[PATCH v4] commit.rc: Add helper for math operation using bc

[Lukas Czerner]

Sometimes using bash $(()) math might not be enough due to some
limitation (big numbers), so add helper using 'bc' program. For
now the results are only in perfect numbers (as in bash) since this is
all I need for now.

This commit also adds _require_math() helper which should be called by
every test which uses _math() since it requires "bc" to be installed on
the system.

Signed-off-by: Lukas Czerner <lczerner at redhat.com>
---
v3: Nothing has changed
v4: Add _require_math helper

 common.rc |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/common.rc b/common.rc
index 35f782b..e948169 100644
--- a/common.rc
+++ b/common.rc
@@ -20,6 +20,26 @@
 #  Mountain View, CA 94043, USA, or: http://www.sgi.com
 #-----------------------------------------------------------------------
 
+BC=$(which bc 2> /dev/null) || BC=
+
+_require_math()
+{
+	if [ -z "$BC" ]; then
+		_notrun "this test requires 'bc' tool for doing math operations"
+	fi
+}
+
+_math()
+{
+	[ $# -le 0 ] && return
+	if [ "$BC" ]; then
+		result=$(LANG=C echo "scale=0; $@" | "$BC" -q 2> /dev/null)
+	else
+		_notrun "this test requires 'bc' tool for doing math operations"
+	fi
+	echo "$result"
+}
+
 dd()
 {
    if [ "$HOSTOS" == "Linux" ]
-- 
1.7.4.4