#! /usr/bin/perl -w

# Read syslog to find when each USB or MMC drive was attached
# If it gets removed and re-attached, only the last one counts.
# If it was attached so long ago that the event is
# no longer visible in syslog, this approach fails.
# If there are more than one such devices, each one
# is shown, in order of time of attachment.

use strict;
use Symbol 'gensym';
use DateTime;

my @moname = ("Jan","Feb","Mar","Apr","May","Jun",
              "Jul","Aug","Sep","Oct","Nov","Dec");
my $tz = DateTime::TimeZone::Local->TimeZone();

main: {
  my %map = ();
  my $sequence = -1;     # keep track of chronological order

# Read /dev/disk/by-id
# Fairly robust way of finding all usb drives.
  foo: {
    my $dh = gensym();
    my $dir= '/dev/disk/by-id';
    my $simple = $dir;
    $simple =~ s'/$'';
    opendir($dh, $dir) || die;
# typical thing we are interested in:
#> /dev/disk/by-id/usb-SanDisk_Ultra_4C531001640417112401-0:0 -> ../../sdb
#> /dev/disk/by-id/mmc-SL64G_0x436a2d8a -> ../../mmcblk0
#
# and in contrast, not interested in:
#> /dev/disk/by-id/usb-USB_2.0_USB_Flash_Drive_2cf51c40bc0343-0:0-part1 -> ../../sdc1

    while(my $entry = readdir $dh) {
      if ($entry =~ m'^(usb|mmc)' && $entry !~ m'-part[0-9]*$') {
        my $fn = "$simple/$entry";
        my $target = readlink $fn;
        if (defined $target) {
           #### print "$fn -> $target\n";
           my $rslt = {};
           my @status = stat $fn;
           my $ctime = $status[10];
           $target =~ s'[./]*'';
           $rslt->{drive} = $target;
           $rslt->{date} = format_date($ctime);
           $rslt->{seq} = $ctime;
           $map{$target} = $rslt;
        } # else not a symlink, should never happen
      }
    }
    closedir $dh;
  }

# sort so that they come out in chronological order:
  for my $drive (sort {${$map{$a}}{seq} <=> ${$map{$b}}{seq}} keys %map) {
    my $rslt = $map{$drive};
    my $special = "/dev/$rslt->{drive}";
    if (-b $special) {
      my $cmd = "blockdev --getsz $special";
      my $pipe = gensym();
      open ($pipe, '-|', $cmd)
        || die "Cannot pipe from '$cmd' : $!\n";
      my $size = <$pipe>;
      if (close $pipe) {
        $size /= 2;            # convert from sectors to kiB
        $size /= 1024;            # convert to MiB
      } else {
        $size = '???';          # probably "permission denied"
                                # when trying to do --getsz
      }

      my $s1 = "DISK=$special";
      my $s2 = "DISKsize__MiB=$size";
      my $s3 = "DISKdate='$rslt->{date}'";
      printf ("%-20s %-20s %s\n", $s1, $s2, $s3);
    }
  }
}

sub format_date{
  my ($epoch) = @_;

  my $dt = DateTime->from_epoch( epoch => $epoch, time_zone => $tz);
  my $year   = $dt->year;
  my $month  = $dt->mon;  # 1-12 - you can also use '$dt->mon'
  my $day    = $dt->day;    # 1-31 - also 'day_of_month', 'mday'
  my $dow    = $dt->day_of_week; # 1-7 (Monday is 1) - also 'dow', 'wday'
  my $hour   = $dt->hour; # 0-23
  my $minute = $dt->minute; # 0-59 - also 'min'
  my $second = $dt->second; # 0-61 (leap seconds!) - also 'sec'
  my $doy    = $dt->day_of_year; # 1-366 (leap years) - also 'doy'
  my $doq    = $dt->day_of_quarter; # 1.. - also 'doq'
  my $qtr    = $dt->quarter; # 1-4
  my $ymd    = $dt->ymd; # 1974-11-30
     $ymd    = $dt->ymd('/'); # 1974/11/30 - also 'date'
  my $hms    = $dt->hms; # 13:30:00
#    $hms    = $dt->hms('|'); # 13|30|00 - also 'time'

  return "$moname[$month-1] $day $hms";
}