dlfcn_test.cpp revision 9419420919ea846bbad5510850c7aaec95021648 
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
35static int g_ctor_function_called = 0;
36
37extern "C" void ctor_function() __attribute__ ((constructor));
38
39extern "C" void ctor_function() {
40  g_ctor_function_called = 17;
41}
42
43TEST(dlfcn, ctor_function_call) {
44  ASSERT_EQ(17, g_ctor_function_called);
45}
46
47TEST(dlfcn, dlsym_in_self) {
48  dlerror(); // Clear any pending errors.
49  void* self = dlopen(NULL, RTLD_NOW);
50  ASSERT_TRUE(self != NULL);
51  ASSERT_TRUE(dlerror() == NULL);
52
53  void* sym = dlsym(self, "DlSymTestFunction");
54  ASSERT_TRUE(sym != NULL);
55
56  void (*function)() = reinterpret_cast<void(*)()>(sym);
57
58  g_called = false;
59  function();
60  ASSERT_TRUE(g_called);
61
62  ASSERT_EQ(0, dlclose(self));
63}
64
65TEST(dlfcn, dlsym_with_dependencies) {
66  void* handle = dlopen("libtest_with_dependency.so", RTLD_NOW);
67  ASSERT_TRUE(handle != NULL);
68  dlerror();
69  // This symbol is in DT_NEEDED library.
70  void* sym = dlsym(handle, "getRandomNumber");
71  ASSERT_TRUE(sym != NULL);
72  int (*fn)(void);
73  fn = reinterpret_cast<int (*)(void)>(sym);
74  EXPECT_EQ(4, fn());
75  dlclose(handle);
76}
77
78TEST(dlfcn, dlopen_noload) {
79  void* handle = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
80  ASSERT_TRUE(handle == NULL);
81  handle = dlopen("libtest_simple.so", RTLD_NOW);
82  void* handle2 = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
83  ASSERT_TRUE(handle != NULL);
84  ASSERT_TRUE(handle2 != NULL);
85  ASSERT_TRUE(handle == handle2);
86  ASSERT_EQ(0, dlclose(handle));
87  ASSERT_EQ(0, dlclose(handle2));
88}
89
90TEST(dlfcn, dlopen_failure) {
91  void* self = dlopen("/does/not/exist", RTLD_NOW);
92  ASSERT_TRUE(self == NULL);
93#if defined(__BIONIC__)
94  ASSERT_STREQ("dlopen failed: library \"/does/not/exist\" not found", dlerror());
95#else
96  ASSERT_STREQ("/does/not/exist: cannot open shared object file: No such file or directory", dlerror());
97#endif
98}
99
100static void* ConcurrentDlErrorFn(void*) {
101  dlopen("/child/thread", RTLD_NOW);
102  return reinterpret_cast<void*>(strdup(dlerror()));
103}
104
105TEST(dlfcn, dlerror_concurrent) {
106  dlopen("/main/thread", RTLD_NOW);
107  const char* main_thread_error = dlerror();
108  ASSERT_SUBSTR("/main/thread", main_thread_error);
109
110  pthread_t t;
111  ASSERT_EQ(0, pthread_create(&t, NULL, ConcurrentDlErrorFn, NULL));
112  void* result;
113  ASSERT_EQ(0, pthread_join(t, &result));
114  char* child_thread_error = static_cast<char*>(result);
115  ASSERT_SUBSTR("/child/thread", child_thread_error);
116  free(child_thread_error);
117
118  ASSERT_SUBSTR("/main/thread", main_thread_error);
119}
120
121TEST(dlfcn, dlsym_failures) {
122  dlerror(); // Clear any pending errors.
123  void* self = dlopen(NULL, RTLD_NOW);
124  ASSERT_TRUE(self != NULL);
125  ASSERT_TRUE(dlerror() == NULL);
126
127  void* sym;
128
129#if defined(__BIONIC__) && !defined(__LP64__)
130  // RTLD_DEFAULT in lp32 bionic is not (void*)0
131  // so it can be distinguished from the NULL handle.
132  sym = dlsym(NULL, "test");
133  ASSERT_TRUE(sym == NULL);
134  ASSERT_SUBSTR("dlsym library handle is null", dlerror());
135#endif
136
137  // NULL symbol name.
138#if defined(__BIONIC__)
139  // glibc marks this parameter non-null and SEGVs if you cheat.
140  sym = dlsym(self, NULL);
141  ASSERT_TRUE(sym == NULL);
142  ASSERT_SUBSTR("", dlerror());
143#endif
144
145  // Symbol that doesn't exist.
146  sym = dlsym(self, "ThisSymbolDoesNotExist");
147  ASSERT_TRUE(sym == NULL);
148  ASSERT_SUBSTR("undefined symbol: ThisSymbolDoesNotExist", dlerror());
149
150  ASSERT_EQ(0, dlclose(self));
151}
152
153TEST(dlfcn, dladdr) {
154  dlerror(); // Clear any pending errors.
