multidd.go

package main

import (
  "flag";
  "log";
  "os";
  "strings";
  "time";
)

func main() {
  var if_f *string = flag.String("if", "", "Input file");
  var of *string = flag.String("of", "", "Output file(s)");
  var bs *int = flag.Int("bs", 4096, "Block size in bytes");
  var statusinterval *int = flag.Int("statusinterval", -1, "Print status every n blocks");

  flag.Parse();
  
  of_arg := *of;
  if strings.HasSuffix(of_arg, ",") {
    of_arg = of_arg[0:len(of_arg)-1];
  }
  
  outs := strings.Split(of_arg, ",", -1);
  chans := make([]chan []byte, len(outs));
  
  var infile *os.File;
  var ok os.Error;
  if infile, ok = os.Open(*if_f, os.O_RDONLY, 0644); ok != nil {
    log.Exitf("Unable to open input file: %s\n", ok);
  }

  for i, out := range outs {
    chans[i] = make(chan []byte);
    if outfile, ok := os.Open(out, os.O_WRONLY | os.O_CREAT, 0644); ok != nil {
      log.Exitf("Unable to poen output file %s: %s\n", out, ok);
    } else {
      go write_blocks(out, outfile, chans[i]);
    }
  }
  
  total_bytes := 0;
  for i := 0; true; i++ {
    if *statusinterval > 0 && i % *statusinterval == 0 {
      log.Stdoutf("Written %d blocks (%d bytes)\n", i, total_bytes);
    }

    var size int;
    var ok os.Error;
    buf := make([]byte, *bs);
    
    // Read a block
    switch size, ok = infile.Read(buf); ok {
    case os.EOF:
      break;
    case nil:
    default:
      log.Exitf("Error reading block: %s\n", ok);
    }
    total_bytes += size;
    
    if size == 0 {
      break;
    }
      
    // Take just the read bytes
    s := buf[0:size];
    
    // Send it to the channels to be written
    for j := 0; j < len(chans); j++ {
      chans[j] <- s;
    }
  }
  infile.Close();
  
  // Send empty buffers to all open channels to let them know they should close
  for i := 0; i < len(chans); i++ {
    chans[i] <- []byte{};
  }
  time.Sleep(5000000);
}

func write_blocks(outname string, outfile *os.File, in chan []byte) {
  for {
    block := <-in;
    if len(block) > 0 {
      if _, err := outfile.Write(block); err != nil {
        log.Exitf("Error writing to %s: %s\n", outname, err);
      }
    } else {
      outfile.Close();
      return;
    }
  }
}