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 */
sysCreateAnonShmem(size_t length)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 */
sysCreatePrivateMap(size_t length,MemMapping * pMap)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 */
getFileStartAndLength(int fd,off_t * start_,size_t * length_)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
sysFakeMapFile(int fd,MemMapping * pMap)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 */
sysMapFileInShmemWritableReadOnly(int fd,MemMapping * pMap)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, %d, 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 */
sysMapFileSegmentInShmem(int fd,off_t start,size_t length,MemMapping * pMap)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 */
sysChangeMapAccess(void * addr,size_t length,int wantReadWrite,MemMapping * pMap)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 */
sysReleaseShmem(MemMapping * pMap)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, %d) failed: %s",
287 pMap->baseAddr, (int)pMap->baseLength, strerror(errno));
288 } else {
289 ALOGV("munmap(%p, %d) 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 */
sysCopyMap(MemMapping * dst,const MemMapping * src)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 */
sysWriteFully(int fd,const void * buf,size_t count,const char * logMsg)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. */
sysCopyFileToFile(int outFd,int inFd,size_t count)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