text: // Copyright 2018 The Prometheus 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 procfs
  
  import (
  	"fmt"
  	"os"
  	"strconv"
  	"strings"
  )
  
  // Namespace represents a single namespace of a process.
  type Namespace struct {
  	Type  string // Namespace type.
  	Inode uint32 // Inode number of the namespace. If two processes are in the same namespace their inodes will match.
  }
  
  // Namespaces contains all of the namespaces that the process is contained in.
  type Namespaces map[string]Namespace
  
  // Namespaces reads from /proc/<pid>/ns/* to get the namespaces of which the
  // process is a member.
  func (p Proc) Namespaces() (Namespaces, error) {
  	d, err := os.Open(p.path("ns"))
  	if err != nil {
  		return nil, err
  	}
  	defer d.Close()
  
  	names, err := d.Readdirnames(-1)
  	if err != nil {
  		return nil, fmt.Errorf("failed to read contents of ns dir: %v", err)
  	}
  
  	ns := make(Namespaces, len(names))
  	for _, name := range names {
  		target, err := os.Readlink(p.path("ns", name))
  		if err != nil {
  			return nil, err
  		}
  
  		fields := strings.SplitN(target, ":", 2)
  		if len(fields) != 2 {
  			return nil, fmt.Errorf("failed to parse namespace type and inode from '%v'", target)
  		}
  
  		typ := fields[0]
  		inode, err := strconv.ParseUint(strings.Trim(fields[1], "[]"), 10, 32)
  		if err != nil {
  			return nil, fmt.Errorf("failed to parse inode from '%v': %v", fields[1], err)
  		}
  
  		ns[name] = Namespace{typ, uint32(inode)}
  	}
  
  	return ns, nil
  }
  