dlfcn_test.cpp revision 7d971ec14b80cac442aeea8d88e9eb2e3ab6f214 
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 and arm64 for now
93#if defined (__aarch64__) || 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 != nullptr) << dlerror();
128  fn_ptr is_ctor_called =  reinterpret_cast<fn_ptr>(dlsym(handle, "is_ctor_called_irelative"));
129  ASSERT_TRUE(is_ctor_called != nullptr) << dlerror();
130  ASSERT_STREQ("false", is_ctor_called());
131
132  is_ctor_called =  reinterpret_cast<fn_ptr>(dlsym(handle, "is_ctor_called_jump_slot"));
133  ASSERT_TRUE(is_ctor_called != nullptr) << dlerror();
134  ASSERT_STREQ("true", is_ctor_called());
135  dlclose(handle);
136}
137#endif
138
139TEST(dlfcn, dlopen_check_relocation_dt_needed_order) {
140  // This is the structure of the test library and
141  // its dt_needed libraries
142  // libtest_relo_check_dt_needed_order.so
143  // |
144  // +-> libtest_relo_check_dt_needed_order_1.so
145  // |
146  // +-> libtest_relo_check_dt_needed_order_2.so
147  //
148  // The root library references relo_test_get_answer_lib - which is defined
149  // in both dt_needed libraries, the correct relocation should
150  // use the function defined in libtest_relo_check_dt_needed_order_1.so
151  void* handle = nullptr;
152  auto guard = make_scope_guard([&]() {
153    dlclose(handle);
154  });
155
156  handle = dlopen("libtest_relo_check_dt_needed_order.so", RTLD_NOW);
157  ASSERT_TRUE(handle != nullptr) << dlerror();
158
159  typedef int (*fn_t) (void);
160  fn_t fn = reinterpret_cast<fn_t>(dlsym(handle, "relo_test_get_answer"));
161  ASSERT_TRUE(fn != nullptr) << dlerror();
162  ASSERT_EQ(1, fn());
163}
164
165TEST(dlfcn, dlopen_check_order) {
166  // Here is how the test library and its dt_needed
167  // libraries are arranged
168  //
169  //  libtest_check_order.so
170  //  |
171  //  +-> libtest_check_order_1_left.so
172  //  |   |
173  //  |   +-> libtest_check_order_a.so
174  //  |   |
175  //  |   +-> libtest_check_order_b.so
176  //  |
177  //  +-> libtest_check_order_2_right.so
178  //  |   |
179  //  |   +-> libtest_check_order_d.so
180  //  |       |
181  //  |       +-> libtest_check_order_b.so
182  //  |
183  //  +-> libtest_check_order_3_c.so
184  //
185  //  load order should be (1, 2, 3, a, b, d)
186  //
187  // get_answer() is defined in (2, 3, a, b, c)
188  // get_answer2() is defined in (b, d)
189  void* sym = dlsym(RTLD_DEFAULT, "dlopen_test_get_answer");
190  ASSERT_TRUE(sym == nullptr);
191  void* handle = dlopen("libtest_check_order.so", RTLD_NOW);
192  ASSERT_TRUE(handle != nullptr);
193  typedef int (*fn_t) (void);
194  fn_t fn, fn2;
195  fn = reinterpret_cast<fn_t>(dlsym(RTLD_DEFAULT, "dlopen_test_get_answer"));
196  ASSERT_TRUE(fn != NULL);
197  fn2 = reinterpret_cast<fn_t>(dlsym(RTLD_DEFAULT, "dlopen_test_get_answer2"));
198  ASSERT_TRUE(fn2 != NULL);
199
200  ASSERT_EQ(42, fn());
201  ASSERT_EQ(43, fn2());
202  dlclose(handle);
203}
204
205// libtest_with_dependency_loop.so -> libtest_with_dependency_loop_a.so ->
206// libtest_with_dependency_loop_b.so -> libtest_with_dependency_loop_c.so ->
207// libtest_with_dependency_loop_a.so
208TEST(dlfcn, dlopen_check_loop) {
209  void* handle = dlopen("libtest_with_dependency_loop.so", RTLD_NOW);
210  ASSERT_TRUE(handle == nullptr);
211  ASSERT_STREQ("dlopen failed: recursive link to \"libtest_with_dependency_loop_a.so\"", dlerror());
212  // This symbol should never be exposed
213  void* f = dlsym(RTLD_DEFAULT, "dlopen_test_invalid_function");
214  ASSERT_TRUE(f == nullptr);
215  ASSERT_SUBSTR("undefined symbol: dlopen_test_invalid_function", dlerror());
216
217  // dlopen second time to make sure that the library wasn't loaded even though dlopen returned null.
