1 /* 2 * Copyright (C) 2017 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 #include "safe_copy.h" 18 19 #include <sys/uio.h> 20 #include <sys/user.h> 21 #include <unistd.h> 22 23 #include <algorithm> 24 25 #include <android-base/macros.h> 26 27 #include "base/bit_utils.h" 28 29 namespace art { 30 31 ssize_t SafeCopy(void *dst, const void *src, size_t len) { 32 #if defined(__linux__) 33 struct iovec dst_iov = { 34 .iov_base = dst, 35 .iov_len = len, 36 }; 37 38 // Split up the remote read across page boundaries. 39 // From the manpage: 40 // A partial read/write may result if one of the remote_iov elements points to an invalid 41 // memory region in the remote process. 42 // 43 // Partial transfers apply at the granularity of iovec elements. These system calls won't 44 // perform a partial transfer that splits a single iovec element. 45 constexpr size_t kMaxIovecs = 64; 46 struct iovec src_iovs[kMaxIovecs]; 47 size_t iovecs_used = 0; 48 49 const char* cur = static_cast<const char*>(src); 50 while (len > 0) { 51 if (iovecs_used == kMaxIovecs) { 52 errno = EINVAL; 53 return -1; 54 } 55 56 src_iovs[iovecs_used].iov_base = const_cast<char*>(cur); 57 if (!IsAlignedParam(cur, PAGE_SIZE)) { 58 src_iovs[iovecs_used].iov_len = AlignUp(cur, PAGE_SIZE) - cur; 59 } else { 60 src_iovs[iovecs_used].iov_len = PAGE_SIZE; 61 } 62 63 src_iovs[iovecs_used].iov_len = std::min(src_iovs[iovecs_used].iov_len, len); 64 65 len -= src_iovs[iovecs_used].iov_len; 66 cur += src_iovs[iovecs_used].iov_len; 67 ++iovecs_used; 68 } 69 70 ssize_t rc = process_vm_readv(getpid(), &dst_iov, 1, src_iovs, iovecs_used, 0); 71 if (rc == -1) { 72 return 0; 73 } 74 return rc; 75 #else 76 UNUSED(dst, src, len); 77 return -1; 78 #endif 79 } 80 81 } // namespace art 82
