dlfcn_test.cpp revision 2ed710976cb0ace31aab565c95a42d4e75623894 
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 gCalled = false;
31extern "C" void DlSymTestFunction() {
32  gCalled = 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  gCalled = false;
47  function();
48  ASSERT_TRUE(gCalled);
49
50  ASSERT_EQ(0, dlclose(self));
51}
52
53TEST(dlfcn, dlopen_failure) {
54  void* self = dlopen("/does/not/exist", RTLD_NOW);
55  ASSERT_TRUE(self == NULL);
56#if __BIONIC__
57  ASSERT_STREQ("dlopen failed: library \"/does/not/exist\" not found", dlerror());
58#else
59  ASSERT_STREQ("/does/not/exist: cannot open shared object file: No such file or directory", dlerror());
60#endif
61}
62
63static void* ConcurrentDlErrorFn(void*) {
64  dlopen("/child/thread", RTLD_NOW);
65  return reinterpret_cast<void*>(strdup(dlerror()));
66}
67
68TEST(dlfcn, dlerror_concurrent) {
69  dlopen("/main/thread", RTLD_NOW);
70  const char* main_thread_error = dlerror();
71  ASSERT_SUBSTR("/main/thread", main_thread_error);
72
73  pthread_t t;
74  ASSERT_EQ(0, pthread_create(&t, NULL, ConcurrentDlErrorFn, NULL));
75  void* result;
76  ASSERT_EQ(0, pthread_join(t, &result));
77  char* child_thread_error = static_cast<char*>(result);
78  ASSERT_SUBSTR("/child/thread", child_thread_error);
79  free(child_thread_error);
80
81  ASSERT_SUBSTR("/main/thread", main_thread_error);
82}
83
84TEST(dlfcn, dlsym_failures) {
85  dlerror(); // Clear any pending errors.
86  void* self = dlopen(NULL, RTLD_NOW);
87  ASSERT_TRUE(self != NULL);
88  ASSERT_TRUE(dlerror() == NULL);
89
90  void* sym;
91
92  // NULL handle.
93  sym = dlsym(NULL, "test");
94  ASSERT_TRUE(sym == NULL);
95#if __BIONIC__
96  ASSERT_SUBSTR("dlsym library handle is null", dlerror());
97#else
98  ASSERT_SUBSTR("undefined symbol: test", dlerror()); // glibc isn't specific about the failure.
99#endif
100
101  // NULL symbol name.
102#if __BIONIC__
103  // glibc marks this parameter non-null and SEGVs if you cheat.
104  sym = dlsym(self, NULL);
105  ASSERT_TRUE(sym == NULL);
106  ASSERT_SUBSTR("", dlerror());
107#endif
108
109  // Symbol that doesn't exist.
110  sym = dlsym(self, "ThisSymbolDoesNotExist");
111  ASSERT_TRUE(sym == NULL);
112  ASSERT_SUBSTR("undefined symbol: ThisSymbolDoesNotExist", dlerror());
113
114  ASSERT_EQ(0, dlclose(self));
115}
116
117TEST(dlfcn, dladdr) {
118  dlerror(); // Clear any pending errors.
119  void* self = dlopen(NULL, RTLD_NOW);
120  ASSERT_TRUE(self != NULL);
121  ASSERT_TRUE(dlerror() == NULL);
122
123  void* sym = dlsym(self, "DlSymTestFunction");
124  ASSERT_TRUE(sym != NULL);
125
126  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
127  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
128
129  Dl_info info;
130  int rc = dladdr(addr, &info);
131  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
132
133  // Get the name of this executable.
134  char executable_path[PATH_MAX];
135  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
136  ASSERT_NE(rc, -1);
137  executable_path[rc] = '\0';
138  std::string executable_name(basename(executable_path));
139
140  // The filename should be that of this executable.
141  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
142  std::string dli_fname(info.dli_fname);
143  dli_fname = basename(&dli_fname[0]);
144  ASSERT_EQ(dli_fname, executable_name);
145
146  // The symbol name should be the symbol we looked up.
147  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
148
149  // The address should be the exact address of the symbol.
150  ASSERT_EQ(info.dli_saddr, sym);
151
152  // Look in /proc/pid/maps to find out what address we were loaded at.
153  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
154  void* base_address = NULL;
155  char path[PATH_MAX];
156  snprintf(path, sizeof(path), "/proc/%d/maps", getpid());
157  char line[BUFSIZ];
158  FILE* fp = fopen(path, "r");
159  ASSERT_TRUE(fp != NULL);
160  while (fgets(line, sizeof(line), fp) != NULL) {
161    uintptr_t start = strtoul(line, 0, 16);
162    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
163    char* path = strchr(line, '/');
164    if (path != NULL && strcmp(executable_path, path) == 0) {
165      base_address = reinterpret_cast<void*>(start);
166      break;
167    }
168  }
169  fclose(fp);
170
171  // The base address should be the address we were loaded at.
172  ASSERT_EQ(info.dli_fbase, base_address);
173
174  ASSERT_EQ(0, dlclose(self));
175}
176
177TEST(dlfcn, dladdr_invalid) {
178  Dl_info info;
179
180  dlerror(); // Clear any pending errors.
181
182  // No symbol corresponding to NULL.
183  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
184  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
185
186  // No symbol corresponding to a stack address.
187  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
188  ASSERT_TRUE(dlerror() == NULL); // dladdr(3) doesn't set dlerror(3).
189}
190
191// Our dynamic linker doesn't support GNU hash tables.
192#if defined(__BIONIC__)
193// GNU-style ELF hash tables are incompatible with the MIPS ABI.
194// MIPS requires .dynsym to be sorted to match the GOT but GNU-style requires sorting by hash code.
195#if !defined(__mips__)
196TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
197  dlerror(); // Clear any pending errors.
198  void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
199  ASSERT_TRUE(handle == NULL);
200  ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
201}
202#endif
203#endif
204
205TEST(dlfcn, dlopen_bad_flags) {
206  dlerror(); // Clear any pending errors.
207  void* handle;
208
209#ifdef __GLIBC__
210  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
211  handle = dlopen(NULL, 0);
212  ASSERT_TRUE(handle == NULL);
213  ASSERT_SUBSTR("invalid", dlerror());
214#endif
215
216  handle = dlopen(NULL, 0xffffffff);
217  ASSERT_TRUE(handle == NULL);
218  ASSERT_SUBSTR("invalid", dlerror());
219
220  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
221  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
222  ASSERT_TRUE(handle != NULL);
223  ASSERT_SUBSTR(NULL, dlerror());
224}
225
226TEST(dlfcn, rtld_default_unknown_symbol) {
227  void* addr = dlsym(RTLD_DEFAULT, "ANY_UNKNOWN_SYMBOL_NAME");
228  ASSERT_TRUE(addr == NULL);
229}
230
231TEST(dlfcn, rtld_default_known_symbol) {
232  void* addr = dlsym(RTLD_DEFAULT, "fopen");
233  ASSERT_TRUE(addr != NULL);
234}
235
236TEST(dlfcn, rtld_next_unknown_symbol) {
237  void* addr = dlsym(RTLD_NEXT, "ANY_UNKNOWN_SYMBOL_NAME");
238  ASSERT_TRUE(addr == NULL);
239}
240
241TEST(dlfcn, rtld_next_known_symbol) {
242  void* addr = dlsym(RTLD_NEXT, "fopen");
243  ASSERT_TRUE(addr != NULL);
244}
245