Don't let our repo answer for a different one

GIT_DIR and GIT_WORK_TREE tell git where our repo is, and every command
we run inherits them — including the ones we point at a submodule or
another worktree. git resolves those against our repo instead, and says
nothing about it: with GIT_DIR set, `git -C mysub log -1` reports the
superproject's commit. So opening lazygit with --git-dir/--work-tree
quietly broke resolving submodule conflicts, stashing and resetting a
submodule, and detaching another worktree; the worktree list came back
claiming every worktree shared our git dir.

Drop the two variables from the commands that address another repo.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

pkg/commands/git_commands/git_command_builder.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
 	"github.com/jesseduffield/lazygit/pkg/config"
+	"github.com/jesseduffield/lazygit/pkg/env"
 )
 
 // OptionalLocksEnvVar is the name of the environment variable that tells git
@@ -18,6 +19,15 @@ import (
 // that opts back in is the foreground files refresh; see FileLoader.gitStatus.
 const OptionalLocksEnvVar = "GIT_OPTIONAL_LOCKS"
 
+// forOtherRepo prepares a command that operates on a repo other than the one
+// we have open — a submodule, or another worktree. GIT_DIR and GIT_WORK_TREE
+// say where our repo is, and every command we run inherits them, so a command
+// pointed at a different repo would be resolved against ours instead: `git -C
+// <submodule> log` would silently log the superproject's commits.
+func forOtherRepo(cmdObj *oscommands.CmdObj) *oscommands.CmdObj {
+	return cmdObj.RemoveEnvVar(env.GitDirEnvVar).RemoveEnvVar(env.GitWorkTreeEnvVar)
+}
+
 // convenience struct for building git commands. Especially useful when
 // including conditional args
 type GitCommandBuilder struct {

pkg/commands/git_commands/repo_paths.go

@@ -176,17 +176,40 @@ func getBareRepoPathsForDir(
 	}, nil
 }
 
+// Asks git about the repo at dir. This is how we find our own repo, so it has
+// to be answered the way git itself would answer it there, GIT_DIR and
+// GIT_WORK_TREE included.
 func callGitRevParseWithDir(
 	cmd oscommands.ICmdObjBuilder,
 	dir string,
 	gitRevArgs ...string,
 ) (string, error) {
+	return runGitRevParse(newGitRevParseCmd(cmd, dir, gitRevArgs...))
+}
+
+// Asks git about a repo that isn't the one we have open; see forOtherRepo.
+func callGitRevParseInOtherRepo(
+	cmd oscommands.ICmdObjBuilder,
+	dir string,
+	gitRevArgs ...string,
+) (string, error) {
+	return runGitRevParse(forOtherRepo(newGitRevParseCmd(cmd, dir, gitRevArgs...)))
+}
+
+func newGitRevParseCmd(
+	cmd oscommands.ICmdObjBuilder,
+	dir string,
+	gitRevArgs ...string,
+) *oscommands.CmdObj {
 	gitRevParse := NewGitCmd("rev-parse").Arg("--path-format=absolute").Arg(gitRevArgs...)
 	if dir != "" {
 		gitRevParse.Dir(dir)
 	}
 
-	gitCmd := cmd.New(gitRevParse.ToArgv()).DontLog()
+	return cmd.New(gitRevParse.ToArgv()).DontLog()
+}
+
+func runGitRevParse(gitCmd *oscommands.CmdObj) (string, error) {
 	res, err := gitCmd.RunWithOutput()
 	if err != nil {
 		return "", errors.Errorf("'%s' failed: %v", gitCmd.ToString(), err)

pkg/commands/git_commands/submodule.go

@@ -157,7 +157,7 @@ func (self *SubmoduleCommands) GetCommitSummary(path string, sha string) (string
 		Config("log.showsignature=false").
 		ToArgv()
 
-	summary, err := self.cmd.New(cmdArgs).DontLog().RunWithOutput()
+	summary, err := forOtherRepo(self.cmd.New(cmdArgs)).DontLog().RunWithOutput()
 	return strings.TrimSpace(summary), err
 }
 
@@ -167,7 +167,7 @@ func (self *SubmoduleCommands) GetCommitSummary(path string, sha string) (string
 // caller then stages the submodule to record the resolution.
 func (self *SubmoduleCommands) CheckoutConflictCommit(path string, sha string) error {
 	cmdArgs := NewGitCmd("checkout").Dir(path).Arg(sha).ToArgv()
-	return self.cmd.New(cmdArgs).Run()
+	return forOtherRepo(self.cmd.New(cmdArgs)).Run()
 }
 
 // ConflictSideLog returns a oneline log, run inside the submodule, of the commits
@@ -179,7 +179,7 @@ func (self *SubmoduleCommands) ConflictSideLog(path string, side string, otherSi
 		Arg("--oneline", "--color=always", otherSide+".."+side).
 		ToArgv()
 
-	return self.cmd.New(cmdArgs).DontLog().RunWithOutput()
+	return forOtherRepo(self.cmd.New(cmdArgs)).DontLog().RunWithOutput()
 }
 
 func (self *SubmoduleCommands) Stash(submodule *models.SubmoduleConfig) error {
@@ -195,7 +195,7 @@ func (self *SubmoduleCommands) Stash(submodule *models.SubmoduleConfig) error {
 		Arg("--include-untracked").
 		ToArgv()
 
