dlfcn_test.cpp revision ce44166c737b6737c3a0820bef10b074a5e36cf8 
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#if defined(__BIONIC__) && !defined(__LP64__)
105  // RTLD_DEFAULT in lp32 bionic is not (void*)0
106  // so it can be distinguished from the NULL handle.
107  sym = dlsym(NULL, "test");
108  ASSERT_TRUE(sym == NULL);
109  ASSERT_SUBSTR("dlsym library handle is null", dlerror());
110#endif
111
112  // NULL symbol name.
113#if defined(__BIONIC__)
114  // glibc marks this parameter non-null and SEGVs if you cheat.
115  sym = dlsym(self, NULL);
116  ASSERT_TRUE(sym == NULL);
117  ASSERT_SUBSTR("", dlerror());
118#endif
119
120  // Symbol that doesn't exist.
121  sym = dlsym(self, "ThisSymbolDoesNotExist");
122  ASSERT_TRUE(sym == NULL);
123  ASSERT_SUBSTR("undefined symbol: ThisSymbolDoesNotExist", dlerror());
124
125  ASSERT_EQ(0, dlclose(self));
126}
127
128TEST(dlfcn, dladdr) {
129  dlerror(); // Clear any pending errors.
130  void* self = dlopen(NULL, RTLD_NOW);
131  ASSERT_TRUE(self != NULL);
132  ASSERT_TRUE(dlerror() == NULL);
133
134  void* sym = dlsym(self, "DlSymTestFunction");
135  ASSERT_TRUE(sym != NULL);
136
137  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
138  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
139
140  Dl_info info;
141  int rc = dladdr(addr, &info);
142  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
143
144  // Get the name of this executable.
145  char executable_path[PATH_MAX];
146  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
147  ASSERT_NE(rc, -1);
148  executable_path[rc] = '\0';
149  std::string executable_name(basename(executable_path));
150
151  // The filename should be that of this executable.
152  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
153  std::string dli_fname(info.dli_fname);
154  dli_fname = basename(&dli_fname[0]);
155  ASSERT_EQ(dli_fname, executable_name);
156
157  // The symbol name should be the symbol we looked up.
158  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
159
160  // The address should be the exact address of the symbol.
161  ASSERT_EQ(info.dli_saddr, sym);
162
163  // Look in /proc/pid/maps to find out what address we were loaded at.
164  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
165  void* base_address = NULL;
166  char path[PATH_MAX];
167  snprintf(path, sizeof(path), "/proc/%d/maps", getpid());
168  char line[BUFSIZ];
169  FILE* fp = fopen(path, "r");
170  ASSERT_TRUE(fp != NULL);
171  while (fgets(line, sizeof(line), fp) != NULL) {
172    uintptr_t start = strtoul(line, 0, 16);
173    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
174    char* path = strchr(line, '/');
175    if (path != NULL && strcmp(executable_path, path) == 0) {
176      base_address = reinterpret_cast<void*>(start);
177      break;
178    }
179  }
180  fclose(fp);
181
182  // The base address should be the address we were loaded at.
183  ASSERT_EQ(info.dli_fbase, base_address);
184
185  ASSERT_EQ(0, dlclose(self));
186}
187
188TEST(dlfcn, dladdr_invalid) {
189  Dl_info info;
190
191  dlerror(); // Clear any pending errors.
192
193  // No symbol corresponding to NULL.
194  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
195  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
196
197  // No symbol corresponding to a stack address.
198  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
199  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
200}
201
202// Our dynamic linker doesn't support GNU hash tables.
203#if defined(__BIONIC__)
204// GNU-style ELF hash tables are incompatible with the MIPS ABI.
205// MIPS requires .dynsym to be sorted to match the GOT but GNU-style requires sorting by hash code.
206#if !defined(__mips__)
207TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
208  dlerror(); // Clear any pending errors.
209  void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
210  ASSERT_TRUE(handle == NULL);
211  ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
212}
213#endif
214#endif
215
216TEST(dlfcn, dlopen_bad_flags) {
217  dlerror(); // Clear any pending errors.
218  void* handle;
219
220#if defined(__GLIBC__)
221  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
222  handle = dlopen(NULL, 0);
223  ASSERT_TRUE(handle == NULL);
224  ASSERT_SUBSTR("invalid", dlerror());
225#endif
226
227  handle = dlopen(NULL, 0xffffffff);
228  ASSERT_TRUE(handle == NULL);
229  ASSERT_SUBSTR("invalid", dlerror());
230
231  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
232  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
233  ASSERT_TRUE(handle != NULL);
234  ASSERT_SUBSTR(NULL, dlerror());
235}
236
237TEST(dlfcn, rtld_default_unknown_symbol) {
238  void* addr = dlsym(RTLD_DEFAULT, "ANY_UNKNOWN_SYMBOL_NAME");
239  ASSERT_TRUE(addr == NULL);
240}
241
242TEST(dlfcn, rtld_default_known_symbol) {
243  void* addr = dlsym(RTLD_DEFAULT, "fopen");
244  ASSERT_TRUE(addr != NULL);
245}
246
247TEST(dlfcn, rtld_next_unknown_symbol) {
248  void* addr = dlsym(RTLD_NEXT, "ANY_UNKNOWN_SYMBOL_NAME");
249  ASSERT_TRUE(addr == NULL);
250}
251
252TEST(dlfcn, rtld_next_known_symbol) {
253  void* addr = dlsym(RTLD_NEXT, "fopen");
254  ASSERT_TRUE(addr != NULL);
255}
256
257TEST(dlfcn, dlsym_weak_func) {
258  dlerror();
259  void* handle = dlopen("libtest_dlsym_weak_func.so",RTLD_NOW);
260  ASSERT_TRUE(handle != NULL);
261
262  int (*weak_func)();
263  weak_func = reinterpret_cast<int (*)()>(dlsym(handle, "weak_func"));
264  ASSERT_TRUE(weak_func != NULL) << "dlerror: " << dlerror();
265  EXPECT_EQ(42, weak_func());
266  dlclose(handle);
267}
268
269TEST(dlfcn, dlopen_symlink) {
270  void* handle1 = dlopen("libdlext_test.so", RTLD_NOW);
271  void* handle2 = dlopen("libdlext_test_v2.so", RTLD_NOW);
272  ASSERT_TRUE(handle1 != NULL);
273  ASSERT_TRUE(handle2 != NULL);
274  ASSERT_EQ(handle1, handle2);
275}
276