pkg/vcs: add repo OptPrecious and OptDontSandbox options

The pkg/vcs code assumed that we fully manage the repo
within an autonomous program. In particular it tried
to repair any errors by dropping and re-creating the repo.
This does not work well for command-line tools that work
with a user-provided repo. Add OptPrecious for such uses.

Update #2171

12 files changed, 75 insertions, 87 deletions

diff --git a/pkg/bisect/bisect_test.go b/pkg/bisect/bisect_test.go
index ee730b724..3bbc2e2ea 100644
--- a/pkg/bisect/bisect_test.go
+++ b/pkg/bisect/bisect_test.go
@@ -106,7 +106,7 @@ func createTestRepo(t *testing.T) string {
 }
 
 func runBisection(t *testing.T, baseDir string, test BisectionTest) (*Result, error) {
-	r, err := vcs.NewRepo("test", "64", baseDir)
+	r, err := vcs.NewRepo("test", "64", baseDir, vcs.OptPrecious)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/pkg/vcs/akaros.go b/pkg/vcs/akaros.go
index 0d3e701fb..33dfb7850 100644
--- a/pkg/vcs/akaros.go
+++ b/pkg/vcs/akaros.go
@@ -12,10 +12,10 @@ type akaros struct {
 	dropbear *git
 }
 
-func newAkaros(vm, dir string) *akaros {
+func newAkaros(dir string, opts []RepoOpt) *akaros {
 	return &akaros{
-		git:      newGit(dir, nil),
-		dropbear: newGit(filepath.Join(dir, "dropbear"), nil),
+		git:      newGit(dir, nil, opts),
+		dropbear: newGit(filepath.Join(dir, "dropbear"), nil, opts),
 	}
 }
 
diff --git a/pkg/vcs/freebsd.go b/pkg/vcs/freebsd.go
deleted file mode 100644
index 222b15b87..000000000
--- a/pkg/vcs/freebsd.go
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright 2019 syzkaller project authors. All rights reserved.
-// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
-
-package vcs
-
-type freebsd struct {
-	*git
-}
-
-func newFreeBSD(vm, dir string) *freebsd {
-	return &freebsd{
-		git: newGit(dir, nil),
-	}
-}
diff --git a/pkg/vcs/fuchsia.go b/pkg/vcs/fuchsia.go
index 97e5f8b47..a604ec51b 100644
--- a/pkg/vcs/fuchsia.go
+++ b/pkg/vcs/fuchsia.go
@@ -12,16 +12,14 @@ import (
 )
 
 type fuchsia struct {
-	vm   string
 	dir  string
 	repo *git
 }
 
-func newFuchsia(vm, dir string) *fuchsia {
+func newFuchsia(dir string, opts []RepoOpt) *fuchsia {
 	return &fuchsia{
-		vm:   vm,
 		dir:  dir,
-		repo: newGit(dir, nil),
+		repo: newGit(dir, nil, opts),
 	}
 }
 
diff --git a/pkg/vcs/git.go b/pkg/vcs/git.go
index f487b60c2..aeb9d734d 100644
--- a/pkg/vcs/git.go
+++ b/pkg/vcs/git.go
@@ -23,16 +23,26 @@ import (
 
 type git struct {
 	dir      string
-	sandbox  bool
 	ignoreCC map[string]bool
+	precious bool
+	sandbox  bool
 }
 
-func newGit(dir string, ignoreCC map[string]bool) *git {
-	return &git{
+func newGit(dir string, ignoreCC map[string]bool, opts []RepoOpt) *git {
+	git := &git{
 		dir:      dir,
-		sandbox:  true,
 		ignoreCC: ignoreCC,
+		sandbox:  true,
 	}
+	for _, opt := range opts {
+		switch opt {
+		case OptPrecious:
+			git.precious = true
+		case OptDontSandbox:
+			git.sandbox = false
+		}
+	}
+	return git
 }
 
 func filterEnv() []string {
@@ -86,11 +96,8 @@ func (git *git) Poll(repo, branch string) (*Commit, error) {
 }
 
 func (git *git) CheckoutBranch(repo, branch string) (*Commit, error) {
-	git.reset()
-	if _, err := git.git("reset", "--hard"); err != nil {
-		if err := git.initRepo(err); err != nil {
-			return nil, err
-		}
+	if err := git.repair(); err != nil {
+		return nil, err
 	}
 	_, err := git.git("fetch", repo, branch)
 	if err != nil {
@@ -103,11 +110,8 @@ func (git *git) CheckoutBranch(repo, branch string) (*Commit, error) {
 }
 
