cpuset: rewrite the parse function from scratch

no intended changes in behaviour.

Signed-off-by: Francesco Romani <[email protected]>

Author: ffromani

Diff for: cpuset.go

@@ -0,0 +1,22 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2020 Red Hat, Inc.
+ */
+
+package cpuset
+
+// Empty returns a empty cpuset, a slice of ints
+func Empty() []int {
+	return []int{}
+}

Diff for: cpuset_empty.go

@@ -0,0 +1,61 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2020 Red Hat, Inc.
+ */
+
+package cpuset
+
+import (
+	"sort"
+	"strconv"
+	"strings"
+)
+
+// Parse takes a string representing a cpuset definition, and returns as sorted slice of ints
+func Parse(s string) ([]int, error) {
+	cpus := Empty()
+	if len(s) == 0 {
+		return cpus, nil
+	}
+
+	for _, item := range strings.Split(s, ",") {
+		item = strings.TrimSpace(item)
+		if !strings.Contains(item, "-") {
+			// single cpu: "2"
+			cpuid, err := strconv.Atoi(item)
+			if err != nil {
+				return cpus, err
+			}
+			cpus = append(cpus, cpuid)
+			continue
+		}
+
+		// range of cpus: "0-3"
+		cpuRange := strings.SplitN(item, "-", 2)
+		cpuBegin, err := strconv.Atoi(cpuRange[0])
+		if err != nil {
+			return cpus, err
+		}
+		cpuEnd, err := strconv.Atoi(cpuRange[1])
+		if err != nil {
+			return cpus, err
+		}
+		for cpuid := cpuBegin; cpuid <= cpuEnd; cpuid++ {
+			cpus = append(cpus, cpuid)
+		}
+	}
+
+	sort.Ints(cpus)
+	return cpus, nil
+}