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 */ 43 struct 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 */ 54 void sysCopyMap(MemMapping* dst, const MemMapping* src); 55 56 /* 57 * Map a file (from fd's current offset) into a shared, read-only memory 58 * segment that can be made writable. (In some cases, such as when 59 * mapping a file on a FAT filesystem, the result may be fully writable.) 60 * 61 * On success, "pMap" is filled in, and zero is returned. 62 */ 63 int sysMapFileInShmemWritableReadOnly(int fd, MemMapping* pMap); 64 65 /* 66 * Map part of a file into a shared, read-only memory segment. 67 * 68 * On success, "pMap" is filled in, and zero is returned. 69 */ 70 int sysMapFileSegmentInShmem(int fd, off_t start, size_t length, 71 MemMapping* pMap); 72 73 /* 74 * Create a private anonymous mapping, useful for large allocations. 75 * 76 * On success, "pMap" is filled in, and zero is returned. 77 */ 78 int sysCreatePrivateMap(size_t length, MemMapping* pMap); 79 80 /* 81 * Change the access rights on one or more pages. If "wantReadWrite" is 82 * zero, the pages will be made read-only; otherwise they will be read-write. 83 * 84 * Returns 0 on success. 85 */ 86 int sysChangeMapAccess(void* addr, size_t length, int wantReadWrite, 87 MemMapping* pmap); 88 89 /* 90 * Release the pages associated with a shared memory segment. 91 * 92 * This does not free "pMap"; it just releases the memory. 93 */ 94 void sysReleaseShmem(MemMapping* pMap); 95 96 /* 97 * Write until all bytes have been written. 98 * 99 * Returns 0 on success, or an errno value on failure. 100 */ 101 int sysWriteFully(int fd, const void* buf, size_t count, const char* logMsg); 102 103 /* 104 * Copy the given number of bytes from one fd to another. Returns 105 * 0 on success, -1 on failure. 106 */ 107 int sysCopyFileToFile(int outFd, int inFd, size_t count); 108 109 #endif // LIBDEX_SYSUTIL_H_ 110