1 files changed, 85 insertions, 0 deletions

diff --git a/plugins-scripts/utils.sh.in b/plugins-scripts/utils.sh.in
index b30b908..5fae6ad 100644
--- a/plugins-scripts/utils.sh.in
+++ b/plugins-scripts/utils.sh.in
@@ -21,3 +21,88 @@ support() {
         $ECHO "@SUPPORT@" | sed -e 's/\n/ /g'
 }
 
+#
+# check_range takes a value and a range string, returning successfully if an
+# alert should be raised based on the range.
+#
+check_range() {
+        local v range yes no err decimal start end cmp match
+        v="$1"
+        range="$2"
+
+        # whether to raise an alert or not
+        yes=0
+        no=1
+        err=2
+
+        # regex to match a decimal number
+        decimal="-?([0-9]+\.?[0-9]*|[0-9]*\.[0-9]+)"
+
+        # compare numbers (including decimals), returning true/false
+        cmp() { awk "BEGIN{ if ($1) exit(0); exit(1)}"; }
+
+        # returns successfully if the string in the first argument matches the
+        # regex in the second
+        match() { echo "$1" | grep -E -q -- "$2"; }
+
+        # make sure value is valid
+        if ! match "$v" "^$decimal$"; then
+                echo "${0##*/}: check_range: invalid value" >&2
+                unset -f cmp match
+                return "$err"
+        fi
+
+        # make sure range is valid
+        if ! match "$range" "^@?(~|$decimal)(:($decimal)?)?$"; then
+                echo "${0##*/}: check_range: invalid range" >&2
+                unset -f cmp match
+                return "$err"
+        fi
+
+        # check for leading @ char, which negates the range
+        if match $range '^@'; then
+                range=${range#@}
+                yes=1
+                no=0
+        fi
+
+        # parse the range string
+        if ! match "$range" ':'; then
+                start=0
+                end="$range"
+        else
+                start="${range%%:*}"
+                end="${range#*:}"
+        fi
+
+        # do the comparison, taking positive ("") and negative infinity ("~")
+        # into account
+        if [ "$start" != "~" ] && [ "$end" != "" ]; then
+                if cmp "$start <= $v" && cmp "$v <= $end"; then
+                        unset -f cmp match
+                        return "$no"
+                else
+                        unset -f cmp match
+                        return "$yes"
+                fi
+        elif [ "$start" != "~" ] && [ "$end" = "" ]; then
+                if cmp "$start <= $v"; then
+                        unset -f cmp match
+                        return "$no"
+                else
+                        unset -f cmp match
+                        return "$yes"
+                fi
+        elif [ "$start" = "~" ] && [ "$end" != "" ]; then
+                if cmp "$v <= $end"; then
+                        unset -f cmp match
+                        return "$no"
+                else
+                        unset -f cmp match
+                        return "$yes"
+                fi
+        else
+                unset -f cmp match
+                return "$no"
+        fi
+}