A virtual jailed shell environment for Go apps backed by an io/fs#FS.
feat: initial commit with cmd/kefka basic rigging
Signed-off-by: Xe Iaso <me@xeiaso.net>
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LICENSE
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LICENSE
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Copyright (c) 2026 Xe Iaso <me@xeiaso.net>
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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cmd/kefka/main.go
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cmd/kefka/main.go
···
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package main
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import (
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"context"
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"errors"
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"fmt"
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"io"
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"os"
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"strings"
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"time"
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"github.com/spf13/pflag"
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"golang.org/x/term"
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"mvdan.cc/sh/v3/interp"
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"mvdan.cc/sh/v3/syntax"
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)
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var (
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command = pflag.StringP("command", "c", "", "if set, run this command")
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timeout = pflag.DurationP("timeout", "T", 5*time.Minute, "the total time a command can run for")
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ErrInteractiveNotImplementedYet = errors.New("kefka: interactive mode not implemented yet")
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)
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func main() {
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pflag.Parse()
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ctx, cancel := context.WithTimeout(context.Background(), *timeout)
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defer cancel()
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if err := run(ctx); err != nil {
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fmt.Fprintln(os.Stderr, "can't run shell:", err)
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}
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}
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func run(ctx context.Context) error {
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sh, err := interp.New(interp.Interactive(true), interp.StdIO(os.Stdin, os.Stdout, os.Stderr))
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if err != nil {
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return fmt.Errorf("can't make shell: %w", err)
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}
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if *command != "" {
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return runReader(ctx, sh, strings.NewReader(*command), "<argument>")
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}
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if pflag.NArg() == 1 {
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return runFile(ctx, sh, pflag.Arg(0))
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}
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if term.IsTerminal(int(os.Stdin.Fd())) {
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return runInteractive(ctx, sh, os.Stdin, os.Stdout, os.Stderr)
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}
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return runReader(ctx, sh, os.Stdin, "<stdin>")
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}
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func runReader(ctx context.Context, sh *interp.Runner, in io.Reader, name string) error {
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prog, err := syntax.NewParser().Parse(in, name)
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if err != nil {
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return err
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}
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sh.Reset()
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return sh.Run(ctx, prog)
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}
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func runFile(ctx context.Context, sh *interp.Runner, fname string) error {
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fin, err := os.Open(fname)
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if err != nil {
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return err
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}
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defer fin.Close()
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return runReader(ctx, sh, fin, fname)
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}
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func runInteractive(ctx context.Context, sh *interp.Runner, stdin io.Reader, stdout, stderr io.Writer) error {
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parser := syntax.NewParser()
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fmt.Fprintf(stdout, "$ ")
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for stmts, err := range parser.InteractiveSeq(stdin) {
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if err != nil {
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return err
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}
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if parser.Incomplete() {
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fmt.Fprintf(stdout, "> ")
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continue
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}
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ctx, cancel := context.WithTimeout(context.Background(), *timeout)
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defer cancel()
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for _, stmt := range stmts {
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err := sh.Run(ctx, stmt)
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if sh.Exited() {
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return err
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}
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}
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fmt.Fprintf(stdout, "$ ")
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}
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return nil
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}
+13
go.mod
+13
go.mod
+20
go.sum
+20
go.sum
···
1
+
github.com/creack/pty v1.1.24 h1:bJrF4RRfyJnbTJqzRLHzcGaZK1NeM5kTC9jGgovnR1s=
2
+
github.com/creack/pty v1.1.24/go.mod h1:08sCNb52WyoAwi2QDyzUCTgcvVFhUzewun7wtTfvcwE=
3
+
github.com/go-quicktest/qt v1.101.0 h1:O1K29Txy5P2OK0dGo59b7b0LR6wKfIhttaAhHUyn7eI=
4
+
github.com/go-quicktest/qt v1.101.0/go.mod h1:14Bz/f7NwaXPtdYEgzsx46kqSxVwTbzVZsDC26tQJow=
5
+
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
6
+
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
7
+
github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
8
+
github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
9
+
github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
10
+
github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
11
+
github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
12
+
github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
13
+
github.com/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
14
+
github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
15
+
golang.org/x/sys v0.42.0 h1:omrd2nAlyT5ESRdCLYdm3+fMfNFE/+Rf4bDIQImRJeo=
16
+
golang.org/x/sys v0.42.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
17
+
golang.org/x/term v0.41.0 h1:QCgPso/Q3RTJx2Th4bDLqML4W6iJiaXFq2/ftQF13YU=
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+
golang.org/x/term v0.41.0/go.mod h1:3pfBgksrReYfZ5lvYM0kSO0LIkAl4Yl2bXOkKP7Ec2A=
19
+
mvdan.cc/sh/v3 v3.13.1 h1:DP3TfgZhDkT7lerUdnp6PTGKyxxzz6T+cOlY/xEvfWk=
20
+
mvdan.cc/sh/v3 v3.13.1/go.mod h1:lXJ8SexMvEVcHCoDvAGLZgFJ9Wsm2sulmoNEXGhYZD0=