1/*
2 * Copyright (C) 2008 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 * System utilities.
19 */
20#ifndef LIBDEX_SYSUTIL_H_
21#define LIBDEX_SYSUTIL_H_
22
23#include <sys/types.h>
24
25/*
26 * System page size.  Normally you're expected to get this from
27 * sysconf(_SC_PAGESIZE) or some system-specific define (usually PAGESIZE
28 * or PAGE_SIZE).  If we use a simple #define the compiler can generate
29 * appropriate masks directly, so we define it here and verify it as the
30 * VM is starting up.
31 *
32 * Must be a power of 2.
33 */
34#ifdef PAGE_SHIFT
35#define SYSTEM_PAGE_SIZE        (1<<PAGE_SHIFT)
36#else
37#define SYSTEM_PAGE_SIZE        4096
38#endif
39
40/*
41 * Use this to keep track of mapped segments.
42 */
43struct MemMapping {
44    void*   addr;           /* start of data */
45    size_t  length;         /* length of data */
46
47    void*   baseAddr;       /* page-aligned base address */
48    size_t  baseLength;     /* length of mapping */
49};
50
51/*
52 * Copy a map.
53 */
54void sysCopyMap(MemMapping* dst, const MemMapping* src);
55
56/*
57 * Load a file into a new shared memory segment.  All data from the current
58 * offset to the end of the file is pulled in.
59 *
60 * The segment is read-write, allowing VM fixups.  (It should be modified
61 * to support .gz/.zip compressed data.)
62 *
63 * On success, "pMap" is filled in, and zero is returned.
64 */
65int sysLoadFileInShmem(int fd, MemMapping* pMap);
66
67/*
68 * Map a file (from fd's current offset) into a shared,
69 * read-only memory segment.
70 *
71 * On success, "pMap" is filled in, and zero is returned.
72 */
73int sysMapFileInShmemReadOnly(int fd, MemMapping* pMap);
74
75/*
76 * Map a file (from fd's current offset) into a shared, read-only memory
77 * segment that can be made writable.  (In some cases, such as when
78 * mapping a file on a FAT filesystem, the result may be fully writable.)
79 *
80 * On success, "pMap" is filled in, and zero is returned.
81 */
82int sysMapFileInShmemWritableReadOnly(int fd, MemMapping* pMap);
83
84/*
85 * Like sysMapFileInShmemReadOnly, but on only part of a file.
86 */
87int sysMapFileSegmentInShmem(int fd, off_t start, size_t length,
88    MemMapping* pMap);
89
90/*
91 * Create a private anonymous mapping, useful for large allocations.
92 *
93 * On success, "pMap" is filled in, and zero is returned.
94 */
95int sysCreatePrivateMap(size_t length, MemMapping* pMap);
96
97/*
98 * Change the access rights on one or more pages.  If "wantReadWrite" is
99 * zero, the pages will be made read-only; otherwise they will be read-write.
100 *
101 * Returns 0 on success.
102 */
103int sysChangeMapAccess(void* addr, size_t length, int wantReadWrite,
104    MemMapping* pmap);
105
106/*
107 * Release the pages associated with a shared memory segment.
108 *
109 * This does not free "pMap"; it just releases the memory.
110 */
111void sysReleaseShmem(MemMapping* pMap);
112
113/*
114 * Write until all bytes have been written.
115 *
116 * Returns 0 on success, or an errno value on failure.
117 */
118int sysWriteFully(int fd, const void* buf, size_t count, const char* logMsg);
119
120/*
121 * Copy the given number of bytes from one fd to another. Returns
122 * 0 on success, -1 on failure.
123 */
124int sysCopyFileToFile(int outFd, int inFd, size_t count);
125
126#endif  // LIBDEX_SYSUTIL_H_
127