#! /bin/sh

# Use df to find a writable directory on a file system different from that
# of the current directory.  If one is found, create a temporary directory
# inside it.

: ${DF=df}
: ${MKDIR=mkdir}

# Try these
: ${CANDIDATE_TMP_DIRS="$TMPDIR /tmp /var/tmp /usr/tmp $HOME"}

other_partition_tmpdir=

# WARNING: using sed like this to extract the mount point will fail
# if the mount point name contains `% '.
dot_mount_point=`$DF --no-sync -P . | sed -n '2s/.*%  *//p'`
for d in $CANDIDATE_TMP_DIRS; do
  d_mount_point=`$DF --no-sync -P $d | sed -n '2s/.*%  *//p'`

  # Same partition?  Skip it.
  test x$d_mount_point = x$dot_mount_point && continue

  # See if we can create a directory in it.
  if $MKDIR "$d/df-$$" > /dev/null 2>&1; then
    other_partition_tmpdir="$d/df-$$"
    break
  fi

done

if test -z $other_partition_tmpdir; then
  cat <<EOF 1>&2
This test requires a writable directory on a different disk partition,
and I couldn\'t find one.  I tried these defaults:
  $CANDIDATE_TMP_DIRS
Set your environment variable CANDIDATE_TMP_DIRS to make this test use
use a different list.
EOF
fi

test "$VERBOSE" = yes && set -x