feat(action): add functions for handling git describe

- the motivations behind this:
- coreboot likes to embed its source version into the compiled binary
- coreboot does that by calling 'git describe ...'
- however with firmware-action we can assume people will include
  coreboot as git submodule, and thus when compiling coreboot in
  container the git commands will fail because of missing .git directory
- to fix this we will run manually the 'git describe' command and then
  pass it in form of env variable into the container

Signed-off-by: AtomicFS <[email protected]>

action/filesystem/git.go

@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: MIT
+
+// Package filesystem / git implements git-related commands
+package filesystem
+
+import (
+	"fmt"
+	"log/slog"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+// gitRun is generic function to execute any git command in sub-directory
+func gitRun(subdir string, command []string) (string, error) {
+	// subdir is relative to current working directory
+
+	// Get current working directory
+	pwd, err := os.Getwd()
+	if err != nil {
+		return "", err
+	}
+
+	// Change current working directory into the repository / submodule
+	defer os.Chdir(pwd) // nolint:errcheck
+	subdirPath := filepath.Join(pwd, subdir)
+	err = os.Chdir(subdirPath)
+	if err != nil {
+		slog.Error(
+			fmt.Sprintf("Failed to change current working directory to '%s'", subdirPath),
+			slog.Any("error", err),
+		)
+		return "", err
+	}
+
+	// Run git describe
+	cmd := exec.Command(command[0], command[1:]...)
+	describe, err := cmd.CombinedOutput()
+	if err != nil {
+		slog.Error(
+			fmt.Sprintf("Failed to run git command in '%s'", subdirPath),
+			slog.Any("error", err),
+		)
+		return "", err
+	}
+
+	return string(describe), nil
+}
+
+// GitDescribeCoreboot is coreboot-specific git describe command
+func GitDescribeCoreboot(repoPath string) (string, error) {
+	describe, err := gitRun(repoPath, []string{"git", "describe", "--abbrev=12", "--dirty", "--always"})
+	if err != nil {
+		return "", err
+	}
+
+	// Remove trailing newline
+	result := strings.TrimSpace(describe)
+
+	// Check validity of the retuned string
+	pattern := regexp.MustCompile(`[\d\w]{13}(\-dirty)?`)
+	valid := pattern.MatchString(result)
+	if !valid {
+		slog.Warn(
+			fmt.Sprintf("Output of 'git describe' for '%s' seems to be invalid, output is: '%s'", repoPath, result),
+		)
+	}
+
+	return result, err
+}

action/filesystem/git_test.go

@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: MIT
+package filesystem
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/stretchr/testify/assert"
+)
+
+func gitRepoPrepare(t *testing.T, tmpDir string) {
+	// Create empty git repository
+	repo, err := git.PlainInit(tmpDir, false)
+	assert.NoError(t, err)
+
+	// Create a worktree to interact with the repo
+	worktree, err := repo.Worktree()
+	assert.NoError(t, err)
+
+	// Create a simple text file for testing
+	filename := "README.md"
+	pathFile := filepath.Join(tmpDir, filename)
+	err = os.WriteFile(pathFile, []byte{}, 0o666)
+	assert.NoError(t, err)
+
+	// Commit the file (must be relative path)
+	_, err = worktree.Add(filename)
+	assert.NoError(t, err)
+
+	commitOpts := &git.CommitOptions{}
+	_, err = worktree.Commit("Initial commit", commitOpts)
+	assert.NoError(t, err)
+}
+
+func TestGitRun(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	pwd, err := os.Getwd()
+	assert.NoError(t, err)
+	defer os.Chdir(pwd) // nolint:errcheck
+	err = os.Chdir(tmpDir)
+	assert.NoError(t, err)
+
+	gitRepoPrepare(t, tmpDir)
+
+	// Test git status
+	stdout, err := gitRun("./", []string{"git", "status"})
+	assert.NoError(t, err)
+	assert.Equal(t, stdout, "On branch master\nnothing to commit, working tree clean\n")
+}
+
+func TestGitDescribeCoreboot(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	pwd, err := os.Getwd()
+	assert.NoError(t, err)
+	defer os.Chdir(pwd) // nolint:errcheck
+	err = os.Chdir(tmpDir)
+	assert.NoError(t, err)
+
+	gitRepoPrepare(t, tmpDir)
+
+	// Test git status
+	_, err = GitDescribeCoreboot("./")
+	assert.NoError(t, err)
+}