dlfcn_test.cpp revision 14669a939d113214a4a20b9318fca0992d5453f0 
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 "private/ScopeGuard.h"
26
27#include <string>
28
29#define ASSERT_SUBSTR(needle, haystack) \
30    ASSERT_PRED_FORMAT2(::testing::IsSubstring, needle, haystack)
31
32static bool g_called = false;
33extern "C" void DlSymTestFunction() {
34  g_called = true;
35}
36
37static int g_ctor_function_called = 0;
38
39extern "C" void ctor_function() __attribute__ ((constructor));
40
41extern "C" void ctor_function() {
42  g_ctor_function_called = 17;
43}
44
45TEST(dlfcn, ctor_function_call) {
46  ASSERT_EQ(17, g_ctor_function_called);
47}
48
49TEST(dlfcn, dlsym_in_self) {
50  dlerror(); // Clear any pending errors.
51  void* self = dlopen(NULL, RTLD_NOW);
52  ASSERT_TRUE(self != NULL);
53  ASSERT_TRUE(dlerror() == NULL);
54
55  void* sym = dlsym(self, "DlSymTestFunction");
56  ASSERT_TRUE(sym != NULL);
57
58  void (*function)() = reinterpret_cast<void(*)()>(sym);
59
60  g_called = false;
61  function();
62  ASSERT_TRUE(g_called);
63
64  ASSERT_EQ(0, dlclose(self));
65}
66
67TEST(dlfcn, dlsym_with_dependencies) {
68  void* handle = dlopen("libtest_with_dependency.so", RTLD_NOW);
69  ASSERT_TRUE(handle != NULL);
70  dlerror();
71  // This symbol is in DT_NEEDED library.
72  void* sym = dlsym(handle, "getRandomNumber");
73  ASSERT_TRUE(sym != NULL);
74  int (*fn)(void);
75  fn = reinterpret_cast<int (*)(void)>(sym);
76  EXPECT_EQ(4, fn());
77  dlclose(handle);
78}
79
80TEST(dlfcn, dlopen_noload) {
81  void* handle = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
82  ASSERT_TRUE(handle == NULL);
83  handle = dlopen("libtest_simple.so", RTLD_NOW);
84  void* handle2 = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
85  ASSERT_TRUE(handle != NULL);
86  ASSERT_TRUE(handle2 != NULL);
87  ASSERT_TRUE(handle == handle2);
88  ASSERT_EQ(0, dlclose(handle));
89  ASSERT_EQ(0, dlclose(handle2));
90}
91
92// ifuncs are only supported on intel for now
93#if defined(__i386__) || defined(__x86_64__)
94TEST(dlfcn, ifunc) {
95  typedef const char* (*fn_ptr)();
96
97  // ifunc's choice depends on whether IFUNC_CHOICE has a value
98  // first check the set case
99  setenv("IFUNC_CHOICE", "set", 1);
100  void* handle = dlopen("libtest_ifunc.so", RTLD_NOW);
101  ASSERT_TRUE(handle != NULL);
102  fn_ptr foo_ptr = reinterpret_cast<fn_ptr>(dlsym(handle, "foo"));
103  fn_ptr foo_library_ptr = reinterpret_cast<fn_ptr>(dlsym(handle, "foo_library"));
104  ASSERT_TRUE(foo_ptr != NULL);
105  ASSERT_TRUE(foo_library_ptr != NULL);
106  ASSERT_EQ(strncmp("set", foo_ptr(), 3), 0);
107  ASSERT_EQ(strncmp("set", foo_library_ptr(), 3), 0);
108  dlclose(handle);
109
110  // then check the unset case
111  unsetenv("IFUNC_CHOICE");
112  handle = dlopen("libtest_ifunc.so", RTLD_NOW);
113  ASSERT_TRUE(handle != NULL);
114  foo_ptr = reinterpret_cast<fn_ptr>(dlsym(handle, "foo"));
115  foo_library_ptr = reinterpret_cast<fn_ptr>(dlsym(handle, "foo_library"));
116  ASSERT_TRUE(foo_ptr != NULL);
117  ASSERT_TRUE(foo_library_ptr != NULL);
118  ASSERT_EQ(strncmp("unset", foo_ptr(), 5), 0);
119  ASSERT_EQ(strncmp("unset", foo_library_ptr(), 3), 0);
120  dlclose(handle);
121}
122
123TEST(dlfcn, ifunc_ctor_call) {
