76 lines
1.4 KiB
Go
76 lines
1.4 KiB
Go
// Package main is a simple command-line application on top of rootfs.Flatten.
|
|
package main
|
|
|
|
import (
|
|
"fmt"
|
|
"io"
|
|
"os"
|
|
"path/filepath"
|
|
"runtime"
|
|
|
|
"git.sr.ht/~motiejus/undocker/rootfs"
|
|
)
|
|
|
|
const _usage = `Usage:
|
|
%s <infile> <outfile>
|
|
|
|
Flatten a Docker container image to a root file system.
|
|
|
|
Arguments:
|
|
<infile>: Input Docker container. Tarball.
|
|
<outfile>: Output tarball, the root file system. '-' is stdout.
|
|
`
|
|
|
|
func main() {
|
|
runtime.GOMAXPROCS(1) // no need to create that many threads
|
|
|
|
if len(os.Args) != 3 {
|
|
fmt.Fprintf(os.Stderr, _usage, filepath.Base(os.Args[0]))
|
|
os.Exit(1)
|
|
}
|
|
|
|
c := &command{flattener: rootfs.Flatten, Stdout: os.Stdout}
|
|
if err := c.execute(os.Args[1], os.Args[2]); err != nil {
|
|
fmt.Errorf("Error: %v", err)
|
|
os.Exit(1)
|
|
}
|
|
os.Exit(0)
|
|
}
|
|
|
|
type command struct {
|
|
flattener func(io.ReadSeeker, io.Writer) error
|
|
Stdout io.Writer
|
|
}
|
|
|
|
func (c *command) execute(infile string, outfile string) (err error) {
|
|
rd, err := os.Open(infile)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer func() {
|
|
err1 := rd.Close()
|
|
if err == nil {
|
|
err = err1
|
|
}
|
|
}()
|
|
|
|
var out io.Writer
|
|
if outfile == "-" {
|
|
out = c.Stdout
|
|
} else {
|
|
outf, err := os.Create(outfile)
|
|
if err != nil {
|
|
return fmt.Errorf("create: %w", err)
|
|
}
|
|
defer func() {
|
|
err1 := outf.Close()
|
|
if err == nil {
|
|
err = err1
|
|
}
|
|
}()
|
|
out = outf
|
|
}
|
|
|
|
return c.flattener(rd, out)
|
|
}
|