Check for unknown flags passed to dlopen(3).

Change-Id: I56f4aab0e5a1487bc32d2c4d231e8bd15c4ac8da

tests/dlfcn_test.cpp

@@ -0,0 +1,220 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include <gtest/gtest.h>
+
+#include <dlfcn.h>
+#include <libgen.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdint.h>
+
+#include <string>
+
+#define ASSERT_SUBSTR(needle, haystack) \
+    ASSERT_PRED_FORMAT2(::testing::IsSubstring, needle, haystack)
+
+static bool gCalled = false;
+extern "C" void DlSymTestFunction() {
+  gCalled = true;
+}
+
+TEST(dlfcn, dlsym_in_self) {
+  dlerror(); // Clear any pending errors.
+  void* self = dlopen(NULL, RTLD_NOW);
+  ASSERT_TRUE(self != NULL);
+  ASSERT_TRUE(dlerror() == NULL);
+
+  void* sym = dlsym(self, "DlSymTestFunction");
+  ASSERT_TRUE(sym != NULL);
+
+  void (*function)() = reinterpret_cast<void(*)()>(sym);
+
+  gCalled = false;
+  function();
+  ASSERT_TRUE(gCalled);
+
+  ASSERT_EQ(0, dlclose(self));
+}
+
+TEST(dlfcn, dlopen_failure) {
+  void* self = dlopen("/does/not/exist", RTLD_NOW);
+  ASSERT_TRUE(self == NULL);
+#if __BIONIC__
+  ASSERT_STREQ("dlopen failed: library \"/does/not/exist\" not found", dlerror());
+#else
+  ASSERT_STREQ("/does/not/exist: cannot open shared object file: No such file or directory", dlerror());
+#endif
+}
+
+static void* ConcurrentDlErrorFn(void*) {
+  dlopen("/child/thread", RTLD_NOW);
+  return reinterpret_cast<void*>(strdup(dlerror()));
+}
+
+TEST(dlfcn, dlerror_concurrent) {
+  dlopen("/main/thread", RTLD_NOW);
+  const char* main_thread_error = dlerror();
+  ASSERT_SUBSTR("/main/thread", main_thread_error);
+
+  pthread_t t;
+  ASSERT_EQ(0, pthread_create(&t, NULL, ConcurrentDlErrorFn, NULL));
+  void* result;
+  ASSERT_EQ(0, pthread_join(t, &result));
+  char* child_thread_error = static_cast<char*>(result);
+  ASSERT_SUBSTR("/child/thread", child_thread_error);
+  free(child_thread_error);
+
+  ASSERT_SUBSTR("/main/thread", main_thread_error);
+}
+
+TEST(dlfcn, dlsym_failures) {
+  dlerror(); // Clear any pending errors.
+  void* self = dlopen(NULL, RTLD_NOW);
+  ASSERT_TRUE(self != NULL);
+  ASSERT_TRUE(dlerror() == NULL);
+
+  void* sym;
+
+  // NULL handle.
+  sym = dlsym(NULL, "test");
+  ASSERT_TRUE(sym == NULL);
+#if __BIONIC__
+  ASSERT_SUBSTR("dlsym library handle is null", dlerror());
+#else
+  ASSERT_SUBSTR("undefined symbol: test", dlerror()); // glibc isn't specific about the failure.
+#endif
+
+  // NULL symbol name.
+#if __BIONIC__
+  // glibc marks this parameter non-null and SEGVs if you cheat.
+  sym = dlsym(self, NULL);
+  ASSERT_TRUE(sym == NULL);
+  ASSERT_SUBSTR("", dlerror());
+#endif
+
+  // Symbol that doesn't exist.
+  sym = dlsym(self, "ThisSymbolDoesNotExist");
+  ASSERT_TRUE(sym == NULL);
+  ASSERT_SUBSTR("undefined symbol: ThisSymbolDoesNotExist", dlerror());
+
+  ASSERT_EQ(0, dlclose(self));
+}
+
+TEST(dlfcn, dladdr) {
+  dlerror(); // Clear any pending errors.
+  void* self = dlopen(NULL, RTLD_NOW);
+  ASSERT_TRUE(self != NULL);
+  ASSERT_TRUE(dlerror() == NULL);
+
+  void* sym = dlsym(self, "DlSymTestFunction");
+  ASSERT_TRUE(sym != NULL);
+
+  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
+  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
+
+  Dl_info info;
+  int rc = dladdr(addr, &info);
+  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
+
+  // Get the name of this executable.
+  char executable_path[PATH_MAX];
+  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
+  ASSERT_NE(rc, -1);
+  executable_path[rc] = '\0';
+  std::string executable_name(basename(executable_path));
+
+  // The filename should be that of this executable.
+  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
+  std::string dli_fname(info.dli_fname);
+  dli_fname = basename(&dli_fname[0]);
+  ASSERT_EQ(dli_fname, executable_name);
+
+  // The symbol name should be the symbol we looked up.
+  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
+
+  // The address should be the exact address of the symbol.
+  ASSERT_EQ(info.dli_saddr, sym);
+
+  // Look in /proc/pid/maps to find out what address we were loaded at.
+  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
+  void* base_address = NULL;
+  char path[PATH_MAX];
+  snprintf(path, sizeof(path), "/proc/%d/maps", getpid());
+  char line[BUFSIZ];
+  FILE* fp = fopen(path, "r");
+  ASSERT_TRUE(fp != NULL);
+  while (fgets(line, sizeof(line), fp) != NULL) {
+    uintptr_t start = strtoul(line, 0, 16);
+    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
+    char* path = strchr(line, '/');
+    if (path != NULL && strcmp(executable_path, path) == 0) {
+      base_address = reinterpret_cast<void*>(start);
+      break;
+    }
+  }
+  fclose(fp);
+
+  // The base address should be the address we were loaded at.
+  ASSERT_EQ(info.dli_fbase, base_address);
+
+  ASSERT_EQ(0, dlclose(self));
+}
+
+TEST(dlfcn, dladdr_invalid) {
+  Dl_info info;
+
+  dlerror(); // Clear any pending errors.
+
+  // No symbol corresponding to NULL.
+  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
+  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
+
+  // No symbol corresponding to a stack address.
+  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
+  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
+}
+
+#if __BIONIC__
+// Our dynamic linker doesn't support GNU hash tables.
+TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
+  dlerror(); // Clear any pending errors.
+  void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
+  ASSERT_TRUE(handle == NULL);
+  ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
+}
+#endif
+
+TEST(dlfcn, dlopen_bad_flags) {
+  dlerror(); // Clear any pending errors.
+  void* handle;
+
+#ifdef __GLIBC__
+  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
+  handle = dlopen(NULL, 0);
+  ASSERT_TRUE(handle == NULL);
+  ASSERT_SUBSTR("invalid", dlerror());
+#endif
+
+  handle = dlopen(NULL, 0xffffffff);
+  ASSERT_TRUE(handle == NULL);
+  ASSERT_SUBSTR("invalid", dlerror());
+
+  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
+  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
+  ASSERT_TRUE(handle != NULL);
+  ASSERT_SUBSTR(NULL, dlerror());
+}