Source: proc.go in package github.com/prometheus/procfs

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 (
	"bytes"
	"fmt"
	"io/ioutil"
	"os"
	"strconv"
	"strings"

	"github.com/prometheus/procfs/internal/fs"
	"github.com/prometheus/procfs/internal/util"
)

Proc provides information about a running process.

The process ID.

	PID int

	fs fs.FS
}

Procs represents a list of Proc structs.

type Procs []Proc

func (p Procs) Len() int           { return len(p) }
func (p Procs) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
func (p Procs) Less(i, j int) bool { return p[i].PID < p[j].PID }

Self returns a process for the current process read via /proc/self.

func Self() (Proc, error) {
	fs, err := NewFS(DefaultMountPoint)
	if err != nil {
		return Proc{}, err
	}
	return fs.Self()
}

NewProc returns a process for the given pid under /proc.

func NewProc(pid int) (Proc, error) {
	fs, err := NewFS(DefaultMountPoint)
	if err != nil {
		return Proc{}, err
	}
	return fs.Proc(pid)
}

AllProcs returns a list of all currently available processes under /proc.

func AllProcs() (Procs, error) {
	fs, err := NewFS(DefaultMountPoint)
	if err != nil {
		return Procs{}, err
	}
	return fs.AllProcs()
}

Self returns a process for the current process.

func (fs FS) Self() (Proc, error) {
	p, err := os.Readlink(fs.proc.Path("self"))
	if err != nil {
		return Proc{}, err
	}
	pid, err := strconv.Atoi(strings.Replace(p, string(fs.proc), "", -1))
	if err != nil {
		return Proc{}, err
	}
	return fs.Proc(pid)
}

NewProc returns a process for the given pid. Deprecated: use fs.Proc() instead

func (fs FS) NewProc(pid int) (Proc, error) {
	return fs.Proc(pid)
}

Proc returns a process for the given pid.

func (fs FS) Proc(pid int) (Proc, error) {
	if _, err := os.Stat(fs.proc.Path(strconv.Itoa(pid))); err != nil {
		return Proc{}, err
	}
	return Proc{PID: pid, fs: fs.proc}, nil
}

AllProcs returns a list of all currently available processes.

func (fs FS) AllProcs() (Procs, error) {
	d, err := os.Open(fs.proc.Path())
	if err != nil {
		return Procs{}, err
	}
	defer d.Close()

	names, err := d.Readdirnames(-1)
	if err != nil {
		return Procs{}, fmt.Errorf("could not read %s: %s", d.Name(), err)
	}

	p := Procs{}
	for _, n := range names {
		pid, err := strconv.ParseInt(n, 10, 64)
		if err != nil {
			continue
		}
		p = append(p, Proc{PID: int(pid), fs: fs.proc})
	}

	return p, nil
}

CmdLine returns the command line of a process.

func (p Proc) CmdLine() ([]string, error) {
	data, err := util.ReadFileNoStat(p.path("cmdline"))
	if err != nil {
		return nil, err
	}

	if len(data) < 1 {
		return []string{}, nil
	}

	return strings.Split(string(bytes.TrimRight(data, string("\x00"))), string(byte(0))), nil
}

Comm returns the command name of a process.

func (p Proc) Comm() (string, error) {
	data, err := util.ReadFileNoStat(p.path("comm"))
	if err != nil {
		return "", err
	}

	return strings.TrimSpace(string(data)), nil
}

Executable returns the absolute path of the executable command of a process.

func (p Proc) Executable() (string, error) {
	exe, err := os.Readlink(p.path("exe"))
	if os.IsNotExist(err) {
		return "", nil
	}

	return exe, err
}

Cwd returns the absolute path to the current working directory of the process.

func (p Proc) Cwd() (string, error) {
	wd, err := os.Readlink(p.path("cwd"))
	if os.IsNotExist(err) {
		return "", nil
	}

	return wd, err
}

RootDir returns the absolute path to the process's root directory (as set by chroot)

func (p Proc) RootDir() (string, error) {
	rdir, err := os.Readlink(p.path("root"))
	if os.IsNotExist(err) {
		return "", nil
	}

	return rdir, err
}

FileDescriptors returns the currently open file descriptors of a process.

func (p Proc) FileDescriptors() ([]uintptr, error) {
	names, err := p.fileDescriptors()
	if err != nil {
		return nil, err
	}

	fds := make([]uintptr, len(names))
	for i, n := range names {
		fd, err := strconv.ParseInt(n, 10, 32)
		if err != nil {
			return nil, fmt.Errorf("could not parse fd %s: %s", n, err)
		}
		fds[i] = uintptr(fd)
	}

	return fds, nil
}

FileDescriptorTargets returns the targets of all file descriptors of a process. If a file descriptor is not a symlink to a file (like a socket), that value will be the empty string.

func (p Proc) FileDescriptorTargets() ([]string, error) {
	names, err := p.fileDescriptors()
	if err != nil {
		return nil, err
	}

	targets := make([]string, len(names))

	for i, name := range names {
		target, err := os.Readlink(p.path("fd", name))
		if err == nil {
			targets[i] = target
		}
	}

	return targets, nil
}

FileDescriptorsLen returns the number of currently open file descriptors of a process.

func (p Proc) FileDescriptorsLen() (int, error) {
	fds, err := p.fileDescriptors()
	if err != nil {
		return 0, err
	}

	return len(fds), nil
}

MountStats retrieves statistics and configuration for mount points in a process's namespace.

func (p Proc) MountStats() ([]*Mount, error) {
	f, err := os.Open(p.path("mountstats"))
	if err != nil {
		return nil, err
	}
	defer f.Close()

	return parseMountStats(f)
}

MountInfo retrieves mount information for mount points in a process's namespace. It supplies information missing in `/proc/self/mounts` and fixes various other problems with that file too.

func (p Proc) MountInfo() ([]*MountInfo, error) {
	data, err := util.ReadFileNoStat(p.path("mountinfo"))
	if err != nil {
		return nil, err
	}
	return parseMountInfo(data)
}

func (p Proc) fileDescriptors() ([]string, error) {
	d, err := os.Open(p.path("fd"))
	if err != nil {
		return nil, err
	}
	defer d.Close()

	names, err := d.Readdirnames(-1)
	if err != nil {
		return nil, fmt.Errorf("could not read %s: %s", d.Name(), err)
	}

	return names, nil
}

func (p Proc) path(pa ...string) string {
	return p.fs.Path(append([]string{strconv.Itoa(p.PID)}, pa...)...)
}

FileDescriptorsInfo retrieves information about all file descriptors of the process.

func (p Proc) FileDescriptorsInfo() (ProcFDInfos, error) {
	names, err := p.fileDescriptors()
	if err != nil {
		return nil, err
	}

	var fdinfos ProcFDInfos

	for _, n := range names {
		fdinfo, err := p.FDInfo(n)
		if err != nil {
			continue
		}
		fdinfos = append(fdinfos, *fdinfo)
	}

	return fdinfos, nil
}

Schedstat returns task scheduling information for the process.

func (p Proc) Schedstat() (ProcSchedstat, error) {
	contents, err := ioutil.ReadFile(p.path("schedstat"))
	if err != nil {
		return ProcSchedstat{}, err
	}
	return parseProcSchedstat(string(contents))