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
56static 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
64static 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 */
72static 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 */
148static 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
171int 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
218found:
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
224int 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