[go] cmd/go/internal/vcs: support git worktrees

[Josh Bleecher Snyder (Gerrit)]

Josh Bleecher Snyder has uploaded the change for review

Commit message

cmd/go/internal/vcs: support git worktrees

Fixes golang/go#58218

Change-Id: Ia155b26514557cf822caf37e727e5a410b0a36a6

Change diff

diff --git a/src/cmd/go/internal/vcs/vcs.go b/src/cmd/go/internal/vcs/vcs.go
index 7c198c5..fdcefac 100644
--- a/src/cmd/go/internal/vcs/vcs.go
+++ b/src/cmd/go/internal/vcs/vcs.go
@@ -161,7 +161,7 @@
 	// config options or certain extensions.
 	Env: []string{"HGPLAIN=1"},
 	RootNames: []rootName{
-		{filename: ".hg", isDir: true},
+		{filename: ".hg", isRoot: isDir},
 	},
 
 	CreateCmd:   []string{"clone -U -- {repo} {dir}"},
@@ -250,7 +250,7 @@
 	Name: "Git",
 	Cmd:  "git",
 	RootNames: []rootName{
-		{filename: ".git", isDir: true},
+		{filename: ".git", isRoot: isDirOrWorktree},
 	},
 
 	CreateCmd:   []string{"clone -- {repo} {dir}", "-go-internal-cd {dir} submodule update --init --recursive"},
@@ -364,7 +364,7 @@
 	Name: "Bazaar",
 	Cmd:  "bzr",
 	RootNames: []rootName{
-		{filename: ".bzr", isDir: true},
+		{filename: ".bzr", isRoot: isDir},
 	},
 
 	CreateCmd: []string{"branch -- {repo} {dir}"},
@@ -487,7 +487,7 @@
 	Name: "Subversion",
 	Cmd:  "svn",
 	RootNames: []rootName{
-		{filename: ".svn", isDir: true},
+		{filename: ".svn", isRoot: isDir},
 	},
 
 	CreateCmd:   []string{"checkout -- {repo} {dir}"},
@@ -570,8 +570,8 @@
 	Name: "Fossil",
 	Cmd:  "fossil",
 	RootNames: []rootName{
-		{filename: ".fslckout", isDir: false},
-		{filename: "_FOSSIL_", isDir: false},
+		{filename: ".fslckout", isRoot: isFile},
+		{filename: "_FOSSIL_", isRoot: isFile},
 	},
 
 	CreateCmd:   []string{"-go-internal-mkdir {dir} clone -- {repo} " + filepath.Join("{dir}", fossilRepoName), "-go-internal-cd {dir} open .fossil"},
@@ -755,7 +755,7 @@
 	if !cfg.ModulesEnabled {
 		dir = filepath.Join(cfg.BuildContext.GOPATH, "src")
 	}
-	os.MkdirAll(dir, 0777) // Ignore errors — if unsuccessful, the command will likely fail.
+	os.MkdirAll(dir, 0o777) // Ignore errors — if unsuccessful, the command will likely fail.
 
 	release, err := base.AcquireNet()
 	if err != nil {
@@ -932,18 +932,63 @@
 // any of the listed root names.
 func isVCSRoot(dir string, rootNames []rootName) bool {
 	for _, root := range rootNames {
-		fi, err := os.Stat(filepath.Join(dir, root.filename))
-		if err == nil && fi.IsDir() == root.isDir {
+		path := filepath.Join(dir, root.filename)
+		if root.isRoot(path) {
 			return true
 		}
 	}
-
 	return false
 }
 