 func (git *git) CheckoutCommit(repo, commit string) (*Commit, error) {
-	git.reset()
-	if _, err := git.git("reset", "--hard"); err != nil {
-		if err := git.initRepo(err); err != nil {
-			return nil, err
-		}
+	if err := git.repair(); err != nil {
+		return nil, err
 	}
 	if err := git.fetchRemote(repo); err != nil {
 		return nil, err
@@ -124,8 +128,10 @@ func (git *git) fetchRemote(repo string) error {
 }
 
 func (git *git) SwitchCommit(commit string) (*Commit, error) {
-	git.git("reset", "--hard")
-	git.git("clean", "-fdx")
+	if !git.precious {
+		git.git("reset", "--hard")
+		git.git("clean", "-fdx")
+	}
 	if _, err := git.git("checkout", commit); err != nil {
 		return nil, err
 	}
@@ -133,6 +139,9 @@ func (git *git) SwitchCommit(commit string) (*Commit, error) {
 }
 
 func (git *git) clone(repo, branch string) error {
+	if git.precious {
+		return fmt.Errorf("won't reinit precious repo")
+	}
 	if err := git.initRepo(nil); err != nil {
 		return err
 	}
@@ -145,12 +154,23 @@ func (git *git) clone(repo, branch string) error {
 	return nil
 }
 
-func (git *git) reset() {
+func (git *git) reset() error {
 	// This function tries to reset git repo state to a known clean state.
+	if git.precious {
+		return nil
+	}
 	git.git("reset", "--hard")
 	git.git("clean", "-fdx")
 	git.git("bisect", "reset")
-	git.git("reset", "--hard")
+	_, err := git.git("reset", "--hard")
+	return err
+}
+
+func (git *git) repair() error {
+	if err := git.reset(); err != nil {
+		return git.initRepo(err)
+	}
+	return nil
 }
 
 func (git *git) initRepo(reason error) error {
diff --git a/pkg/vcs/git_repo_test.go b/pkg/vcs/git_repo_test.go
index 4deb1a381..a2610315f 100644
--- a/pkg/vcs/git_repo_test.go
+++ b/pkg/vcs/git_repo_test.go
@@ -28,7 +28,7 @@ func TestGitRepo(t *testing.T) {
 	defer os.RemoveAll(baseDir)
 	repo1 := CreateTestRepo(t, baseDir, "repo1")
 	repo2 := CreateTestRepo(t, baseDir, "repo2")
-	repo := newGit(filepath.Join(baseDir, "repo"), nil)
+	repo := newGit(filepath.Join(baseDir, "repo"), nil, nil)
 	{
 		com, err := repo.Poll(repo1.Dir, "master")
 		if err != nil {
diff --git a/pkg/vcs/git_test_util.go b/pkg/vcs/git_test_util.go
index 5ef6c50c3..a1dbf0dd9 100644
--- a/pkg/vcs/git_test_util.go
+++ b/pkg/vcs/git_test_util.go
@@ -49,7 +49,7 @@ func MakeTestRepo(t *testing.T, dir string) *TestRepo {
 		Dir:     dir,
 		name:    filepath.Base(dir),
 		Commits: make(map[string]map[string]*Commit),
-		repo:    newGit(dir, ignoreCC),
+		repo:    newGit(dir, ignoreCC, []RepoOpt{OptPrecious, OptDontSandbox}),
 	}
 	repo.Git("init")
 	repo.Git("config", "--add", "user.email", userEmail)
@@ -123,7 +123,7 @@ func CloneTestRepo(t *testing.T, baseDir, name string, originRepo *TestRepo) *Te
 		Dir:     dir,
 		name:    filepath.Base(dir),
 		Commits: make(map[string]map[string]*Commit),
-		repo:    newGit(dir, ignoreCC),
+		repo:    newGit(dir, ignoreCC, []RepoOpt{OptPrecious, OptDontSandbox}),
 	}
 	repo.Git("clone", originRepo.Dir, repo.Dir)
 	return repo
diff --git a/pkg/vcs/linux.go b/pkg/vcs/linux.go
index c4e2a90a5..2d20af53c 100644
--- a/pkg/vcs/linux.go
+++ b/pkg/vcs/linux.go
@@ -26,15 +26,17 @@ type linux struct {
 	*git
 }
 
