Work on worktree support

libs/git/repository.go

@@ -1,7 +1,6 @@
 package git
 
 import (
-	"bufio"
 	"errors"
 	"fmt"
 	"io/fs"
@@ -24,8 +23,18 @@ type Repository struct {
 	// directory where we process .gitignore files.
 	real bool
 
-	// root is the absolute path to the repository root.
-	root vfs.Path
+	// rootDir is the path to the root of the repository checkout.
+	// This can be either the main repository checkout or a worktree.
+	rootDir vfs.Path
+
+	// gitDir is the equivalent of $GIT_DIR and points to the
+	// `.git` directory of a repository or a worktree.
+	gitDir vfs.Path
+
+	// gitCommonDir is the equivalent of $GIT_COMMON_DIR and points to the
+	// `.git` directory of the main working tree (common between worktrees).
+	// This is equivalent to [gitDir] if this is the main working tree.
+	gitCommonDir vfs.Path
 
 	// ignore contains a list of ignore patterns indexed by the
 	// path prefix relative to the repository root.
@@ -45,12 +54,11 @@ type Repository struct {
 
 // Root returns the absolute path to the repository root.
 func (r *Repository) Root() string {
-	return r.root.Native()
+	return r.rootDir.Native()
 }
 
 func (r *Repository) CurrentBranch() (string, error) {
-	// load .git/HEAD
-	ref, err := LoadReferenceFile(r.root, path.Join(GitDirectoryName, "HEAD"))
+	ref, err := LoadReferenceFile(r.gitDir, "HEAD")
 	if err != nil {
 		return "", err
 	}
@@ -66,8 +74,7 @@ func (r *Repository) CurrentBranch() (string, error) {
 }
 
 func (r *Repository) LatestCommit() (string, error) {
-	// load .git/HEAD
-	ref, err := LoadReferenceFile(r.root, path.Join(GitDirectoryName, "HEAD"))
+	ref, err := LoadReferenceFile(r.gitDir, "HEAD")
 	if err != nil {
 		return "", err
 	}
@@ -81,12 +88,12 @@ func (r *Repository) LatestCommit() (string, error) {
 		return ref.Content, nil
 	}
 
-	// read reference from .git/HEAD
+	// Read reference from $GIT_DIR/HEAD
 	branchHeadPath, err := ref.ResolvePath()
 	if err != nil {
 		return "", err
 	}
-	branchHeadRef, err := LoadReferenceFile(r.root, path.Join(GitDirectoryName, branchHeadPath))
+	branchHeadRef, err := LoadReferenceFile(r.gitCommonDir, branchHeadPath)
 	if err != nil {
 		return "", err
 	}
@@ -120,54 +127,13 @@ func (r *Repository) OriginUrl() string {
 	return parsedUrl.String()
 }
 
-func readGitDir(root vfs.Path) (string, error) {
-	file, err := root.Open(".git")
-	if err != nil {
-		return "", fmt.Errorf("error opening file: %w", err)
-	}
-	defer file.Close()
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		line := scanner.Text()
-		if strings.HasPrefix(line, "gitdir: ") {
-			// Extract the path after "gitdir: "
-			return strings.TrimSpace(strings.TrimPrefix(line, "gitdir: ")), nil
-		}
-	}
-
-	if err := scanner.Err(); err != nil {
-		return "", fmt.Errorf("error reading file: %w", err)
-	}
-
-	return "", errors.New("gitdir line not found")
-}
-
-func (r *Repository) resolveGitRoot() vfs.Path {
-	fileInfo, err := r.root.Stat(".git")
-	if err != nil {
-		return r.root
-	}
-	if fileInfo.IsDir() {
-		return r.root
-	}
-	gitDir, err := readGitDir(r.root)
-	if err != nil {
-		return r.root
-	}
-	return vfs.MustNew(gitDir)
-}
-
 // loadConfig loads and combines user specific and repository specific configuration files.
 func (r *Repository) loadConfig() error {
 	config, err := globalGitConfig()
 	if err != nil {
 		return fmt.Errorf("unable to load user specific gitconfig: %w", err)
 	}
-	root := r.resolveGitRoot()
-	if root == nil {
-		return fmt.Errorf("unable to resolve git root")
-	}
-	err = config.loadFile(root, ".git/config")
+	err = config.loadFile(r.gitCommonDir, "config")
 	if err != nil {
 		return fmt.Errorf("unable to load repository specific gitconfig: %w", err)
 	}
@@ -175,12 +141,6 @@ func (r *Repository) loadConfig() error {
 	return nil
 }
 
