github.com/hugh712/snapd@v0.0.0-20200910133618-1a99902bd583/kernel/kernel.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 kernel
    21  
    22  import (
    23  	"fmt"
    24  	"io/ioutil"
    25  	"os"
    26  	"path/filepath"
    27  	"regexp"
    28  
    29  	"gopkg.in/yaml.v2"
    30  
    31  	"github.com/snapcore/snapd/gadget/edition"
    32  )
    33  
    34  type Asset struct {
    35  	Edition edition.Number `yaml:"edition,omitempty"`
    36  	Content []string       `yaml:"content,omitempty"`
    37  }
    38  
    39  type Info struct {
    40  	Assets map[string]*Asset `yaml:"assets,omitempty"`
    41  }
    42  
    43  // XXX: should we be more liberal? start conservative
    44  var validAssetName = regexp.MustCompile("^[a-zA-Z0-9]+$")
    45  
    46  // InfoFromKernelYaml reads the provided kernel metadata.
    47  func InfoFromKernelYaml(kernelYaml []byte) (*Info, error) {
    48  	var ki Info
    49  
    50  	if err := yaml.Unmarshal(kernelYaml, &ki); err != nil {
    51  		return nil, fmt.Errorf("cannot parse kernel metadata: %v", err)
    52  	}
    53  
    54  	for name := range ki.Assets {
    55  		if !validAssetName.MatchString(name) {
    56  			return nil, fmt.Errorf("invalid asset name %q, please use only alphanumeric characters", name)
    57  		}
    58  	}
    59  
    60  	return &ki, nil
    61  }
    62  
    63  // ReadInfo reads the kernel specific metadata from meta/kernel.yaml
    64  // in the snap root directory if the file exists.
    65  func ReadInfo(kernelSnapRootDir string) (*Info, error) {
    66  	p := filepath.Join(kernelSnapRootDir, "meta", "kernel.yaml")
    67  	content, err := ioutil.ReadFile(p)
    68  	// meta/kernel.yaml is optional so we should not error here if
    69  	// it is missing
    70  	if os.IsNotExist(err) {
    71  		return &Info{}, nil
    72  	}
    73  	if err != nil {
    74  		return nil, fmt.Errorf("cannot read kernel info: %v", err)
    75  	}
    76  	return InfoFromKernelYaml(content)
    77  }