124  typedef const char* (*fn_ptr)();
125
126  void* handle = dlopen("libtest_ifunc.so", RTLD_NOW);
127  ASSERT_TRUE(handle != NULL) << dlerror();
128  fn_ptr is_ctor_called =  reinterpret_cast<fn_ptr>(dlsym(handle, "is_ctor_called"));
129  ASSERT_TRUE(is_ctor_called != NULL) << dlerror();
130  ASSERT_STREQ("true", is_ctor_called());
131  dlclose(handle);
132}
133#endif
134
135TEST(dlfcn, dlopen_check_relocation_dt_needed_order) {
136  // This is the structure of the test library and
137  // its dt_needed libraries
138  // libtest_relo_check_dt_needed_order.so
139  // |
140  // +-> libtest_relo_check_dt_needed_order_1.so
141  // |
142  // +-> libtest_relo_check_dt_needed_order_2.so
143  //
144  // The root library references relo_test_get_answer_lib - which is defined
145  // in both dt_needed libraries, the correct relocation should
146  // use the function defined in libtest_relo_check_dt_needed_order_1.so
147  void* handle = nullptr;
148  auto guard = create_scope_guard([&]() {
149    dlclose(handle);
150  });
151
152  handle = dlopen("libtest_relo_check_dt_needed_order.so", RTLD_NOW);
153  ASSERT_TRUE(handle != nullptr) << dlerror();
154
155  typedef int (*fn_t) (void);
156  fn_t fn = reinterpret_cast<fn_t>(dlsym(handle, "relo_test_get_answer"));
157  ASSERT_TRUE(fn != nullptr) << dlerror();
158  ASSERT_EQ(1, fn());
159}
160
161TEST(dlfcn, dlopen_check_order) {
162  // Here is how the test library and its dt_needed
163  // libraries are arranged
164  //
165  //  libtest_check_order.so
166  //  |
167  //  +-> libtest_check_order_1_left.so
168  //  |   |
169  //  |   +-> libtest_check_order_a.so
170  //  |   |
171  //  |   +-> libtest_check_order_b.so
172  //  |
173  //  +-> libtest_check_order_2_right.so
174  //  |   |
175  //  |   +-> libtest_check_order_d.so
176  //  |       |
177  //  |       +-> libtest_check_order_b.so
178  //  |
179  //  +-> libtest_check_order_3_c.so
180  //
181  //  load order should be (1, 2, 3, a, b, d)
182  //
183  // get_answer() is defined in (2, 3, a, b, c)
184  // get_answer2() is defined in (b, d)
185  void* sym = dlsym(RTLD_DEFAULT, "dlopen_test_get_answer");
186  ASSERT_TRUE(sym == nullptr);
187  void* handle = dlopen("libtest_check_order.so", RTLD_NOW);
188  ASSERT_TRUE(handle != nullptr);
189  typedef int (*fn_t) (void);
190  fn_t fn, fn2;
191  fn = reinterpret_cast<fn_t>(dlsym(RTLD_DEFAULT, "dlopen_test_get_answer"));
192  ASSERT_TRUE(fn != NULL);
193  fn2 = reinterpret_cast<fn_t>(dlsym(RTLD_DEFAULT, "dlopen_test_get_answer2"));
194  ASSERT_TRUE(fn2 != NULL);
195
196  ASSERT_EQ(42, fn());
197  ASSERT_EQ(43, fn2());
198  dlclose(handle);
199}
200
201// libtest_with_dependency_loop.so -> libtest_with_dependency_loop_a.so ->
202// libtest_with_dependency_loop_b.so -> libtest_with_dependency_loop_c.so ->
203// libtest_with_dependency_loop_a.so
204TEST(dlfcn, dlopen_check_loop) {
205  void* handle = dlopen("libtest_with_dependency_loop.so", RTLD_NOW);
206  ASSERT_TRUE(handle == NULL);
207  ASSERT_STREQ("dlopen failed: recursive link to \"libtest_with_dependency_loop_a.so\"", dlerror());
208}
209
210TEST(dlfcn, dlopen_failure) {
211  void* self = dlopen("/does/not/exist", RTLD_NOW);
212  ASSERT_TRUE(self == NULL);
213#if defined(__BIONIC__)
