Skip to contents

Salvage entries on ADF disks

Source: R/undelete.R
salvage_adf_entry.Rd

Functions to attempt to salvage files and directories from virtual disks (ADF).

Usage

adf_dumpster_dive(dev, vol = 0L, ...)

salvage_adf_entry(dev, vol = 0L, sector, ...)

Arguments

dev

The virtual adf device for which information needs to be obtained. It should be of class adf_device which can be created with create_adf_device() or connect_adf().

vol

Volume index number on the device starting at 0. Default is 0. Note that floppy disks can only have 1 volume installed.

...

Ignored

sector

Sector number of the file/directory header that you wish to salvage

Value

In case of adf_dumpster_dive() a data.frame is returned with records that could potentially be salvaged from the disk. In case of salvage_adf_entry(), the disk (adf_device class object) is returned, where (if successful) the record is restored.

Details

When a file or directory is removed from a virtual device (or a physical device for that matter), the record is removed from its parent directory hash table and its bitmap flags are flipped to mark the file blocks as available. This means that the actual record of the file and its contents is still on the disk, until they are overwritten. You can use these functions to salvage such entries.

You can use adf_dumster_dive() to scan for entries that could potentially be salvaged. Than you can use salvage_adf_entry() to attempt to salvage an entry.

Note that these functions won't work when you have flushed the file (see remove_adf_entry()). In that case the actual record of the file and its data have been permanently removed.

Examples

my_device <- demo_adf(write_protected = FALSE)
# The demo disk contains a deleted file that could be salvaged:
salvageable <- adf_dumpster_dive(my_device)

# Let's recover it:
salvage_adf_entry(my_device, sector = salvageable$sect)
#> Bootable DOS Floppy DD
#>   Volume 0 [-i-]: adfExampleOFS (2.2%)

# It is now listed as an entry on the disk:
list_adf_entries(my_device, recursive = TRUE)
#> DIR  DEWR...     Devs
#> FILE DEWR...iguration
#> DIR  DEWR...        S
#> FILE DEWR...-Sequence
#> DIR  DEWR...     this
#> DIR  DEWR...       is
#> DIR  DEWR...        a
#> DIR  DEWR...     deep
#> DIR  DEWR...     path
#> DIR  DEWR...     mods
#> FILE DEWR...mod.intro
#> FILE DEWR...r egg.txt

close(my_device)