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The Android Open Source Project1dc9e472009-03-03 19:28:35 -08001/*
2 * Copyright (C) 2007 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#include <dlfcn.h>
17#include <pthread.h>
Dima Zavin2e855792009-05-20 18:28:09 -070018#include <stdio.h>
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080019#include "linker.h"
David 'Digit' Turner5c734642010-01-20 12:36:51 -080020#include "linker_format.h"
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080021
22/* This file hijacks the symbols stubbed out in libdl.so. */
23
24#define DL_SUCCESS 0
Dima Zavin2e855792009-05-20 18:28:09 -070025#define DL_ERR_CANNOT_LOAD_LIBRARY 1
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080026#define DL_ERR_INVALID_LIBRARY_HANDLE 2
27#define DL_ERR_BAD_SYMBOL_NAME 3
28#define DL_ERR_SYMBOL_NOT_FOUND 4
29#define DL_ERR_SYMBOL_NOT_GLOBAL 5
30
Dima Zavin2e855792009-05-20 18:28:09 -070031static char dl_err_buf[1024];
32static const char *dl_err_str;
33
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080034static const char *dl_errors[] = {
Dima Zavin2e855792009-05-20 18:28:09 -070035 [DL_ERR_CANNOT_LOAD_LIBRARY] = "Cannot load library",
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080036 [DL_ERR_INVALID_LIBRARY_HANDLE] = "Invalid library handle",
37 [DL_ERR_BAD_SYMBOL_NAME] = "Invalid symbol name",
38 [DL_ERR_SYMBOL_NOT_FOUND] = "Symbol not found",
39 [DL_ERR_SYMBOL_NOT_GLOBAL] = "Symbol is not global",
40};
41
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080042#define likely(expr) __builtin_expect (expr, 1)
43#define unlikely(expr) __builtin_expect (expr, 0)
44
Pavel Chupine19d7022012-02-20 10:49:13 +040045pthread_mutex_t dl_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER;
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080046
Dima Zavin2e855792009-05-20 18:28:09 -070047static void set_dlerror(int err)
48{
David 'Digit' Turner5c734642010-01-20 12:36:51 -080049 format_buffer(dl_err_buf, sizeof(dl_err_buf), "%s: %s", dl_errors[err],
Dima Zavin2e855792009-05-20 18:28:09 -070050 linker_get_error());
51 dl_err_str = (const char *)&dl_err_buf[0];
52};
53
54void *dlopen(const char *filename, int flag)
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080055{
56 soinfo *ret;
57
58 pthread_mutex_lock(&dl_lock);
59 ret = find_library(filename);
60 if (unlikely(ret == NULL)) {
Dima Zavin2e855792009-05-20 18:28:09 -070061 set_dlerror(DL_ERR_CANNOT_LOAD_LIBRARY);
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080062 } else {
David 'Digit' Turner16084162012-06-12 16:25:37 +020063 soinfo_call_constructors(ret);
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080064 ret->refcount++;
65 }
66 pthread_mutex_unlock(&dl_lock);
67 return ret;
68}
69
70const char *dlerror(void)
71{
Dima Zavin2e855792009-05-20 18:28:09 -070072 const char *tmp = dl_err_str;
73 dl_err_str = NULL;
74 return (const char *)tmp;
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080075}
76
77void *dlsym(void *handle, const char *symbol)
78{
Iliyan Malchev9ea64da2009-09-28 18:21:30 -070079 soinfo *found;
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080080 Elf32_Sym *sym;
81 unsigned bind;
82
83 pthread_mutex_lock(&dl_lock);
Dima Zavin2e855792009-05-20 18:28:09 -070084
Elliott Hughesbedfe382012-08-14 14:07:59 -070085 if(unlikely(handle == 0)) {
Dima Zavin2e855792009-05-20 18:28:09 -070086 set_dlerror(DL_ERR_INVALID_LIBRARY_HANDLE);
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080087 goto err;
88 }
89 if(unlikely(symbol == 0)) {
Dima Zavin2e855792009-05-20 18:28:09 -070090 set_dlerror(DL_ERR_BAD_SYMBOL_NAME);
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080091 goto err;
92 }
Dima Zavin2e855792009-05-20 18:28:09 -070093
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080094 if(handle == RTLD_DEFAULT) {
Matt Fischer1698d9e2009-12-31 12:17:56 -060095 sym = lookup(symbol, &found, NULL);
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080096 } else if(handle == RTLD_NEXT) {
Matt Fischer1698d9e2009-12-31 12:17:56 -060097 void *ret_addr = __builtin_return_address(0);
98 soinfo *si = find_containing_library(ret_addr);