+// rootName specifies how to identify the root directory of a VCS.
 type rootName struct {
-	filename string
-	isDir    bool
+	filename string                 // name of file or directory to look for
+	isRoot   func(path string) bool // isRoot reports whether path signifies a VCS root
+}
+
+// isDir reports whether path is a directory.
+func isDir(path string) bool {
+	fi, err := os.Stat(path)
+	return err == nil && fi.IsDir()
+}
+
+// isFile reports whether path is a regular file.
+func isFile(path string) bool {
+	fi, err := os.Stat(path)
+	return err == nil && fi.Mode().IsRegular()
+}
+
+// isDirOrWorktree reports whether path is a directory or a git worktree .git file.
+// See https://go.dev/issue/58218.
+func isDirOrWorktree(path string) bool {
+	fi, err := os.Stat(path)
+	if err != nil {
+		return false
+	}
+	if fi.IsDir() {
+		return true
+	}
+	// Is it a git worktree file?
+	// The format is "gitdir: <path>\n".
+	if !fi.Mode().IsRegular() || fi.Size() == 0 || fi.Size() > 4096 {
+		return false
+	}
+	raw, err := os.ReadFile(path)
+	if err != nil {
+		return false
+	}
+	rest, ok := strings.CutPrefix(string(raw), "gitdir:")
+	if !ok {
+		return false
+	}
+	gitdir := strings.TrimSpace(rest)
+	if gitdir == "" {
+		return false
+	}
+	if !filepath.IsAbs(gitdir) {
+		gitdir = filepath.Join(filepath.Dir(path), gitdir)
+	}
+	return isDir(gitdir)
 }
 
 type vcsNotFoundError struct {
diff --git a/src/cmd/go/internal/vcs/vcs_test.go b/src/cmd/go/internal/vcs/vcs_test.go
index 361d85b..5b66b95 100644
--- a/src/cmd/go/internal/vcs/vcs_test.go
+++ b/src/cmd/go/internal/vcs/vcs_test.go
@@ -6,7 +6,6 @@
 
 import (
 	"errors"
-	"fmt"
 	"internal/testenv"
 	"os"
 	"path/filepath"
@@ -215,40 +214,61 @@
 // Test that vcs.FromDir correctly inspects a given directory and returns the
 // right VCS and repo directory.
 func TestFromDir(t *testing.T) {
-	tempDir := t.TempDir()
-
-	for _, vcs := range vcsList {
-		for r, root := range vcs.RootNames {
-			vcsName := fmt.Sprint(vcs.Name, r)
-			dir := filepath.Join(tempDir, "example.com", vcsName, root.filename)
-			if root.isDir {
-				err := os.MkdirAll(dir, 0755)
-				if err != nil {
-					t.Fatal(err)
-				}
-			} else {
-				err := os.MkdirAll(filepath.Dir(dir), 0755)
-				if err != nil {
-					t.Fatal(err)
-				}
-				f, err := os.Create(dir)
-				if err != nil {
-					t.Fatal(err)
-				}
-				f.Close()
-			}
-
-			wantRepoDir := filepath.Dir(dir)
-			gotRepoDir, gotVCS, err := FromDir(dir, tempDir)
-			if err != nil {
-				t.Errorf("FromDir(%q, %q): %v", dir, tempDir, err)
-				continue
-			}
-			if gotRepoDir != wantRepoDir || gotVCS.Name != vcs.Name {
-				t.Errorf("FromDir(%q, %q) = RepoDir(%s), VCS(%s); want RepoDir(%s), VCS(%s)", dir, tempDir, gotRepoDir, gotVCS.Name, wantRepoDir, vcs.Name)
-			}
-		}
+	tests := []struct {
+		name   string
+		vcs    string
+		root   string
+		create func(path string) error
+	}{
+		{"hg", "Mercurial", ".hg", mkdir},
+		{"git_dir", "Git", ".git", mkdir},
+		{"git_worktree", "Git", ".git", createGitWorktreeFile},
+		{"bzr", "Bazaar", ".bzr", mkdir},
+		{"svn", "Subversion", ".svn", mkdir},
+		{"fossil_fslckout", "Fossil", ".fslckout", touch},
+		{"fossil_FOSSIL_", "Fossil", "_FOSSIL_", touch},
 	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tempDir := t.TempDir()
+			repoDir := filepath.Join(tempDir, "example.com")
+			if err := mkdir(repoDir); err != nil {
+				t.Fatal(err)
+			}
+			rootPath := filepath.Join(repoDir, tt.root)
+			if err := tt.create(rootPath); err != nil {
+				t.Fatal(err)
+			}
+			gotRepoDir, gotVCS, err := FromDir(repoDir, tempDir)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if gotRepoDir != repoDir {
+				t.Errorf("RepoDir = %q, want %q", gotRepoDir, repoDir)
+			}
+			if gotVCS.Name != tt.vcs {
+				t.Errorf("VCS = %q, want %q", gotVCS.Name, tt.vcs)
+			}
+		})
+	}
+}
+
+func mkdir(path string) error {
+	return os.Mkdir(path, 0o755)
+}
+
+func touch(path string) error {
+	return os.WriteFile(path, nil, 0o644)
+}
+
+func createGitWorktreeFile(path string) error {
+	gitdir := path + ".worktree"
+	// gitdir must point to a real directory
+	if err := mkdir(gitdir); err != nil {
+		return err
+	}
+	return os.WriteFile(path, []byte("gitdir: "+gitdir+"\n"), 0o644)
 }
 
