dlfcn_test.cpp revision d97e9f546ea195686a78e539315b273393609b9e 
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, dlsym_local_symbol) {
54  void* handle = dlopen("libtest_local_symbol.so", RTLD_NOW);
55  ASSERT_TRUE(handle != NULL);
56  dlerror();
57  void* sym = dlsym(handle, "private_taxicab_number");
58  ASSERT_TRUE(sym == NULL);
59  ASSERT_STREQ("undefined symbol: private_taxicab_number", dlerror());
60
61  uint32_t (*f)(void);
62  f = reinterpret_cast<uint32_t (*)(void)>(dlsym(handle, "dlsym_local_symbol_get_taxicab_number_using_dlsym"));
63  ASSERT_TRUE(f != NULL);
64  ASSERT_EQ(1729, f());
65}
66
67TEST(dlfcn, dlopen_noload) {
68  void* handle = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
69  ASSERT_TRUE(handle == NULL);
70  handle = dlopen("libtest_simple.so", RTLD_NOW);
71  void* handle2 = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
72  ASSERT_TRUE(handle != NULL);
73  ASSERT_TRUE(handle2 != NULL);
74  ASSERT_TRUE(handle == handle2);
75  ASSERT_EQ(0, dlclose(handle));
76  ASSERT_EQ(0, dlclose(handle2));
77}
78
79TEST(dlfcn, dlopen_failure) {
80  void* self = dlopen("/does/not/exist", RTLD_NOW);
81  ASSERT_TRUE(self == NULL);
82#if defined(__BIONIC__)
83  ASSERT_STREQ("dlopen failed: library \"/does/not/exist\" not found", dlerror());
84#else
85  ASSERT_STREQ("/does/not/exist: cannot open shared object file: No such file or directory", dlerror());
86#endif
87}
88
89static void* ConcurrentDlErrorFn(void*) {
90  dlopen("/child/thread", RTLD_NOW);
91  return reinterpret_cast<void*>(strdup(dlerror()));
92}
93
94TEST(dlfcn, dlerror_concurrent) {
95  dlopen("/main/thread", RTLD_NOW);
96  const char* main_thread_error = dlerror();
97  ASSERT_SUBSTR("/main/thread", main_thread_error);
98
99  pthread_t t;
100  ASSERT_EQ(0, pthread_create(&t, NULL, ConcurrentDlErrorFn, NULL));
101  void* result;
102  ASSERT_EQ(0, pthread_join(t, &result));
103  char* child_thread_error = static_cast<char*>(result);
104  ASSERT_SUBSTR("/child/thread", child_thread_error);
105  free(child_thread_error);
106
107  ASSERT_SUBSTR("/main/thread", main_thread_error);
108}
109
110TEST(dlfcn, dlsym_failures) {
111  dlerror(); // Clear any pending errors.
112  void* self = dlopen(NULL, RTLD_NOW);
113  ASSERT_TRUE(self != NULL);
114  ASSERT_TRUE(dlerror() == NULL);
115
116  void* sym;
117
118#if defined(__BIONIC__) && !defined(__LP64__)
119  // RTLD_DEFAULT in lp32 bionic is not (void*)0
120  // so it can be distinguished from the NULL handle.
121  sym = dlsym(NULL, "test");
122  ASSERT_TRUE(sym == NULL);
123  ASSERT_SUBSTR("dlsym library handle is null", dlerror());
124#endif
125
126  // NULL symbol name.
127#if defined(__BIONIC__)
128  // glibc marks this parameter non-null and SEGVs if you cheat.
129  sym = dlsym(self, NULL);
130  ASSERT_TRUE(sym == NULL);
131  ASSERT_SUBSTR("", dlerror());
132#endif
133
134  // Symbol that doesn't exist.
135  sym = dlsym(self, "ThisSymbolDoesNotExist");
136  ASSERT_TRUE(sym == NULL);
137  ASSERT_SUBSTR("undefined symbol: ThisSymbolDoesNotExist", dlerror());
138
139  ASSERT_EQ(0, dlclose(self));
140}
141
142TEST(dlfcn, dladdr) {
143  dlerror(); // Clear any pending errors.
144  void* self = dlopen(NULL, RTLD_NOW);
145  ASSERT_TRUE(self != NULL);
146  ASSERT_TRUE(dlerror() == NULL);
147
148  void* sym = dlsym(self, "DlSymTestFunction");
149  ASSERT_TRUE(sym != NULL);
150
151  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
152  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
153
154  Dl_info info;
155  int rc = dladdr(addr, &info);
156  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
157
158  // Get the name of this executable.
159  char executable_path[PATH_MAX];
160  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
161  ASSERT_NE(rc, -1);
162  executable_path[rc] = '\0';
163  std::string executable_name(basename(executable_path));
164
165  // The filename should be that of this executable.