99
100 sym = NULL;
101 if(si && si->next) {
102 sym = lookup(symbol, &found, si->next);
103 }
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800104 } else {
Iliyan Malchev9ea64da2009-09-28 18:21:30 -0700105 found = (soinfo*)handle;
David 'Digit' Turner16084162012-06-12 16:25:37 +0200106 sym = soinfo_lookup(found, symbol);
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800107 }
108
109 if(likely(sym != 0)) {
110 bind = ELF32_ST_BIND(sym->st_info);
Dima Zavin2e855792009-05-20 18:28:09 -0700111
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800112 if(likely((bind == STB_GLOBAL) && (sym->st_shndx != 0))) {
Raghu Gandhamc1993ca2012-09-21 12:21:02 -0700113 unsigned ret = sym->st_value + found->load_bias;
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800114 pthread_mutex_unlock(&dl_lock);
115 return (void*)ret;
116 }
117
Dima Zavin2e855792009-05-20 18:28:09 -0700118 set_dlerror(DL_ERR_SYMBOL_NOT_GLOBAL);
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800119 }
Dima Zavin2e855792009-05-20 18:28:09 -0700120 else
121 set_dlerror(DL_ERR_SYMBOL_NOT_FOUND);
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800122
123err:
124 pthread_mutex_unlock(&dl_lock);
125 return 0;
126}
127
Mathias Agopianbda5da02011-09-27 22:30:19 -0700128int dladdr(const void *addr, Dl_info *info)
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600129{
130 int ret = 0;
131
132 pthread_mutex_lock(&dl_lock);
133
134 /* Determine if this address can be found in any library currently mapped */
135 soinfo *si = find_containing_library(addr);
136
137 if(si) {
138 memset(info, 0, sizeof(Dl_info));
139
140 info->dli_fname = si->name;
Raghu Gandhame6dc2a62012-09-25 15:50:33 -0700141 /* Address at which the shared object is loaded */
142 info->dli_fbase = (void*)si->base;
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600143
144 /* Determine if any symbol in the library contains the specified address */
David 'Digit' Turner16084162012-06-12 16:25:37 +0200145 Elf32_Sym *sym = soinfo_find_symbol(si, addr);
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600146
147 if(sym != NULL) {
148 info->dli_sname = si->strtab + sym->st_name;
Raghu Gandhamc1993ca2012-09-21 12:21:02 -0700149 info->dli_saddr = (void*)(si->load_bias + sym->st_value);
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600150 }
151
152 ret = 1;
153 }
154
155 pthread_mutex_unlock(&dl_lock);
156
157 return ret;
158}
159
Elliott Hughesbedfe382012-08-14 14:07:59 -0700160int dlclose(void* handle) {
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800161 pthread_mutex_lock(&dl_lock);
Elliott Hughesbedfe382012-08-14 14:07:59 -0700162 int result = soinfo_unload((soinfo*)handle);
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800163 pthread_mutex_unlock(&dl_lock);
Elliott Hughesbedfe382012-08-14 14:07:59 -0700164 return result;
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800165}
166
167#if defined(ANDROID_ARM_LINKER)
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600168// 0000000 00011111 111112 22222222 2333333 333344444444445555555
169// 0123456 78901234 567890 12345678 9012345 678901234567890123456
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800170#define ANDROID_LIBDL_STRTAB \
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600171 "dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0dl_unwind_find_exidx\0"
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800172
Raghu Gandhamd7daacb2012-07-31 12:07:22 -0700173#elif defined(ANDROID_X86_LINKER) || defined(ANDROID_MIPS_LINKER)
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600174// 0000000 00011111 111112 22222222 2333333 3333444444444455
175// 0123456 78901234 567890 12345678 9012345 6789012345678901
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800176#define ANDROID_LIBDL_STRTAB \
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600177 "dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0dl_iterate_phdr\0"
David 'Digit' Turner177a7702012-02-01 19:38:58 +0100178#else
Raghu Gandhamd7daacb2012-07-31 12:07:22 -0700179#error Unsupported architecture. Only ARM, MIPS, and x86 are presently supported.