-// newIgnoreFile constructs a new [ignoreRules] implementation backed by
-// a file using the specified path relative to the repository root.
-func (r *Repository) newIgnoreFile(relativeIgnoreFilePath string) ignoreRules {
-	return newIgnoreFile(r.resolveGitRoot(), relativeIgnoreFilePath)
-}
-
 // getIgnoreRules returns a slice of [ignoreRules] that apply
 // for the specified prefix. The prefix must be cleaned by the caller.
 // It lazily initializes an entry for the specified prefix if it
@@ -191,7 +151,7 @@ func (r *Repository) getIgnoreRules(prefix string) []ignoreRules {
 		return fs
 	}
 
-	r.ignore[prefix] = append(r.ignore[prefix], r.newIgnoreFile(path.Join(prefix, gitIgnoreFileName)))
+	r.ignore[prefix] = append(r.ignore[prefix], newIgnoreFile(r.rootDir, path.Join(prefix, gitIgnoreFileName)))
 	return r.ignore[prefix]
 }
 
@@ -247,7 +207,7 @@ func (r *Repository) Ignore(relPath string) (bool, error) {
 
 func NewRepository(path vfs.Path) (*Repository, error) {
 	real := true
-	rootPath, err := vfs.FindLeafInTree(path, GitDirectoryName)
+	rootDir, err := vfs.FindLeafInTree(path, GitDirectoryName)
 	if err != nil {
 		if !errors.Is(err, fs.ErrNotExist) {
 			return nil, err
@@ -255,12 +215,21 @@ func NewRepository(path vfs.Path) (*Repository, error) {
 		// Cannot find `.git` directory.
 		// Treat the specified path as a potential repository root.
 		real = false
-		rootPath = path
+		rootDir = path
+	}
+
+	// Derive $GIT_DIR and $GIT_COMMON_DIR paths if this is a real repository.
+	// If it isn't a real repository, they'll point to the (non-existent) `.git` directory.
+	gitDir, gitCommonDir, err := resolveGitDirs(rootDir)
+	if err != nil {
+		return nil, err
 	}
 
 	repo := &Repository{
 		real:         real,
-		root:   rootPath,
+		rootDir:      rootDir,
+		gitDir:       gitDir,
+		gitCommonDir: gitCommonDir,
 		ignore:       make(map[string][]ignoreRules),
 	}
 
@@ -295,9 +264,9 @@ func NewRepository(path vfs.Path) (*Repository, error) {
 			".git",
 		}),
 		// Load repository-wide excludes file.
-		repo.newIgnoreFile(".git/info/excludes"),
+		newIgnoreFile(repo.gitCommonDir, "info/excludes"),
 		// Load root gitignore file.
-		repo.newIgnoreFile(".gitignore"),
+		newIgnoreFile(repo.rootDir, ".gitignore"),
 	}
 
 	return repo, nil

libs/git/view.go

@@ -80,7 +80,7 @@ func NewView(root vfs.Path) (*View, error) {
 
 	// Target path must be relative to the repository root path.
 	target := root.Native()
-	prefix := repo.root.Native()
+	prefix := repo.rootDir.Native()
 	if !strings.HasPrefix(target, prefix) {
 		return nil, fmt.Errorf("path %q is not within repository root %q", root.Native(), prefix)
 	}
@@ -107,17 +107,6 @@ func (v *View) EnsureValidGitIgnoreExists() error {
 		return nil
 	}
 
-	// Hard code .databricks ignore pattern so that we never sync it (irrespective)
-	// of .gitignore patterns
-	v.repo.addIgnoreRule(newStringIgnoreRules([]string{
-		".databricks",
-	}))
-
-	// Bail if we are in a worktree
-	if v.repo.Root() != v.repo.resolveGitRoot().Native() {
-		return nil
-	}
-
 	// Create .gitignore with .databricks entry
 	gitIgnorePath := filepath.Join(v.repo.Root(), v.targetPath, ".gitignore")
 	file, err := os.OpenFile(gitIgnorePath, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0644)
@@ -126,6 +115,12 @@ func (v *View) EnsureValidGitIgnoreExists() error {
 	}
 	defer file.Close()
 
