FileMap.cpp revision 7c1b96a165f970a09ed239bb4fb3f1b0d8f2a407 
1/*
2 * Copyright (C) 2006 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// Shared file mapping class.
19//
20
21#define LOG_TAG "filemap"
22
23#include <utils/FileMap.h>
24#include <utils/Log.h>
25
26#include <stdio.h>
27#include <stdlib.h>
28
29#ifdef HAVE_POSIX_FILEMAP
30#include <sys/mman.h>
31#endif
32
33#include <string.h>
34#include <memory.h>
35#include <errno.h>
36#include <assert.h>
37
38using namespace android;
39
40/*static*/ long FileMap::mPageSize = -1;
41
42
43/*
44 * Constructor.  Create an empty object.
45 */
46FileMap::FileMap(void)
47    : mRefCount(1), mFileName(NULL), mBasePtr(NULL), mBaseLength(0),
48      mDataPtr(NULL), mDataLength(0)
49{
50}
51
52/*
53 * Destructor.
54 */
55FileMap::~FileMap(void)
56{
57    assert(mRefCount == 0);
58
59    //printf("+++ removing FileMap %p %u\n", mDataPtr, mDataLength);
60
61    mRefCount = -100;       // help catch double-free
62    if (mFileName != NULL) {
63        free(mFileName);
64    }
65#ifdef HAVE_POSIX_FILEMAP
66    if (munmap(mBasePtr, mBaseLength) != 0) {
67        LOGD("munmap(%p, %d) failed\n", mBasePtr, (int) mBaseLength);
68    }
69#endif
70#ifdef HAVE_WIN32_FILEMAP
71    if ( UnmapViewOfFile(mBasePtr) == 0) {
72        LOGD("UnmapViewOfFile(%p) failed, error = %ld\n", mBasePtr,
73              GetLastError() );
74    }
75    CloseHandle(mFileMapping);
76    CloseHandle(mFileHandle);
77#endif
78}
79
80
81/*
82 * Create a new mapping on an open file.
83 *
84 * Closing the file descriptor does not unmap the pages, so we don't
85 * claim ownership of the fd.
86 *
87 * Returns "false" on failure.
88 */
89bool FileMap::create(const char* origFileName, int fd, off_t offset, size_t length, bool readOnly)
90{
91#ifdef HAVE_WIN32_FILEMAP
92    int     adjust;
93    off_t   adjOffset;
94    size_t  adjLength;
95
96    if (mPageSize == -1) {
97        SYSTEM_INFO  si;
98
99        GetSystemInfo( &si );
100        mPageSize = si.dwAllocationGranularity;
101    }
102
103    DWORD  protect = readOnly ? PAGE_READONLY : PAGE_READWRITE;
104
105    mFileHandle  = (HANDLE) _get_osfhandle(fd);
106    mFileMapping = CreateFileMapping( mFileHandle, NULL, protect, 0, 0, NULL);
107    if (mFileMapping == NULL) {
108        LOGE("CreateFileMapping(%p, %lx) failed with error %ld\n",
109              mFileHandle, protect, GetLastError() );
110        return false;
111    }
112
113    adjust    = offset % mPageSize;
114    adjOffset = offset - adjust;
115    adjLength = length + adjust;
116
117    mBasePtr = MapViewOfFile( mFileMapping,
118                              readOnly ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
119                              0,
120                              (DWORD)(adjOffset),
121                              adjLength );
122    if (mBasePtr == NULL) {
123        LOGE("MapViewOfFile(%ld, %ld) failed with error %ld\n",
124              adjOffset, adjLength, GetLastError() );
125        CloseHandle(mFileMapping);
126        mFileMapping = INVALID_HANDLE_VALUE;
127        return false;
128    }
129#endif
130#ifdef HAVE_POSIX_FILEMAP
131    int     prot, flags, adjust;
132    off_t   adjOffset;
133    size_t  adjLength;
134
135    void* ptr;
136
137    assert(mRefCount == 1);
138    assert(fd >= 0);
139    assert(offset >= 0);
140    assert(length > 0);
141
142    /* init on first use */
143    if (mPageSize == -1) {
144#if NOT_USING_KLIBC
145        mPageSize = sysconf(_SC_PAGESIZE);
146        if (mPageSize == -1) {
147            LOGE("could not get _SC_PAGESIZE\n");
148            return false;
149        }
150#else
151        /* this holds for Linux, Darwin, Cygwin, and doesn't pain the ARM */
152        mPageSize = 4096;
153#endif
154    }
155
156    adjust   = offset % mPageSize;
157try_again:
158    adjOffset = offset - adjust;
159    adjLength = length + adjust;
160
161    flags = MAP_SHARED;
162    prot = PROT_READ;
163    if (!readOnly)
164        prot |= PROT_WRITE;
165
166    ptr = mmap(NULL, adjLength, prot, flags, fd, adjOffset);
167    if (ptr == MAP_FAILED) {
168    	// Cygwin does not seem to like file mapping files from an offset.
169    	// So if we fail, try again with offset zero
170    	if (adjOffset > 0) {
171    		adjust = offset;
172    		goto try_again;
173    	}
174
175        LOGE("mmap(%ld,%ld) failed: %s\n",
176            (long) adjOffset, (long) adjLength, strerror(errno));
177        return false;
178    }
179    mBasePtr = ptr;
180#endif /* HAVE_POSIX_FILEMAP */
181
182    mFileName = origFileName != NULL ? strdup(origFileName) : NULL;
183    mBaseLength = adjLength;
184    mDataOffset = offset;
185    mDataPtr = (char*) mBasePtr + adjust;
186    mDataLength = length;
187
188    assert(mBasePtr != NULL);
189
190    LOGV("MAP: base %p/%d data %p/%d\n",
191        mBasePtr, (int) mBaseLength, mDataPtr, (int) mDataLength);
192
193    return true;
194}
195
196/*
197 * Provide guidance to the system.
198 */
199int FileMap::advise(MapAdvice advice)
200{
201#if HAVE_MADVISE
202    int cc, sysAdvice;
203
204    switch (advice) {
205        case NORMAL:        sysAdvice = MADV_NORMAL;        break;
206        case RANDOM:        sysAdvice = MADV_RANDOM;        break;
207        case SEQUENTIAL:    sysAdvice = MADV_SEQUENTIAL;    break;
208        case WILLNEED:      sysAdvice = MADV_WILLNEED;      break;
209        case DONTNEED:      sysAdvice = MADV_DONTNEED;      break;
210        default:
211                            assert(false);
212                            return -1;
213    }
214
215    cc = madvise(mBasePtr, mBaseLength, sysAdvice);
216    if (cc != 0)
217        LOGW("madvise(%d) failed: %s\n", sysAdvice, strerror(errno));
218    return cc;
219#else
220	return -1;
221#endif // HAVE_MADVISE
222}
223