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800180#endif
181
182
183static Elf32_Sym libdl_symtab[] = {
184 // total length of libdl_info.strtab, including trailing 0
185 // This is actually the the STH_UNDEF entry. Technically, it's
186 // supposed to have st_name == 0, but instead, it points to an index
187 // in the strtab with a \0 to make iterating through the symtab easier.
188 { st_name: sizeof(ANDROID_LIBDL_STRTAB) - 1,
189 },
190 { st_name: 0, // starting index of the name in libdl_info.strtab
191 st_value: (Elf32_Addr) &dlopen,
192 st_info: STB_GLOBAL << 4,
193 st_shndx: 1,
194 },
195 { st_name: 7,
196 st_value: (Elf32_Addr) &dlclose,
197 st_info: STB_GLOBAL << 4,
198 st_shndx: 1,
199 },
200 { st_name: 15,
201 st_value: (Elf32_Addr) &dlsym,
202 st_info: STB_GLOBAL << 4,
203 st_shndx: 1,
204 },
205 { st_name: 21,
206 st_value: (Elf32_Addr) &dlerror,
207 st_info: STB_GLOBAL << 4,
208 st_shndx: 1,
209 },
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800210 { st_name: 29,
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600211 st_value: (Elf32_Addr) &dladdr,
212 st_info: STB_GLOBAL << 4,
213 st_shndx: 1,
214 },
215#ifdef ANDROID_ARM_LINKER
216 { st_name: 36,
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800217 st_value: (Elf32_Addr) &dl_unwind_find_exidx,
218 st_info: STB_GLOBAL << 4,
219 st_shndx: 1,
220 },
Raghu Gandhamd7daacb2012-07-31 12:07:22 -0700221#elif defined(ANDROID_X86_LINKER) || defined(ANDROID_MIPS_LINKER)
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600222 { st_name: 36,
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800223 st_value: (Elf32_Addr) &dl_iterate_phdr,
224 st_info: STB_GLOBAL << 4,
225 st_shndx: 1,
226 },
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800227#endif
228};
229
230/* Fake out a hash table with a single bucket.
231 * A search of the hash table will look through
232 * libdl_symtab starting with index [1], then
233 * use libdl_chains to find the next index to
234 * look at. libdl_chains should be set up to
235 * walk through every element in libdl_symtab,
236 * and then end with 0 (sentinel value).
237 *
238 * I.e., libdl_chains should look like
239 * { 0, 2, 3, ... N, 0 } where N is the number
240 * of actual symbols, or nelems(libdl_symtab)-1
241 * (since the first element of libdl_symtab is not
242 * a real symbol).
243 *
244 * (see _elf_lookup())
245 *
246 * Note that adding any new symbols here requires
247 * stubbing them out in libdl.
248 */
249static unsigned libdl_buckets[1] = { 1 };
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600250static unsigned libdl_chains[7] = { 0, 2, 3, 4, 5, 6, 0 };
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800251
252soinfo libdl_info = {
253 name: "libdl.so",
254 flags: FLAG_LINKED,
255
256 strtab: ANDROID_LIBDL_STRTAB,
257 symtab: libdl_symtab,
258
259 nbucket: 1,
Matt Fischere2a8b1f2009-12-31 12:17:40 -0600260 nchain: 7,
The Android Open Source Project1dc9e472009-03-03 19:28:35 -0800261 bucket: libdl_buckets,
262 chain: libdl_chains,
263};