# -------------------------------------------------------
@ Function(open)
# -------------------------------------------------------
@ Returns(int,fd)
@ Params(const char *path, int flags, mode_t mode)
@ Requires(sys/types,sys/stat,fcntl)

@ Description
This function opens the file specified by path according to the request specified by flags.
@ Code
- Check that path is a valid path
- Check that flags contains a valid request
- Attempt to open the specified file
- Return file descriptor or -1
@ EndCode

# -------------------------------------------------------
@ Function(close)
# -------------------------------------------------------
@ Returns(int,rc)
@ Params(int fd)
@ Requires(unistd)

@ Description
This function closes the file specified by file descriptor fd.
@ Code
- Check that fd is a valid descriptor
- Attempt to close the specified file
- Return 0 for ok or -1 in case of error
@ EndCode

# -------------------------------------------------------
@ Function(read)
# -------------------------------------------------------
@ Returns(ssize_t,nbytes)
@ Params(int fd, void *buf, size_t n)
@ Requires(unistd)

@ Description
This function reads n bytes from the file specified by descriptor fd and copies them to the memory area addressed by buf.
@ Code
- Check that fd is a valid descriptor
- Check that buf points to a valid memory area
- Check that n is a non-negative number
- Attempt to read the requested number of bytes
- Return number of bytes actually read, 0 in case of end of file, -1 in case of error.
@ EndCode

# -------------------------------------------------------
@ Function(write)
# -------------------------------------------------------
@ Returns(ssize_t,nbytes)
@ Params(int fd, const void *buf, size_t n)
@ Requires(unistd)

@ Description
This function writes n bytes to the file specified by descriptor fd copying them from the memory area addressed by buf.
@ Code
- Check that fd is a valid descriptor
- Check that buf points to a valid memory area
- Check that n is a non-negative number
- Attempt to write the requested number of bytes
- Return number of bytes actually written, -1 in case of error.
@ EndCode