-var _ Bisecter = new(linux)
-var _ ConfigMinimizer = new(linux)
+var (
+	_ Bisecter        = new(linux)
+	_ ConfigMinimizer = new(linux)
+)
 
-func newLinux(dir string) *linux {
+func newLinux(dir string, opts []RepoOpt) *linux {
 	ignoreCC := map[string]bool{
 		"stable@vger.kernel.org": true,
 	}
 	return &linux{
-		git: newGit(dir, ignoreCC),
+		git: newGit(dir, ignoreCC, opts),
 	}
 }
 
diff --git a/pkg/vcs/netbsd.go b/pkg/vcs/netbsd.go
deleted file mode 100644
index 6b710f4ca..000000000
--- a/pkg/vcs/netbsd.go
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright 2018 syzkaller project authors. All rights reserved.
-// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
-
-package vcs
-
-type netbsd struct {
-	*git
-}
-
-func newNetBSD(vm, dir string) *netbsd {
-	return &netbsd{
-		git: newGit(dir, nil),
-	}
-}
diff --git a/pkg/vcs/openbsd.go b/pkg/vcs/openbsd.go
deleted file mode 100644
index f97290f99..000000000
--- a/pkg/vcs/openbsd.go
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright 2018 syzkaller project authors. All rights reserved.
-// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
-
-package vcs
-
-type openbsd struct {
-	*git
-}
-
-func newOpenBSD(vm, dir string) *openbsd {
-	return &openbsd{
-		git: newGit(dir, nil),
-	}
-}
diff --git a/pkg/vcs/testos.go b/pkg/vcs/testos.go
index ad6df6b1e..20a63973a 100644
--- a/pkg/vcs/testos.go
+++ b/pkg/vcs/testos.go
@@ -14,9 +14,9 @@ type testos struct {
 
 var _ ConfigMinimizer = new(testos)
 
-func newTestos(dir string) *testos {
+func newTestos(dir string, opts []RepoOpt) *testos {
 	return &testos{
-		git: newGit(dir, nil),
+		git: newGit(dir, nil, opts),
 	}
 }
 
diff --git a/pkg/vcs/vcs.go b/pkg/vcs/vcs.go
index 1f12fa85a..4185bf165 100644
--- a/pkg/vcs/vcs.go
+++ b/pkg/vcs/vcs.go
@@ -155,29 +155,39 @@ type BisectEnv struct {
 	KernelConfig []byte
 }
 
-func NewRepo(os, vm, dir string) (Repo, error) {
+type RepoOpt int
+
+const (
+	// RepoPrecious is intended for command-line tools that work with a user-provided repo.
+	// Such repo won't be re-created to recover from errors, but rather return errors.
+	// If this option is not specified, the repo can be re-created from scratch to recover from any errors.
+	OptPrecious RepoOpt = iota
+	// Don't use sandboxing suitable for pkg/build.
+	OptDontSandbox
+)
+
+func NewRepo(os, vm, dir string, opts ...RepoOpt) (Repo, error) {
 	switch os {
 	case "linux":
-		return newLinux(dir), nil
+		return newLinux(dir, opts), nil
 	case "akaros":
-		return newAkaros(vm, dir), nil
+		return newAkaros(dir, opts), nil
 	case "fuchsia":
-		return newFuchsia(vm, dir), nil
+		return newFuchsia(dir, opts), nil
 	case "openbsd":
-		return newOpenBSD(vm, dir), nil
+		return newGit(dir, nil, opts), nil
 	case "netbsd":
-		return newNetBSD(vm, dir), nil
+		return newGit(dir, nil, opts), nil
 	case "freebsd":
-		return newFreeBSD(vm, dir), nil
+		return newGit(dir, nil, opts), nil
 	case "test":
-		return newTestos(dir), nil
+		return newTestos(dir, opts), nil
 	}
 	return nil, fmt.Errorf("vcs is unsupported for %v", os)
 }
 
 func NewSyzkallerRepo(dir string) Repo {
-	git := newGit(dir, nil)
-	git.sandbox = false
+	git := newGit(dir, nil, []RepoOpt{OptDontSandbox})
 	return git
 }