github.com/Prakhar-Agarwal-byte/moby@v0.0.0-20231027092010-a14e3e8ab87e/pkg/process/process_unix.go (about)

     1  //go:build !windows
     2  
     3  package process
     4  
     5  import (
     6  	"bytes"
     7  	"fmt"
     8  	"os"
     9  	"path/filepath"
    10  	"runtime"
    11  	"strconv"
    12  
    13  	"golang.org/x/sys/unix"
    14  )
    15  
    16  // Alive returns true if process with a given pid is running. It only considers
    17  // positive PIDs; 0 (all processes in the current process group), -1 (all processes
    18  // with a PID larger than 1), and negative (-n, all processes in process group
    19  // "n") values for pid are never considered to be alive.
    20  func Alive(pid int) bool {
    21  	if pid < 1 {
    22  		return false
    23  	}
    24  	switch runtime.GOOS {
    25  	case "darwin":
    26  		// OS X does not have a proc filesystem. Use kill -0 pid to judge if the
    27  		// process exists. From KILL(2): https://www.freebsd.org/cgi/man.cgi?query=kill&sektion=2&manpath=OpenDarwin+7.2.1
    28  		//
    29  		// Sig may be one of the signals specified in sigaction(2) or it may
    30  		// be 0, in which case error checking is performed but no signal is
    31  		// actually sent. This can be used to check the validity of pid.
    32  		err := unix.Kill(pid, 0)
    33  
    34  		// Either the PID was found (no error) or we get an EPERM, which means
    35  		// the PID exists, but we don't have permissions to signal it.
    36  		return err == nil || err == unix.EPERM
    37  	default:
    38  		_, err := os.Stat(filepath.Join("/proc", strconv.Itoa(pid)))
    39  		return err == nil
    40  	}
    41  }
    42  
    43  // Kill force-stops a process. It only considers positive PIDs; 0 (all processes
    44  // in the current process group), -1 (all processes with a PID larger than 1),
    45  // and negative (-n, all processes in process group "n") values for pid are
    46  // ignored. Refer to [KILL(2)] for details.
    47  //
    48  // [KILL(2)]: https://man7.org/linux/man-pages/man2/kill.2.html
    49  func Kill(pid int) error {
    50  	if pid < 1 {
    51  		return fmt.Errorf("invalid PID (%d): only positive PIDs are allowed", pid)
    52  	}
    53  	err := unix.Kill(pid, unix.SIGKILL)
    54  	if err != nil && err != unix.ESRCH {
    55  		return err
    56  	}
    57  	return nil
    58  }
    59  
    60  // Zombie return true if process has a state with "Z". It only considers positive
    61  // PIDs; 0 (all processes in the current process group), -1 (all processes with
    62  // a PID larger than 1), and negative (-n, all processes in process group "n")
    63  // values for pid are ignored. Refer to [PROC(5)] for details.
    64  //
    65  // [PROC(5)]: https://man7.org/linux/man-pages/man5/proc.5.html
    66  func Zombie(pid int) (bool, error) {
    67  	if pid < 1 {
    68  		return false, nil
    69  	}
    70  	data, err := os.ReadFile(fmt.Sprintf("/proc/%d/stat", pid))
    71  	if err != nil {
    72  		if os.IsNotExist(err) {
    73  			return false, nil
    74  		}
    75  		return false, err
    76  	}
    77  	if cols := bytes.SplitN(data, []byte(" "), 4); len(cols) >= 3 && string(cols[2]) == "Z" {
    78  		return true, nil
    79  	}
    80  	return false, nil
    81  }