FileMap.cpp revision 1a55aa5e34f201b060da9a84ec9702401f05be18 
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#if defined(HAVE_WIN32_FILEMAP) && !defined(__USE_MINGW_ANSI_STDIO)
27# define PRId32 "I32d"
28# define PRIx32 "I32x"
29# define PRId64 "I64d"
30#else
31#include <inttypes.h>
32#endif
33#include <stdio.h>
34#include <stdlib.h>
35
36#ifdef HAVE_POSIX_FILEMAP
37#include <sys/mman.h>
38#endif
39
40#include <string.h>
41#include <memory.h>
42#include <errno.h>
43#include <assert.h>
44
45using namespace android;
46
47/*static*/ long FileMap::mPageSize = -1;
48
49// Constructor.  Create an empty object.
50FileMap::FileMap(void)
51    : mRefCount(1), mFileName(NULL), mBasePtr(NULL), mBaseLength(0),
52      mDataPtr(NULL), mDataLength(0)
53{
54}
55
56// Destructor.
57FileMap::~FileMap(void)
58{
59    assert(mRefCount == 0);
60
61    //printf("+++ removing FileMap %p %zu\n", mDataPtr, mDataLength);
62
63    mRefCount = -100;       // help catch double-free
64    if (mFileName != NULL) {
65        free(mFileName);
66    }
67#ifdef HAVE_POSIX_FILEMAP
68    if (mBasePtr && munmap(mBasePtr, mBaseLength) != 0) {
69        ALOGD("munmap(%p, %zu) failed\n", mBasePtr, mBaseLength);
70    }
71#endif
72#ifdef HAVE_WIN32_FILEMAP
73    if (mBasePtr && UnmapViewOfFile(mBasePtr) == 0) {
74        ALOGD("UnmapViewOfFile(%p) failed, error = %" PRId32 "\n", mBasePtr,
75              GetLastError() );
76    }
77    if (mFileMapping != INVALID_HANDLE_VALUE) {
78        CloseHandle(mFileMapping);
79    }
80#endif
81}
82
83
84// Create a new mapping on an open file.
85//
86// Closing the file descriptor does not unmap the pages, so we don't
87// claim ownership of the fd.
88//
89// Returns "false" on failure.
90bool FileMap::create(const char* origFileName, int fd, off64_t offset, size_t length,
91        bool readOnly)
92{
93#ifdef HAVE_WIN32_FILEMAP
94    int     adjust;
95    off64_t adjOffset;
96    size_t  adjLength;
97
98    if (mPageSize == -1) {
99        SYSTEM_INFO  si;
100
101        GetSystemInfo( &si );
102        mPageSize = si.dwAllocationGranularity;
103    }
104
105    DWORD  protect = readOnly ? PAGE_READONLY : PAGE_READWRITE;
106
107    mFileHandle  = (HANDLE) _get_osfhandle(fd);
108    mFileMapping = CreateFileMapping( mFileHandle, NULL, protect, 0, 0, NULL);
109    if (mFileMapping == NULL) {
110        ALOGE("CreateFileMapping(%p, %" PRIx32 ") failed with error %" PRId32 "\n",
111              mFileHandle, protect, GetLastError() );
112        return false;
113    }
114
115    adjust    = offset % mPageSize;
116    adjOffset = offset - adjust;
117    adjLength = length + adjust;
118
119    mBasePtr = MapViewOfFile( mFileMapping,
120                              readOnly ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
121                              0,
122                              (DWORD)(adjOffset),
123                              adjLength );
124    if (mBasePtr == NULL) {
125        ALOGE("MapViewOfFile(%" PRId64 ", %zu) failed with error %" PRId32 "\n",
126              adjOffset, adjLength, GetLastError() );
127        CloseHandle(mFileMapping);
128        mFileMapping = INVALID_HANDLE_VALUE;
129        return false;
130    }
131#endif
132#ifdef HAVE_POSIX_FILEMAP
133    int     prot, flags, adjust;
134    off64_t adjOffset;
135    size_t  adjLength;
136
137    void* ptr;
138
139    assert(mRefCount == 1);
140    assert(fd >= 0);
141    assert(offset >= 0);
142    assert(length > 0);
143
144    // init on first use
145    if (mPageSize == -1) {
146#if NOT_USING_KLIBC
147        mPageSize = sysconf(_SC_PAGESIZE);
148        if (mPageSize == -1) {
149            ALOGE("could not get _SC_PAGESIZE\n");
150            return false;
151        }
152#else
153        // this holds for Linux, Darwin, Cygwin, and doesn't pain the ARM
154        mPageSize = 4096;
155#endif
156    }
157
158    adjust   = offset % mPageSize;
159try_again:
160    adjOffset = offset - adjust;
161    adjLength = length + adjust;
162
163    flags = MAP_SHARED;
164    prot = PROT_READ;
165    if (!readOnly)
166        prot |= PROT_WRITE;
167
168    ptr = mmap(NULL, adjLength, prot, flags, fd, adjOffset);
169    if (ptr == MAP_FAILED) {
170        // Cygwin does not seem to like file mapping files from an offset.
171        // So if we fail, try again with offset zero
172        if (adjOffset > 0) {
173            adjust = offset;
174            goto try_again;
175        }
176
177        ALOGE("mmap(%lld,%zu) failed: %s\n",
178            (long long)adjOffset, adjLength, strerror(errno));
179        return false;
180    }
181    mBasePtr = ptr;
182#endif // HAVE_POSIX_FILEMAP
183
184    mFileName = origFileName != NULL ? strdup(origFileName) : NULL;
185    mBaseLength = adjLength;
186    mDataOffset = offset;
187    mDataPtr = (char*) mBasePtr + adjust;
188    mDataLength = length;
189
190    assert(mBasePtr != NULL);
191
192    ALOGV("MAP: base %p/%zu data %p/%zu\n",
193        mBasePtr, mBaseLength, mDataPtr, mDataLength);
194
195    return true;
196}
197
198// Provide guidance to the system.
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        ALOGW("madvise(%d) failed: %s\n", sysAdvice, strerror(errno));
218    return cc;
219#else
220    return -1;
221#endif // HAVE_MADVISE
222}
223