FileMap.cpp revision 819b480b935a99fc8114b622644f42dec9e3a177 
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(__MINGW32__) && !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#if !defined(__MINGW32__)
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#if defined(__MINGW32__)
68    if (mBasePtr && UnmapViewOfFile(mBasePtr) == 0) {
69        ALOGD("UnmapViewOfFile(%p) failed, error = %" PRId32 "\n", mBasePtr,
70              GetLastError() );
71    }
72    if (mFileMapping != INVALID_HANDLE_VALUE) {
73        CloseHandle(mFileMapping);
74    }
75#else
76    if (mBasePtr && munmap(mBasePtr, mBaseLength) != 0) {
77        ALOGD("munmap(%p, %zu) failed\n", mBasePtr, mBaseLength);
78    }
79#endif
80}
81
82
83// Create a new mapping on an open file.
84//
85// Closing the file descriptor does not unmap the pages, so we don't
86// claim ownership of the fd.
87//
88// Returns "false" on failure.
89bool FileMap::create(const char* origFileName, int fd, off64_t offset, size_t length,
90        bool readOnly)
91{
92#if defined(__MINGW32__)
93    int     adjust;
94    off64_t adjOffset;
95    size_t  adjLength;
96
97    if (mPageSize == -1) {
98        SYSTEM_INFO  si;
99
100        GetSystemInfo( &si );
101        mPageSize = si.dwAllocationGranularity;
102    }
103
104    DWORD  protect = readOnly ? PAGE_READONLY : PAGE_READWRITE;
105
106    mFileHandle  = (HANDLE) _get_osfhandle(fd);
107    mFileMapping = CreateFileMapping( mFileHandle, NULL, protect, 0, 0, NULL);
108    if (mFileMapping == NULL) {
109        ALOGE("CreateFileMapping(%p, %" PRIx32 ") failed with error %" PRId32 "\n",
110              mFileHandle, protect, GetLastError() );
111        return false;
112    }
113
114    adjust    = offset % mPageSize;
115    adjOffset = offset - adjust;
116    adjLength = length + adjust;
117
118    mBasePtr = MapViewOfFile( mFileMapping,
119                              readOnly ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
120                              0,
121                              (DWORD)(adjOffset),
122                              adjLength );
123    if (mBasePtr == NULL) {
124        ALOGE("MapViewOfFile(%" PRId64 ", %zu) failed with error %" PRId32 "\n",
125              adjOffset, adjLength, GetLastError() );
126        CloseHandle(mFileMapping);
127        mFileMapping = INVALID_HANDLE_VALUE;
128        return false;
129    }
130#else // !defined(__MINGW32__)
131    int     prot, flags, adjust;
132    off64_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            ALOGE("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        ALOGE("mmap(%lld,%zu) failed: %s\n",
176            (long long)adjOffset, adjLength, strerror(errno));
177        return false;
178    }
179    mBasePtr = ptr;
180#endif // !defined(__MINGW32__)
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    ALOGV("MAP: base %p/%zu data %p/%zu\n",
191        mBasePtr, mBaseLength, mDataPtr, mDataLength);
192
193    return true;
194}
195
196// Provide guidance to the system.
197int FileMap::advise(MapAdvice advice)
198{
199#if !defined(_WIN32)
200    int cc, sysAdvice;
201
202    switch (advice) {
203        case NORMAL:        sysAdvice = MADV_NORMAL;        break;
204        case RANDOM:        sysAdvice = MADV_RANDOM;        break;
205        case SEQUENTIAL:    sysAdvice = MADV_SEQUENTIAL;    break;
206        case WILLNEED:      sysAdvice = MADV_WILLNEED;      break;
207        case DONTNEED:      sysAdvice = MADV_DONTNEED;      break;
208        default:
209                            assert(false);
210                            return -1;
211    }
212
213    cc = madvise(mBasePtr, mBaseLength, sysAdvice);
214    if (cc != 0)
215        ALOGW("madvise(%d) failed: %s\n", sysAdvice, strerror(errno));
216    return cc;
217#else
218    return -1;
219#endif
220}
221