166  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
167  std::string dli_fname(info.dli_fname);
168  dli_fname = basename(&dli_fname[0]);
169  ASSERT_EQ(dli_fname, executable_name);
170
171  // The symbol name should be the symbol we looked up.
172  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
173
174  // The address should be the exact address of the symbol.
175  ASSERT_EQ(info.dli_saddr, sym);
176
177  // Look in /proc/pid/maps to find out what address we were loaded at.
178  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
179  void* base_address = NULL;
180  char path[PATH_MAX];
181  snprintf(path, sizeof(path), "/proc/%d/maps", getpid());
182  char line[BUFSIZ];
183  FILE* fp = fopen(path, "r");
184  ASSERT_TRUE(fp != NULL);
185  while (fgets(line, sizeof(line), fp) != NULL) {
186    uintptr_t start = strtoul(line, 0, 16);
187    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
188    char* path = strchr(line, '/');
189    if (path != NULL && strcmp(executable_path, path) == 0) {
190      base_address = reinterpret_cast<void*>(start);
191      break;
192    }
193  }
194  fclose(fp);
195
196  // The base address should be the address we were loaded at.
197  ASSERT_EQ(info.dli_fbase, base_address);
198
199  ASSERT_EQ(0, dlclose(self));
200}
201
202TEST(dlfcn, dladdr_invalid) {
203  Dl_info info;
204
205  dlerror(); // Clear any pending errors.
206
207  // No symbol corresponding to NULL.
208  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
209  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
210
211  // No symbol corresponding to a stack address.
212  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
213  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
214}
215
216// Our dynamic linker doesn't support GNU hash tables.
217#if defined(__BIONIC__)
218// GNU-style ELF hash tables are incompatible with the MIPS ABI.
219// MIPS requires .dynsym to be sorted to match the GOT but GNU-style requires sorting by hash code.
220#if !defined(__mips__)
221TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
222  dlerror(); // Clear any pending errors.
223  void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
224  ASSERT_TRUE(handle == NULL);
225  ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
226}
227#endif
228#endif
229
230TEST(dlfcn, dlopen_bad_flags) {
231  dlerror(); // Clear any pending errors.
232  void* handle;
233
234#if defined(__GLIBC__)
235  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
236  handle = dlopen(NULL, 0);
237  ASSERT_TRUE(handle == NULL);
238  ASSERT_SUBSTR("invalid", dlerror());
239#endif
240
241  handle = dlopen(NULL, 0xffffffff);
242  ASSERT_TRUE(handle == NULL);
243  ASSERT_SUBSTR("invalid", dlerror());
244
245  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
246  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
247  ASSERT_TRUE(handle != NULL);
248  ASSERT_SUBSTR(NULL, dlerror());
249}
250
251TEST(dlfcn, rtld_default_unknown_symbol) {
252  void* addr = dlsym(RTLD_DEFAULT, "ANY_UNKNOWN_SYMBOL_NAME");
253  ASSERT_TRUE(addr == NULL);
254}
255
256TEST(dlfcn, rtld_default_known_symbol) {
257  void* addr = dlsym(RTLD_DEFAULT, "fopen");
258  ASSERT_TRUE(addr != NULL);
259}
260
261TEST(dlfcn, rtld_next_unknown_symbol) {
262  void* addr = dlsym(RTLD_NEXT, "ANY_UNKNOWN_SYMBOL_NAME");
263  ASSERT_TRUE(addr == NULL);
264}
265
266TEST(dlfcn, rtld_next_known_symbol) {
267  void* addr = dlsym(RTLD_NEXT, "fopen");
268  ASSERT_TRUE(addr != NULL);
269}
270
271TEST(dlfcn, dlsym_weak_func) {
272  dlerror();
273  void* handle = dlopen("libtest_dlsym_weak_func.so",RTLD_NOW);
274  ASSERT_TRUE(handle != NULL);
275
276  int (*weak_func)();
277  weak_func = reinterpret_cast<int (*)()>(dlsym(handle, "weak_func"));
278  ASSERT_TRUE(weak_func != NULL) << "dlerror: " << dlerror();
279  EXPECT_EQ(42, weak_func());
280  dlclose(handle);
281}
282
283TEST(dlfcn, dlopen_symlink) {
284  void* handle1 = dlopen("libdlext_test.so", RTLD_NOW);
285  void* handle2 = dlopen("libdlext_test_v2.so", RTLD_NOW);
286  ASSERT_TRUE(handle1 != NULL);
287  ASSERT_TRUE(handle2 != NULL);
288  ASSERT_EQ(handle1, handle2);
289}
290