218  // This may happen if during cleanup the root library or one of the depended libs were not removed
219  // from soinfo list.
220  handle = dlopen("libtest_with_dependency_loop.so", RTLD_NOW | RTLD_NOLOAD);
221  ASSERT_TRUE(handle == nullptr);
222  ASSERT_STREQ("dlopen failed: library \"libtest_with_dependency_loop.so\" wasn't loaded and RTLD_NOLOAD prevented it", dlerror());
223}
224
225TEST(dlfcn, dlopen_failure) {
226  void* self = dlopen("/does/not/exist", RTLD_NOW);
227  ASSERT_TRUE(self == NULL);
228#if defined(__BIONIC__)
229  ASSERT_STREQ("dlopen failed: library \"/does/not/exist\" not found", dlerror());
230#else
231  ASSERT_STREQ("/does/not/exist: cannot open shared object file: No such file or directory", dlerror());
232#endif
233}
234
235static void* ConcurrentDlErrorFn(void*) {
236  dlopen("/child/thread", RTLD_NOW);
237  return reinterpret_cast<void*>(strdup(dlerror()));
238}
239
240TEST(dlfcn, dlerror_concurrent) {
241  dlopen("/main/thread", RTLD_NOW);
242  const char* main_thread_error = dlerror();
243  ASSERT_SUBSTR("/main/thread", main_thread_error);
244
245  pthread_t t;
246  ASSERT_EQ(0, pthread_create(&t, NULL, ConcurrentDlErrorFn, NULL));
247  void* result;
248  ASSERT_EQ(0, pthread_join(t, &result));
249  char* child_thread_error = static_cast<char*>(result);
250  ASSERT_SUBSTR("/child/thread", child_thread_error);
251  free(child_thread_error);
252
253  ASSERT_SUBSTR("/main/thread", main_thread_error);
254}
255
256TEST(dlfcn, dlsym_failures) {
257  dlerror(); // Clear any pending errors.
258  void* self = dlopen(NULL, RTLD_NOW);
259  ASSERT_TRUE(self != NULL);
260  ASSERT_TRUE(dlerror() == NULL);
261
262  void* sym;
263
264#if defined(__BIONIC__) && !defined(__LP64__)
265  // RTLD_DEFAULT in lp32 bionic is not (void*)0
266  // so it can be distinguished from the NULL handle.
267  sym = dlsym(NULL, "test");
268  ASSERT_TRUE(sym == NULL);
269  ASSERT_SUBSTR("dlsym library handle is null", dlerror());
270#endif
271
272  // NULL symbol name.
273#if defined(__BIONIC__)
274  // glibc marks this parameter non-null and SEGVs if you cheat.
275  sym = dlsym(self, NULL);
276  ASSERT_TRUE(sym == NULL);
277  ASSERT_SUBSTR("", dlerror());
278#endif
279
280  // Symbol that doesn't exist.
281  sym = dlsym(self, "ThisSymbolDoesNotExist");
282  ASSERT_TRUE(sym == NULL);
283  ASSERT_SUBSTR("undefined symbol: ThisSymbolDoesNotExist", dlerror());
284
285  ASSERT_EQ(0, dlclose(self));
286}
287
288TEST(dlfcn, dladdr) {
289  dlerror(); // Clear any pending errors.
290  void* self = dlopen(NULL, RTLD_NOW);
291  ASSERT_TRUE(self != NULL);
292  ASSERT_TRUE(dlerror() == NULL);
293
294  void* sym = dlsym(self, "DlSymTestFunction");
295  ASSERT_TRUE(sym != NULL);
296
297  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
298  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
299
300  Dl_info info;
301  int rc = dladdr(addr, &info);
302  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
303
304  // Get the name of this executable.
305  char executable_path[PATH_MAX];
306  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
307  ASSERT_NE(rc, -1);
308  executable_path[rc] = '\0';
309  std::string executable_name(basename(executable_path));
310
311  // The filename should be that of this executable.
312  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
313  std::string dli_fname(info.dli_fname);
314  dli_fname = basename(&dli_fname[0]);
315  ASSERT_EQ(dli_fname, executable_name);
316
317  // The symbol name should be the symbol we looked up.
