Refactor git command stdio pipe (#36422)

Most potential deadlock problems should have been fixed, and new code is
unlikely to cause new problems with the new design.

Also raise the minimum Git version required to 2.6.0 (released in 2015)

modules/git/pipeline/namerev.go

@@ -4,25 +4,54 @@
 package pipeline
 
 import (
+	"bufio"
 	"context"
-	"fmt"
-	"io"
-	"sync"
+	"errors"
+	"strings"
 
 	"code.gitea.io/gitea/modules/git/gitcmd"
+
+	"golang.org/x/sync/errgroup"
 )
 
-// NameRevStdin runs name-rev --stdin
-func NameRevStdin(ctx context.Context, shasToNameReader *io.PipeReader, nameRevStdinWriter *io.PipeWriter, wg *sync.WaitGroup, tmpBasePath string) {
-	defer wg.Done()
-	defer shasToNameReader.Close()
-	defer nameRevStdinWriter.Close()
+func fillResultNameRev(ctx context.Context, basePath string, results []*LFSResult) error {
+	// Should really use a go-git function here but name-rev is not completed and recapitulating it is not simple
+	wg := errgroup.Group{}
+	cmd := gitcmd.NewCommand("name-rev", "--stdin", "--name-only", "--always").WithDir(basePath)
+	stdin, stdinClose := cmd.MakeStdinPipe()
+	stdout, stdoutClose := cmd.MakeStdoutPipe()
+	defer stdinClose()
+	defer stdoutClose()
 
-	if err := gitcmd.NewCommand("name-rev", "--stdin", "--name-only", "--always").
-		WithDir(tmpBasePath).
-		WithStdin(shasToNameReader).
-		WithStdout(nameRevStdinWriter).
-		RunWithStderr(ctx); err != nil {
-		_ = shasToNameReader.CloseWithError(fmt.Errorf("git name-rev [%s]: %w", tmpBasePath, err))
-	}
+	wg.Go(func() error {
+		scanner := bufio.NewScanner(stdout)
+		i := 0
+		for scanner.Scan() {
+			line := scanner.Text()
+			if len(line) == 0 {
+				continue
+			}
+			result := results[i]
+			result.FullCommitName = line
+			result.BranchName = strings.Split(line, "~")[0]
+			i++
+		}
+		return scanner.Err()
+	})
+	wg.Go(func() error {
+		defer stdinClose()
+		for _, result := range results {
+			_, err := stdin.Write([]byte(result.SHA))
+			if err != nil {
+				return err
+			}
+			_, err = stdin.Write([]byte{'\n'})
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+	err := cmd.RunWithStderr(ctx)
+	return errors.Join(err, wg.Wait())
 }