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Add easier error handling #9

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Add easier error handling #9

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45 changes: 22 additions & 23 deletions cmd/extract/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -28,27 +28,34 @@ const (
typeFullBackup = 2
)

var debug = os.Getenv("DEBUG") == "1"

func main() {
if len(os.Args) != 3 {
_, _ = fmt.Fprintf(os.Stderr, "usage: %s path-to-backup mnemonic\n", filepath.Base(os.Args[0]))
os.Exit(1)
}

backupPath := os.Args[1]
err := extractAppBackup(backupPath)
if err != nil {
_, _ = fmt.Fprintf(os.Stderr, "error: %s\n", err)
os.Exit(1)
}
}

func extractAppBackup(backupPath string) error {
metadataPath := filepath.Join(backupPath, ".backup.metadata")
_, err := os.Stat(metadataPath)
if errors.Is(err, os.ErrNotExist) {
_, _ = fmt.Fprintln(os.Stderr, "error: not a backup (missing .backup.metadata)")
os.Exit(1)
return fmt.Errorf("not a backup (missing .backup.metadata)")
} else if err != nil {
_, _ = fmt.Fprintf(os.Stderr, "error: failed to stat %q: %s\n", metadataPath, err)
os.Exit(1)
return fmt.Errorf("failed to stat %q: %s\n", metadataPath, err)
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@jackwilsdon jackwilsdon May 19, 2023 •
edited
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Can we remove the newlines from any returned errors? We're ending up with an extra one for some errors now as we're also adding a newline when writing the error to stderr.

}

metadataFile, err := os.Open(metadataPath)
if err != nil {
_, _ = fmt.Fprintf(os.Stderr, "error: failed to open %q: %s\n", metadataPath, err)
os.Exit(1)
return fmt.Errorf("failed to open %q: %s\n", metadataPath, err)
}
defer func() {
_ = metadataFile.Close()
Expand All @@ -57,24 +64,20 @@ func main() {
metadataReader := bufio.NewReader(metadataFile)
version, err := metadataReader.ReadByte()
if err != nil {
_, _ = fmt.Fprintf(os.Stderr, "error: failed to read version from %q: %s\n", metadataPath, err)
os.Exit(1)
return fmt.Errorf("failed to read version from %q: %s\n", metadataPath, err)
}
if version != 1 {
_, _ = fmt.Fprintf(os.Stderr, "error: unsupported version %d (only version 1 is supported)\n", version)
os.Exit(1)
return fmt.Errorf("unsupported version %d (only version 1 is supported)\n", version)
}

debug := os.Getenv("DEBUG") == "1"
if debug {
fmt.Printf("version: %d\n", version)
}

backupName := filepath.Base(backupPath)
token, err := strconv.ParseUint(backupName, 10, 64)
if err != nil {
_, _ = fmt.Fprintf(os.Stderr, "error: failed to parse backup name %q: %s\n", backupName, err)
os.Exit(1)
return fmt.Errorf("failed to parse backup name %q: %s\n", backupName, err)
}

if debug {
Expand All @@ -100,35 +103,30 @@ func main() {
binary.BigEndian.PutUint64(associatedData[2:], token)
metadataBytes, err := decrypt(metadataReader, key, associatedData)
if err != nil {
_, _ = fmt.Fprintf(os.Stderr, "error: failed to decrypt metadata: %s\n", err)
os.Exit(1)
return fmt.Errorf("failed to decrypt metadata: %s\n", err)
}
if debug {
fmt.Printf("metadata: %s\n", string(metadataBytes))
}

var metadataMap map[string]json.RawMessage
if err := json.Unmarshal(metadataBytes, &metadataMap); err != nil {
_, _ = fmt.Fprintf(os.Stderr, "error: failed to unmarshal metadata: %s\n", err)
os.Exit(1)
return fmt.Errorf("failed to unmarshal metadata: %s\n", err)
}

metadataMetaBytes, ok := metadataMap["@meta@"]
if !ok {
_, _ = fmt.Fprintf(os.Stderr, "error: missing @meta@ key\n")
os.Exit(1)
return fmt.Errorf("missing @meta@ key\n")
}
var metadataMeta struct {
Version byte `json:"version"`
Salt string `json:"salt"`
}
if err := json.Unmarshal(metadataMetaBytes, &metadataMeta); err != nil {
_, _ = fmt.Fprintf(os.Stderr, "error: failed to unmarshal @meta@: %s\n", err)
os.Exit(1)
return fmt.Errorf("failed to unmarshal @meta@: %s\n", err)
}
if metadataMeta.Version != version {
_, _ = fmt.Fprintf(os.Stderr, "error: @meta@ version %d does not match metadata file version %d\n", metadataMeta.Version, version)
os.Exit(1)
return fmt.Errorf("@meta@ version %d does not match metadata file version %d\n", metadataMeta.Version, version)
}

for packageName, packageMetaBytes := range metadataMap {
Expand Down Expand Up @@ -212,6 +210,7 @@ func main() {
_, _ = fmt.Fprintf(os.Stderr, "warning: failed to extract %q: %s\n", packageName, err)
}
}
return nil
}

func mnemonicToSeed(mnemonic string) ([]byte, error) {
Expand Down