Switch corruption_test to use InMemEnv.

This change switches corruption_test, which previously used direct file
I/O to corrupt table files for open databases, to use InMemEnv. Using an
Env eliminates some platform dependencies thus simplifying the tests.

Also removed EnvWindowsTestHelper::RelaxFilePermissions().  This was
only added because the Windows Env opens files for exclusive access.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=239305329

3 files changed, 5 insertions, 26 deletions

diff --git a/util/env_windows.cc b/util/env_windows.cc
index 3b4496b..93555a8 100644
--- a/util/env_windows.cc
+++ b/util/env_windows.cc
@@ -43,9 +43,6 @@ constexpr int kDefaultMmapLimit = sizeof(void*) >= 8 ? 1000 : 0;
 // Modified by EnvWindowsTestHelper::SetReadOnlyMMapLimit().
 int g_mmap_limit = kDefaultMmapLimit;
 
-// Relax some file access permissions for testing.
-bool g_relax_permissions = false;
-
 std::string GetWindowsErrorMessage(DWORD error_code) {
   std::string message;
   char* error_text = nullptr;
@@ -366,10 +363,6 @@ class WindowsEnv : public Env {
     *result = nullptr;
     DWORD desired_access = GENERIC_READ;
     DWORD share_mode = FILE_SHARE_READ;
-    if (g_relax_permissions) {
-      desired_access |= GENERIC_WRITE;
-      share_mode |= FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
-    }
     ScopedHandle handle =
         ::CreateFileA(fname.c_str(), desired_access, share_mode, nullptr,
                       OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
@@ -385,10 +378,6 @@ class WindowsEnv : public Env {
     *result = nullptr;
     DWORD desired_access = GENERIC_READ;
     DWORD share_mode = FILE_SHARE_READ;
-    if (g_relax_permissions) {
-      // desired_access |= GENERIC_WRITE;
-      share_mode |= FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
-    }
     DWORD file_flags = FILE_ATTRIBUTE_READONLY;
 
     ScopedHandle handle =
@@ -433,10 +422,6 @@ class WindowsEnv : public Env {
                          WritableFile** result) override {
     DWORD desired_access = GENERIC_WRITE;
     DWORD share_mode = 0;
-    if (g_relax_permissions) {
-      desired_access |= GENERIC_READ;
-      share_mode |= FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
-    }
 
     ScopedHandle handle =
         ::CreateFileA(fname.c_str(), desired_access, share_mode, nullptr,
@@ -721,11 +706,6 @@ void EnvWindowsTestHelper::SetReadOnlyMMapLimit(int limit) {
   g_mmap_limit = limit;
 }
 
-void EnvWindowsTestHelper::RelaxFilePermissions() {
-  assert(default_env == nullptr);
-  g_relax_permissions = true;
-}
-
 Env* Env::Default() {
   std::call_once(once, InitDefaultEnv);
   return default_env;
diff --git a/util/env_windows_test_helper.h b/util/env_windows_test_helper.h
index 5ffbe44..e6f6020 100644
--- a/util/env_windows_test_helper.h
+++ b/util/env_windows_test_helper.h
@@ -18,11 +18,6 @@ class EnvWindowsTestHelper {
   // Set the maximum number of read-only files that will be mapped via mmap.
   // Must be called before creating an Env.
   static void SetReadOnlyMMapLimit(int limit);
-
-  // Relax file permissions for tests. This results in most files being opened
-  // with read-write permissions. This is helpful for corruption tests that
-  // need to corrupt the database files for open databases.
-  static void RelaxFilePermissions();
 };
 
 }  // namespace leveldb
diff --git a/util/testutil.h b/util/testutil.h
index dc77ac3..3934242 100644
--- a/util/testutil.h
+++ b/util/testutil.h
@@ -5,6 +5,7 @@
 #ifndef STORAGE_LEVELDB_UTIL_TESTUTIL_H_
 #define STORAGE_LEVELDB_UTIL_TESTUTIL_H_
 
+#include "helpers/memenv/memenv.h"
 #include "leveldb/env.h"
 #include "leveldb/slice.h"
 #include "util/random.h"
@@ -32,9 +33,12 @@ class ErrorEnv : public EnvWrapper {
   bool writable_file_error_;
   int num_writable_file_errors_;
 
-  ErrorEnv() : EnvWrapper(Env::Default()),
+  ErrorEnv() : EnvWrapper(NewMemEnv(Env::Default())),
                writable_file_error_(false),
                num_writable_file_errors_(0) { }
+  ~ErrorEnv() override {
+    delete target();
+  }
 
   virtual Status NewWritableFile(const std::string& fname,
                                  WritableFile** result) {