goat: use "-" convention for standard io on repo export and repo mst …

…commands

cmd/goat/repo.go

@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -24,7 +23,6 @@ import (
 	ipld "github.com/ipfs/go-ipld-format"
 	"github.com/urfave/cli/v2"
 	"github.com/xlab/treeprint"
-	"golang.org/x/term"
 )
 
 var cmdRepo = &cli.Command{
@@ -125,16 +123,25 @@ func runRepoExport(cctx *cli.Context) error {
 		now := time.Now().Format("20060102150405")
 		carPath = fmt.Sprintf("%s.%s.car", username, now)
 	}
-	// NOTE: there is a race condition, but nice to give a friendly error earlier before downloading
-	if _, err := os.Stat(carPath); err == nil {
-		return fmt.Errorf("file already exists: %s", carPath)
+	output, err := getFileOrStdout(carPath)
+	if err != nil {
+		if errors.Is(err, os.ErrExist) {
+			return fmt.Errorf("file already exists: %s", carPath)
+		}
+		return err
+	}
+	defer output.Close()
+	if (carPath != stdIOPath) {
+		fmt.Printf("downloading from %s to: %s\n", xrpcc.Host, carPath)
 	}
-	fmt.Printf("downloading from %s to: %s\n", xrpcc.Host, carPath)
 	repoBytes, err := comatproto.SyncGetRepo(ctx, &xrpcc, ident.DID.String(), "")
 	if err != nil {
 		return err
 	}
-	return os.WriteFile(carPath, repoBytes, 0666)
+	if _, err := output.Write(repoBytes); err != nil {
+		return err
+	}
+	return nil
 }
 
 func runRepoImport(cctx *cli.Context) error {
@@ -227,19 +234,13 @@ func runRepoMST(cctx *cli.Context) error {
 		fullCID: cctx.Bool("full-cid"),
 		root:    cctx.String("root"),
 	}
-	// determine whether to read from file argument or stdin
-	var inputCAR io.Reader
-	if opts.carPath != "" {
-		fi, err := os.Open(opts.carPath)
-		if err != nil {
-			return err
-		}
-		inputCAR = fi
-	} else {
-		if term.IsTerminal(int(os.Stdin.Fd())) {
-			return fmt.Errorf("need to provide path to CAR file as argument")
-		}
-		inputCAR = os.Stdin
+	// read from file or stdin
+	if opts.carPath == "" {
+		return fmt.Errorf("need to provide path to CAR file as argument")
+	}
+	inputCAR, err := getFileOrStdin(opts.carPath)
+	if (err != nil) {
+		return err
 	}
 	// read repository tree in to memory
 	r, err := repo.ReadRepoFromCar(ctx, inputCAR)

cmd/goat/util.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"context"
+	"io"
+	"os"
 
 	"github.com/bluesky-social/indigo/atproto/identity"
 	"github.com/bluesky-social/indigo/atproto/syntax"
@@ -16,3 +18,28 @@ func resolveIdent(ctx context.Context, arg string) (*identity.Identity, error) {
 	dir := identity.DefaultDirectory()
 	return dir.Lookup(ctx, *id)
 }
+
+const stdIOPath = "-"
+
+func getFileOrStdin(path string) (io.Reader, error) {
+	if (path == stdIOPath) {
+		return os.Stdin, nil
+	}
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	return file, nil
+}
+
+func getFileOrStdout(path string) (io.WriteCloser, error) {
+	if (path == stdIOPath) {
+		return os.Stdout, nil
+	}
+	file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0666)
+	if err != nil {
+		return nil, err
+	}
+	return file, nil
+}
+

go.mod

@@ -69,7 +69,6 @@ require (
 	go.uber.org/zap v1.26.0
 	golang.org/x/crypto v0.21.0
 	golang.org/x/sync v0.7.0
-	golang.org/x/term v0.18.0
 	golang.org/x/text v0.14.0
 	golang.org/x/time v0.3.0
 	golang.org/x/tools v0.15.0

go.sum

@@ -915,8 +915,6 @@ golang.org/x/term v0.4.0/go.mod h1:9P2UbLfCdcvo3p/nzKvsmas4TnlujnuoV9hGgYzW1lQ=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
 golang.org/x/term v0.8.0/go.mod h1:xPskH00ivmX89bAKVGSKKtLOWNx2+17Eiy94tnKShWo=
 golang.org/x/term v0.11.0/go.mod h1:zC9APTIj3jG3FdV/Ons+XE1riIZXG4aZ4GTHiPZJPIU=
-golang.org/x/term v0.18.0 h1:FcHjZXDMxI8mM3nwhX9HlKop4C0YQvCVCdwYl2wOtE8=
-golang.org/x/term v0.18.0/go.mod h1:ILwASektA3OnRv7amZ1xhE/KTR+u50pbXfZ03+6Nx58=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=