155  void* self = dlopen(NULL, RTLD_NOW);
156  ASSERT_TRUE(self != NULL);
157  ASSERT_TRUE(dlerror() == NULL);
158
159  void* sym = dlsym(self, "DlSymTestFunction");
160  ASSERT_TRUE(sym != NULL);
161
162  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
163  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
164
165  Dl_info info;
166  int rc = dladdr(addr, &info);
167  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
168
169  // Get the name of this executable.
170  char executable_path[PATH_MAX];
171  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
172  ASSERT_NE(rc, -1);
173  executable_path[rc] = '\0';
174  std::string executable_name(basename(executable_path));
175
176  // The filename should be that of this executable.
177  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
178  std::string dli_fname(info.dli_fname);
179  dli_fname = basename(&dli_fname[0]);
180  ASSERT_EQ(dli_fname, executable_name);
181
182  // The symbol name should be the symbol we looked up.
183  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
184
185  // The address should be the exact address of the symbol.
186  ASSERT_EQ(info.dli_saddr, sym);
187
188  // Look in /proc/pid/maps to find out what address we were loaded at.
189  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
190  void* base_address = NULL;
191  char path[PATH_MAX];
192  snprintf(path, sizeof(path), "/proc/%d/maps", getpid());
193  char line[BUFSIZ];
194  FILE* fp = fopen(path, "r");
195  ASSERT_TRUE(fp != NULL);
196  while (fgets(line, sizeof(line), fp) != NULL) {
197    uintptr_t start = strtoul(line, 0, 16);
198    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
199    char* path = strchr(line, '/');
200    if (path != NULL && strcmp(executable_path, path) == 0) {
201      base_address = reinterpret_cast<void*>(start);
202      break;
203    }
204  }
205  fclose(fp);
206
207  // The base address should be the address we were loaded at.
208  ASSERT_EQ(info.dli_fbase, base_address);
209
210  ASSERT_EQ(0, dlclose(self));
211}
212
213TEST(dlfcn, dladdr_invalid) {
214  Dl_info info;
215
216  dlerror(); // Clear any pending errors.
217
218  // No symbol corresponding to NULL.
219  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
220  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
221
222  // No symbol corresponding to a stack address.
223  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
224  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
225}
226
227// Our dynamic linker doesn't support GNU hash tables.
228#if defined(__BIONIC__)
229// GNU-style ELF hash tables are incompatible with the MIPS ABI.
230// MIPS requires .dynsym to be sorted to match the GOT but GNU-style requires sorting by hash code.
231#if !defined(__mips__)
232TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
233  dlerror(); // Clear any pending errors.
234  void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
235  ASSERT_TRUE(handle == NULL);
236  ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
237}
238#endif
239#endif
240
241TEST(dlfcn, dlopen_bad_flags) {
242  dlerror(); // Clear any pending errors.
243  void* handle;
244
245#if defined(__GLIBC__)
246  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
247  handle = dlopen(NULL, 0);
248  ASSERT_TRUE(handle == NULL);
249  ASSERT_SUBSTR("invalid", dlerror());
250#endif
251
252  handle = dlopen(NULL, 0xffffffff);
253  ASSERT_TRUE(handle == NULL);
254  ASSERT_SUBSTR("invalid", dlerror());
255
256  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
257  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
258  ASSERT_TRUE(handle != NULL);
259  ASSERT_SUBSTR(NULL, dlerror());
260}
261
262TEST(dlfcn, rtld_default_unknown_symbol) {
263  void* addr = dlsym(RTLD_DEFAULT, "ANY_UNKNOWN_SYMBOL_NAME");
264  ASSERT_TRUE(addr == NULL);
265}
266
267TEST(dlfcn, rtld_default_known_symbol) {
268  void* addr = dlsym(RTLD_DEFAULT, "fopen");
269  ASSERT_TRUE(addr != NULL);
270}
271
272TEST(dlfcn, rtld_next_unknown_symbol) {
273  void* addr = dlsym(RTLD_NEXT, "ANY_UNKNOWN_SYMBOL_NAME");
274  ASSERT_TRUE(addr == NULL);
275}
276
277TEST(dlfcn, rtld_next_known_symbol) {
278  void* addr = dlsym(RTLD_NEXT, "fopen");
279  ASSERT_TRUE(addr != NULL);
280}
281
282TEST(dlfcn, dlsym_weak_func) {
283  dlerror();
284  void* handle = dlopen("libtest_dlsym_weak_func.so",RTLD_NOW);
285  ASSERT_TRUE(handle != NULL);
286
287  int (*weak_func)();
288  weak_func = reinterpret_cast<int (*)()>(dlsym(handle, "weak_func"));
289  ASSERT_TRUE(weak_func != NULL) << "dlerror: " << dlerror();
290  EXPECT_EQ(42, weak_func());
291  dlclose(handle);
292}
293
294TEST(dlfcn, dlopen_symlink) {
295  void* handle1 = dlopen("libdlext_test.so", RTLD_NOW);
296  void* handle2 = dlopen("libdlext_test_v2.so", RTLD_NOW);
297  ASSERT_TRUE(handle1 != NULL);
298  ASSERT_TRUE(handle2 != NULL);
299  ASSERT_EQ(handle1, handle2);
300}
301