TUN-4356: Set AUTOMAXPROCS to the CPU limit when running in a Linux container

vendor/go.uber.org/automaxprocs/internal/cgroups/mountpoint.go

@@ -0,0 +1,166 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// +build linux
+
+package cgroups
+
+import (
+	"bufio"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+const (
+	_mountInfoSep               = " "
+	_mountInfoOptsSep           = ","
+	_mountInfoOptionalFieldsSep = "-"
+)
+
+const (
+	_miFieldIDMountID = iota
+	_miFieldIDParentID
+	_miFieldIDDeviceID
+	_miFieldIDRoot
+	_miFieldIDMountPoint
+	_miFieldIDOptions
+	_miFieldIDOptionalFields
+
+	_miFieldCountFirstHalf
+)
+
+const (
+	_miFieldOffsetFSType = iota
+	_miFieldOffsetMountSource
+	_miFieldOffsetSuperOptions
+
+	_miFieldCountSecondHalf
+)
+
+const _miFieldCountMin = _miFieldCountFirstHalf + _miFieldCountSecondHalf
+
+// MountPoint is the data structure for the mount points in
+// `/proc/$PID/mountinfo`. See also proc(5) for more information.
+type MountPoint struct {
+	MountID        int
+	ParentID       int
+	DeviceID       string
+	Root           string
+	MountPoint     string
+	Options        []string
+	OptionalFields []string
+	FSType         string
+	MountSource    string
+	SuperOptions   []string
+}
+
+// NewMountPointFromLine parses a line read from `/proc/$PID/mountinfo` and
+// returns a new *MountPoint.
+func NewMountPointFromLine(line string) (*MountPoint, error) {
+	fields := strings.Split(line, _mountInfoSep)
+
+	if len(fields) < _miFieldCountMin {
+		return nil, mountPointFormatInvalidError{line}
+	}
+
+	mountID, err := strconv.Atoi(fields[_miFieldIDMountID])
+	if err != nil {
+		return nil, err
+	}
+
+	parentID, err := strconv.Atoi(fields[_miFieldIDParentID])
+	if err != nil {
+		return nil, err
+	}
+
+	for i, field := range fields[_miFieldIDOptionalFields:] {
+		if field == _mountInfoOptionalFieldsSep {
+			fsTypeStart := _miFieldIDOptionalFields + i + 1
+
+			if len(fields) != fsTypeStart+_miFieldCountSecondHalf {
+				return nil, mountPointFormatInvalidError{line}
+			}
+
+			miFieldIDFSType := _miFieldOffsetFSType + fsTypeStart
+			miFieldIDMountSource := _miFieldOffsetMountSource + fsTypeStart
+			miFieldIDSuperOptions := _miFieldOffsetSuperOptions + fsTypeStart
+
+			return &MountPoint{
+				MountID:        mountID,
+				ParentID:       parentID,
+				DeviceID:       fields[_miFieldIDDeviceID],
+				Root:           fields[_miFieldIDRoot],
+				MountPoint:     fields[_miFieldIDMountPoint],
+				Options:        strings.Split(fields[_miFieldIDOptions], _mountInfoOptsSep),
+				OptionalFields: fields[_miFieldIDOptionalFields:(fsTypeStart - 1)],
+				FSType:         fields[miFieldIDFSType],
+				MountSource:    fields[miFieldIDMountSource],
+				SuperOptions:   strings.Split(fields[miFieldIDSuperOptions], _mountInfoOptsSep),
+			}, nil
+		}
+	}
+
+	return nil, mountPointFormatInvalidError{line}
+}
+
+// Translate converts an absolute path inside the *MountPoint's file system to
+// the host file system path in the mount namespace the *MountPoint belongs to.
+func (mp *MountPoint) Translate(absPath string) (string, error) {
+	relPath, err := filepath.Rel(mp.Root, absPath)
+
+	if err != nil {
+		return "", err
+	}
+	if relPath == ".." || strings.HasPrefix(relPath, "../") {
+		return "", pathNotExposedFromMountPointError{
+			mountPoint: mp.MountPoint,
+			root:       mp.Root,
+			path:       absPath,
+		}
+	}
+
+	return filepath.Join(mp.MountPoint, relPath), nil
+}
+
+// parseMountInfo parses procPathMountInfo (usually at `/proc/$PID/mountinfo`)
+// and yields parsed *MountPoint into newMountPoint.
+func parseMountInfo(procPathMountInfo string, newMountPoint func(*MountPoint) error) error {
+	mountInfoFile, err := os.Open(procPathMountInfo)
+	if err != nil {
+		return err
+	}
+	defer mountInfoFile.Close()
+
+	scanner := bufio.NewScanner(mountInfoFile)
+
+	for scanner.Scan() {
+		mountPoint, err := NewMountPointFromLine(scanner.Text())
+		if err != nil {
+			return err
+		}
+		if err := newMountPoint(mountPoint); err != nil {
+			return err
+		}
+	}
+
+	return scanner.Err()
+}