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 /* 18 * System utilities. 19 */ 20 #include "DexFile.h" 21 #include "SysUtil.h" 22 23 #include <stdlib.h> 24 #include <stdio.h> 25 #include <unistd.h> 26 #include <string.h> 27 #ifdef HAVE_POSIX_FILEMAP 28 # include <sys/mman.h> 29 #endif 30 #include <limits.h> 31 #include <errno.h> 32 33 #include <JNIHelp.h> // TEMP_FAILURE_RETRY may or may not be in unistd 34 35 36 /* 37 * Create an anonymous shared memory segment large enough to hold "length" 38 * bytes. The actual segment may be larger because mmap() operates on 39 * page boundaries (usually 4K). 40 */ 41 static void* sysCreateAnonShmem(size_t length) 42 { 43 #ifdef HAVE_POSIX_FILEMAP 44 void* ptr; 45 46 ptr = mmap(NULL, length, PROT_READ | PROT_WRITE, 47 MAP_SHARED | MAP_ANON, -1, 0); 48 if (ptr == MAP_FAILED) { 49 ALOGW("mmap(%d, RW, SHARED|ANON) failed: %s", (int) length, 50 strerror(errno)); 51 return NULL; 52 } 53 54 return ptr; 55 #else 56 ALOGE("sysCreateAnonShmem not implemented."); 57 return NULL; 58 #endif 59 } 60 61 /* 62 * Create a private anonymous storage area. 63 */ 64 int sysCreatePrivateMap(size_t length, MemMapping* pMap) 65 { 66 void* memPtr; 67 68 memPtr = sysCreateAnonShmem(length); 69 if (memPtr == NULL) 70 return -1; 71 72 pMap->addr = pMap->baseAddr = memPtr; 73 pMap->length = pMap->baseLength = length; 74 return 0; 75 } 76 77 /* 78 * Determine the current offset and remaining length of the open file. 79 */ 80 static int getFileStartAndLength(int fd, off_t *start_, size_t *length_) 81 { 82 off_t start, end; 83 size_t length; 84 85 assert(start_ != NULL); 86 assert(length_ != NULL); 87 88 start = lseek(fd, 0L, SEEK_CUR); 89 end = lseek(fd, 0L, SEEK_END); 90 (void) lseek(fd, start, SEEK_SET); 91 92 if (start == (off_t) -1 || end == (off_t) -1) { 93 ALOGE("could not determine length of file"); 94 return -1; 95 } 96 97 length = end - start; 98 if (length == 0) { 99 ALOGE("file is empty"); 100 return -1; 101 } 102 103 *start_ = start; 104 *length_ = length; 105 106 return 0; 107 } 108 109 #ifndef HAVE_POSIX_FILEMAP 110 int sysFakeMapFile(int fd, MemMapping* pMap) 111 { 112 /* No MMAP, just fake it by copying the bits. 113 For Win32 we could use MapViewOfFile if really necessary 114 (see libs/utils/FileMap.cpp). 115 */ 116 off_t start; 117 size_t length; 118 void* memPtr; 119 120 assert(pMap != NULL); 121 122 if (getFileStartAndLength(fd, &start, &length) < 0) 123 return -1; 124 125 memPtr = malloc(length); 126 if (read(fd, memPtr, length) < 0) { 127 ALOGW("read(fd=%d, start=%d, length=%d) failed: %s", (int) length, 128 fd, (int) start, strerror(errno)); 129 return -1; 130 } 131 132 pMap->baseAddr = pMap->addr = memPtr; 133 pMap->baseLength = pMap->length = length; 134 135 return 0; 136 } 137 #endif 138 139 /* 140 * Map a file (from fd's current offset) into a private, read-write memory 141 * segment that will be marked read-only (a/k/a "writable read-only"). The 142 * file offset must be a multiple of the system page size. 143 * 144 * In some cases the mapping will be fully writable (e.g. for files on 145 * FAT filesystems). 