github.com/hugh712/snapd@v0.0.0-20200910133618-1a99902bd583/cmd/snap-bootstrap/cmd_recovery_chooser_trigger.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 main
    21  
    22  import (
    23  	"fmt"
    24  	"os"
    25  	"time"
    26  
    27  	"github.com/jessevdk/go-flags"
    28  
    29  	"github.com/snapcore/snapd/cmd/snap-bootstrap/triggerwatch"
    30  	"github.com/snapcore/snapd/logger"
    31  )
    32  
    33  func init() {
    34  	const (
    35  		short = "Detect Ubuntu Core recovery chooser trigger"
    36  		long  = ""
    37  	)
    38  
    39  	addCommandBuilder(func(parser *flags.Parser) {
    40  		if _, err := parser.AddCommand("recovery-chooser-trigger", short, long, &cmdRecoveryChooserTrigger{}); err != nil {
    41  			panic(err)
    42  		}
    43  	})
    44  }
    45  
    46  var (
    47  	triggerwatchWait = triggerwatch.Wait
    48  
    49  	// default trigger wait timeout
    50  	defaultTimeout = 10 * time.Second
    51  
    52  	// default marker file location
    53  	defaultMarkerFile = "/run/snapd-recovery-chooser-triggered"
    54  )
    55  
    56  type cmdRecoveryChooserTrigger struct {
    57  	MarkerFile  string `long:"marker-file" value-name:"filename" description:"trigger marker file location"`
    58  	WaitTimeout string `long:"wait-timeout" value-name:"duration" description:"trigger wait timeout"`
    59  }
    60  
    61  func (c *cmdRecoveryChooserTrigger) Execute(args []string) error {
    62  	// TODO:UC20: check in the gadget if there is a hook or some binary we
    63  	// should run for trigger detection. This will require some design work
    64  	// and also thinking if/how such a hook can be confined.
    65  
    66  	timeout := defaultTimeout
    67  	markerFile := defaultMarkerFile
    68  
    69  	if c.WaitTimeout != "" {
    70  		userTimeout, err := time.ParseDuration(c.WaitTimeout)
    71  		if err != nil {
    72  			logger.Noticef("cannot parse duration %q, using default", c.WaitTimeout)
    73  		} else {
    74  			timeout = userTimeout
    75  		}
    76  	}
    77  	if c.MarkerFile != "" {
    78  		markerFile = c.MarkerFile
    79  	}
    80  	logger.Noticef("trigger wait timeout %v", timeout)
    81  	logger.Noticef("marker file %v", markerFile)
    82  
    83  	_, err := os.Stat(markerFile)
    84  	if err == nil {
    85  		logger.Noticef("marker already present")
    86  		return nil
    87  	}
    88  
    89  	err = triggerwatchWait(timeout)
    90  	if err != nil {
    91  		switch err {
    92  		case triggerwatch.ErrTriggerNotDetected:
    93  			logger.Noticef("trigger not detected")
    94  			return nil
    95  		case triggerwatch.ErrNoMatchingInputDevices:
    96  			logger.Noticef("no matching input devices")
    97  			return nil
    98  		default:
    99  			return err
   100  		}
   101  	}
   102  
   103  	// got the trigger, try to create the marker file
   104  	m, err := os.Create(markerFile)
   105  	if err != nil {
   106  		return fmt.Errorf("cannot create the marker file: %q", err)
   107  	}
   108  	m.Close()
   109  
   110  	return nil
   111  }