tests/dd/sparse.sh

   1 #!/bin/sh
   2
   3 # Copyright (C) 2012-2023 Free Software Foundation, Inc.
   4
   5 # This program is free software: you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation, either version 3 of the License, or
   8 # (at your option) any later version.
   9
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 # GNU General Public License for more details.
  14
  15 # You should have received a copy of the GNU General Public License
  16 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
  17
  18 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
  19 print_ver_ dd
  20 is_local_dir_ . || very_expensive_
  21 require_sparse_support_
  22
  23 # Ensure basic sparse generation works
  24 truncate -s1M sparse
  25 dd bs=32K if=sparse of=sparse.dd conv=sparse
  26 test $(stat -c %s sparse) = $(stat -c %s sparse.dd) || fail=1
  27
  28 # Demonstrate that conv=sparse with oflag=append,
  29 # will do ineffective seeks in the output
  30 printf 'a\000\000b' > file.in
  31 printf 'ab' > exp
  32 dd if=file.in bs=1 conv=sparse oflag=append > out
  33 compare exp out || fail=1
  34
  35 # Demonstrate conv=sparse with conv=notrunc,
  36 # where data in file.out is not overwritten with NULs
  37 printf '____' > out
  38 printf 'a__b' > exp
  39 dd if=file.in bs=1 conv=sparse,notrunc of=out
  40 compare exp out || fail=1
  41
  42 # Ensure we fall back to write if seek fails
  43 dd if=file.in bs=1 conv=sparse | cat > file.out
  44 cmp file.in file.out || fail=1
  45
  46 # Setup for block size tests: create a 3MiB file with a 1MiB
  47 # stretch of NUL bytes in the middle.
  48 rm -f file.in
  49 dd if=/dev/urandom of=file.in bs=1M count=3 iflag=fullblock || fail=1
  50 dd if=/dev/zero    of=file.in bs=1M count=1 seek=1 conv=notrunc || fail=1
  51
  52 kb_alloc() { du -k "$1"|cut -f1; }
  53
  54 # sync out data for async allocators like NFS/BTRFS
  55 # sync file.in || fail=1
  56
  57 # If our just-created input file appears to be too small,
  58 # skip the remaining tests.  On at least Solaris 10 with NFS,
  59 # file.in is reported to occupy <= 1KiB for about 50 seconds
  60 # after its creation.
  61 if test $(kb_alloc file.in) -gt 3000; then
  62
  63   # Ensure NUL blocks smaller than the *output* block size are not made sparse.
  64   # Here, with a 2MiB block size, dd's conv=sparse must *not* introduce a hole.
  65   dd if=file.in of=file.out ibs=1M obs=2M conv=sparse || fail=1
  66
  67   # Intermittently BTRFS returns 0 allocation for file.out unless synced
  68   sync file.out || framework_failure_
  69   test 2500 -lt $(kb_alloc file.out) || fail=1
  70
  71   # Note we recreate a sparse file first to avoid
  72   # speculative preallocation seen in XFS, where a write() that
  73   # extends a file can preallocate some extra space that
  74   # a subsequent seek will not convert to a hole.
  75   rm -f file.out
  76   truncate --size=3M file.out
  77
  78   # Ensure that this 1MiB *output* block of NULs *is* converted to a hole.
  79   dd if=file.in of=file.out ibs=2M obs=1M conv=sparse,notrunc
  80   if test $(kb_alloc file.out) -ge 2500; then
  81     # Double check the failure by creating a sparse file in
  82     # the traditional manner for comparison, as we're not guaranteed
  83     # that seek=1M will create a hole.  apfs on darwin 19.2.0 for example
  84     # was seen to not to create holes < 16MiB.
  85     dd if=file.in of=manual.out bs=1M count=1 || fail=1
  86     dd if=file.in of=manual.out bs=1M count=1 seek=2 conv=notrunc || fail=1
  87
  88     test $(kb_alloc file.out) -eq $(kb_alloc manual.out) || fail=1
  89   fi
  90
  91 fi
  92
  93 Exit $fail