dlfcn_test.cpp revision 319356e39cc91b4eb94b1974756f1cfc0a137351 
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
90// ifuncs are only supported on intel for now
91#if defined(__i386__) || defined(__x86_64__)
92TEST(dlfcn, ifunc) {
93  typedef const char* (*fn_ptr)();
94
95  // ifunc's choice depends on whether IFUNC_CHOICE has a value
96  // first check the set case
97  setenv("IFUNC_CHOICE", "set", 1);
98  void* handle = dlopen("libtest_ifunc.so", RTLD_NOW);
99  ASSERT_TRUE(handle != NULL);
100  fn_ptr foo_ptr = reinterpret_cast<fn_ptr>(dlsym(handle, "foo"));
101  fn_ptr foo_library_ptr = reinterpret_cast<fn_ptr>(dlsym(handle, "foo_library"));
102  ASSERT_TRUE(foo_ptr != NULL);
103  ASSERT_TRUE(foo_library_ptr != NULL);
104  ASSERT_EQ(strncmp("set", foo_ptr(), 3), 0);
105  ASSERT_EQ(strncmp("set", foo_library_ptr(), 3), 0);
106  dlclose(handle);
107
108  // then check the unset case
109  unsetenv("IFUNC_CHOICE");
110  handle = dlopen("libtest_ifunc.so", RTLD_NOW);
111  ASSERT_TRUE(handle != NULL);
112  foo_ptr = reinterpret_cast<fn_ptr>(dlsym(handle, "foo"));
113  foo_library_ptr = reinterpret_cast<fn_ptr>(dlsym(handle, "foo_library"));
114  ASSERT_TRUE(foo_ptr != NULL);
115  ASSERT_TRUE(foo_library_ptr != NULL);
116  ASSERT_EQ(strncmp("unset", foo_ptr(), 5), 0);
117  ASSERT_EQ(strncmp("unset", foo_library_ptr(), 3), 0);
118  dlclose(handle);
119}
120
121TEST(dlfcn, ifunc_ctor_call) {
122  typedef const char* (*fn_ptr)();
123
124  void* handle = dlopen("libtest_ifunc.so", RTLD_NOW);
125  ASSERT_TRUE(handle != NULL) << dlerror();
126  fn_ptr is_ctor_called =  reinterpret_cast<fn_ptr>(dlsym(handle, "is_ctor_called"));
127  ASSERT_TRUE(is_ctor_called != NULL) << dlerror();
128  ASSERT_STREQ("true", is_ctor_called());
129  dlclose(handle);
130}
131#endif
132
133TEST(dlfcn, dlopen_failure) {
134  void* self = dlopen("/does/not/exist", RTLD_NOW);
135  ASSERT_TRUE(self == NULL);
136#if defined(__BIONIC__)
137  ASSERT_STREQ("dlopen failed: library \"/does/not/exist\" not found", dlerror());
138#else
139  ASSERT_STREQ("/does/not/exist: cannot open shared object file: No such file or directory", dlerror());
140#endif
141}
142
143static void* ConcurrentDlErrorFn(void*) {
144  dlopen("/child/thread", RTLD_NOW);
145  return reinterpret_cast<void*>(strdup(dlerror()));
146}
147
148TEST(dlfcn, dlerror_concurrent) {
149  dlopen("/main/thread", RTLD_NOW);
150  const char* main_thread_error = dlerror();
151  ASSERT_SUBSTR("/main/thread", main_thread_error);
152
153  pthread_t t;
154  ASSERT_EQ(0, pthread_create(&t, NULL, ConcurrentDlErrorFn, NULL));
155  void* result;
156  ASSERT_EQ(0, pthread_join(t, &result));
157  char* child_thread_error = static_cast<char*>(result);
158  ASSERT_SUBSTR("/child/thread", child_thread_error);
159  free(child_thread_error);
160
161  ASSERT_SUBSTR("/main/thread", main_thread_error);
162}
163
164TEST(dlfcn, dlsym_failures) {
165  dlerror(); // Clear any pending errors.
166  void* self = dlopen(NULL, RTLD_NOW);
167  ASSERT_TRUE(self != NULL);
168  ASSERT_TRUE(dlerror() == NULL);
169
170  void* sym;
171
172#if defined(__BIONIC__) && !defined(__LP64__)
173  // RTLD_DEFAULT in lp32 bionic is not (void*)0
174  // so it can be distinguished from the NULL handle.
175  sym = dlsym(NULL, "test");
176  ASSERT_TRUE(sym == NULL);
177  ASSERT_SUBSTR("dlsym library handle is null", dlerror());
178#endif
179
180  // NULL symbol name.
181#if defined(__BIONIC__)
182  // glibc marks this parameter non-null and SEGVs if you cheat.
183  sym = dlsym(self, NULL);
184  ASSERT_TRUE(sym == NULL);
185  ASSERT_SUBSTR("", dlerror());
186#endif
187
188  // Symbol that doesn't exist.
189  sym = dlsym(self, "ThisSymbolDoesNotExist");
190  ASSERT_TRUE(sym == NULL);
191  ASSERT_SUBSTR("undefined symbol: ThisSymbolDoesNotExist", dlerror());
192
193  ASSERT_EQ(0, dlclose(self));
194}
195
196TEST(dlfcn, dladdr) {
197  dlerror(); // Clear any pending errors.
