Release the Abseil Logging library

PiperOrigin-RevId: 470080638
Change-Id: I8d9ddfabc7704c383ed5a73abf0411f4c58a4bf7

1 files changed, 339 insertions, 0 deletions

diff --git a/absl/log/stripping_test.cc b/absl/log/stripping_test.cc
new file mode 100644
index 00000000..1672e3af
--- /dev/null
+++ b/absl/log/stripping_test.cc
@@ -0,0 +1,339 @@
+//
+// Copyright 2022 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Tests for stripping of literal strings.
+// ---------------------------------------
+//
+// When a `LOG` statement can be trivially proved at compile time to never fire,
+// e.g. due to `ABSL_MIN_LOG_LEVEL`, `NDEBUG`, or some explicit condition, data
+// streamed in can be dropped from the compiled program completely if they are
+// not used elsewhere.  This most commonly affects string literals, which users
+// often want to strip to reduce binary size and/or redact information about
+// their program's internals (e.g. in a release build).
+//
+// These tests log strings and then validate whether they appear in the compiled
+// binary.  This is done by opening the file corresponding to the running test
+// and running a simple string search on its contents.  The strings to be logged
+// and searched for must be unique, and we must take care not to emit them into
+// the binary in any other place, e.g. when searching for them.  The latter is
+// accomplished by computing them using base64; the source string appears in the
+// binary but the target string is computed at runtime.
+
+#include <stdio.h>
+
+#if defined(__MACH__)
+#include <mach-o/dyld.h>
+#elif defined(_WIN32)
+#include <Windows.h>
+#include <tchar.h>
+#endif
+
+#include <algorithm>
+#include <functional>
+#include <memory>
+#include <ostream>
+#include <string>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/base/internal/strerror.h"
+#include "absl/flags/internal/program_name.h"
+#include "absl/log/check.h"
+#include "absl/log/internal/test_helpers.h"
+#include "absl/log/log.h"
+#include "absl/strings/escaping.h"
+#include "absl/strings/str_format.h"
+#include "absl/strings/string_view.h"
+
+namespace {
+using ::testing::_;
+using ::testing::Eq;
+using ::testing::NotNull;
+
+using absl::log_internal::kAbslMinLogLevel;
+
+std::string Base64UnescapeOrDie(absl::string_view data) {
+  std::string decoded;
+  CHECK(absl::Base64Unescape(data, &decoded));
+  return decoded;
+}
+
+// -----------------------------------------------------------------------------
+// A Googletest matcher which searches the running binary for a given string
+// -----------------------------------------------------------------------------
+
+// This matcher is used to validate that literal strings streamed into
+// `LOG` statements that ought to be compiled out (e.g. `LOG_IF(INFO, false)`)
+// do not appear in the binary.
+//
+// Note that passing the string to be sought directly to `FileHasSubstr()` all
+// but forces its inclusion in the binary regardless of the logging library's
+// behavior. For example:
+//
+//   LOG_IF(INFO, false) << "you're the man now dog";
+//   // This will always pass:
+//   // EXPECT_THAT(fp, FileHasSubstr("you're the man now dog"));
+//   // So use this instead:
+//   EXPECT_THAT(fp, FileHasSubstr(
+//       Base64UnescapeOrDie("eW91J3JlIHRoZSBtYW4gbm93IGRvZw==")));
+
+class FileHasSubstrMatcher final : public ::testing::MatcherInterface<FILE*> {
+ public:
+  explicit FileHasSubstrMatcher(absl::string_view needle) : needle_(needle) {}
+
+  bool MatchAndExplain(
+      FILE* fp, ::testing::MatchResultListener* listener) const override {
+    std::string buf(
+        std::max<std::string::size_type>(needle_.size() * 2, 163840000), '\0');
+    size_t buf_start_offset = 0;  // The file offset of the byte at `buf[0]`.
+    size_t buf_data_size = 0;     // The number of bytes of `buf` which contain
+                                  // data.
+
+    ::fseek(fp, 0, SEEK_SET);
+    while (true) {
+      // Fill the buffer to capacity or EOF:
+      while (buf_data_size < buf.size()) {
+        const size_t ret = fread(&buf[buf_data_size], sizeof(char),
+                                 buf.size() - buf_data_size, fp);
+        if (ret == 0) break;
+        buf_data_size += ret;
+      }
+      if (ferror(fp)) {
+        *listener << "error reading file";
+        return false;
+      }
+      const absl::string_view haystack(&buf[0], buf_data_size);
+      const auto off = haystack.find(needle_);
+      if (off != haystack.npos) {
+        *listener << "string found at offset " << buf_start_offset + off;
+        return true;
+      }
+      if (feof(fp)) {
+        *listener << "string not found";
+        return false;
+      }
+      // Copy the end of `buf` to the beginning so we catch matches that span
+      // buffer boundaries.  `buf` and `buf_data_size` are always large enough
+      // that these ranges don't overlap.
