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
27#define LOG_TAG "HAL"
28#include <utils/Log.h>
29
30/** Base path of the hal modules */
31#if defined(__LP64__)
32#define HAL_LIBRARY_PATH1 "/system/lib64/hw"
33#define HAL_LIBRARY_PATH2 "/vendor/lib64/hw"
34#define HAL_LIBRARY_PATH3 "/odm/lib64/hw"
35#else
36#define HAL_LIBRARY_PATH1 "/system/lib/hw"
37#define HAL_LIBRARY_PATH2 "/vendor/lib/hw"
38#define HAL_LIBRARY_PATH3 "/odm/lib/hw"
39#endif
40
41/**
42 * There are a set of variant filename for modules. The form of the filename
43 * is "<MODULE_ID>.variant.so" so for the led module the Dream variants
44 * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be:
45 *
46 * led.trout.so
47 * led.msm7k.so
48 * led.ARMV6.so
49 * led.default.so
50 */
51
52static const char *variant_keys[] = {
53    "ro.hardware",  /* This goes first so that it can pick up a different
54                       file on the emulator. */
55    "ro.product.board",
56    "ro.board.platform",
57    "ro.arch"
58};
59
60static const int HAL_VARIANT_KEYS_COUNT =
61    (sizeof(variant_keys)/sizeof(variant_keys[0]));
62
63/**
64 * Load the file defined by the variant and if successful
65 * return the dlopen handle and the hmi.
66 * @return 0 = success, !0 = failure.
67 */
68static int load(const char *id,
69        const char *path,
70        const struct hw_module_t **pHmi)
71{
72    int status = -EINVAL;
73    void *handle = NULL;
74    struct hw_module_t *hmi = NULL;
75
76    /*
77     * load the symbols resolving undefined symbols before
78     * dlopen returns. Since RTLD_GLOBAL is not or'd in with
79     * RTLD_NOW the external symbols will not be global
80     */
81    handle = dlopen(path, RTLD_NOW);
82    if (handle == NULL) {
83        char const *err_str = dlerror();
84        ALOGE("load: module=%s\n%s", path, err_str?err_str:"unknown");
85        status = -EINVAL;
86        goto done;
87    }
88
89    /* Get the address of the struct hal_module_info. */
90    const char *sym = HAL_MODULE_INFO_SYM_AS_STR;
91    hmi = (struct hw_module_t *)dlsym(handle, sym);
92    if (hmi == NULL) {
93        ALOGE("load: couldn't find symbol %s", sym);
94        status = -EINVAL;
95        goto done;
96    }
97
98    /* Check that the id matches */
99    if (strcmp(id, hmi->id) != 0) {
100        ALOGE("load: id=%s != hmi->id=%s", id, hmi->id);
101        status = -EINVAL;
102        goto done;
103    }
104
105    hmi->dso = handle;
106
107    /* success */
108    status = 0;
109
110    done:
111    if (status != 0) {
112        hmi = NULL;
113        if (handle != NULL) {
114            dlclose(handle);
115            handle = NULL;
116        }
117    } else {
118        ALOGV("loaded HAL id=%s path=%s hmi=%p handle=%p",
119                id, path, *pHmi, handle);
120    }
121
122    *pHmi = hmi;
123
124    return status;
125}
126
127/*
128 * Check if a HAL with given name and subname exists, if so return 0, otherwise
129 * otherwise return negative.  On success path will contain the path to the HAL.
130 */
131static int hw_module_exists(char *path, size_t path_len, const char *name,
132                            const char *subname)
133{
134    snprintf(path, path_len, "%s/%s.%s.so",
135             HAL_LIBRARY_PATH3, name, subname);
136    if (access(path, R_OK) == 0)
137        return 0;
138
139    snprintf(path, path_len, "%s/%s.%s.so",
140             HAL_LIBRARY_PATH2, name, subname);
141    if (access(path, R_OK) == 0)
142        return 0;
143
144    snprintf(path, path_len, "%s/%s.%s.so",
145             HAL_LIBRARY_PATH1, name, subname);
146    if (access(path, R_OK) == 0)
147        return 0;
148
149    return -ENOENT;
150}
151
152int hw_get_module_by_class(const char *class_id, const char *inst,
153                           const struct hw_module_t **module)
154{
155    int i = 0;
156    char prop[PATH_MAX] = {0};
157    char path[PATH_MAX] = {0};
158    char name[PATH_MAX] = {0};
159    char prop_name[PATH_MAX] = {0};
160
161
162    if (inst)
163        snprintf(name, PATH_MAX, "%s.%s", class_id, inst);
164    else
165        strlcpy(name, class_id, PATH_MAX);
166
167    /*
168     * Here we rely on the fact that calling dlopen multiple times on
169     * the same .so will simply increment a refcount (and not load
170     * a new copy of the library).
171     * We also assume that dlopen() is thread-safe.
172     */
173
174    /* First try a property specific to the class and possibly instance */
175    snprintf(prop_name, sizeof(prop_name), "ro.hardware.%s", name);
176    if (property_get(prop_name, prop, NULL) > 0) {
177        if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
178            goto found;
179        }
180    }
181
182    /* Loop through the configuration variants looking for a module */
183    for (i=0 ; i<HAL_VARIANT_KEYS_COUNT; i++) {
184        if (property_get(variant_keys[i], prop, NULL) == 0) {
185            continue;
186        }
187        if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
188            goto found;
189        }
190    }
191
192    /* Nothing found, try the default */
193    if (hw_module_exists(path, sizeof(path), name, "default") == 0) {
194        goto found;
195    }
196
197    return -ENOENT;
198
199found:
200    /* load the module, if this fails, we're doomed, and we should not try
201     * to load a different variant. */
202    return load(class_id, path, module);
203}
204
205int hw_get_module(const char *id, const struct hw_module_t **module)
206{
207    return hw_get_module_by_class(id, NULL, module);
208}
209