iotests: Check for enabled drivers before testing them

It is possible to enable only a subset of the block drivers with the
"--block-drv-rw-whitelist" option of the "configure" script. All other
drivers are marked as unusable (or only included as read-only with the
"--block-drv-ro-whitelist" option). If an iotest is now using such a
disabled block driver, it is failing - which is bad, since at least the
tests in the "auto" group should be able to deal with this situation.
Thus let's introduce a "_require_drivers" function that can be used by
the shell tests to check for the availability of certain drivers first,
and marks the test as "not run" if one of the drivers is missing.

This patch mainly targets the test in the "auto" group which should
never fail in such a case, but also improves some of the other tests
along the way. Note that we also assume that the "qcow2" and "file"
drivers are always available - otherwise it does not make sense to
run "make check-block" at all (which only tests with qcow2 by default).

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-id: 20190823133552.11680-1-thuth@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

tests/qemu-iotests/071

@@ -38,6 +38,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 
 _supported_fmt qcow2
 _supported_proto file
+_require_drivers blkdebug blkverify
 
 do_run_qemu()
 {

tests/qemu-iotests/081

@@ -41,6 +41,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 _supported_fmt raw
 _supported_proto file
 _supported_os Linux
+_require_drivers quorum
 
 do_run_qemu()
 {
@@ -55,9 +56,6 @@ run_qemu()
                           | _filter_qemu_io | _filter_generated_node_ids
 }
 
-test_quorum=$($QEMU_IMG --help|grep quorum)
-[ "$test_quorum" = "" ] && _supported_fmt quorum
-
 quorum="driver=raw,file.driver=quorum,file.vote-threshold=2"
 quorum="$quorum,file.children.0.file.filename=$TEST_DIR/1.raw"
 quorum="$quorum,file.children.1.file.filename=$TEST_DIR/2.raw"

tests/qemu-iotests/099

@@ -42,6 +42,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 _supported_fmt qcow qcow2 qed vdi vhdx vmdk vpc
 _supported_proto file
 _supported_os Linux
+_require_drivers blkdebug blkverify
 _unsupported_imgopts "subformat=monolithicFlat" "subformat=twoGbMaxExtentFlat" \
     "subformat=twoGbMaxExtentSparse"
 

tests/qemu-iotests/120

@@ -40,6 +40,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 _supported_fmt generic
 _supported_proto file
 _unsupported_fmt luks
+_require_drivers raw
 
 _make_test_img 64M
 

tests/qemu-iotests/162

@@ -39,9 +39,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 . ./common.filter
 
 _supported_fmt generic
-
-test_ssh=$($QEMU_IMG --help | grep '^Supported formats:.* ssh\( \|$\)')
-[ "$test_ssh" = "" ] && _notrun "ssh support required"
+_require_drivers ssh
 
 echo
 echo '=== NBD ==='

tests/qemu-iotests/184

@@ -33,6 +33,7 @@ trap "exit \$status" 0 1 2 3 15
 . ./common.filter
 
 _supported_os Linux
+_require_drivers throttle
 
 do_run_qemu()
 {

tests/qemu-iotests/186

@@ -38,6 +38,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 
 _supported_fmt qcow2
 _supported_proto file
+_require_drivers null-co
 
 if [ "$QEMU_DEFAULT_MACHINE" != "pc" ]; then
     _notrun "Requires a PC machine"

tests/qemu-iotests/common.rc

@@ -520,5 +520,19 @@ _require_command()
     [ -x "$c" ] || _notrun "$1 utility required, skipped this test"
 }
 
+# Check that a set of drivers has been whitelisted in the QEMU binary
+#
+_require_drivers()
+{
+    available=$($QEMU -drive format=help | \
+                sed -e '/Supported formats:/!d' -e 's/Supported formats://')
+    for driver
+    do
+        if ! echo "$available" | grep -q " $driver\( \|$\)"; then
+            _notrun "$driver not available"
+        fi
+    done
+}
+
 # make sure this script returns success
 true