chore: Improve the git status speed.

By using the native git client its possible to improve the speed
significantly.

Signed-off-by: Matthias Glastra <[email protected]>

attestation/git/git.go

@@ -221,14 +221,32 @@ func (a *Attestor) Attest(ctx *attestation.AttestationContext) error {
 
 	a.TreeHash = commit.TreeHash.String()
 
+	if GitExists() {
+		a.Status, err = GitGetStatus(ctx.WorkingDir())
+		if err != nil {
+			return err
+		}
+	} else {
+		a.Status, err = GoGitGetStatus(repo)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func GoGitGetStatus(repo *git.Repository) (map[string]Status, error) {
+	var gitStatuses map[string]Status = make(map[string]Status)
+
 	worktree, err := repo.Worktree()
 	if err != nil {
-		return err
+		return map[string]Status{}, err
 	}
 
 	status, err := worktree.Status()
 	if err != nil {
-		return err
+		return map[string]Status{}, err
 	}
 
 	for file, status := range status {
@@ -241,10 +259,10 @@ func (a *Attestor) Attest(ctx *attestation.AttestationContext) error {
 			Staging:  statusCodeString(status.Staging),
 		}
 
-		a.Status[file] = attestStatus
+		gitStatuses[file] = attestStatus
 	}
 
-	return nil
+	return gitStatuses, nil
 }
 
 func (a *Attestor) Data() *Attestor {

attestation/git/git_bin.go

@@ -0,0 +1,70 @@
+// Copyright 2023 The Witness Contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package git
+
+import (
+	"os/exec"
+	"strings"
+
+	"github.com/go-git/go-git/v5"
+)
+
+// GitExists checks if the git binary is available.
+// This can be used to fall back to go-git implementation.
+func GitExists() bool {
+
+	_, err := exec.LookPath("git")
+	if err != nil {
+		return false
+	} else {
+		return true
+	}
+}
+
+func GitGetStatus(workDir string) (map[string]Status, error) {
+
+	// Execute the git status --porcelain command
+	cmd := exec.Command("git", "-C", workDir, "status", "--porcelain")
+	outputBytes, err := cmd.Output()
+	if err != nil {
+		return map[string]Status{}, err
+	}
+
+	// Convert the output to a string and split into lines
+	output := string(outputBytes)
+	lines := strings.Split(output, "\n")
+
+	// Iterate over the lines and parse the status
+	var gitStatuses map[string]Status = make(map[string]Status)
+	for _, line := range lines {
+		// Skip empty lines
+		if len(line) == 0 {
+			continue
+		}
+
+		// The first two characters are the status codes
+		repoStatus := statusCodeString(git.StatusCode(line[0]))
+		worktreeStatus := statusCodeString(git.StatusCode(line[1]))
+		filePath := strings.TrimSpace(line[2:])
+
+		// Append the parsed status to the list
+		gitStatuses[filePath] = Status{
+			Staging:  repoStatus,
+			Worktree: worktreeStatus,
+		}
+	}
+
+	return gitStatuses, nil
+}