github.com/google/trillian-examples@v0.0.0-20240520080811-0d40d35cef0e/binary_transparency/firmware/devices/dummy/flash.go (about) 1 // Copyright 2020 Google LLC. All Rights Reserved. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 // Package dummy provides a fake device to demo flashing firmware. 16 package dummy 17 18 import ( 19 "encoding/json" 20 "fmt" 21 "os" 22 "path/filepath" 23 24 "github.com/google/trillian-examples/binary_transparency/firmware/api" 25 "github.com/google/trillian-examples/binary_transparency/firmware/cmd/flash_tool/devices" 26 ) 27 28 const ( 29 bundlePath = "bundle.json" 30 firmwarePath = "firmware.bin" 31 ) 32 33 // Device is a fake device using the local filesystem for storage. 34 type Device struct { 35 // bundle holds all the update data except the firmware image. 36 bundle api.ProofBundle 37 38 storage string 39 } 40 41 var _ devices.Device = Device{} 42 43 // New creates a new dummy device instance using data from flags. 44 // TODO(al): figure out how/whether to remove the flag from in here. 45 func New(storage string) (*Device, error) { 46 dStat, err := os.Stat(storage) 47 if err != nil { 48 return nil, fmt.Errorf("unable to stat device storage dir %q: %w", storage, err) 49 } 50 if !dStat.Mode().IsDir() { 51 return nil, fmt.Errorf("device storage %q is not a directory", storage) 52 } 53 54 d := &Device{ 55 storage: storage, 56 } 57 58 fPath := filepath.Join(storage, bundlePath) 59 f, err := os.OpenFile(fPath, os.O_RDONLY, os.ModePerm) 60 if err != nil { 61 if os.IsNotExist(err) { 62 return d, devices.ErrNeedsInit(fmt.Errorf("couldn't read bundle file %q: %w", fPath, err)) 63 } 64 return d, fmt.Errorf("failed to read bundle file %q: %w", fPath, err) 65 } 66 defer func() { 67 _ = f.Close() 68 }() 69 70 err = json.NewDecoder(f).Decode(&d.bundle) 71 return d, err 72 } 73 74 // DeviceCheckpoint returns the latest log checkpoint stored on the device. 75 func (d Device) DeviceCheckpoint() ([]byte, error) { 76 return d.bundle.Checkpoint, nil 77 } 78 79 // ApplyUpdate applies the firmware update to the dummy device. 80 // The firmware image is stored in the dummy state directory in the firmware.bin file, 81 // and the rest of the update bundle is stored in the bundle.json file. 82 func (d Device) ApplyUpdate(u api.UpdatePackage) error { 83 fwFile := filepath.Join(d.storage, firmwarePath) 84 bundleFile := filepath.Join(d.storage, bundlePath) 85 86 if err := os.WriteFile(bundleFile, u.ProofBundle, os.ModePerm); err != nil { 87 return fmt.Errorf("failed to write proof bundle to %q: %q", bundleFile, err) 88 } 89 90 fw := u.FirmwareImage 91 if err := os.WriteFile(fwFile, fw, os.ModePerm); err != nil { 92 return fmt.Errorf("failed to write firmware image to %q: %q", fwFile, err) 93 } 94 95 return nil 96 }