1 /*
2  * Copyright (C) 2008 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 <hardware/hardware.h>
18 
19 #include <cutils/properties.h>
20 
21 #include <dlfcn.h>
22 #include <string.h>
23 #include <pthread.h>
24 #include <errno.h>
25 #include <limits.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <unistd.h>
29 
30 #define LOG_TAG "HAL"
31 #include <log/log.h>
32 
33 #if !defined(__ANDROID_RECOVERY__)
34 #include <vndksupport/linker.h>
35 #endif
36 
37 /** Base path of the hal modules */
38 #if defined(__LP64__)
39 #define HAL_LIBRARY_PATH1 "/system/lib64/hw"
40 #define HAL_LIBRARY_PATH2 "/vendor/lib64/hw"
41 #define HAL_LIBRARY_PATH3 "/odm/lib64/hw"
42 #else
43 #define HAL_LIBRARY_PATH1 "/system/lib/hw"
44 #define HAL_LIBRARY_PATH2 "/vendor/lib/hw"
45 #define HAL_LIBRARY_PATH3 "/odm/lib/hw"
46 #endif
47 
48 /**
49  * There are a set of variant filename for modules. The form of the filename
50  * is "<MODULE_ID>.variant.so" so for the led module the Dream variants
51  * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be:
52  *
53  * led.trout.so
54  * led.msm7k.so
55  * led.ARMV6.so
56  * led.default.so
57  */
58 
59 static const char *variant_keys[] = {
60     "ro.hardware",  /* This goes first so that it can pick up a different
61                        file on the emulator. */
62     "ro.product.board",
63     "ro.board.platform",
64     "ro.arch"
65 };
66 
67 static const int HAL_VARIANT_KEYS_COUNT =
68     (sizeof(variant_keys)/sizeof(variant_keys[0]));
69 
70 /**
71  * Load the file defined by the variant and if successful
72  * return the dlopen handle and the hmi.
73  * @return 0 = success, !0 = failure.
74  */
75 static int load(const char *id,
76         const char *path,
77         const struct hw_module_t **pHmi)
78 {
79     int status = -EINVAL;
80     void *handle = NULL;
81     struct hw_module_t *hmi = NULL;
82 #ifdef __ANDROID_VNDK__
83     const bool try_system = false;
84 #else
85     const bool try_system = true;
86 #endif
87 
88     /*
89      * load the symbols resolving undefined symbols before
90      * dlopen returns. Since RTLD_GLOBAL is not or'd in with
91      * RTLD_NOW the external symbols will not be global
92      */
93     if (try_system &&
94         strncmp(path, HAL_LIBRARY_PATH1, strlen(HAL_LIBRARY_PATH1)) == 0) {
95         /* If the library is in system partition, no need to check
96          * sphal namespace. Open it with dlopen.
97          */
98         handle = dlopen(path, RTLD_NOW);
99     } else {
100 #if defined(__ANDROID_RECOVERY__)
101         handle = dlopen(path, RTLD_NOW);
102 #else
103         handle = android_load_sphal_library(path, RTLD_NOW);
104 #endif
105     }
106     if (handle == NULL) {
107         char const *err_str = dlerror();
108         ALOGE("load: module=%s\n%s", path, err_str?err_str:"unknown");
109         status = -EINVAL;
110         goto done;
111     }
112 
113     /* Get the address of the struct hal_module_info. */
114     const char *sym = HAL_MODULE_INFO_SYM_AS_STR;
115     hmi = (struct hw_module_t *)dlsym(handle, sym);
116     if (hmi == NULL) {
117         ALOGE("load: couldn't find symbol %s", sym);
118         status = -EINVAL;
119         goto done;
120     }
121 
122     /* Check that the id matches */
123     if (strcmp(id, hmi->id) != 0) {
124         ALOGE("load: id=%s != hmi->id=%s", id, hmi->id);
125         status = -EINVAL;
126         goto done;
127     }
128 
129     hmi->dso = handle;
130 
131     /* success */
132     status = 0;
133 
134     done:
135     if (status != 0) {
136         hmi = NULL;
137         if (handle != NULL) {
138             dlclose(handle);
139             handle = NULL;
140         }
141     } else {
142         ALOGV("loaded HAL id=%s path=%s hmi=%p handle=%p",
143                 id, path, hmi, handle);
144     }
145 
146     *pHmi = hmi;
147 
148     return status;
149 }
150 
151 /*
152  * If path is in in_path.
