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tar-split/concept/main.go

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1.9 KiB
Go

// +build ignore
package main
import (
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"github.com/vbatts/tar-split/archive/tar"
)
func main() {
flag.Parse()
log.SetOutput(os.Stderr)
for _, arg := range flag.Args() {
func() {
// Open the tar archive
fh, err := os.Open(arg)
if err != nil {
log.Fatal(err, arg)
}
defer fh.Close()
output, err := os.Create(fmt.Sprintf("%s.out", arg))
if err != nil {
log.Fatal(err)
}
defer output.Close()
log.Printf("writing %q to %q", fh.Name(), output.Name())
fi, err := fh.Stat()
if err != nil {
log.Fatal(err, fh.Name())
}
size := fi.Size()
var sum int64
tr := tar.NewReader(fh)
tr.RawAccounting = true
for {
hdr, err := tr.Next()
if err != nil {
if err != io.EOF {
log.Println(err)
}
// even when an EOF is reached, there is often 1024 null bytes on
// the end of an archive. Collect them too.
post := tr.RawBytes()
output.Write(post)
sum += int64(len(post))
fmt.Printf("EOF padding: %d\n", len(post))
break
}
pre := tr.RawBytes()
output.Write(pre)
sum += int64(len(pre))
var i int64
if i, err = io.Copy(output, tr); err != nil {
log.Println(err)
break
}
sum += i
fmt.Println(hdr.Name, "pre:", len(pre), "read:", i)
}
// it is allowable, and not uncommon that there is further padding on the
// end of an archive, apart from the expected 1024 null bytes
remainder, err := ioutil.ReadAll(fh)
if err != nil && err != io.EOF {
log.Fatal(err, fh.Name())
}
output.Write(remainder)
sum += int64(len(remainder))
fmt.Printf("Remainder: %d\n", len(remainder))
if size != sum {
fmt.Printf("Size: %d; Sum: %d; Diff: %d\n", size, sum, size-sum)
fmt.Printf("Compare like `cmp -bl %s %s | less`\n", fh.Name(), output.Name())
} else {
fmt.Printf("Size: %d; Sum: %d\n", size, sum)
}
}()
}
}