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// Copyright 2018 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 platform
import (
"fmt"
"io/ioutil"
"strconv"
"strings"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
)
// systemMMapMinAddrSource is the source file.
const systemMMapMinAddrSource = "/proc/sys/vm/mmap_min_addr"
// systemMMapMinAddr is the system's minimum map address.
var systemMMapMinAddr uint64
// SystemMMapMinAddr returns the minimum system address.
func SystemMMapMinAddr() usermem.Addr {
return usermem.Addr(systemMMapMinAddr)
}
// MMapMinAddr is a size zero struct that implements MinUserAddress based on
// the system minimum address. It is suitable for embedding in platforms that
// rely on the system mmap, and thus require the system minimum.
type MMapMinAddr struct {
}
// MinUserAddress implements platform.MinUserAddresss.
func (*MMapMinAddr) MinUserAddress() usermem.Addr {
return SystemMMapMinAddr()
}
func init() {
// Open the source file.
b, err := ioutil.ReadFile(systemMMapMinAddrSource)
if err != nil {
panic(fmt.Sprintf("couldn't open %s: %v", systemMMapMinAddrSource, err))
}
// Parse the result.
systemMMapMinAddr, err = strconv.ParseUint(strings.TrimSpace(string(b)), 10, 64)
if err != nil {
panic(fmt.Sprintf("couldn't parse %s from %s: %v", string(b), systemMMapMinAddrSource, err))
}
}
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