1 files changed, 76 insertions, 0 deletions
diff --git a/tests/dd/no-allocate.sh b/tests/dd/no-allocate.sh
new file mode 100755
index 0000000..a9c3b43
--- /dev/null
+++ b/tests/dd/no-allocate.sh
@@ -0,0 +1,76 @@
+#!/bin/sh
+# make sure that dd doesn't allocate memory unnecessarily
+
+# Copyright (C) 2013-2016 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ dd
+
+# Determine basic amount of memory needed.
+echo . > f || framework_failure_
+vm=$(get_min_ulimit_v_ timeout 10 dd if=f of=f2 status=none) \
+  || skip_ "this shell lacks ulimit support"
+rm f f2 || framework_failure_
+
+# count and skip are zero, we don't need to allocate memory
+(ulimit -v $vm && dd  bs=30M count=0) || fail=1
+(ulimit -v $vm && dd ibs=30M count=0) || fail=1
+(ulimit -v $vm && dd obs=30M count=0) || fail=1
+
+check_dd_seek_alloc() {
+  local file="$1"
+  local buf="$2"
+  test "$file" = 'in' && { dd_file=if; dd_op=skip; }
+  test "$file" = 'out' && { dd_file=of; dd_op=seek; }
+  test "$buf" = 'in' && { dd_buf=ibs; }
+  test "$buf" = 'out' && { dd_buf=obs; }
+  test "$buf" = 'both' && { dd_buf=bs; }
+
+  # Provide input to the "tape"
+  timeout 10 dd count=1 if=/dev/zero of=tape&
+
+  # Allocate buffer and read from the "tape"
+  (ulimit -v $vm \
+     && timeout 10 dd $dd_buf=30M $dd_op=1 count=0 $dd_file=tape)
+  local ret=$?
+
+  # Be defensive in case the tape reader is blocked for some reason
+  test $ret = 124 && framework_failure_
+
+  # This should happen without delay,
+  # and is used to ensure we've not multiple writers to the "tape"
+  wait
+
+  # We want the "tape" reader to fail iff allocating
+  # a large buffer corresponding to the file being read
+  case "$file$buf" in
+    inout|outin) test $ret = 0;;
+    *) test $ret != 0;;
+  esac
+}
+
+# Use a fifo for which seek fails, but read does not.
+# For non seekable output we need to allocate a buffer
+# when simulating seeking with a read.
+if mkfifo tape; then
+  for file in 'in' 'out'; do
+    for buf in 'both' 'in' 'out'; do
+      check_dd_seek_alloc "$file" "$buf" || fail=1
+    done
+  done
+fi
+
+Exit $fail