| 1 | /* |
| 2 | * Copyright (c) 2012 Carsten Munk <carsten.munk@gmail.com> |
| 3 | * Copyright (c) 2013 Christophe Chapuis <chris.chapuis@gmail.com> |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | * |
| 17 | */ |
| 18 | |
| 19 | #include "hooks_shm.h" |
| 20 | |
| 21 | #define _GNU_SOURCE |
| 22 | |
| 23 | #include <stddef.h> |
| 24 | #include <stdlib.h> |
| 25 | #include <stdio.h> |
| 26 | #include <sys/stat.h> |
| 27 | #include <fcntl.h> |
| 28 | #include <pthread.h> |
| 29 | #include <errno.h> |
| 30 | #include <sys/ipc.h> |
| 31 | #include <sys/shm.h> |
| 32 | #include <sys/mman.h> |
| 33 | |
| 34 | /* Debug */ |
| 35 | #include "logging.h" |
| 36 | #define LOGD(message, ...) HYBRIS_DEBUG_LOG(HOOKS, message, ##__VA_ARGS__) |
| 37 | |
| 38 | #define HYBRIS_DATA_SIZE 4000 |
| 39 | #define HYBRIS_SHM_MASK 0xFF000000UL |
| 40 | #define HYBRIS_SHM_PATH "/hybris_shm_data" |
| 41 | |
| 42 | /* Structure of a shared memory region */ |
| 43 | typedef struct _hybris_shm_data_t { |
| 44 | pthread_mutex_t access_mutex; |
| 45 | int current_offset; |
| 46 | int max_offset; |
| 47 | unsigned char data; |
| 48 | } hybris_shm_data_t; |
| 49 | |
| 50 | /* A helper to switch between the size of the data and the size of the shm object */ |
| 51 | const int HYBRIS_SHM_DATA_HEADER_SIZE = (sizeof(hybris_shm_data_t) - sizeof(unsigned char)); |
| 52 | |
| 53 | /* pointer to the shared memory region */ |
| 54 | static hybris_shm_data_t *_hybris_shm_data = NULL; |
| 55 | |
| 56 | /* the SHM mem_id of the shared memory region */ |
| 57 | static int _hybris_shm_fd = -1; |
| 58 | |
| 59 | /* the size of the shared memory region that is currently mmap'ed to this process */ |
| 60 | static int _current_mapped_size = 0; |
| 61 | |
| 62 | /* forward-declare the internal static methods */ |
| 63 | static void _release_shm(void); |
| 64 | static void _sync_mmap_with_shm(void); |
| 65 | static void _hybris_shm_init(void); |
| 66 | static void _hybris_shm_extend_region(void); |
| 67 | |
| 68 | /* |
| 69 | * Detach the allocated memory region, and mark it for deletion |
| 70 | */ |
| 71 | static void _release_shm(void) |
| 72 | { |
| 73 | if (_hybris_shm_data) { |
| 74 | munmap(_hybris_shm_data, _current_mapped_size); /* unmap from this process */ |
| 75 | _hybris_shm_data = NULL; /* pointer is no more valid */ |
| 76 | } |
| 77 | if (_hybris_shm_fd >= 0) { |
| 78 | close(_hybris_shm_fd); /* close the shm file descriptor */ |
| 79 | _hybris_shm_fd = -1; |
| 80 | } |
| 81 | shm_unlink(HYBRIS_SHM_PATH); /* request the deletion of the shm region */ |
| 82 | } |
| 83 | |
| 84 | /* |
| 85 | * Synchronize the size of the mmap with the size of the shm region |
| 86 | */ |
| 87 | static void _sync_mmap_with_shm() |
| 88 | { |
| 89 | if (_hybris_shm_fd >= 0 && _hybris_shm_data) { |
| 90 | if (_current_mapped_size < _hybris_shm_data->max_offset + HYBRIS_SHM_DATA_HEADER_SIZE) { |
| 91 | /* Note that mremap may change the address pointed by _hybris_shm_data. |
