diff --git a/cmd/bolt/main.go b/cmd/bolt/main.go index 2ca878c..246d04c 100644 --- a/cmd/bolt/main.go +++ b/cmd/bolt/main.go @@ -42,6 +42,9 @@ var ( // ErrNonDivisibleBatchSize is returned when the batch size can't be evenly // divided by the iteration count. ErrNonDivisibleBatchSize = errors.New("number of iterations must be divisible by the batch size") + + // ErrPageIDRequired is returned when a required page id is not specified. + ErrPageIDRequired = errors.New("page id required") ) func main() { @@ -87,6 +90,8 @@ func (m *Main) Run(args ...string) error { return newBenchCommand(m).Run(args[1:]...) case "check": return newCheckCommand(m).Run(args[1:]...) + case "dump": + return newDumpCommand(m).Run(args[1:]...) case "info": return newInfoCommand(m).Run(args[1:]...) case "pages": @@ -264,6 +269,118 @@ Info prints basic information about the Bolt database at PATH. `, "\n") } +// DumpCommand represents the "dump" command execution. +type DumpCommand struct { + Stdin io.Reader + Stdout io.Writer + Stderr io.Writer +} + +// newDumpCommand returns a DumpCommand. +func newDumpCommand(m *Main) *DumpCommand { + return &DumpCommand{ + Stdin: m.Stdin, + Stdout: m.Stdout, + Stderr: m.Stderr, + } +} + +// Run executes the command. +func (cmd *DumpCommand) Run(args ...string) error { + // Parse flags. + fs := flag.NewFlagSet("", flag.ContinueOnError) + help := fs.Bool("h", false, "") + pageID := fs.Int("page", -1, "") + if err := fs.Parse(args); err != nil { + return err + } else if *help { + fmt.Fprintln(cmd.Stderr, cmd.Usage()) + return ErrUsage + } + + // Require database path and page id. + path := fs.Arg(0) + if path == "" { + return ErrPathRequired + } else if _, err := os.Stat(path); os.IsNotExist(err) { + return ErrFileNotFound + } else if *pageID == -1 { + return ErrPageIDRequired + } + + // Open database to retrieve page size. + db, err := bolt.Open(path, 0666, nil) + if err != nil { + return err + } + pageSize := db.Info().PageSize + _ = db.Close() + + // Open database file handler. + f, err := os.Open(path) + if err != nil { + return err + } + defer func() { _ = f.Close() }() + + // Print page to stdout. + return cmd.PrintPage(cmd.Stdout, f, *pageID, pageSize) +} + +// PrintPage prints a given page as hexidecimal. +func (cmd *DumpCommand) PrintPage(w io.Writer, r io.ReaderAt, pageID int, pageSize int) error { + const bytesPerLineN = 16 + + // Read page into buffer. + buf := make([]byte, pageSize) + addr := pageID * pageSize + if n, err := r.ReadAt(buf, int64(addr)); err != nil { + return err + } else if n != pageSize { + return io.ErrUnexpectedEOF + } + + // Write out to writer in 16-byte lines. + var prev []byte + var skipped bool + for offset := 0; offset < pageSize; offset += bytesPerLineN { + // Retrieve current 16-byte line. + line := buf[offset : offset+bytesPerLineN] + isLastLine := (offset == (pageSize - bytesPerLineN)) + + // If it's the same as the previous line then print a skip. + if bytes.Equal(line, prev) && !isLastLine { + if !skipped { + fmt.Fprintf(w, "%07x *\n", addr+offset) + skipped = true + } + } else { + // Print line as hexadecimal in 2-byte groups. + fmt.Fprintf(w, "%07x %04x %04x %04x %04x %04x %04x %04x %04x\n", addr+offset, + line[0:2], line[2:4], line[4:6], line[6:8], + line[8:10], line[10:12], line[12:14], line[14:16], + ) + + skipped = false + } + + // Save the previous line. + prev = line + } + fmt.Fprint(w, "\n") + + return nil +} + +// Usage returns the help message. +func (cmd *DumpCommand) Usage() string { + return strings.TrimLeft(` +usage: bolt dump -page PAGEID PATH + +Dump prints a hexidecimal dump of a single page. +`, "\n") +} + // PagesCommand represents the "pages" command execution. type PagesCommand struct { Stdin io.Reader