The upper level Amanda code (including some of the other tape_xxx routines) calls the following routines which implement a virtual tape table:
int tape_access(filename, mode) Acts like access(2) on possibly virtual devices
int tape_open(filename, mode) Acts like open(2) on possibly virtual devices
int tape_stat(filename, buf) Acts like stat(2) on possibly virtual devices
int tapefd_close(tapefd) Acts like close(2) on possibly virtual devices
int tapefd_fsf(tapefd, count) Forward skips the (possibly virtual) device.
int tapefd_read(tapefd, buffer, count) Reads a block from the (possibly virtual) device.
int tapefd_rewind(tapefd) Reads a block from a (possibly virtual) device.
void tapefd_resetofs(tapefd) Uses lseek() tricks to reset the write/read offset counter on a virtual tape device.
int tapefd_unload(tapefd) Unloads the media from a (possibly virtual) device.
int tapefd_status(tapefd) pr- ints status of the (possibly virtual) device to standard output.
int tapefd_weof(tapefd, count) writes a filemark/moves to the next file on a device for writing.
int tapefd_write(tapefd, buffer, count) writes a block of data to a (possibly virtual) device.
For a tape type xxx, the following routines must be provided, and entered - into the table "vtable" in tape-src/tapeio.c:
int xxx_tape_access(filename, mode)
int xxx_tape_open(filename, mode)
int xxx_tape_stat(filename, buf)
int xxx_tapefd_close(xxx_tapefd)
int xxx_tapefd_fsf(xxx_tapefd, count)
int xxx_tapefd_read(xxx_tapefd, buffer, count)
int xxx_tapefd_rewind(xxx_tapefd)
void xxx_tapefd_resetofs(xxx_tapefd)
int xxx_tapefd_unload(xxx_tapefd)
int xxx_tapefd_status(xxx_tapefd)
int xxx_tapefd_weof(xxx_tapefd, count)
int xxx_tapefd_write(xxx_tapefd, buffer, count)
Along with a prefix string which will identify the type. The initial vtape layer has two types "plain" and "rait" (Redundant Array of Inexpensive Tapes) but we hope to add a "rmt" (remote tape client), and possibly "dvd" types soon.