| 92 | * But as we never point directly into _hybris_shm_data, it's fine. |
| 93 | * */ |
| 94 | _hybris_shm_data = (hybris_shm_data_t *)mremap( _hybris_shm_data, _current_mapped_size, |
| 95 | _hybris_shm_data->max_offset + HYBRIS_SHM_DATA_HEADER_SIZE, |
| 96 | MREMAP_MAYMOVE ); |
| 97 | |
| 98 | _current_mapped_size = _hybris_shm_data->max_offset + HYBRIS_SHM_DATA_HEADER_SIZE; |
| 99 | } |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | /* |
| 104 | * Initialize the shared memory region for hybris, in order to store |
| 105 | * pshared mutex, condition and rwlock |
| 106 | */ |
| 107 | static void _hybris_shm_init() |
| 108 | { |
| 109 | if (_hybris_shm_fd < 0) { |
| 110 | const size_t size_to_map = HYBRIS_SHM_DATA_HEADER_SIZE + HYBRIS_DATA_SIZE; /* 4000 bytes for the data, plus the header size */ |
| 111 | |
| 112 | /* initialize or get shared memory segment */ |
| 113 | _hybris_shm_fd = shm_open(HYBRIS_SHM_PATH, O_RDWR, 0660); |
| 114 | if (_hybris_shm_fd >= 0) { |
| 115 | /* Map the memory object */ |
| 116 | _hybris_shm_data = (hybris_shm_data_t *)mmap( NULL, size_to_map, |
| 117 | PROT_READ | PROT_WRITE, MAP_SHARED, |
| 118 | _hybris_shm_fd, 0 ); |
| 119 | _current_mapped_size = size_to_map; |
| 120 | |
| 121 | _sync_mmap_with_shm(); |
| 122 | } |
| 123 | else { |
| 124 | LOGD("Creating a new shared memory segment."); |
| 125 | |
| 126 | _hybris_shm_fd = shm_open(HYBRIS_SHM_PATH, O_RDWR | O_CREAT, 0660); |
| 127 | if (_hybris_shm_fd >= 0) { |
| 128 | ftruncate( _hybris_shm_fd, size_to_map ); |
| 129 | /* Map the memory object */ |
| 130 | _hybris_shm_data = (hybris_shm_data_t *)mmap( NULL, size_to_map, |
| 131 | PROT_READ | PROT_WRITE, MAP_SHARED, |
| 132 | _hybris_shm_fd, 0 ); |
| 133 | if (_hybris_shm_data == MAP_FAILED) { |
| 134 | HYBRIS_ERROR_LOG(HOOKS, "ERROR: mmap failed: %s\n", strerror(errno)); |
| 135 | _release_shm(); |
| 136 | } |
| 137 | else { |
| 138 | _current_mapped_size = size_to_map; |
| 139 | /* Initialize the memory object */ |
| 140 | memset((void*)_hybris_shm_data, 0, size_to_map); |
| 141 | _hybris_shm_data->max_offset = HYBRIS_DATA_SIZE; |
| 142 | |
| 143 | pthread_mutexattr_t attr; |
| 144 | pthread_mutexattr_init(&attr); |
| 145 | pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED); |
| 146 | pthread_mutex_init(&_hybris_shm_data->access_mutex, &attr); |
| 147 | pthread_mutexattr_destroy(&attr); |
| 148 | |
| 149 | atexit(_release_shm); |
| 150 | } |
| 151 | } |
| 152 | else { |
| 153 | HYBRIS_ERROR_LOG(HOOKS, "ERROR: Couldn't create shared memory segment !"); |
| 154 | } |
| 155 | } |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | /* |
| 160 | * Extend the SHM region's size |
| 161 | */ |
| 162 | static void _hybris_shm_extend_region() |
| 163 | { |
| 164 | ftruncate( _hybris_shm_fd, _current_mapped_size + HYBRIS_DATA_SIZE ); |
| 165 | _hybris_shm_data->max_offset += HYBRIS_DATA_SIZE; |
| 166 | |