146 * 147 * On success, returns 0 and fills out "pMap". On failure, returns a nonzero 148 * value and does not disturb "pMap". 149 */ 150 int sysMapFileInShmemWritableReadOnly(int fd, MemMapping* pMap) 151 { 152 #ifdef HAVE_POSIX_FILEMAP 153 off_t start; 154 size_t length; 155 void* memPtr; 156 157 assert(pMap != NULL); 158 159 if (getFileStartAndLength(fd, &start, &length) < 0) 160 return -1; 161 162 memPtr = mmap(NULL, length, PROT_READ | PROT_WRITE, MAP_FILE | MAP_PRIVATE, 163 fd, start); 164 if (memPtr == MAP_FAILED) { 165 ALOGW("mmap(%d, R/W, FILE|PRIVATE, %d, %d) failed: %s", (int) length, 166 fd, (int) start, strerror(errno)); 167 return -1; 168 } 169 if (mprotect(memPtr, length, PROT_READ) < 0) { 170 /* this fails with EACCESS on FAT filesystems, e.g. /sdcard */ 171 int err = errno; 172 ALOGV("mprotect(%p, %zd, PROT_READ) failed: %s", 173 memPtr, length, strerror(err)); 174 ALOGD("mprotect(RO) failed (%d), file will remain read-write", err); 175 } 176 177 pMap->baseAddr = pMap->addr = memPtr; 178 pMap->baseLength = pMap->length = length; 179 180 return 0; 181 #else 182 return sysFakeMapFile(fd, pMap); 183 #endif 184 } 185 186 /* 187 * Map part of a file into a shared, read-only memory segment. The "start" 188 * offset is absolute, not relative. 189 * 190 * On success, returns 0 and fills out "pMap". On failure, returns a nonzero 191 * value and does not disturb "pMap". 192 */ 193 int sysMapFileSegmentInShmem(int fd, off_t start, size_t length, 194 MemMapping* pMap) 195 { 196 #ifdef HAVE_POSIX_FILEMAP 197 size_t actualLength; 198 off_t actualStart; 199 int adjust; 200 void* memPtr; 201 202 assert(pMap != NULL); 203 204 /* adjust to be page-aligned */ 205 adjust = start % SYSTEM_PAGE_SIZE; 206 actualStart = start - adjust; 207 actualLength = length + adjust; 208 209 memPtr = mmap(NULL, actualLength, PROT_READ, MAP_FILE | MAP_SHARED, 210 fd, actualStart); 211 if (memPtr == MAP_FAILED) { 212 ALOGW("mmap(%d, R, FILE|SHARED, %d, %d) failed: %s", 213 (int) actualLength, fd, (int) actualStart, strerror(errno)); 214 return -1; 215 } 216 217 pMap->baseAddr = memPtr; 218 pMap->baseLength = actualLength; 219 pMap->addr = (char*)memPtr + adjust; 220 pMap->length = length; 221 222 LOGVV("mmap seg (st=%d ln=%d): bp=%p bl=%d ad=%p ln=%d", 223 (int) start, (int) length, 224 pMap->baseAddr, (int) pMap->baseLength, 225 pMap->addr, (int) pMap->length); 226 227 return 0; 228 #else 229 ALOGE("sysMapFileSegmentInShmem not implemented."); 230 return -1; 231 #endif 232 } 233 234 /* 235 * Change the access rights on one or more pages to read-only or read-write. 236 * 237 * Returns 0 on success. 238 */ 239 int sysChangeMapAccess(void* addr, size_t length, int wantReadWrite, 240 MemMapping* pMap) 241 { 242 #ifdef HAVE_POSIX_FILEMAP 243 /* 244 * Verify that "addr" is part of this mapping file. 245 */ 246 if (addr < pMap->baseAddr || 247 (u1*)addr >= (u1*)pMap->baseAddr + pMap->baseLength) 248 { 249 ALOGE("Attempted to change %p; map is %p - %p", 250 addr, pMap->baseAddr, (u1*)pMap->baseAddr + pMap->baseLength); 251 return -1; 252 } 253 254 /* 255 * Align "addr" to a page boundary and adjust "length" appropriately. 