base logging: fix errno restoring, severity conditionality, dangling ifs

Fix LOG() to properly save and restore errno. Test this properly.

Only do logging if severity is >= the minimum.

Fix dangling if statements in CHECK(), CHECK_STR{EQ,NE}(). Test this
properly.

Fix base logging tests on Windows. All libbase_tests now pass on
Windows.

Change place to lock, so the lock can protect logging of all data in
LogMessage.

Change-Id: I7ff531c67ae10a99ef0a2bbfe279aa77282d5ae9
Signed-off-by: Spencer Low <CompareAndSwap@gmail.com>
diff --git a/base/logging_test.cpp b/base/logging_test.cpp
index c12dfa5..9cf1aad 100644
--- a/base/logging_test.cpp
+++ b/base/logging_test.cpp
@@ -18,6 +18,10 @@
 
 #include <libgen.h>
 
+#if defined(_WIN32)
+#include <signal.h>
+#endif
+
 #include <regex>
 #include <string>
 
@@ -49,6 +53,11 @@
 
  private:
   void init() {
+#if defined(_WIN32)
+    // On Windows, stderr is often buffered, so make sure it is unbuffered so
+    // that we can immediately read back what was written to stderr.
+    ASSERT_EQ(0, setvbuf(stderr, NULL, _IONBF, 0));
+#endif
     old_stderr_ = dup(STDERR_FILENO);
     ASSERT_NE(-1, old_stderr_);
     ASSERT_NE(-1, dup2(fd(), STDERR_FILENO));
@@ -57,21 +66,58 @@
   void reset() {
     ASSERT_NE(-1, dup2(old_stderr_, STDERR_FILENO));
     ASSERT_EQ(0, close(old_stderr_));
+    // Note: cannot restore prior setvbuf() setting.
   }
 
   TemporaryFile temp_file_;
   int old_stderr_;
 };
 
+#if defined(_WIN32)
+static void ExitSignalAbortHandler(int) {
+  _exit(3);
+}
+#endif
+
+static void SuppressAbortUI() {
+#if defined(_WIN32)
+  // We really just want to call _set_abort_behavior(0, _CALL_REPORTFAULT) to
+  // suppress the Windows Error Reporting dialog box, but that API is not
+  // available in the OS-supplied C Runtime, msvcrt.dll, that we currently
+  // use (it is available in the Visual Studio C runtime).
+  //
+  // Instead, we setup a SIGABRT handler, which is called in abort() right
+  // before calling Windows Error Reporting. In the handler, we exit the
+  // process just like abort() does.
+  ASSERT_NE(SIG_ERR, signal(SIGABRT, ExitSignalAbortHandler));
+#endif
+}
+
 TEST(logging, CHECK) {
-  ASSERT_DEATH(CHECK(false), "Check failed: false ");
+  ASSERT_DEATH({SuppressAbortUI(); CHECK(false);}, "Check failed: false ");
   CHECK(true);
 
-  ASSERT_DEATH(CHECK_EQ(0, 1), "Check failed: 0 == 1 ");
+  ASSERT_DEATH({SuppressAbortUI(); CHECK_EQ(0, 1);}, "Check failed: 0 == 1 ");
   CHECK_EQ(0, 0);
 
-  ASSERT_DEATH(CHECK_STREQ("foo", "bar"), R"(Check failed: "foo" == "bar")");
+  ASSERT_DEATH({SuppressAbortUI(); CHECK_STREQ("foo", "bar");},
+               R"(Check failed: "foo" == "bar")");
   CHECK_STREQ("foo", "foo");
+
+  // Test whether CHECK() and CHECK_STREQ() have a dangling if with no else.
+  bool flag = false;
+  if (true)
+    CHECK(true);
+  else
+    flag = true;
+  EXPECT_FALSE(flag) << "CHECK macro probably has a dangling if with no else";
+
+  flag = false;
+  if (true)
+    CHECK_STREQ("foo", "foo");
+  else
+    flag = true;
+  EXPECT_FALSE(flag) << "CHECK_STREQ probably has a dangling if with no else";
 }
 
 std::string make_log_pattern(android::base::LogSeverity severity,
@@ -85,7 +131,7 @@
 }
 
 TEST(logging, LOG) {
-  ASSERT_DEATH(LOG(FATAL) << "foobar", "foobar");
+  ASSERT_DEATH({SuppressAbortUI(); LOG(FATAL) << "foobar";}, "foobar");
 
   // We can't usefully check the output of any of these on Windows because we
   // don't have std::regex, but we can at least make sure we printed at least as
@@ -148,6 +194,50 @@
     ASSERT_TRUE(std::regex_search(output, message_regex)) << output;
 #endif
   }
+
+  // Test whether LOG() saves and restores errno.
+  {
+    CapturedStderr cap;
+    errno = 12345;
+    LOG(INFO) << (errno = 67890);
+    EXPECT_EQ(12345, errno) << "errno was not restored";
+
+    ASSERT_EQ(0, lseek(cap.fd(), SEEK_SET, 0));
+
+    std::string output;
+    android::base::ReadFdToString(cap.fd(), &output);
+    EXPECT_NE(nullptr, strstr(output.c_str(), "67890")) << output;
+
+#if !defined(_WIN32)
+    std::regex message_regex(
+        make_log_pattern(android::base::INFO, "67890"));
+    ASSERT_TRUE(std::regex_search(output, message_regex)) << output;
+#endif
+  }
+
+  // Test whether LOG() has a dangling if with no else.
+  {
+    CapturedStderr cap;
+
+    // Do the test two ways: once where we hypothesize that LOG()'s if
+    // will evaluate to true (when severity is high enough) and once when we
+    // expect it to evaluate to false (when severity is not high enough).
+    bool flag = false;
+    if (true)
+      LOG(INFO) << "foobar";
+    else
+      flag = true;
+
+    EXPECT_FALSE(flag) << "LOG macro probably has a dangling if with no else";
+
+    flag = false;
+    if (true)
+      LOG(VERBOSE) << "foobar";
+    else
+      flag = true;
+
+    EXPECT_FALSE(flag) << "LOG macro probably has a dangling if with no else";
+  }
 }
 
 TEST(logging, PLOG) {