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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 
45 using namespace android;
46 
47 /*static*/ long FileMap::mPageSize = -1;
48 
49 // Constructor.  Create an empty object.
FileMap(void)50 FileMap::FileMap(void)
51     : mRefCount(1), mFileName(NULL), mBasePtr(NULL), mBaseLength(0),
52       mDataPtr(NULL), mDataLength(0)
53 {
54 }
55 
56 // Destructor.
~FileMap(void)57 FileMap::~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.
create(const char * origFileName,int fd,off64_t offset,size_t length,bool readOnly)90 bool 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;
159 try_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.
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         ALOGW("madvise(%d) failed: %s\n", sysAdvice, strerror(errno));
218     return cc;
219 #else
220     return -1;
221 #endif // HAVE_MADVISE
222 }
223