Support VFS2 save/restore.

Inode number consistency checks are now skipped in save/restore tests for
reasons described in greatest detail in StatTest.StateDoesntChangeAfterRename.
They pass in VFS1 due to the bug described in new test case
SimpleStatTest.DifferentFilesHaveDifferentDeviceInodeNumberPairs.

Fixes #1663

PiperOrigin-RevId: 338776148

7 files changed, 70 insertions, 72 deletions

diff --git a/test/util/BUILD b/test/util/BUILD
index 26c2b6a2f..1b028a477 100644
--- a/test/util/BUILD
+++ b/test/util/BUILD
@@ -155,6 +155,10 @@ cc_library(
     ],
     hdrs = ["save_util.h"],
     defines = select_system(),
+    deps = [
+        ":logging",
+        "@com_google_absl//absl/types:optional",
+    ],
 )
 
 cc_library(
diff --git a/test/util/posix_error.cc b/test/util/posix_error.cc
index cebf7e0ac..deed0c05b 100644
--- a/test/util/posix_error.cc
+++ b/test/util/posix_error.cc
@@ -87,7 +87,7 @@ bool PosixErrorIsMatcherCommonImpl::MatchAndExplain(
     return false;
   }
 
-  if (!message_matcher_.Matches(error.error_message())) {
+  if (!message_matcher_.Matches(error.message())) {
     return false;
   }
 
diff --git a/test/util/posix_error.h b/test/util/posix_error.h
index ad666bce0..b634a7f78 100644
--- a/test/util/posix_error.h
+++ b/test/util/posix_error.h
@@ -26,11 +26,6 @@
 namespace gvisor {
 namespace testing {
 
-class PosixErrorIsMatcherCommonImpl;
-
-template <typename T>
-class PosixErrorOr;
-
 class ABSL_MUST_USE_RESULT PosixError {
  public:
   PosixError() {}
@@ -49,7 +44,8 @@ class ABSL_MUST_USE_RESULT PosixError {
   // PosixErrorOr.
   const PosixError& error() const { return *this; }
 
-  std::string error_message() const { return msg_; }
+  int errno_value() const { return errno_; }
+  std::string message() const { return msg_; }
 
   // ToString produces a full string representation of this posix error
   // including the printable representation of the errno and the error message.
@@ -61,14 +57,8 @@ class ABSL_MUST_USE_RESULT PosixError {
   void IgnoreError() const {}
 
  private:
-  int errno_value() const { return errno_; }
   int errno_ = 0;
   std::string msg_;
-
-  friend class PosixErrorIsMatcherCommonImpl;
-
-  template <typename T>
-  friend class PosixErrorOr;
 };
 
 template <typename T>
@@ -94,15 +84,12 @@ class ABSL_MUST_USE_RESULT PosixErrorOr {
   template <typename U>
   PosixErrorOr& operator=(PosixErrorOr<U> other);
 
-  // Return a reference to the error or NoError().
-  PosixError error() const;
-
-  // Returns this->error().error_message();
-  std::string error_message() const;
-
   // Returns true if this PosixErrorOr contains some T.
   bool ok() const;
 
+  // Return a copy of the contained PosixError or NoError().
+  PosixError error() const;
+
   // Returns a reference to our current value, or CHECK-fails if !this->ok().
   const T& ValueOrDie() const&;
   T& ValueOrDie() &;
@@ -115,7 +102,6 @@ class ABSL_MUST_USE_RESULT PosixErrorOr {
   void IgnoreError() const {}
 
  private:
-  int errno_value() const;
   absl::variant<T, PosixError> value_;
 
   friend class PosixErrorIsMatcherCommonImpl;
@@ -171,16 +157,6 @@ PosixError PosixErrorOr<T>::error() const {
 }
 
 template <typename T>
-int PosixErrorOr<T>::errno_value() const {
-  return error().errno_value();
-}
-
-template <typename T>
-std::string PosixErrorOr<T>::error_message() const {
-  return error().error_message();
-}
-
-template <typename T>
 bool PosixErrorOr<T>::ok() const {
   return absl::holds_alternative<T>(value_);
 }
diff --git a/test/util/save_util.cc b/test/util/save_util.cc
index 384d626f0..59d47e06e 100644
--- a/test/util/save_util.cc
+++ b/test/util/save_util.cc
@@ -21,35 +21,47 @@
 #include <atomic>
 #include <cerrno>
 
