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
38 using namespace android;
39
40 /*static*/ long FileMap::mPageSize = -1;
41
42
43 /*
44 * Constructor. Create an empty object.
45 */
FileMap(void)46 FileMap::FileMap(void)
47 : mRefCount(1), mFileName(NULL), mBasePtr(NULL), mBaseLength(0),
48 mDataPtr(NULL), mDataLength(0)
49 {
50 }
51
52 /*
53 * Destructor.
54 */
~FileMap(void)55 FileMap::~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 */
create(const char * origFileName,int fd,off_t offset,size_t length,bool readOnly)89 bool 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;
157 try_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 */
advise(MapAdvice advice)199 int 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