dlfcn_test.cpp revision ca1c80220e9b16fde7a761ca1c2c63dbe8071e0f 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <gtest/gtest.h>
18
19#include <dlfcn.h>
20#include <libgen.h>
21#include <limits.h>
22#include <stdio.h>
23#include <stdint.h>
24
25#include <string>
26
27#define ASSERT_SUBSTR(needle, haystack) \
28    ASSERT_PRED_FORMAT2(::testing::IsSubstring, needle, haystack)
29
30static bool g_called = false;
31extern "C" void DlSymTestFunction() {
32  g_called = true;
33}
34
35TEST(dlfcn, dlsym_in_self) {
36  dlerror(); // Clear any pending errors.
37  void* self = dlopen(NULL, RTLD_NOW);
38  ASSERT_TRUE(self != NULL);
39  ASSERT_TRUE(dlerror() == NULL);
40
41  void* sym = dlsym(self, "DlSymTestFunction");
42  ASSERT_TRUE(sym != NULL);
43
44  void (*function)() = reinterpret_cast<void(*)()>(sym);
45
46  g_called = false;
47  function();
48  ASSERT_TRUE(g_called);
49
50  ASSERT_EQ(0, dlclose(self));
51}
52
53TEST(dlfcn, dlopen_noload) {
54  void* handle = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
55  ASSERT_TRUE(handle == NULL);
56  handle = dlopen("libtest_simple.so", RTLD_NOW);
57  void* handle2 = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
58  ASSERT_TRUE(handle != NULL);
59  ASSERT_TRUE(handle2 != NULL);
60  ASSERT_TRUE(handle == handle2);
61  ASSERT_EQ(0, dlclose(handle));
62  ASSERT_EQ(0, dlclose(handle2));
63}
64
65TEST(dlfcn, dlopen_failure) {
66  void* self = dlopen("/does/not/exist", RTLD_NOW);
67  ASSERT_TRUE(self == NULL);
68#if defined(__BIONIC__)
69  ASSERT_STREQ("dlopen failed: library \"/does/not/exist\" not found", dlerror());
70#else
71  ASSERT_STREQ("/does/not/exist: cannot open shared object file: No such file or directory", dlerror());
72#endif
73}
74
75static void* ConcurrentDlErrorFn(void*) {
76  dlopen("/child/thread", RTLD_NOW);
77  return reinterpret_cast<void*>(strdup(dlerror()));
78}
79
80TEST(dlfcn, dlerror_concurrent) {
81  dlopen("/main/thread", RTLD_NOW);
82  const char* main_thread_error = dlerror();
83  ASSERT_SUBSTR("/main/thread", main_thread_error);
84
85  pthread_t t;
86  ASSERT_EQ(0, pthread_create(&t, NULL, ConcurrentDlErrorFn, NULL));
87  void* result;
88  ASSERT_EQ(0, pthread_join(t, &result));
89  char* child_thread_error = static_cast<char*>(result);
90  ASSERT_SUBSTR("/child/thread", child_thread_error);
91  free(child_thread_error);
92
93  ASSERT_SUBSTR("/main/thread", main_thread_error);
94}
95
96TEST(dlfcn, dlsym_failures) {
97  dlerror(); // Clear any pending errors.
98  void* self = dlopen(NULL, RTLD_NOW);
99  ASSERT_TRUE(self != NULL);
100  ASSERT_TRUE(dlerror() == NULL);
101
102  void* sym;
103
104  // lp64 RTLD_DEFAULT=(void*)0
105#if !defined(__LP64__)
106  // NULL handle.
107  sym = dlsym(NULL, "test");
108  ASSERT_TRUE(sym == NULL);
109#if defined(__BIONIC__)
110  ASSERT_SUBSTR("dlsym library handle is null", dlerror());
111#else
112  ASSERT_SUBSTR("undefined symbol: test", dlerror()); // glibc isn't specific about the failure.
113#endif
114#endif // !defined(__LP64__)
115
116  // NULL symbol name.
117#if defined(__BIONIC__)
118  // glibc marks this parameter non-null and SEGVs if you cheat.
119  sym = dlsym(self, NULL);
120  ASSERT_TRUE(sym == NULL);
121  ASSERT_SUBSTR("", dlerror());
122#endif
123
124  // Symbol that doesn't exist.
125  sym = dlsym(self, "ThisSymbolDoesNotExist");
126  ASSERT_TRUE(sym == NULL);
127  ASSERT_SUBSTR("undefined symbol: ThisSymbolDoesNotExist", dlerror());
128
129  ASSERT_EQ(0, dlclose(self));
130}
131
132TEST(dlfcn, dladdr) {
133  dlerror(); // Clear any pending errors.
