Support 'nft -f -' to read from stdin

In libnftables, detect if given filename is '-' and treat it as the
common way of requesting to read from stdin, then open /dev/stdin
instead. (Calling 'nft -f /dev/stdin' worked before as well, but this
makes it official.)

With this in place and bash's support for here strings, review all tests
in tests/shell for needless use of temp files. Note that two categories
of test cases were intentionally left unchanged:

- Tests creating potentially large rulesets to avoid running into shell
  parameter length limits.
- Tests for 'include' directive for obvious reasons.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 3 insertions, 13 deletions

diff --git a/tests/shell/testcases/import/vm_json_import_0 b/tests/shell/testcases/import/vm_json_import_0
index e5ecbcc4..a8d546ff 100755
--- a/tests/shell/testcases/import/vm_json_import_0
+++ b/tests/shell/testcases/import/vm_json_import_0
@@ -1,14 +1,5 @@
 #!/bin/bash
 
-tmpfile=$(mktemp)
-
-if [ ! -w $tmpfile ] ; then
-	echo "Failed to create tmp file" >&2
-	exit 0
-fi
-
-trap "rm -rf $tmpfile" EXIT # cleanup if aborted
-
 RULESET="table ip mangle {
 	set blackhole {
 		type ipv4_addr
@@ -56,8 +47,7 @@ table ip6 x {
 	}
 }"
 
-echo "$RULESET" > $tmpfile
-$NFT -f $tmpfile
-$NFT export vm json > $tmpfile
+$NFT -f - <<< $RULESET
+RULESET_JSON=$($NFT export vm json)
 $NFT flush ruleset
-cat $tmpfile | $NFT import vm json
+$NFT import vm json <<< $RULESET_JSON