+      memcpy(&buf[0], &buf[buf_data_size - needle_.size()], needle_.size());
+      buf_start_offset += buf_data_size - needle_.size();
+      buf_data_size = needle_.size();
+    }
+  }
+  void DescribeTo(std::ostream* os) const override {
+    *os << "contains the string \"" << needle_ << "\" (base64(\""
+        << Base64UnescapeOrDie(needle_) << "\"))";
+  }
+
+  void DescribeNegationTo(std::ostream* os) const override {
+    *os << "does not ";
+    DescribeTo(os);
+  }
+
+ private:
+  std::string needle_;
+};
+
+class StrippingTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+#ifndef NDEBUG
+    // Non-optimized builds don't necessarily eliminate dead code at all, so we
+    // don't attempt to validate stripping against such builds.
+    GTEST_SKIP() << "StrippingTests skipped since this build is not optimized";
+#elif defined(__EMSCRIPTEN__)
+    // These tests require a way to examine the running binary and look for
+    // strings; there's no portable way to do that.
+    GTEST_SKIP()
+        << "StrippingTests skipped since this platform is not optimized";
+#endif
+  }
+
+  // Opens this program's executable file.  Returns `nullptr` and writes to
+  // `stderr` on failure.
+  std::unique_ptr<FILE, std::function<void(FILE*)>> OpenTestExecutable() {
+#if defined(__linux__)
+    std::unique_ptr<FILE, std::function<void(FILE*)>> fp(
+        fopen("/proc/self/exe", "rb"), [](FILE* fp) { fclose(fp); });
+    if (!fp) {
+      const std::string err = absl::base_internal::StrError(errno);
+      absl::FPrintF(stderr, "Failed to open /proc/self/exe: %s\n", err);
+    }
+    return fp;
+#elif defined(__Fuchsia__)
+    // TODO(b/242579714): We need to restore the test coverage on this platform.
+    std::unique_ptr<FILE, std::function<void(FILE*)>> fp(
+        fopen(absl::StrCat("/pkg/bin/",
+                           absl::flags_internal::ShortProgramInvocationName())
+                  .c_str(),
+              "rb"),
+        [](FILE* fp) { fclose(fp); });
+    if (!fp) {
+      const std::string err = absl::base_internal::StrError(errno);
+      absl::FPrintF(stderr, "Failed to open /pkg/bin/<binary name>: %s\n", err);
+    }
+    return fp;
+#elif defined(__MACH__)
+    uint32_t size = 0;
+    int ret = _NSGetExecutablePath(nullptr, &size);
+    if (ret != -1) {
+      absl::FPrintF(stderr,
+                    "Failed to get executable path: "
+                    "_NSGetExecutablePath(nullptr) returned %d\n",
+                    ret);
+      return nullptr;
+    }
+    std::string path(size, '\0');
+    ret = _NSGetExecutablePath(&path[0], &size);
+    if (ret != 0) {
+      absl::FPrintF(
+          stderr,
+          "Failed to get executable path: _NSGetExecutablePath(buffer) "
+          "returned %d\n",
+          ret);
+      return nullptr;
+    }
+    std::unique_ptr<FILE, std::function<void(FILE*)>> fp(
+        fopen(path.c_str(), "rb"), [](FILE* fp) { fclose(fp); });
+    if (!fp) {
+      const std::string err = absl::base_internal::StrError(errno);
+      absl::FPrintF(stderr, "Failed to open executable at %s: %s\n", path, err);
+    }
+    return fp;
+#elif defined(_WIN32)
+    std::basic_string<TCHAR> path(4096, _T('\0'));
+    while (true) {
+      const uint32_t ret = ::GetModuleFileName(nullptr, &path[0], path.size());
+      if (ret == 0) {
+        absl::FPrintF(
+            stderr,
+            "Failed to get executable path: GetModuleFileName(buffer) "
+            "returned 0\n");
+        return nullptr;
+      }
+      if (ret < path.size()) break;
+      path.resize(path.size() * 2, _T('\0'));
+    }
+    std::unique_ptr<FILE, std::function<void(FILE*)>> fp(
+        _tfopen(path.c_str(), "rb"), [](FILE* fp) { fclose(fp); });
+    if (!fp) absl::FPrintF(stderr, "Failed to open executable\n");
+    return fp;
+#else
+    absl::FPrintF(stderr,
+                  "OpenTestExecutable() unimplemented on this platform\n");
+    return nullptr;
+#endif
+  }
+
+  ::testing::Matcher<FILE*> FileHasSubstr(absl::string_view needle) {
+    return MakeMatcher(new FileHasSubstrMatcher(needle));
+  }
+};
+
+// This tests whether out methodology for testing stripping works on this
+// platform by looking for one string that definitely ought to be there and one
+// that definitely ought not to.  If this fails, none of the `StrippingTest`s
+// are going to produce meaningful results.
