * Returns -1 if an error occurred, otherwise 0.
 150    *
 151    * Known Limitations:
 152    *   - st_mtime is currently not implemented and is set to 0.
 153    *   - st_mode is limited to
 154    *     - S_IFDIR: file is a directory
 155    *     - S_IFREG: file is a regular file
 156    */
 157   int stat (const char * path, ACE_stat *statbuf);
 158
 159   /**
 160    * Get status of file given by file descriptor.
 161    *
 162    * Returns -1 if an error occurred, otherwise 0.
 163    *
 164    * Known Limitations:
 165    *   - st_mtime is currently not implemented and returns 0
 166    *   - In MFS there seems to be no direct way to get st_msize from a MQX file
 167    *     alone. The only way to get a file size using the documented API seems
 168    *     to be IO_IOCTL_FIND_FIRST_FILE, which requires the path. For now this
 169    *     will be set to 0.
 170    *   - st_mode is limited to
 171    *     - S_IFDIR: file is a directory
 172    *     - S_IFREG: file is a regular file
 173    *     - S_IFCHR: file is a special character device file, (e.g. ACE_STDOUT)
 174    */
 175   int fstat (int fd, ACE_stat *statbuf);
 176   ///@}
 177
 178 private:
 179   /// The singleton instance of the class
 180   static MQX_Filesystem instance_;
 181
 182   MQX_Filesystem();
 183
 184   /**
 185    * @name Current Filesystem for resolving relative paths.
 186    */
 187   ///@{
 188   MQX_FILE_PTR current_fs_;
 189   char current_fs_name_[IOCFG_FS_MAX_DEVLEN];
 190   unsigned current_fs_name_len_;
 191   ///@}
 192
 193   /**
 194    * @name Manage open files using file descriptors.
 195    */
 196   ///@{
 197   struct File {
 198     /// DLib File Descriptor. Invalid if -1.
 199     int fd;
 200     /// MQX File
 201     MQX_FILE_PTR mqx_file;
 202     /// Mark this as special character device file (Standard Streams)
 203     bool chardev_file;
 204   };
 205   File files_[FOPEN_MAX];
 206
 207   /**
 208    * Last file descriptor created.
 209    */
 210   int last_fd_;
 211
 212   /**
 213    * Max VALUE for File Descriptors.
 214    *
 215    * NOTE: Max open file count is FOPEN_MAX, defined by DLib. This creates a
 216    * limit on the number of unique file descriptor values.
 217    */
 218   int max_fd_;
 219
 220   /**
 221    * Get a File struct for the file descriptor.
 222    *
 223    * Returns NULL and sets EBADF if no such file exists
 224    */
 225   File *get_file (int fd);
 226
 227   /**
 228    * Get a File struct pointer to use for a new file.
 229    *
 230    * Returns NULL and sets ENFILE if exceeded max number of open files.
 231    */
 232   File *get_new_file ();
 233   ///@}
 234
 235   /**
 236    * Check to see if the current filesystem is valid, if not reset it.
 237    *
 238    * Returns true if reseting failed, otherwise false. Failure would probably
 239    * mean no filesystems are mounted.
 240    */
 241   bool check_state ();
 242
 243   /**
 244    * Set the supplied pointer as the filesystem of the current working
 245    * directory.
 246    */
 247   void update_fs (MQX_FILE_PTR fs);
 248
 249   /**
 250    * Resolve the filesystem of the supplied path and return it.
 251    *
 252    * This will be the filesystem of the current working directory if the path
 253    * is relative. Sets the fs_name_len to the length of the device name in the
 254    * path. This would be 0 if the path is relative.
 255    */
 256   MQX_FILE_PTR resolve_fs (const char *path, int *fs_name_len);
 257 };
 258
 259 #endif // ACE_MQX
 260 #endif // MQX_FILESYSTEM_HEADER