+	// Hard code .databricks ignore pattern so that we never sync it (irrespective)
+	// of .gitignore patterns
+	v.repo.addIgnoreRule(newStringIgnoreRules([]string{
+		".databricks",
+	}))
+
 	_, err = file.WriteString("\n.databricks\n")
 	if err != nil {
 		return err

libs/git/worktree.go

@@ -0,0 +1,122 @@
+package git
+
+import (
+	"bufio"
+	"errors"
+	"io/fs"
+	"path/filepath"
+	"strings"
+
+	"github.com/databricks/cli/libs/vfs"
+)
+
+func readLines(root vfs.Path, name string) ([]string, error) {
+	file, err := root.Open(name)
+	if err != nil {
+		return nil, err
+	}
+
+	defer file.Close()
+
+	var lines []string
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+
+	return lines, scanner.Err()
+}
+
+// readGitDir reads the value of the `.git` file in a worktree.
+func readGitDir(root vfs.Path) (string, error) {
+	lines, err := readLines(root, GitDirectoryName)
+	if err != nil {
+		return "", err
+	}
+
+	var gitDir string
+	for _, line := range lines {
+		parts := strings.SplitN(line, ": ", 2)
+		if len(parts) != 2 {
+			continue
+		}
+
+		if parts[0] == "gitdir" {
+			gitDir = strings.TrimSpace(parts[1])
+		}
+	}
+
+	if gitDir == "" {
+		return "", errors.New("gitdir line not found")
+	}
+
+	return gitDir, nil
+}
+
+// readGitCommonDir reads the value of the `commondir` file in the `.git` directory of a worktree.
+// This file typically contains "../.." to point to $GIT_COMMON_DIR.
+func readGitCommonDir(gitDir vfs.Path) (string, error) {
+	lines, err := readLines(gitDir, "commondir")
+	if err != nil {
+		return "", err
+	}
+
+	if len(lines) == 0 {
+		return "", errors.New("commondir file not found")
+	}
+
+	return lines[0], nil
+}
+
+// resolveGitDirs resolves the paths for $GIT_DIR and $GIT_COMMON_DIR.
+// The path argument is the root of the checkout where (supposedly) a `.git` file or directory exists.
+func resolveGitDirs(root vfs.Path) (vfs.Path, vfs.Path, error) {
+	fileInfo, err := root.Stat(GitDirectoryName)
+	if err != nil {
+		// If the `.git` file or directory does not exist, then this is not a git repository.
+		// Return paths that we know don't exist, so we do not need to perform nil checks in the caller.
+		if errors.Is(err, fs.ErrNotExist) {
+			gitDir := vfs.MustNew(filepath.Join(root.Native(), GitDirectoryName))
+			return gitDir, gitDir, nil
+		}
+		return nil, nil, err
+	}
+
+	// If the path is a directory, then it is the main working tree.
+	// Both $GIT_DIR and $GIT_COMMON_DIR point to the same directory.
+	if fileInfo.IsDir() {
+		gitDir := vfs.MustNew(filepath.Join(root.Native(), GitDirectoryName))
+		return gitDir, gitDir, nil
+	}
+
+	// If the path is not a directory, then it is a worktree.
+	// Read value for $GIT_DIR.
+	gitDirValue, err := readGitDir(root)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Resolve $GIT_DIR.
+	var gitDir vfs.Path
+	if filepath.IsAbs(gitDirValue) {
+		gitDir = vfs.MustNew(gitDirValue)
+	} else {
+		gitDir = vfs.MustNew(filepath.Join(root.Native(), gitDirValue))
+	}
+
+	// Read value for $GIT_COMMON_DIR.
+	gitCommonDirValue, err := readGitCommonDir(gitDir)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Resolve $GIT_COMMON_DIR.
+	var gitCommonDir vfs.Path
+	if filepath.IsAbs(gitCommonDirValue) {
+		gitCommonDir = vfs.MustNew(gitCommonDirValue)
+	} else {
+		gitCommonDir = vfs.MustNew(filepath.Join(gitDir.Native(), gitCommonDirValue))
+	}
+
+	return gitDir, gitCommonDir, nil
+}

libs/git/worktree_test.go

@@ -0,0 +1 @@
+package git