| 167 | _sync_mmap_with_shm(); |
| 168 | } |
| 169 | |
| 170 | /************ public functions *******************/ |
| 171 | |
| 172 | /* |
| 173 | * Determine if the pointer that has been extracted by hybris is |
| 174 | * pointing to an address in the shared memory |
| 175 | */ |
| 176 | int hybris_is_pointer_in_shm(void *ptr) |
| 177 | { |
| 178 | if ((unsigned int)ptr >= HYBRIS_SHM_MASK) |
| 179 | return 1; |
| 180 | |
| 181 | return 0; |
| 182 | } |
| 183 | |
| 184 | /* |
| 185 | * Convert this offset pointer to the shared memory to an |
| 186 | * absolute pointer that can be used in user space |
| 187 | */ |
| 188 | void *hybris_get_shmpointer(hybris_shm_pointer_t handle) |
| 189 | { |
| 190 | void *realpointer = NULL; |
| 191 | if (hybris_is_pointer_in_shm((void*)handle)) { |
| 192 | if (_hybris_shm_fd < 0) { |
| 193 | /* if we are not yet attached to any shm region, then do it now */ |
| 194 | _hybris_shm_init(); |
| 195 | } |
| 196 | |
| 197 | pthread_mutex_lock(&_hybris_shm_data->access_mutex); |
| 198 | |
| 199 | _sync_mmap_with_shm(); /* make sure our mmap is sync'ed */ |
| 200 | |
| 201 | if (_hybris_shm_data != NULL) { |
| 202 | unsigned int offset = handle & (~HYBRIS_SHM_MASK); |
| 203 | realpointer = &(_hybris_shm_data->data) + offset; |
| 204 | |
| 205 | /* Be careful when activating this trace: this method is called *a lot* ! |
| 206 | LOGD("handle = %x, offset = %d, realpointer = %x)", handle, offset, realpointer); |
| 207 | */ |
| 208 | } |
| 209 | |
| 210 | pthread_mutex_unlock(&_hybris_shm_data->access_mutex); |
| 211 | } |
| 212 | |
| 213 | return realpointer; |
| 214 | } |
| 215 | |
| 216 | /* |
| 217 | * Allocate a space in the shared memory region of hybris |
| 218 | */ |
| 219 | hybris_shm_pointer_t hybris_shm_alloc(size_t size) |
| 220 | { |
| 221 | hybris_shm_pointer_t location = 0; |
| 222 | |
| 223 | if (_hybris_shm_fd < 0) { |
| 224 | /* if we are not yet attached to any shm region, then do it now */ |
| 225 | _hybris_shm_init(); |
| 226 | } |
| 227 | |
| 228 | pthread_mutex_lock(&_hybris_shm_data->access_mutex); |
| 229 | |
| 230 | /* Make sure our mmap is sync'ed */ |
| 231 | _sync_mmap_with_shm(); |
| 232 | |
| 233 | if (_hybris_shm_data == NULL || _hybris_shm_fd < 0) |
| 234 | return 0; |
| 235 | |
| 236 | if (_hybris_shm_data->current_offset + size >= _hybris_shm_data->max_offset) { |
| 237 | /* the current buffer if full: extend it a little bit more */ |
| 238 | _hybris_shm_extend_region(); |
| 239 | _sync_mmap_with_shm(); |
| 240 | } |
| 241 | |
| 242 | /* there is now enough place in this pool */ |
| 243 | location = _hybris_shm_data->current_offset | HYBRIS_SHM_MASK; |
| 244 | LOGD("Allocated a shared object (size = %d, at offset %d)", size, _hybris_shm_data->current_offset); |
| 245 | |
| 246 | _hybris_shm_data->current_offset += size; |
| 247 | |
| 248 | pthread_mutex_unlock(&_hybris_shm_data->access_mutex); |
| 249 | |
| 250 | return location; |
| 251 | } |