318  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
319
320  // The address should be the exact address of the symbol.
321  ASSERT_EQ(info.dli_saddr, sym);
322
323  // Look in /proc/pid/maps to find out what address we were loaded at.
324  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
325  void* base_address = NULL;
326  char line[BUFSIZ];
327  FILE* fp = fopen("/proc/self/maps", "r");
328  ASSERT_TRUE(fp != NULL);
329  while (fgets(line, sizeof(line), fp) != NULL) {
330    uintptr_t start = strtoul(line, 0, 16);
331    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
332    char* path = strchr(line, '/');
333    if (path != NULL && strcmp(executable_path, path) == 0) {
334      base_address = reinterpret_cast<void*>(start);
335      break;
336    }
337  }
338  fclose(fp);
339
340  // The base address should be the address we were loaded at.
341  ASSERT_EQ(info.dli_fbase, base_address);
342
343  ASSERT_EQ(0, dlclose(self));
344}
345
346TEST(dlfcn, dladdr_invalid) {
347  Dl_info info;
348
349  dlerror(); // Clear any pending errors.
350
351  // No symbol corresponding to NULL.
352  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
353  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
354
355  // No symbol corresponding to a stack address.
356  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
357  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
358}
359
360// Our dynamic linker doesn't support GNU hash tables.
361#if defined(__BIONIC__)
362// GNU-style ELF hash tables are incompatible with the MIPS ABI.
363// MIPS requires .dynsym to be sorted to match the GOT but GNU-style requires sorting by hash code.
364#if !defined(__mips__)
365TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
366  dlerror(); // Clear any pending errors.
367  void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
368  ASSERT_TRUE(handle == NULL);
369  ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
370}
371#endif
372#endif
373
374TEST(dlfcn, dlopen_bad_flags) {
375  dlerror(); // Clear any pending errors.
376  void* handle;
377
378#if defined(__GLIBC__)
379  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
380  handle = dlopen(NULL, 0);
381  ASSERT_TRUE(handle == NULL);
382  ASSERT_SUBSTR("invalid", dlerror());
383#endif
384
385  handle = dlopen(NULL, 0xffffffff);
386  ASSERT_TRUE(handle == NULL);
387  ASSERT_SUBSTR("invalid", dlerror());
388
389  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
390  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
391  ASSERT_TRUE(handle != NULL);
392  ASSERT_SUBSTR(NULL, dlerror());
393}
394
395TEST(dlfcn, rtld_default_unknown_symbol) {
396  void* addr = dlsym(RTLD_DEFAULT, "ANY_UNKNOWN_SYMBOL_NAME");
397  ASSERT_TRUE(addr == NULL);
398}
399
400TEST(dlfcn, rtld_default_known_symbol) {
401  void* addr = dlsym(RTLD_DEFAULT, "fopen");
402  ASSERT_TRUE(addr != NULL);
403}
404
405TEST(dlfcn, rtld_next_unknown_symbol) {
406  void* addr = dlsym(RTLD_NEXT, "ANY_UNKNOWN_SYMBOL_NAME");
407  ASSERT_TRUE(addr == NULL);
408}
409
410TEST(dlfcn, rtld_next_known_symbol) {
411  void* addr = dlsym(RTLD_NEXT, "fopen");
412  ASSERT_TRUE(addr != NULL);
413}
414
415TEST(dlfcn, dlsym_weak_func) {
416  dlerror();
417  void* handle = dlopen("libtest_dlsym_weak_func.so",RTLD_NOW);
418  ASSERT_TRUE(handle != NULL);
419
420  int (*weak_func)();
421  weak_func = reinterpret_cast<int (*)()>(dlsym(handle, "weak_func"));
422  ASSERT_TRUE(weak_func != NULL) << "dlerror: " << dlerror();
423  EXPECT_EQ(42, weak_func());
424  dlclose(handle);
425}
426
427TEST(dlfcn, dlopen_symlink) {
428  void* handle1 = dlopen("libdlext_test.so", RTLD_NOW);
429  void* handle2 = dlopen("libdlext_test_v2.so", RTLD_NOW);
430  ASSERT_TRUE(handle1 != NULL);
431  ASSERT_TRUE(handle2 != NULL);
432  ASSERT_EQ(handle1, handle2);
433}
434