 func TestIsSecure(t *testing.T) {
diff --git a/src/cmd/go/testdata/script/version_buildvcs_git_worktree.txt b/src/cmd/go/testdata/script/version_buildvcs_git_worktree.txt
new file mode 100644
index 0000000..651d169
--- /dev/null
+++ b/src/cmd/go/testdata/script/version_buildvcs_git_worktree.txt
@@ -0,0 +1,46 @@
+# Test that 'go build' stamps VCS information when building from a git worktree.
+# See https://go.dev/issue/58218.
+
+[!git] skip
+[short] skip
+
+# Create repo with a commit.
+cd repo
+exec git init
+exec git config user.email g.o.p...@go.dev
+exec git config user.name Gopher
+exec git add -A
+exec git commit -m 'initial commit'
+
+# Sanity check: building from main repo includes VCS info.
+go build -o main.exe .
+go version -m main.exe
+stdout '^\tbuild\tvcs=git$'
+stdout '^\tbuild\tvcs.modified=false$'
+
+# Create a worktree and build from it.
+exec git worktree add ../worktree HEAD
+cd ../worktree
+go build -o worktree.exe .
+go version -m worktree.exe
+stdout '^\tbuild\tvcs=git$'
+stdout '^\tbuild\tvcs.modified=false$'
+
+# Verify that vcs.modified is detected in the worktree.
+cp ../changed.go a.go
+go build -o modified.exe .
+go version -m modified.exe
+stdout '^\tbuild\tvcs.modified=true$'
+
+-- repo/go.mod --
+module example.com/worktree
+
+go 1.18
+-- repo/a.go --
+package main
+
+func main() {}
+-- changed.go --
+package main
+
+func main() { _ = 1 }

Change information

Files:

• M src/cmd/go/internal/vcs/vcs.go
• M src/cmd/go/internal/vcs/vcs_test.go
• A src/cmd/go/testdata/script/version_buildvcs_git_worktree.txt

Change size: M

Delta: 3 files changed, 157 insertions(+), 46 deletions(-)

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[Ian Lance Taylor (Gerrit)]

Attention needed from Josh Bleecher Snyder

Ian Lance Taylor added 2 comments

File src/cmd/go/internal/vcs/vcs.go

Line 758, Patchset 1 (Latest): os.MkdirAll(dir, 0o777) // Ignore errors — if unsuccessful, the command will likely fail.

Ian Lance Taylor . unresolved

Nit: minor cleanups like this should generally be in different CLs.

Line 946, Patchset 1 (Latest): isRoot func(path string) bool // isRoot reports whether path signifies a VCS root

Ian Lance Taylor . unresolved

Your code is a more or less straightforward step from the existing code, but consider something like

    type isVCSRoot interface {
        isRoot(dir string) bool
    }
    
    type vcsFileRoot string
    
    func (vfr vcsFileRoot) isRoot(dir string) {
        fi, err := os.Stat(filepath.Join(dir, string(vfr)))

        return err == nil && fi.Mode().IsRegular()
    }
    

    type vcsDirRoot string
    
    func (vfd vcsDirRoot) isRoot(dir string) {
        fi, err := os.Stat(filepath.Join(dir, string(vfd)))

        return err == nil && fi.IsDir()
    }

Then above write things like

    var vcsFossil = ...
        []isVCSRoot{
            vcsFileRoot(".fslckout"),
            vcsFileRoot("_FOSSIL_"),
        }

and

    func isVCSRoot(dir string, roots []isVCSRoot) bool {
        for _, root := range roots {
            if root.isRoot(dir) {
                return true
            }
        }
        return false
    }

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Josh Bleecher Snyder uploaded patch set #2 to this change.

