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// 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`)
}
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