+TEST_F(StrippingTest, Control) {
+  constexpr char kEncodedPositiveControl[] =
+      "U3RyaXBwaW5nVGVzdC5Qb3NpdGl2ZUNvbnRyb2w=";
+  const std::string encoded_negative_control =
+      absl::Base64Escape("StrippingTest.NegativeControl");
+
+  // Verify this mainly so we can encode other strings and know definitely they
+  // won't encode to `kEncodedPositiveControl`.
+  EXPECT_THAT(Base64UnescapeOrDie("U3RyaXBwaW5nVGVzdC5Qb3NpdGl2ZUNvbnRyb2w="),
+              Eq("StrippingTest.PositiveControl"));
+
+  auto exe = OpenTestExecutable();
+  ASSERT_THAT(exe, NotNull());
+  EXPECT_THAT(exe.get(), FileHasSubstr(kEncodedPositiveControl));
+  EXPECT_THAT(exe.get(), Not(FileHasSubstr(encoded_negative_control)));
+}
+
+TEST_F(StrippingTest, Literal) {
+  // We need to load a copy of the needle string into memory (so we can search
+  // for it) without leaving it lying around in plaintext in the executable file
+  // as would happen if we used a literal.  We might (or might not) leave it
+  // lying around later; that's what the tests are for!
+  const std::string needle = absl::Base64Escape("StrippingTest.Literal");
+  LOG(INFO) << "U3RyaXBwaW5nVGVzdC5MaXRlcmFs";
+  auto exe = OpenTestExecutable();
+  ASSERT_THAT(exe, NotNull());
+  if (absl::LogSeverity::kInfo >= kAbslMinLogLevel) {
+    EXPECT_THAT(exe.get(), FileHasSubstr(needle));
+  } else {
+    EXPECT_THAT(exe.get(), Not(FileHasSubstr(needle)));
+  }
+}
+
+TEST_F(StrippingTest, LiteralInExpression) {
+  // We need to load a copy of the needle string into memory (so we can search
+  // for it) without leaving it lying around in plaintext in the executable file
+  // as would happen if we used a literal.  We might (or might not) leave it
+  // lying around later; that's what the tests are for!
+  const std::string needle =
+      absl::Base64Escape("StrippingTest.LiteralInExpression");
+  LOG(INFO) << absl::StrCat("secret: ",
+                            "U3RyaXBwaW5nVGVzdC5MaXRlcmFsSW5FeHByZXNzaW9u");
+  std::unique_ptr<FILE, std::function<void(FILE*)>> exe = OpenTestExecutable();
+  ASSERT_THAT(exe, NotNull());
+  if (absl::LogSeverity::kInfo >= kAbslMinLogLevel) {
+    EXPECT_THAT(exe.get(), FileHasSubstr(needle));
+  } else {
+    EXPECT_THAT(exe.get(), Not(FileHasSubstr(needle)));
+  }
+}
+
+TEST_F(StrippingTest, Fatal) {
+  // We need to load a copy of the needle string into memory (so we can search
+  // for it) without leaving it lying around in plaintext in the executable file
+  // as would happen if we used a literal.  We might (or might not) leave it
+  // lying around later; that's what the tests are for!
+  const std::string needle = absl::Base64Escape("StrippingTest.Fatal");
+  EXPECT_DEATH_IF_SUPPORTED(LOG(FATAL) << "U3RyaXBwaW5nVGVzdC5GYXRhbA==", "");
+  std::unique_ptr<FILE, std::function<void(FILE*)>> exe = OpenTestExecutable();
+  ASSERT_THAT(exe, NotNull());
+  if (absl::LogSeverity::kFatal >= kAbslMinLogLevel) {
+    EXPECT_THAT(exe.get(), FileHasSubstr(needle));
+  } else {
+    EXPECT_THAT(exe.get(), Not(FileHasSubstr(needle)));
+  }
+}
+
+TEST_F(StrippingTest, Level) {
+  const std::string needle = absl::Base64Escape("StrippingTest.Level");
+  volatile auto severity = absl::LogSeverity::kWarning;
+  // Ensure that `severity` is not a compile-time constant to prove that
+  // stripping works regardless:
+  LOG(LEVEL(severity)) << "U3RyaXBwaW5nVGVzdC5MZXZlbA==";
+  std::unique_ptr<FILE, std::function<void(FILE*)>> exe = OpenTestExecutable();
+  ASSERT_THAT(exe, NotNull());
+  if (absl::LogSeverity::kFatal >= kAbslMinLogLevel) {
+    // This can't be stripped at compile-time because it might evaluate to a
+    // level that shouldn't be stripped.
+    EXPECT_THAT(exe.get(), FileHasSubstr(needle));
+  } else {
+#if defined(_MSC_VER) || defined(__APPLE__)
+    // Dead code elimination misses this case.
+#else
+    // All levels should be stripped, so it doesn't matter what the severity
+    // winds up being.
+    EXPECT_THAT(exe.get(), Not(FileHasSubstr(needle)));
+#endif
+  }
+}
+
+}  // namespace