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