github.com/hugh712/snapd@v0.0.0-20200910133618-1a99902bd583/overlord/devicestate/devicectx.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2018-2019 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 devicestate
    21  
    22  import (
    23  	"github.com/snapcore/snapd/asserts"
    24  	"github.com/snapcore/snapd/overlord/snapstate"
    25  	"github.com/snapcore/snapd/overlord/state"
    26  )
    27  
    28  // DeviceCtx picks a device context from state, optional task or an
    29  // optionally pre-provided one. Returns ErrNoState if a model
    30  // assertion is not yet known.
    31  // In particular if task belongs to a remodeling change this will find
    32  // the appropriate remodel context.
    33  func DeviceCtx(st *state.State, task *state.Task, providedDeviceCtx snapstate.DeviceContext) (snapstate.DeviceContext, error) {
    34  	if providedDeviceCtx != nil {
    35  		return providedDeviceCtx, nil
    36  	}
    37  	// use the remodelContext if the task is part of a remodel change
    38  	remodCtx, err := remodelCtxFromTask(task)
    39  	if err == nil {
    40  		return remodCtx, nil
    41  	}
    42  	if err != nil && err != state.ErrNoState {
    43  		return nil, err
    44  	}
    45  	modelAs, err := findModel(st)
    46  	if err != nil {
    47  		return nil, err
    48  	}
    49  
    50  	devMgr := deviceMgr(st)
    51  	return &modelDeviceContext{groundDeviceContext{
    52  		model:      modelAs,
    53  		systemMode: devMgr.SystemMode(),
    54  	}}, nil
    55  }
    56  
    57  type groundDeviceContext struct {
    58  	model      *asserts.Model
    59  	systemMode string
    60  }
    61  
    62  func (dc *groundDeviceContext) Model() *asserts.Model {
    63  	return dc.model
    64  }
    65  
    66  func (dc *groundDeviceContext) GroundContext() snapstate.DeviceContext {
    67  	return dc
    68  }
    69  
    70  func (dc *groundDeviceContext) Store() snapstate.StoreService {
    71  	panic("retrieved ground context is not intended to drive store operations")
    72  }
    73  
    74  func (dc *groundDeviceContext) ForRemodeling() bool {
    75  	return false
    76  }
    77  
    78  func (dc *groundDeviceContext) SystemMode() string {
    79  	return dc.systemMode
    80  }
    81  
    82  func (dc groundDeviceContext) Classic() bool {
    83  	return dc.model.Classic()
    84  }
    85  
    86  func (dc groundDeviceContext) Kernel() string {
    87  	return dc.model.Kernel()
    88  }
    89  
    90  func (dc groundDeviceContext) Base() string {
    91  	return dc.model.Base()
    92  }
    93  
    94  func (dc groundDeviceContext) RunMode() bool {
    95  	return dc.systemMode == "run"
    96  }
    97  
    98  // HasModeenv is true if the grade is set
    99  // TODO:UC20: will classic devices with uc20 models have a modeenv? I think so?
   100  func (dc groundDeviceContext) HasModeenv() bool {
   101  	return dc.model.Grade() != asserts.ModelGradeUnset
   102  }
   103  
   104  // sanity
   105  var _ snapstate.DeviceContext = &groundDeviceContext{}
   106  
   107  type modelDeviceContext struct {
   108  	groundDeviceContext
   109  }
   110  
   111  func (dc *modelDeviceContext) Store() snapstate.StoreService {
   112  	return nil
   113  }
   114  
   115  // sanity
   116  var _ snapstate.DeviceContext = &modelDeviceContext{}