214  ASSERT_STREQ("dlopen failed: library \"/does/not/exist\" not found", dlerror());
215#else
216  ASSERT_STREQ("/does/not/exist: cannot open shared object file: No such file or directory", dlerror());
217#endif
218}
219
220static void* ConcurrentDlErrorFn(void*) {
221  dlopen("/child/thread", RTLD_NOW);
222  return reinterpret_cast<void*>(strdup(dlerror()));
223}
224
225TEST(dlfcn, dlerror_concurrent) {
226  dlopen("/main/thread", RTLD_NOW);
227  const char* main_thread_error = dlerror();
228  ASSERT_SUBSTR("/main/thread", main_thread_error);
229
230  pthread_t t;
231  ASSERT_EQ(0, pthread_create(&t, NULL, ConcurrentDlErrorFn, NULL));
232  void* result;
233  ASSERT_EQ(0, pthread_join(t, &result));
234  char* child_thread_error = static_cast<char*>(result);
235  ASSERT_SUBSTR("/child/thread", child_thread_error);
236  free(child_thread_error);
237
238  ASSERT_SUBSTR("/main/thread", main_thread_error);
239}
240
241TEST(dlfcn, dlsym_failures) {
242  dlerror(); // Clear any pending errors.
243  void* self = dlopen(NULL, RTLD_NOW);
244  ASSERT_TRUE(self != NULL);
245  ASSERT_TRUE(dlerror() == NULL);
246
247  void* sym;
248
249#if defined(__BIONIC__) && !defined(__LP64__)
250  // RTLD_DEFAULT in lp32 bionic is not (void*)0
251  // so it can be distinguished from the NULL handle.
252  sym = dlsym(NULL, "test");
253  ASSERT_TRUE(sym == NULL);
254  ASSERT_SUBSTR("dlsym library handle is null", dlerror());
255#endif
256
257  // NULL symbol name.
258#if defined(__BIONIC__)
259  // glibc marks this parameter non-null and SEGVs if you cheat.
260  sym = dlsym(self, NULL);
261  ASSERT_TRUE(sym == NULL);
262  ASSERT_SUBSTR("", dlerror());
263#endif
264
265  // Symbol that doesn't exist.
266  sym = dlsym(self, "ThisSymbolDoesNotExist");
267  ASSERT_TRUE(sym == NULL);
268  ASSERT_SUBSTR("undefined symbol: ThisSymbolDoesNotExist", dlerror());
269
270  ASSERT_EQ(0, dlclose(self));
271}
272
273TEST(dlfcn, dladdr) {
274  dlerror(); // Clear any pending errors.
275  void* self = dlopen(NULL, RTLD_NOW);
276  ASSERT_TRUE(self != NULL);
277  ASSERT_TRUE(dlerror() == NULL);
278
279  void* sym = dlsym(self, "DlSymTestFunction");
280  ASSERT_TRUE(sym != NULL);
281
282  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
283  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
284
285  Dl_info info;
286  int rc = dladdr(addr, &info);
287  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
288
289  // Get the name of this executable.
290  char executable_path[PATH_MAX];
291  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
292  ASSERT_NE(rc, -1);
293  executable_path[rc] = '\0';
294  std::string executable_name(basename(executable_path));
295
296  // The filename should be that of this executable.
297  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
298  std::string dli_fname(info.dli_fname);
299  dli_fname = basename(&dli_fname[0]);
300  ASSERT_EQ(dli_fname, executable_name);
301
302  // The symbol name should be the symbol we looked up.
303  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
304
305  // The address should be the exact address of the symbol.
306  ASSERT_EQ(info.dli_saddr, sym);
307
308  // Look in /proc/pid/maps to find out what address we were loaded at.
