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package main
import (
"errors"
"fmt"
"io"
"log"
"os"
"time"
"github.com/urfave/cli/v2"
"gitlab.com/gitlab-org/gitaly/v16/internal/git"
"gitlab.com/gitlab-org/gitaly/v16/internal/signature"
)
func gpgApp() *cli.App {
return &cli.App{
Flags: []cli.Flag{
&cli.IntFlag{Name: "status-fd"},
&cli.BoolFlag{Name: "verify"},
&cli.BoolFlag{Name: "bsau"},
},
Action: func(cCtx *cli.Context) error {
// Git passes the --status-fd=2 flag into the gpg call.
if cCtx.Int("status-fd") != 2 {
return errors.New("expected --status-fd=2")
}
signingKeys, err := signature.ParseSigningKeys(cCtx.Args().First())
if err != nil {
return fmt.Errorf("reading signed key file %s : %w", cCtx.Args().First(), err)
}
contents, err := io.ReadAll(cCtx.App.Reader)
if err != nil {
return fmt.Errorf("reading contents from stdin: %w", err)
}
// Signing a commit can be nondeterministic if not done at the same second
// We use `GIT_AUTHOR_DATE` to ensure that the signature is deterministic
date := time.Now()
authorDate, exists := os.LookupEnv("GIT_AUTHOR_DATE")
if exists {
date, err = time.ParseInLocation(git.Rfc2822DateFormat, authorDate, time.FixedZone("", 0))
if err != nil {
return fmt.Errorf("error parsing GIT_AUTHOR_DATE: %w", err)
}
}
sig, err := signingKeys.CreateSignature(contents, date)
if err != nil {
return fmt.Errorf("creating signature: %w", err)
}
// Git looks for this output string as part of GPG output.
if _, err := cCtx.App.ErrWriter.Write([]byte("[GNUPG:] SIG_CREATED ")); err != nil {
return fmt.Errorf("printing to stdout: %w", err)
}
if _, err := cCtx.App.Writer.Write(sig); err != nil {
return fmt.Errorf("printing to stdout: %w", err)
}
if _, err := cCtx.App.Writer.Write([]byte("\n")); err != nil {
return fmt.Errorf("printing to stdout: %w", err)
}
return nil
},
}
}
// This binary is used to support signing through providing the path to the
// actual signing key. Git itself does not support this since it simply calls
// out to gpg(1), which only supports fetching keys from the gpg database.
// This binary is used as a stopgap measure since we can set Git's gpg.program
// config to point to this binary, which interprets the key_id passed in as the
// path to the signing key.
// In the future, we will modify Git so that commit-tree can take in a raw
// commit message that we can add a signature to, at which point we can sign
// commits manually and get rid of this binary.
func main() {
if err := gpgApp().Run(os.Args); err != nil {
log.Fatal(err)
}
}
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