fileSystem.h

/*
 * fileSystem.h
 *
 *  Modified on: 24/03/2023
 *      Author: Robert Sheehan
 */

#define EBADVOLNAME	101 // bad volume name
#define EBADDEV		102 // something bad reported by the device
#define ENOROOM		103 // no more room on the device
#define ENOSUCHFILE	104 // the file does not exist
#define EOTHER		105 // any other file system error

/*
 * This should be declared in system.c.
 * When any of the functions cause an error to occur
 * this should be filled in with a suitable value from
 * the #defines above.
 */
extern int file_errno;

/*
 * Formats the device for use by this file system.
 * The volume name must be < 64 bytes long.
 * All information previously on the device is lost.
 * Also creates the root directory "/".
 * Returns 0 if no problem or -1 if the call failed.
 */
int format(char *volumeName);

/*
 * Places the volume's name in the result.
 * Returns 0 if no problem or -1 if the call failed.
 */
int volumeName(char *result);

/*
 * Makes a file with a fully qualified pathname starting with "/".
 * It automatically creates all intervening directories.
 * Pathnames can consist of any printable ASCII characters (0x20 - 0x7e)
 * including the space character.
 * The occurrence of "/" is interpreted as starting a new directory
 * (or the file name).
 * Each section of the pathname must be between 1 and 7 bytes long (not
 * counting the "/"s).
 * The pathname cannot finish with a "/" so the only way to create a directory
 * is to create a file in that directory. This is not true for the root
 * directory "/" as this needs to be created when format is called.
 * The total length of a pathname is limited only by the size of the device.
 * Returns 0 if no problem or -1 if the call failed.
 */
int create(char *pathName);

/*
 * Returns a list of all files in the named directory.
 * The "result" string is filled in with the output.
 * The result looks like this

/dir1:
file1	42
file2	0

 * The fully qualified pathname of the directory followed by a colon and
 * then each file name followed by a tab "\t" and then its file size.
 * Each file on a separate line.
 * The directoryName is a full pathname.
 */
void list(char *result, char *directoryName);

/*
 * Writes data onto the end of the file.
 * Copies "length" bytes from data and appends them to the file.
 * The filename is a full pathname.
 * The file must have been created before this call is made.
 * Returns 0 if no problem or -1 if the call failed.
 */
int a2write(char *fileName, void *data, int length);

/*
 * Reads data from the start of the file.
 * Maintains a file position so that subsequent reads continue
 * from where the last read finished.
 * The filename is a full pathname.
 * The file must have been created before this call is made.
 * Returns 0 if no problem or -1 if the call failed.
 */
int a2read(char *fileName, void *data, int length);

/*
 * Repositions the file pointer for the file at the specified location.
 * All positive integers are byte offsets from the start of the file.
 * 0 is the beginning of the file.
 * If the location is after the end of the file, move the location
 * pointer to the end of the file.
 * The filename is a full pathname.
 * The file must have been created before this call is made.
 * Returns 0 if no problem or -1 if the call failed.
 */
int seek(char *fileName, int location);