309  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
310  void* base_address = NULL;
311  char line[BUFSIZ];
312  FILE* fp = fopen("/proc/self/maps", "r");
313  ASSERT_TRUE(fp != NULL);
314  while (fgets(line, sizeof(line), fp) != NULL) {
315    uintptr_t start = strtoul(line, 0, 16);
316    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
317    char* path = strchr(line, '/');
318    if (path != NULL && strcmp(executable_path, path) == 0) {
319      base_address = reinterpret_cast<void*>(start);
320      break;
321    }
322  }
323  fclose(fp);
324
325  // The base address should be the address we were loaded at.
326  ASSERT_EQ(info.dli_fbase, base_address);
327
328  ASSERT_EQ(0, dlclose(self));
329}
330
331TEST(dlfcn, dladdr_invalid) {
332  Dl_info info;
333
334  dlerror(); // Clear any pending errors.
335
336  // No symbol corresponding to NULL.
337  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
338  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
339
340  // No symbol corresponding to a stack address.
341  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
342  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
343}
344
345// Our dynamic linker doesn't support GNU hash tables.
346#if defined(__BIONIC__)
347// GNU-style ELF hash tables are incompatible with the MIPS ABI.
348// MIPS requires .dynsym to be sorted to match the GOT but GNU-style requires sorting by hash code.
349#if !defined(__mips__)
350TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
351  dlerror(); // Clear any pending errors.
352  void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
353  ASSERT_TRUE(handle == NULL);
354  ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
355}
356#endif
357#endif
358
359TEST(dlfcn, dlopen_bad_flags) {
360  dlerror(); // Clear any pending errors.
361  void* handle;
362
363#if defined(__GLIBC__)
364  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
365  handle = dlopen(NULL, 0);
366  ASSERT_TRUE(handle == NULL);
367  ASSERT_SUBSTR("invalid", dlerror());
368#endif
369
370  handle = dlopen(NULL, 0xffffffff);
371  ASSERT_TRUE(handle == NULL);
372  ASSERT_SUBSTR("invalid", dlerror());
373
374  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
375  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
376  ASSERT_TRUE(handle != NULL);
377  ASSERT_SUBSTR(NULL, dlerror());
378}
379
380TEST(dlfcn, rtld_default_unknown_symbol) {
381  void* addr = dlsym(RTLD_DEFAULT, "ANY_UNKNOWN_SYMBOL_NAME");
382  ASSERT_TRUE(addr == NULL);
383}
384
385TEST(dlfcn, rtld_default_known_symbol) {
386  void* addr = dlsym(RTLD_DEFAULT, "fopen");
387  ASSERT_TRUE(addr != NULL);
388}
389
390TEST(dlfcn, rtld_next_unknown_symbol) {
391  void* addr = dlsym(RTLD_NEXT, "ANY_UNKNOWN_SYMBOL_NAME");
392  ASSERT_TRUE(addr == NULL);
393}
394
395TEST(dlfcn, rtld_next_known_symbol) {
396  void* addr = dlsym(RTLD_NEXT, "fopen");
397  ASSERT_TRUE(addr != NULL);
398}
399
400TEST(dlfcn, dlsym_weak_func) {
401  dlerror();
402  void* handle = dlopen("libtest_dlsym_weak_func.so",RTLD_NOW);
403  ASSERT_TRUE(handle != NULL);
404
405  int (*weak_func)();
406  weak_func = reinterpret_cast<int (*)()>(dlsym(handle, "weak_func"));
407  ASSERT_TRUE(weak_func != NULL) << "dlerror: " << dlerror();
408  EXPECT_EQ(42, weak_func());
409  dlclose(handle);
410}
411
412TEST(dlfcn, dlopen_symlink) {
413  void* handle1 = dlopen("libdlext_test.so", RTLD_NOW);
414  void* handle2 = dlopen("libdlext_test_v2.so", RTLD_NOW);
415  ASSERT_TRUE(handle1 != NULL);
416  ASSERT_TRUE(handle2 != NULL);
417  ASSERT_EQ(handle1, handle2);
418  dlclose(handle1);
419  dlclose(handle2);
420}
421