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#if !defined(__MINGW32__)
28# include <sys/mman.h>
29#endif
30#include <limits.h>
31#include <errno.h>
32
33#include <nativehelper/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 */
41static void* sysCreateAnonShmem(size_t length)
42{
43#if !defined(__MINGW32__)
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 */
64int 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 */
80static 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#if defined(__MINGW32__)
110int 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        free(memPtr);
130        return -1;
131    }
132
133    pMap->baseAddr = pMap->addr = memPtr;
134    pMap->baseLength = pMap->length = length;
135
136    return 0;
137}
138#endif
139
140/*
141 * Map a file (from fd's current offset) into a private, read-write memory
142 * segment that will be marked read-only (a/k/a "writable read-only").  The
143 * file offset must be a multiple of the system page size.
144 *
145 * In some cases the mapping will be fully writable (e.g. for files on
146 * FAT filesystems).
147 *
148 * On success, returns 0 and fills out "pMap".  On failure, returns a nonzero
149 * value and does not disturb "pMap".
150 */
151int sysMapFileInShmemWritableReadOnly(int fd, MemMapping* pMap)
152{
153#if !defined(__MINGW32__)
154    off_t start;
155    size_t length;
156    void* memPtr;
157
158    assert(pMap != NULL);
159
160    if (getFileStartAndLength(fd, &start, &length) < 0)
161        return -1;
162
163    memPtr = mmap(NULL, length, PROT_READ | PROT_WRITE, MAP_FILE | MAP_PRIVATE,
164            fd, start);
165    if (memPtr == MAP_FAILED) {
166        ALOGW("mmap(%d, R/W, FILE|PRIVATE, %d, %d) failed: %s", (int) length,
167            fd, (int) start, strerror(errno));
168        return -1;
169    }
170    if (mprotect(memPtr, length, PROT_READ) < 0) {
171        /* this fails with EACCESS on FAT filesystems, e.g. /sdcard */
172        int err = errno;
173        ALOGV("mprotect(%p, %zd, PROT_READ) failed: %s",
174            memPtr, length, strerror(err));
175        ALOGD("mprotect(RO) failed (%d), file will remain read-write", err);
176    }
177
178    pMap->baseAddr = pMap->addr = memPtr;
179    pMap->baseLength = pMap->length = length;
180
181    return 0;
182#else
183    return sysFakeMapFile(fd, pMap);
184#endif
185}
186
187/*
188 * Map part of a file into a shared, read-only memory segment.  The "start"
189 * offset is absolute, not relative.
190 *
191 * On success, returns 0 and fills out "pMap".  On failure, returns a nonzero
192 * value and does not disturb "pMap".
193 */
194int sysMapFileSegmentInShmem(int fd, off_t start, size_t length,
195    MemMapping* pMap)
196{
197#if !defined(__MINGW32__)
198    size_t actualLength;
199    off_t actualStart;
200    int adjust;
201    void* memPtr;
202
203    assert(pMap != NULL);
204
205    /* adjust to be page-aligned */
206    adjust = start % SYSTEM_PAGE_SIZE;
207    actualStart = start - adjust;
208    actualLength = length + adjust;
209
210    memPtr = mmap(NULL, actualLength, PROT_READ, MAP_FILE | MAP_SHARED,
211                fd, actualStart);
212    if (memPtr == MAP_FAILED) {
213        ALOGW("mmap(%d, R, FILE|SHARED, %d, %d) failed: %s",
214            (int) actualLength, fd, (int) actualStart, strerror(errno));
215        return -1;
216    }
217
218    pMap->baseAddr = memPtr;
219    pMap->baseLength = actualLength;
220    pMap->addr = (char*)memPtr + adjust;
221    pMap->length = length;
222
223    LOGVV("mmap seg (st=%d ln=%d): bp=%p bl=%d ad=%p ln=%d",
224        (int) start, (int) length,
225        pMap->baseAddr, (int) pMap->baseLength,
226        pMap->addr, (int) pMap->length);
227
228    return 0;
229#else
230    ALOGE("sysMapFileSegmentInShmem not implemented.");
231    return -1;
232#endif
233}
234
235/*
236 * Change the access rights on one or more pages to read-only or read-write.
237 *
238 * Returns 0 on success.
239 */
240int sysChangeMapAccess(void* addr, size_t length, int wantReadWrite,
241    MemMapping* pMap)
242{
243#if !defined(__MINGW32__)
244    /*
245     * Verify that "addr" is part of this mapping file.
246     */
247    if (addr < pMap->baseAddr ||
248        (u1*)addr >= (u1*)pMap->baseAddr + pMap->baseLength)
249    {
250        ALOGE("Attempted to change %p; map is %p - %p",
251            addr, pMap->baseAddr, (u1*)pMap->baseAddr + pMap->baseLength);
252        return -1;
253    }
254
255    /*
256     * Align "addr" to a page boundary and adjust "length" appropriately.
257     * (The address must be page-aligned, the length doesn't need to be,
258     * but we do need to ensure we cover the same range.)
259     */
260    u1* alignAddr = (u1*) ((uintptr_t) addr & ~(SYSTEM_PAGE_SIZE-1));
261    size_t alignLength = length + ((u1*) addr - alignAddr);
262
263    //ALOGI("%p/%zd --> %p/%zd", addr, length, alignAddr, alignLength);
264    int prot = wantReadWrite ? (PROT_READ|PROT_WRITE) : (PROT_READ);
265    if (mprotect(alignAddr, alignLength, prot) != 0) {
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 */
279void sysReleaseShmem(MemMapping* pMap)
280{
281#if !defined(__MINGW32__)
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 */
306void 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 */
316int 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. */
336int 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