github.com/ethanhsieh/snapd@v0.0.0-20210615102523-3db9b8e4edc5/sandbox/cgroup/process.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2020 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package cgroup
    21  
    22  import (
    23  	"fmt"
    24  	"path/filepath"
    25  	"strings"
    26  )
    27  
    28  func snapNameFromPidUsingTrackingCgroup(pid int) (string, error) {
    29  	// Maybe we have application tracking and can use it?
    30  	path, err := ProcessPathInTrackingCgroup(pid)
    31  	if err != nil {
    32  		return "", err
    33  	}
    34  	if parsedTag := securityTagFromCgroupPath(path); parsedTag != nil {
    35  		return parsedTag.InstanceName(), nil
    36  	}
    37  	return "", fmt.Errorf("cannot find snap security tag")
    38  }
    39  
    40  func snapNameFromPidUsingFreezerCgroup(pid int) (string, error) {
    41  	// This logic only makes sense with cgroup v1.
    42  	if IsUnified() {
    43  		return "", fmt.Errorf("not supported")
    44  	}
    45  
    46  	// Find the path in the freezer cgroup.
    47  	group, err := ProcGroup(pid, MatchV1Controller("freezer"))
    48  	if err != nil {
    49  		return "", fmt.Errorf("cannot determine cgroup path of pid %v: %v", pid, err)
    50  	}
    51  	if !strings.HasPrefix(group, "/snap.") {
    52  		return "", fmt.Errorf("cannot find a snap for pid %v", pid)
    53  	}
    54  
    55  	// Extract the snap name form the path.
    56  	snapName := strings.SplitN(filepath.Base(group), ".", 2)[1]
    57  	if snapName == "" {
    58  		return "", fmt.Errorf("snap name in cgroup path is empty")
    59  	}
    60  	return snapName, nil
    61  }
    62  
    63  func SnapNameFromPid(pid int) (string, error) {
    64  	if snapName, err := snapNameFromPidUsingTrackingCgroup(pid); err == nil {
    65  		return snapName, nil
    66  	}
    67  	return snapNameFromPidUsingFreezerCgroup(pid)
    68  }