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[Josh Bleecher Snyder (Gerrit)]

Attention needed from Ian Lance Taylor

Josh Bleecher Snyder added 3 comments

Patchset-level comments

File-level comment, Patchset 2 (Latest):

Josh Bleecher Snyder . resolved

Thanks, PTAL.

File src/cmd/go/internal/vcs/vcs.go

Line 758, Patchset 1: os.MkdirAll(dir, 0o777) // Ignore errors — if unsuccessful, the command will likely fail.

Ian Lance Taylor . unresolved

Nit: minor cleanups like this should generally be in different CLs.

Josh Bleecher Snyder

done, CL 736440

Line 946, Patchset 1: isRoot func(path string) bool // isRoot reports whether path signifies a VCS root

Ian Lance Taylor . unresolved

Your code is a more or less straightforward step from the existing code, but consider something like

    type isVCSRoot interface {
        isRoot(dir string) bool
    }
    
    type vcsFileRoot string
    
    func (vfr vcsFileRoot) isRoot(dir string) {
        fi, err := os.Stat(filepath.Join(dir, string(vfr)))
        return err == nil && fi.Mode().IsRegular()
    }
    
    type vcsDirRoot string
    
    func (vfd vcsDirRoot) isRoot(dir string) {
        fi, err := os.Stat(filepath.Join(dir, string(vfd)))
        return err == nil && fi.IsDir()
    }

Then above write things like

    var vcsFossil = ...
        []isVCSRoot{
            vcsFileRoot(".fslckout"),
            vcsFileRoot("_FOSSIL_"),
        }

and

    func isVCSRoot(dir string, roots []isVCSRoot) bool {
        for _, root := range roots {
            if root.isRoot(dir) {
                return true
            }
        }
        return false
    }

Josh Bleecher Snyder

Done. I adjusted the naming a bit to avoid collisions and improve clarity.

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3 comments

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File-level comment, Patchset 2 (Latest):

Ian Lance Taylor . resolved

Thanks.

File src/cmd/go/internal/vcs/vcs.go

Line 758, Patchset 1: os.MkdirAll(dir, 0o777) // Ignore errors — if unsuccessful, the command will likely fail.

Ian Lance Taylor . resolved

Nit: minor cleanups like this should generally be in different CLs.

Josh Bleecher Snyder

done, CL 736440

Ian Lance Taylor

Acknowledged

Line 946, Patchset 1: isRoot func(path string) bool // isRoot reports whether path signifies a VCS root

Ian Lance Taylor . resolved

Your code is a more or less straightforward step from the existing code, but consider something like

    type isVCSRoot interface {
        isRoot(dir string) bool
    }
    
    type vcsFileRoot string
    
    func (vfr vcsFileRoot) isRoot(dir string) {
        fi, err := os.Stat(filepath.Join(dir, string(vfr)))
        return err == nil && fi.Mode().IsRegular()
    }
    
    type vcsDirRoot string
    
    func (vfd vcsDirRoot) isRoot(dir string) {
        fi, err := os.Stat(filepath.Join(dir, string(vfd)))
        return err == nil && fi.IsDir()
    }

Then above write things like

    var vcsFossil = ...
        []isVCSRoot{
            vcsFileRoot(".fslckout"),
            vcsFileRoot("_FOSSIL_"),
        }

and

    func isVCSRoot(dir string, roots []isVCSRoot) bool {
        for _, root := range roots {
            if root.isRoot(dir) {
                return true
            }
        }
        return false
    }

Josh Bleecher Snyder

Done. I adjusted the naming a bit to avoid collisions and improve clarity.

Ian Lance Taylor

Done

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