134  void* self = dlopen(NULL, RTLD_NOW);
135  ASSERT_TRUE(self != NULL);
136  ASSERT_TRUE(dlerror() == NULL);
137
138  void* sym = dlsym(self, "DlSymTestFunction");
139  ASSERT_TRUE(sym != NULL);
140
141  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
142  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
143
144  Dl_info info;
145  int rc = dladdr(addr, &info);
146  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
147
148  // Get the name of this executable.
149  char executable_path[PATH_MAX];
150  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
151  ASSERT_NE(rc, -1);
152  executable_path[rc] = '\0';
153  std::string executable_name(basename(executable_path));
154
155  // The filename should be that of this executable.
156  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
157  std::string dli_fname(info.dli_fname);
158  dli_fname = basename(&dli_fname[0]);
159  ASSERT_EQ(dli_fname, executable_name);
160
161  // The symbol name should be the symbol we looked up.
162  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
163
164  // The address should be the exact address of the symbol.
165  ASSERT_EQ(info.dli_saddr, sym);
166
167  // Look in /proc/pid/maps to find out what address we were loaded at.
168  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
169  void* base_address = NULL;
170  char path[PATH_MAX];
171  snprintf(path, sizeof(path), "/proc/%d/maps", getpid());
172  char line[BUFSIZ];
173  FILE* fp = fopen(path, "r");
174  ASSERT_TRUE(fp != NULL);
175  while (fgets(line, sizeof(line), fp) != NULL) {
176    uintptr_t start = strtoul(line, 0, 16);
177    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
178    char* path = strchr(line, '/');
179    if (path != NULL && strcmp(executable_path, path) == 0) {
180      base_address = reinterpret_cast<void*>(start);
181      break;
182    }
183  }
184  fclose(fp);
185
186  // The base address should be the address we were loaded at.
187  ASSERT_EQ(info.dli_fbase, base_address);
188
189  ASSERT_EQ(0, dlclose(self));
190}
191
192TEST(dlfcn, dladdr_invalid) {
193  Dl_info info;
194
195  dlerror(); // Clear any pending errors.
196
197  // No symbol corresponding to NULL.
198  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
199  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
200
201  // No symbol corresponding to a stack address.
202  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
203  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
204}
205
206// Our dynamic linker doesn't support GNU hash tables.
207#if defined(__BIONIC__)
208// GNU-style ELF hash tables are incompatible with the MIPS ABI.
209// MIPS requires .dynsym to be sorted to match the GOT but GNU-style requires sorting by hash code.
210#if !defined(__mips__)
211TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
212  dlerror(); // Clear any pending errors.
213  void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
214  ASSERT_TRUE(handle == NULL);
215  ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
216}
217#endif
218#endif
219
220TEST(dlfcn, dlopen_bad_flags) {
221  dlerror(); // Clear any pending errors.
222  void* handle;
223
224#if defined(__GLIBC__)
225  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
226  handle = dlopen(NULL, 0);
227  ASSERT_TRUE(handle == NULL);
228  ASSERT_SUBSTR("invalid", dlerror());
229#endif
230
231  handle = dlopen(NULL, 0xffffffff);
232  ASSERT_TRUE(handle == NULL);
233  ASSERT_SUBSTR("invalid", dlerror());
234
235  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
236  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
237  ASSERT_TRUE(handle != NULL);
238  ASSERT_SUBSTR(NULL, dlerror());
239}
240
241TEST(dlfcn, rtld_default_unknown_symbol) {
242  void* addr = dlsym(RTLD_DEFAULT, "ANY_UNKNOWN_SYMBOL_NAME");
243  ASSERT_TRUE(addr == NULL);
244}
245
246TEST(dlfcn, rtld_default_known_symbol) {
247  void* addr = dlsym(RTLD_DEFAULT, "fopen");
248  ASSERT_TRUE(addr != NULL);
249}
250
251TEST(dlfcn, rtld_next_unknown_symbol) {
252  void* addr = dlsym(RTLD_NEXT, "ANY_UNKNOWN_SYMBOL_NAME");
253  ASSERT_TRUE(addr == NULL);
254}
255
256TEST(dlfcn, rtld_next_known_symbol) {
257  void* addr = dlsym(RTLD_NEXT, "fopen");
258  ASSERT_TRUE(addr != NULL);
259}
260
261TEST(dlfcn, dlopen_symlink) {
262  void* handle1 = dlopen("libdlext_test.so", RTLD_NOW);
263  void* handle2 = dlopen("libdlext_test_v2.so", RTLD_NOW);
264  ASSERT_TRUE(handle1 != NULL);
265  ASSERT_TRUE(handle2 != NULL);
266  ASSERT_EQ(handle1, handle2);
267}
268