tests/dd/reblock.sh

   1 #!/bin/sh
   2 # test dd reblocking vs. bs=
   3
   4 # Copyright (C) 2008-2017 Free Software Foundation, Inc.
   5
   6 # This program is free software: you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation, either version 3 of the License, or
   9 # (at your option) any later version.
  10
  11 # This program is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 # GNU General Public License for more details.
  15
  16 # You should have received a copy of the GNU General Public License
  17 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18
  19 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
  20 print_ver_ dd
  21
  22 # 2 short reads -> 1 full write + 1 partial write
  23 cat <<\EOF > exp-reblock || framework_failure_
  24 0+2 records in
  25 1+1 records out
  26 4 bytes copied
  27 EOF
  28
  29 # 2 short reads -> 2 partial writes
  30 cat <<\EOF > exp-no-reblock || framework_failure_
  31 0+2 records in
  32 0+2 records out
  33 4 bytes copied
  34 EOF
  35
  36
  37 # Use a fifo rather than a pipe in the tests below
  38 # so that the producer (printf subshell) will wait
  39 # until the consumer (dd) opens the fifo therefore
  40 # increasing the chance that dd will read the data
  41 # from each printf separately.
  42 mkfifo_or_skip_ dd.fifo
  43
  44 dd_reblock_1()
  45 {
  46   local delay="$1"
  47
  48   # ensure that dd reblocks when bs= is not specified
  49   dd ibs=3 obs=3 if=dd.fifo > out 2> err&
  50   (printf 'ab'; sleep $delay; printf 'cd') > dd.fifo
  51   wait #for dd to complete
  52   sed 's/,.*//' err > k && mv k err
  53   compare exp-reblock err
  54 }
  55
  56 retry_delay_ dd_reblock_1 .1 6 || fail=1
  57
  58 dd_reblock_2()
  59 {
  60   local delay="$1"
  61
  62   # Demonstrate that bs=N supersedes even following ibs= and obs= settings.
  63   dd bs=3 ibs=1 obs=1 if=dd.fifo > out 2> err&
  64   (printf 'ab'; sleep $delay; printf 'cd') > dd.fifo
  65   wait #for dd to complete
  66   sed 's/,.*//' err > k && mv k err
  67   compare exp-no-reblock err
  68 }
  69
  70 retry_delay_ dd_reblock_2 .1 6 || fail=1
  71
  72 Exit $fail