-	return self.cmd.New(cmdArgs).Run()
+	return forOtherRepo(self.cmd.New(cmdArgs)).Run()
 }
 
 func (self *SubmoduleCommands) Reset(submodule *models.SubmoduleConfig) error {
@@ -229,7 +229,7 @@ func (self *SubmoduleCommands) UpdateAll() error {
 // need not be.
 func (self *SubmoduleCommands) runInParentModule(submodule *models.SubmoduleConfig, cmdObj *oscommands.CmdObj) error {
 	if submodule.ParentModule != nil {
-		cmdObj.SetWd(submodule.ParentModule.FullPath())
+		forOtherRepo(cmdObj.SetWd(submodule.ParentModule.FullPath()))
 	}
 	return cmdObj.Run()
 }

pkg/commands/git_commands/submodule_test.go

@@ -1,10 +1,13 @@
 package git_commands
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/go-errors/errors"
 	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
+	"github.com/jesseduffield/lazygit/pkg/env"
+	"github.com/samber/lo"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -80,6 +83,27 @@ func TestSubmoduleCheckoutConflictCommit(t *testing.T) {
 	runner.CheckForMissingCalls()
 }
 
+// A command that runs inside a submodule mustn't inherit the GIT_DIR and
+// GIT_WORK_TREE that say where the superproject is; git would answer it from
+// there instead, and the answer would look perfectly plausible.
+func TestSubmoduleCommandDoesntUseOurGitLocation(t *testing.T) {
+	t.Setenv(env.GitDirEnvVar, "/path/to/repo/.git")
+	t.Setenv(env.GitWorkTreeEnvVar, "/path/to/repo")
+
+	runner := oscommands.NewFakeRunner(t).
+		ExpectFunc("has neither GIT_DIR nor GIT_WORK_TREE", func(cmdObj *oscommands.CmdObj) bool {
+			return lo.NoneBy(cmdObj.GetEnvVars(), func(envVar string) bool {
+				return strings.HasPrefix(envVar, env.GitDirEnvVar+"=") ||
+					strings.HasPrefix(envVar, env.GitWorkTreeEnvVar+"=")
+			})
+		}, "bbbbbbb the subject\n", nil)
+	instance := buildSubmoduleCommands(commonDeps{runner: runner})
+
+	_, err := instance.GetCommitSummary("mysub", "bbbbbbb")
+	assert.NoError(t, err)
+	runner.CheckForMissingCalls()
+}
+
 func TestSubmoduleConflictSideLog(t *testing.T) {
 	runner := oscommands.NewFakeRunner(t).
 		ExpectGitArgs([]string{"-C", "mysub", "log", "--oneline", "--color=always", "ccccccc..bbbbbbb"}, "bbbbbbb left\n", nil)

pkg/commands/git_commands/worktree.go

@@ -51,7 +51,7 @@ func (self *WorktreeCommands) Delete(worktreePath string, force bool) error {
 func (self *WorktreeCommands) Detach(worktreePath string) error {
 	cmdArgs := NewGitCmd("checkout").Arg("--detach").GitDir(filepath.Join(worktreePath, ".git")).ToArgv()
 
-	return self.cmd.New(cmdArgs).Run()
+	return forOtherRepo(self.cmd.New(cmdArgs)).Run()
 }
 
 func WorktreeForBranch(branch *models.Branch, worktrees []*models.Worktree) (*models.Worktree, bool) {

pkg/commands/git_commands/worktree_loader.go

@@ -77,7 +77,7 @@ func (self *WorktreeLoader) GetWorktrees() ([]*models.Worktree, error) {
 			if worktree.IsPathMissing {
 				return
 			}
-			gitDir, err := callGitRevParseWithDir(self.cmd, worktree.Path, "--absolute-git-dir")
+			gitDir, err := callGitRevParseInOtherRepo(self.cmd, worktree.Path, "--absolute-git-dir")
 			if err != nil {
 				self.Log.Warnf("Could not find git dir for worktree %s: %v", worktree.Path, err)
 				return

pkg/env/env.go

@@ -6,23 +6,30 @@ import (
 
 // This package encapsulates accessing/mutating the ENV of the program.
 
+// The variables with which git can be told where a repo is, rather than having
+// it find out from the working directory.
+const (
+	GitDirEnvVar      = "GIT_DIR"
+	GitWorkTreeEnvVar = "GIT_WORK_TREE"
+)
+
 func GetGitDirEnv() string {
-	return os.Getenv("GIT_DIR")
+	return os.Getenv(GitDirEnvVar)
 }
 
 func SetGitDirEnv(value string) {
-	os.Setenv("GIT_DIR", value)
+	os.Setenv(GitDirEnvVar, value)
 }
 
 func GetWorkTreeEnv() string {
-	return os.Getenv("GIT_WORK_TREE")
+	return os.Getenv(GitWorkTreeEnvVar)
 }
 
 func SetWorkTreeEnv(value string) {
-	os.Setenv("GIT_WORK_TREE", value)
+	os.Setenv(GitWorkTreeEnvVar, value)
 }
 
 func UnsetGitLocationEnvVars() {
-	_ = os.Unsetenv("GIT_DIR")
-	_ = os.Unsetenv("GIT_WORK_TREE")
+	_ = os.Unsetenv(GitDirEnvVar)
+	_ = os.Unsetenv(GitWorkTreeEnvVar)
 }