198  void* self = dlopen(NULL, RTLD_NOW);
199  ASSERT_TRUE(self != NULL);
200  ASSERT_TRUE(dlerror() == NULL);
201
202  void* sym = dlsym(self, "DlSymTestFunction");
203  ASSERT_TRUE(sym != NULL);
204
205  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
206  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
207
208  Dl_info info;
209  int rc = dladdr(addr, &info);
210  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
211
212  // Get the name of this executable.
213  char executable_path[PATH_MAX];
214  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
215  ASSERT_NE(rc, -1);
216  executable_path[rc] = '\0';
217  std::string executable_name(basename(executable_path));
218
219  // The filename should be that of this executable.
220  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
221  std::string dli_fname(info.dli_fname);
222  dli_fname = basename(&dli_fname[0]);
223  ASSERT_EQ(dli_fname, executable_name);
224
225  // The symbol name should be the symbol we looked up.
226  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
227
228  // The address should be the exact address of the symbol.
229  ASSERT_EQ(info.dli_saddr, sym);
230
231  // Look in /proc/pid/maps to find out what address we were loaded at.
232  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
233  void* base_address = NULL;
234  char line[BUFSIZ];
235  FILE* fp = fopen("/proc/self/maps", "r");
236  ASSERT_TRUE(fp != NULL);
237  while (fgets(line, sizeof(line), fp) != NULL) {
238    uintptr_t start = strtoul(line, 0, 16);
239    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
240    char* path = strchr(line, '/');
241    if (path != NULL && strcmp(executable_path, path) == 0) {
242      base_address = reinterpret_cast<void*>(start);
243      break;
244    }
245  }
246  fclose(fp);
247
248  // The base address should be the address we were loaded at.
249  ASSERT_EQ(info.dli_fbase, base_address);
250
251  ASSERT_EQ(0, dlclose(self));
252}
253
254TEST(dlfcn, dladdr_invalid) {
255  Dl_info info;
256
257  dlerror(); // Clear any pending errors.
258
259  // No symbol corresponding to NULL.
260  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
261  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
262
263  // No symbol corresponding to a stack address.
264  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
265  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
266}
267
268// Our dynamic linker doesn't support GNU hash tables.
269#if defined(__BIONIC__)
270// GNU-style ELF hash tables are incompatible with the MIPS ABI.
271// MIPS requires .dynsym to be sorted to match the GOT but GNU-style requires sorting by hash code.
272#if !defined(__mips__)
273TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
274  dlerror(); // Clear any pending errors.
275  void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
276  ASSERT_TRUE(handle == NULL);
277  ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
278}
279#endif
280#endif
281
282TEST(dlfcn, dlopen_bad_flags) {
283  dlerror(); // Clear any pending errors.
284  void* handle;
285
286#if defined(__GLIBC__)
287  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
288  handle = dlopen(NULL, 0);
289  ASSERT_TRUE(handle == NULL);
290  ASSERT_SUBSTR("invalid", dlerror());
291#endif
292
293  handle = dlopen(NULL, 0xffffffff);
294  ASSERT_TRUE(handle == NULL);
295  ASSERT_SUBSTR("invalid", dlerror());
296
297  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
298  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
299  ASSERT_TRUE(handle != NULL);
300  ASSERT_SUBSTR(NULL, dlerror());
301}
302
303TEST(dlfcn, rtld_default_unknown_symbol) {
304  void* addr = dlsym(RTLD_DEFAULT, "ANY_UNKNOWN_SYMBOL_NAME");
305  ASSERT_TRUE(addr == NULL);
306}
307
308TEST(dlfcn, rtld_default_known_symbol) {
309  void* addr = dlsym(RTLD_DEFAULT, "fopen");
310  ASSERT_TRUE(addr != NULL);
311}
312
313TEST(dlfcn, rtld_next_unknown_symbol) {
314  void* addr = dlsym(RTLD_NEXT, "ANY_UNKNOWN_SYMBOL_NAME");
315  ASSERT_TRUE(addr == NULL);
316}
317
318TEST(dlfcn, rtld_next_known_symbol) {
319  void* addr = dlsym(RTLD_NEXT, "fopen");
320  ASSERT_TRUE(addr != NULL);
321}
322
323TEST(dlfcn, dlsym_weak_func) {
324  dlerror();
325  void* handle = dlopen("libtest_dlsym_weak_func.so",RTLD_NOW);
326  ASSERT_TRUE(handle != NULL);
327
328  int (*weak_func)();
329  weak_func = reinterpret_cast<int (*)()>(dlsym(handle, "weak_func"));
330  ASSERT_TRUE(weak_func != NULL) << "dlerror: " << dlerror();
331  EXPECT_EQ(42, weak_func());
332  dlclose(handle);
333}
334
335TEST(dlfcn, dlopen_symlink) {
336  void* handle1 = dlopen("libdlext_test.so", RTLD_NOW);
337  void* handle2 = dlopen("libdlext_test_v2.so", RTLD_NOW);
338  ASSERT_TRUE(handle1 != NULL);
339  ASSERT_TRUE(handle2 != NULL);
340  ASSERT_EQ(handle1, handle2);
341  dlclose(handle1);
342  dlclose(handle2);
343}
344