launcher: Use actual executable path instead of argv[0]

When Jazzer is executed from `PATH`, `argv[0]` will just be `jazzer`,
which we can't find `jazzer_standalone.jar` relative to.

BUILD.bazel

@@ -18,6 +18,7 @@ pkg_tar(
         "@platforms//os:windows": ".\\",
         "//conditions:default": "./",
     }),
+    visibility = ["//tests:__pkg__"],
 )
 
 alias(

launcher/fuzzed_data_provider_test.cpp

@@ -39,7 +39,7 @@ class FuzzedDataProviderTest : public ::testing::Test {
     FLAGS_cp = Runfiles::CreateForTest()->Rlocation(
         "jazzer/launcher/testdata/fuzz_target_mocks_deploy.jar");
 
-    jvm_ = std::make_unique<JVM>("test_executable");
+    jvm_ = std::make_unique<JVM>();
   }
 
   static void TearDownTestCase() { jvm_.reset(nullptr); }

launcher/jazzer_main.cpp

@@ -104,6 +104,6 @@ int main(int argc, char **argv) {
     }
   }
 
-  StartLibFuzzer(std::unique_ptr<jazzer::JVM>(new jazzer::JVM(argv[0])),
+  StartLibFuzzer(std::unique_ptr<jazzer::JVM>(new jazzer::JVM()),
                  std::vector<std::string>(argv + 1, argv + argc));
 }

launcher/jvm_tooling.cpp

@@ -16,6 +16,13 @@
 
 #if defined(_ANDROID)
 #include <dlfcn.h>
+#elif defined(__APPLE__)
+#include <mach-o/dyld.h>
+#elif defined(_WIN32)
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#else  // Assume Linux
+#include <unistd.h>
 #endif
 
 #include <cstdlib>
@@ -50,6 +57,24 @@ constexpr auto kJazzerBazelRunfilesPath =
     "jazzer_standalone_deploy.jar";
 constexpr auto kJazzerFileName = "jazzer_standalone.jar";
 
+// Returns the absolute path to the current executable. Compared to argv[0],
+// this path can always be used to locate the Jazzer JAR next to it, even when
+// Jazzer is executed from PATH.
+std::string getExecutablePath() {
+  char buf[655536];
+#if defined(__APPLE__)
+  uint32_t buf_size = sizeof(buf);
+  if (_NSGetExecutablePath(buf, &buf_size) != 0) {
+#elif defined(_WIN32)
+  if (GetModuleFileNameA(NULL, buf, sizeof(buf)) == 0) {
+#else  // Assume Linux
+  if (readlink("/proc/self/exe", buf, sizeof(buf)) == -1) {
+#endif
+    return "";
+  }
+  return {buf};
+}
+
 std::string dirFromFullPath(const std::string &path) {
   const auto pos = path.rfind(kPathSeparator);
   if (pos != std::string::npos) {
@@ -60,17 +85,20 @@ std::string dirFromFullPath(const std::string &path) {
 
 // getInstrumentorAgentPath searches for the fuzzing instrumentation agent and
 // returns the location if it is found. Otherwise it calls exit(0).
-std::string getInstrumentorAgentPath(const std::string &executable_path) {
+std::string getInstrumentorAgentPath() {
   // User provided agent location takes precedence.
   if (!FLAGS_agent_path.empty()) {
     if (std::ifstream(FLAGS_agent_path).good()) return FLAGS_agent_path;
     std::cerr << "ERROR: Could not find " << kJazzerFileName << " at \""
               << FLAGS_agent_path << "\"" << std::endl;
     exit(1);
   }
-  // First check if we are running inside the Bazel tree and use the agent
-  // runfile.
-  {
+
+  auto executable_path = getExecutablePath();
+
+  if (!executable_path.empty()) {
+    // First check if we are running inside the Bazel tree and use the agent
+    // runfile.
     using bazel::tools::cpp::runfiles::Runfiles;
     std::string error;
     std::unique_ptr<Runfiles> runfiles(Runfiles::Create(
@@ -80,13 +108,14 @@ std::string getInstrumentorAgentPath(const std::string &executable_path) {
       if (!bazel_path.empty() && std::ifstream(bazel_path).good())
         return bazel_path;
     }
+
+    // If the agent is not in the bazel path we look next to the jazzer binary.
+    const auto dir = dirFromFullPath(executable_path);
+    auto agent_path =
+        absl::StrFormat("%s%c%s", dir, kPathSeparator, kJazzerFileName);
+    if (std::ifstream(agent_path).good()) return agent_path;
   }
 
