74 lines
1.4 KiB
Go
74 lines
1.4 KiB
Go
package cmdrootfs
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import (
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"errors"
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"fmt"
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"io"
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"os"
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goflags "github.com/jessevdk/go-flags"
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"github.com/motiejus/code/undocker/rootfs"
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)
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const _description = "Flatten a docker container image to a tarball"
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type (
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// Command is an implementation of go-flags.Command
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Command struct {
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flattener func(io.ReadSeeker, io.Writer) error
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Stdout io.Writer
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PositionalArgs struct {
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Infile goflags.Filename `long:"infile" desc:"Input tarball"`
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Outfile string `long:"outfile" desc:"Output path, stdout is '-'"`
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} `positional-args:"yes" required:"yes"`
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}
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)
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func NewCommand() *Command {
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return &Command{
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flattener: rootfs.Flatten,
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Stdout: os.Stdout,
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}
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}
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func (*Command) ShortDesc() string { return _description }
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func (*Command) LongDesc() string { return _description }
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// Execute executes rootfs Command
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func (c *Command) Execute(args []string) (err error) {
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if len(args) != 0 {
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return errors.New("too many args")
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}
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rd, err := os.Open(string(c.PositionalArgs.Infile))
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if err != nil {
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return err
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}
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defer func() {
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err1 := rd.Close()
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if err == nil {
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err = err1
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}
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}()
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var out io.Writer
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if fname := string(c.PositionalArgs.Outfile); fname == "-" {
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out = c.Stdout
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} else {
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outf, err := os.Create(fname)
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if err != nil {
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return fmt.Errorf("create: %w", err)
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}
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defer func() {
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err1 := outf.Close()
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if err == nil {
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err = err1
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}
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}()
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out = outf
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}
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return c.flattener(rd, out)
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}
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