1 files changed, 70 insertions, 0 deletions
diff --git a/runsc/sandbox/memory.go b/runsc/sandbox/memory.go
new file mode 100644
index 000000000..77b88eb89
--- /dev/null
+++ b/runsc/sandbox/memory.go
@@ -0,0 +1,70 @@
+// Copyright 2021 The gVisor Authors.
+//
+// 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.
+
+package sandbox
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// totalSystemMemory extracts "MemTotal" from "/proc/meminfo".
+func totalSystemMemory() (uint64, error) {
+	f, err := os.Open("/proc/meminfo")
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+	return parseTotalSystemMemory(f)
+}
+
+func parseTotalSystemMemory(r io.Reader) (uint64, error) {
+	for scanner := bufio.NewScanner(r); scanner.Scan(); {
+		line := scanner.Text()
+		totalStr := strings.TrimPrefix(line, "MemTotal:")
+		if len(totalStr) < len(line) {
+			fields := strings.Fields(totalStr)
+			if len(fields) == 0 || len(fields) > 2 {
+				return 0, fmt.Errorf(`malformed "MemTotal": %q`, line)
+			}
+			totalStr = fields[0]
+			unit := ""
+			if len(fields) == 2 {
+				unit = fields[1]
+			}
+			mem, err := strconv.ParseUint(totalStr, 10, 64)
+			if err != nil {
+				return 0, err
+			}
+			switch unit {
+			case "":
+				// do nothing.
+			case "kB":
+				memKb := mem
+				mem = memKb * 1024
+				if mem < memKb {
+					return 0, fmt.Errorf(`"MemTotal" too large: %d`, memKb)
+				}
+			default:
+				return 0, fmt.Errorf("unknown unit %q: %q", unit, line)
+			}
+			return mem, nil
+		}
+	}
+	return 0, fmt.Errorf(`malformed "/proc/meminfo": "MemTotal" not found`)
+}