-  // If the agent is not in the bazel path we look next to the jazzer binary.
-  const auto dir = dirFromFullPath(executable_path);
-  auto agent_path =
-      absl::StrFormat("%s%c%s", dir, kPathSeparator, kJazzerFileName);
-  if (std::ifstream(agent_path).good()) return agent_path;
   std::cerr << "ERROR: Could not find " << kJazzerFileName
             << ". Please provide the pathname via the --agent_path flag."
             << std::endl;
@@ -170,7 +199,7 @@ JNI_CreateJavaVM_t LoadAndroidVMLibs() {
 }
 #endif
 
-std::string GetClassPath(const std::string &executable_path) {
+std::string GetClassPath() {
   // combine class path from command line flags and JAVA_FUZZER_CLASSPATH env
   // variable
   std::string class_path = absl::StrFormat("-Djava.class.path=%s", FLAGS_cp);
@@ -179,13 +208,12 @@ std::string GetClassPath(const std::string &executable_path) {
     class_path += absl::StrCat(ARG_SEPARATOR, class_path_from_env);
   }
 
-  class_path +=
-      absl::StrCat(ARG_SEPARATOR, getInstrumentorAgentPath(executable_path));
+  class_path += absl::StrCat(ARG_SEPARATOR, getInstrumentorAgentPath());
   return class_path;
 }
 
-JVM::JVM(const std::string &executable_path) {
-  std::string class_path = GetClassPath(executable_path);
+JVM::JVM() {
+  std::string class_path = GetClassPath();
 
   std::vector<JavaVMOption> options;
   options.push_back(

launcher/jvm_tooling.h

@@ -40,7 +40,7 @@ class JVM {
  public:
   // Creates a JVM instance with default options + options that were provided as
   // command line flags.
-  explicit JVM(const std::string &executable_path);
+  explicit JVM();
 
   // Destroy the running JVM instance.
   ~JVM();

launcher/jvm_tooling_test.cpp

@@ -39,7 +39,7 @@ class JvmToolingTest : public ::testing::Test {
     FLAGS_cp = Runfiles::CreateForTest()->Rlocation(
         "jazzer/launcher/testdata/fuzz_target_mocks_deploy.jar");
 
-    jvm_ = std::unique_ptr<JVM>(new JVM("test_executable"));
+    jvm_ = std::unique_ptr<JVM>(new JVM());
   }
 
   static void TearDownTestCase() { jvm_.reset(nullptr); }

tests/BUILD.bazel

@@ -445,3 +445,13 @@ java_fuzz_target_test(
         "//tests/src/test/proto:simple_java_proto",
     ],
 )
+
+sh_test(
+    name = "jazzer_from_path_test",
+    srcs = ["src/test/shell/jazzer_from_path_test.sh"],
+    args = ["$(rlocationpath //:jazzer_release)"],
+    data = [
+        "//:jazzer_release",
+        "@bazel_tools//tools/bash/runfiles",
+    ],
+)

tests/src/test/shell/jazzer_from_path_test.sh

@@ -0,0 +1,43 @@
+#!/bin/bash
+# Copyright 2022 Code Intelligence GmbH
+#
+# 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
+#
+#      http://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.
+
+# Verify that the Jazzer launcher finds the jar when executed from PATH.
+
+
+# --- begin runfiles.bash initialization v3 ---
+# Copy-pasted from the Bazel Bash runfiles library v3.
+set -uo pipefail; set +e; f=bazel_tools/tools/bash/runfiles/runfiles.bash
+source "${RUNFILES_DIR:-/dev/null}/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "${RUNFILES_MANIFEST_FILE:-/dev/null}" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$0.runfiles/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.exe.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  { echo>&2 "ERROR: cannot find $f"; exit 1; }; f=; set -e
+# --- end runfiles.bash initialization v3 ---
+
+# Unpack the release archive to a temporary directory.
+jazzer_release="$(rlocation "$1")"
+tmp="$(mktemp -d)"
+trap 'rm -r "$tmp"' EXIT
+# GNU tar on Windows requires --force-local to support colons in archives names,
+# macOS tar does not support it.
+tar -xzf "$jazzer_release" -C "$tmp" --force-local || tar -xzf "$jazzer_release" -C "$tmp"
+
+# Add the Jazzer launcher to PATH first so that it is picked over host Jazzer
+# installations.
+PATH="$tmp:$PATH"
+export PATH
+
+jazzer --version