153  */
154 static bool path_in_path(const char *path, const char *in_path) {
155     char real_path[PATH_MAX];
156     if (realpath(path, real_path) == NULL) return false;
157 
158     char real_in_path[PATH_MAX];
159     if (realpath(in_path, real_in_path) == NULL) return false;
160 
161     const size_t real_in_path_len = strlen(real_in_path);
162     if (strncmp(real_path, real_in_path, real_in_path_len) != 0) {
163         return false;
164     }
165 
166     return strlen(real_path) > real_in_path_len &&
167         real_path[real_in_path_len] == '/';
168 }
169 
170 /*
171  * Check if a HAL with given name and subname exists, if so return 0, otherwise
172  * otherwise return negative.  On success path will contain the path to the HAL.
173  */
174 static int hw_module_exists(char *path, size_t path_len, const char *name,
175                             const char *subname)
176 {
177     snprintf(path, path_len, "%s/%s.%s.so",
178              HAL_LIBRARY_PATH3, name, subname);
179     if (path_in_path(path, HAL_LIBRARY_PATH3) && access(path, R_OK) == 0)
180         return 0;
181 
182     snprintf(path, path_len, "%s/%s.%s.so",
183              HAL_LIBRARY_PATH2, name, subname);
184     if (path_in_path(path, HAL_LIBRARY_PATH2) && access(path, R_OK) == 0)
185         return 0;
186 
187 #ifndef __ANDROID_VNDK__
188     snprintf(path, path_len, "%s/%s.%s.so",
189              HAL_LIBRARY_PATH1, name, subname);
190     if (path_in_path(path, HAL_LIBRARY_PATH1) && access(path, R_OK) == 0)
191         return 0;
192 #endif
193 
194     return -ENOENT;
195 }
196 
197 int hw_get_module_by_class(const char *class_id, const char *inst,
198                            const struct hw_module_t **module)
199 {
200     int i = 0;
201     char prop[PATH_MAX] = {0};
202     char path[PATH_MAX] = {0};
203     char name[PATH_MAX] = {0};
204     char prop_name[PATH_MAX] = {0};
205 
206 
207     if (inst)
208         snprintf(name, PATH_MAX, "%s.%s", class_id, inst);
209     else
210         strlcpy(name, class_id, PATH_MAX);
211 
212     /*
213      * Here we rely on the fact that calling dlopen multiple times on
214      * the same .so will simply increment a refcount (and not load
215      * a new copy of the library).
216      * We also assume that dlopen() is thread-safe.
217      */
218 
219     /* First try a property specific to the class and possibly instance */
220     snprintf(prop_name, sizeof(prop_name), "ro.hardware.%s", name);
221     if (property_get(prop_name, prop, NULL) > 0) {
222         if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
223             goto found;
224         }
225     }
226 
227     /* Loop through the configuration variants looking for a module */
228     for (i=0 ; i<HAL_VARIANT_KEYS_COUNT; i++) {
229         if (property_get(variant_keys[i], prop, NULL) == 0) {
230             continue;
231         }
232         if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
233             goto found;
234         }
235     }
236 
237     /* Nothing found, try the default */
238     if (hw_module_exists(path, sizeof(path), name, "default") == 0) {
239         goto found;
240     }
241 
242     return -ENOENT;
243 
244 found:
245     /* load the module, if this fails, we're doomed, and we should not try
246      * to load a different variant. */
247     return load(class_id, path, module);
248 }
249 
250 int hw_get_module(const char *id, const struct hw_module_t **module)
251 {
252     return hw_get_module_by_class(id, NULL, module);
253 }
254