-#define GVISOR_COOPERATIVE_SAVE_TEST "GVISOR_COOPERATIVE_SAVE_TEST"
+#include "absl/types/optional.h"
 
 namespace gvisor {
 namespace testing {
 namespace {
 
-enum class CooperativeSaveMode {
-  kUnknown = 0,  // cooperative_save_mode is statically-initialized to 0
-  kAvailable,
-  kNotAvailable,
-};
-
-std::atomic<CooperativeSaveMode> cooperative_save_mode;
-
-bool CooperativeSaveEnabled() {
-  auto mode = cooperative_save_mode.load();
-  if (mode == CooperativeSaveMode::kUnknown) {
-    mode = (getenv(GVISOR_COOPERATIVE_SAVE_TEST) != nullptr)
-               ? CooperativeSaveMode::kAvailable
-               : CooperativeSaveMode::kNotAvailable;
-    cooperative_save_mode.store(mode);
+std::atomic<absl::optional<bool>> cooperative_save_present;
+std::atomic<absl::optional<bool>> random_save_present;
+
+bool CooperativeSavePresent() {
+  auto present = cooperative_save_present.load();
+  if (!present.has_value()) {
+    present = getenv("GVISOR_COOPERATIVE_SAVE_TEST") != nullptr;
+    cooperative_save_present.store(present);
+  }
+  return present.value();
+}
+
+bool RandomSavePresent() {
+  auto present = random_save_present.load();
+  if (!present.has_value()) {
+    present = getenv("GVISOR_RANDOM_SAVE_TEST") != nullptr;
+    random_save_present.store(present);
   }
-  return mode == CooperativeSaveMode::kAvailable;
+  return present.value();
 }
 
 std::atomic<int> save_disable;
 
 }  // namespace
 
+bool IsRunningWithSaveRestore() {
+  return CooperativeSavePresent() || RandomSavePresent();
+}
+
+void MaybeSave() {
+  if (CooperativeSavePresent() && save_disable.load() == 0) {
+    internal::DoCooperativeSave();
+  }
+}
+
 DisableSave::DisableSave() { save_disable++; }
 
 DisableSave::~DisableSave() { reset(); }
@@ -61,11 +73,5 @@ void DisableSave::reset() {
   }
 }
 
-namespace internal {
-bool ShouldSave() {
-  return CooperativeSaveEnabled() && (save_disable.load() == 0);
-}
-}  // namespace internal
-
 }  // namespace testing
 }  // namespace gvisor
diff --git a/test/util/save_util.h b/test/util/save_util.h
index bddad6120..e7218ae88 100644
--- a/test/util/save_util.h
+++ b/test/util/save_util.h
@@ -17,9 +17,17 @@
 
 namespace gvisor {
 namespace testing {
-// Disable save prevents saving while the given function executes.
+
+// Returns true if the environment in which the calling process is executing
+// allows the test to be checkpointed and restored during execution.
+bool IsRunningWithSaveRestore();
+
+// May perform a co-operative save cycle.
 //
-// This lasts the duration of the object, unless reset is called.
+// errno is guaranteed to be preserved.
+void MaybeSave();
+
+// Causes MaybeSave to become a no-op until destroyed or reset.
 class DisableSave {
  public:
   DisableSave();
@@ -37,13 +45,13 @@ class DisableSave {
   bool reset_ = false;
 };
 
-// May perform a co-operative save cycle.
+namespace internal {
+
+// Causes a co-operative save cycle to occur.
 //
 // errno is guaranteed to be preserved.
-void MaybeSave();
+void DoCooperativeSave();
 
-namespace internal {
-bool ShouldSave();
 }  // namespace internal
 
 }  // namespace testing
diff --git a/test/util/save_util_linux.cc b/test/util/save_util_linux.cc
index fbac94912..57431b3ea 100644
--- a/test/util/save_util_linux.cc
+++ b/test/util/save_util_linux.cc
@@ -30,19 +30,19 @@
 
 namespace gvisor {
 namespace testing {
-
-void MaybeSave() {
-  if (internal::ShouldSave()) {
-    int orig_errno = errno;
-    // We use it to trigger saving the sentry state
-    // when this syscall is called.
-    // Notice: this needs to be a valid syscall
-    // that is not used in any of the syscall tests.
-    syscall(SYS_TRIGGER_SAVE, nullptr, 0);
-    errno = orig_errno;
-  }
+namespace internal {
+
+void DoCooperativeSave() {
+  int orig_errno = errno;
+  // We use it to trigger saving the sentry state
+  // when this syscall is called.
+  // Notice: this needs to be a valid syscall
+  // that is not used in any of the syscall tests.
+  syscall(SYS_TRIGGER_SAVE, nullptr, 0);
+  errno = orig_errno;
 }
 
+}  // namespace internal
 }  // namespace testing
 }  // namespace gvisor
 
diff --git a/test/util/save_util_other.cc b/test/util/save_util_other.cc
index 931af2c29..7749ded76 100644
--- a/test/util/save_util_other.cc
+++ b/test/util/save_util_other.cc
@@ -14,13 +14,17 @@
 
 #ifndef __linux__
 
+#include "test/util/logging.h"
+
 namespace gvisor {
 namespace testing {
+namespace internal {
 
-void MaybeSave() {
-  // Saving is never available in a non-linux environment.
+void DoCooperativeSave() {
+  TEST_CHECK_MSG(false, "DoCooperativeSave not implemented");
 }
 
+}  // namespace internal
 }  // namespace testing
 }  // namespace gvisor