external/gpl2/lvm2/dist/test/mkdtemp

   1 #!/bin/sh
   2 # Create a temporary directory, sort of like mktemp -d does.
   3
   4 # Copyright (C) 2007 Red Hat, Inc. All rights reserved.
   5 #
   6 # This copyrighted material is made available to anyone wishing to use,
   7 # modify, copy, or redistribute it subject to the terms and conditions
   8 # of the GNU General Public License v.2.
   9 #
  10 # You should have received a copy of the GNU General Public License
  11 # along with this program; if not, write to the Free Software Foundation,
  12 # Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  13
  14 # Written by Jim Meyering.
  15
  16 # Usage: mkdtemp /tmp phoey.XXXXXXXXXX
  17
  18 # First, try to use the mktemp program.
  19 # Failing that, we'll roll our own mktemp-like function:
  20 #  - try to get random bytes from /dev/urandom
  21 #  - failing that, generate output from a combination of quickly-varying
  22 #      sources and gzip.  Ignore non-varying gzip header, and extract
  23 #      "random" bits from there.
  24 #  - given those bits, map to file-name bytes using tr, and try to create
  25 #      the desired directory.
  26 #  - make only $MAX_TRIES attempts
  27
  28 ME=$(basename "$0")
  29 die() { echo >&2 "$ME: $@"; exit 1; }
  30
  31 MAX_TRIES=4
  32
  33 rand_bytes()
  34 {
  35   n=$1
  36
  37   chars=abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789
  38
  39   dev_rand=/dev/urandom
  40   if test -r "$dev_rand"; then
  41     # Note: 256-length($chars) == 194; 3 copies of $chars is 186 + 8 = 194.
  42     head -c$n "$dev_rand" | tr -c $chars 01234567$chars$chars$chars
  43     return
  44   fi
  45
  46   cmds='date; date +%N; free; who -a; w; ps auxww; ps ef; netstat -n'
  47   data=$( (eval "$cmds") 2>&1 | gzip )
  48
  49   n_plus_50=$(expr $n + 50)
  50
  51   # Ensure that $data has length at least 50+$n
  52   while :; do
  53     len=$(echo "$data"|wc -c)
  54     test $n_plus_50 -le $len && break;
  55     data=$( (echo "$data"; eval "$cmds") 2>&1 | gzip )
  56   done
  57
  58   echo "$data" \
  59     | dd bs=1 skip=50 count=$n 2>/dev/null \
  60     | tr -c $chars 01234567$chars$chars$chars
  61 }
  62
  63 mkdtemp()
  64 {
  65   case $# in
  66   2);;
  67   *) die "Usage: $ME DIR TEMPLATE";;
  68   esac
  69
  70   destdir=$1
  71   template=$2
  72
  73   case $template in
  74   *XXXX) ;;
  75   *) die "invalid template: $template (must have a suffix of at least 4 X's)";;
  76   esac
  77
  78   fail=0
  79
  80   # First, try to use mktemp.
  81   d=$(env -u TMPDIR mktemp -d -t -p "$destdir" "$template" 2>/dev/null) \
  82     || fail=1
  83
  84   # The resulting name must be in the specified directory.
  85   case $d in "$destdir"*);; *) fail=1;; esac
  86
  87   # It must have created the directory.
  88   test -d "$d" || fail=1
  89
  90   # It must have 0700 permissions.
  91   perms=$(ls -dgo "$d" 2>/dev/null) || fail=1
  92   case $perms in drwx------*) ;; *) fail=1;; esac
  93
  94   test $fail = 0 && {
  95     echo "$d"
  96     return
  97   }
  98
  99   # If we reach this point, we'll have to create a directory manually.
 100
 101   # Get a copy of the template without its suffix of X's.
 102   base_template=$(echo "$template"|sed 's/XX*$//')
 103
 104   # Calculate how many X's we've just removed.
 105   nx=$(expr length "$template" - length "$base_template")
 106
 107   err=
 108   i=1
 109   while :; do
 110     X=$(rand_bytes $nx)
 111     candidate_dir="$destdir/$base_template$X"
 112     err=$(mkdir -m 0700 "$candidate_dir" 2>&1) \
 113       && { echo "$candidate_dir"; return; }
 114     test $MAX_TRIES -le $i && break;
 115     i=$(expr $i + 1)
 116   done
 117   die "$err"
 118 }
 119
 120 mkdtemp "$@"