256 * (The address must be page-aligned, the length doesn't need to be, 257 * but we do need to ensure we cover the same range.) 258 */ 259 u1* alignAddr = (u1*) ((uintptr_t) addr & ~(SYSTEM_PAGE_SIZE-1)); 260 size_t alignLength = length + ((u1*) addr - alignAddr); 261 262 //ALOGI("%p/%zd --> %p/%zd", addr, length, alignAddr, alignLength); 263 int prot = wantReadWrite ? (PROT_READ|PROT_WRITE) : (PROT_READ); 264 if (mprotect(alignAddr, alignLength, prot) != 0) { 265 int err = errno; 266 ALOGV("mprotect (%p,%zd,%d) failed: %s", 267 alignAddr, alignLength, prot, strerror(errno)); 268 return (errno != 0) ? errno : -1; 269 } 270 #endif 271 272 /* for "fake" mapping, no need to do anything */ 273 return 0; 274 } 275 276 /* 277 * Release a memory mapping. 278 */ 279 void sysReleaseShmem(MemMapping* pMap) 280 { 281 #ifdef HAVE_POSIX_FILEMAP 282 if (pMap->baseAddr == NULL && pMap->baseLength == 0) 283 return; 284 285 if (munmap(pMap->baseAddr, pMap->baseLength) < 0) { 286 ALOGW("munmap(%p, %zd) failed: %s", 287 pMap->baseAddr, pMap->baseLength, strerror(errno)); 288 } else { 289 ALOGV("munmap(%p, %zd) succeeded", pMap->baseAddr, pMap->baseLength); 290 pMap->baseAddr = NULL; 291 pMap->baseLength = 0; 292 } 293 #else 294 /* Free the bits allocated by sysMapFileInShmem. */ 295 if (pMap->baseAddr != NULL) { 296 free(pMap->baseAddr); 297 pMap->baseAddr = NULL; 298 } 299 pMap->baseLength = 0; 300 #endif 301 } 302 303 /* 304 * Make a copy of a MemMapping. 305 */ 306 void sysCopyMap(MemMapping* dst, const MemMapping* src) 307 { 308 memcpy(dst, src, sizeof(MemMapping)); 309 } 310 311 /* 312 * Write until all bytes have been written. 313 * 314 * Returns 0 on success, or an errno value on failure. 315 */ 316 int sysWriteFully(int fd, const void* buf, size_t count, const char* logMsg) 317 { 318 while (count != 0) { 319 ssize_t actual = TEMP_FAILURE_RETRY(write(fd, buf, count)); 320 if (actual < 0) { 321 int err = errno; 322 ALOGE("%s: write failed: %s", logMsg, strerror(err)); 323 return err; 324 } else if (actual != (ssize_t) count) { 325 ALOGD("%s: partial write (will retry): (%d of %zd)", 326 logMsg, (int) actual, count); 327 buf = (const void*) (((const u1*) buf) + actual); 328 } 329 count -= actual; 330 } 331 332 return 0; 333 } 334 335 /* See documentation comment in header file. */ 336 int sysCopyFileToFile(int outFd, int inFd, size_t count) 337 { 338 const size_t kBufSize = 32768; 339 unsigned char buf[kBufSize]; 340 341 while (count != 0) { 342 size_t getSize = (count > kBufSize) ? kBufSize : count; 343 344 ssize_t actual = TEMP_FAILURE_RETRY(read(inFd, buf, getSize)); 345 if (actual != (ssize_t) getSize) { 346 ALOGW("sysCopyFileToFile: copy read failed (%d vs %zd)", 347 (int) actual, getSize); 348 return -1; 349 } 350 351 if (sysWriteFully(outFd, buf, getSize, "sysCopyFileToFile") != 0) 352 return -1; 353 354 count -= getSize; 355 } 356 357 return 0; 358 } 359
