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84 lines
2.2 KiB
84 lines
2.2 KiB
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "safe_copy.h"
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#ifdef __linux__
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#include <sys/uio.h>
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#include <sys/user.h>
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#endif
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#include <unistd.h>
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#include <algorithm>
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#include <android-base/macros.h>
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#include "bit_utils.h"
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namespace art {
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ssize_t SafeCopy(void *dst, const void *src, size_t len) {
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#if defined(__linux__)
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struct iovec dst_iov = {
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.iov_base = dst,
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.iov_len = len,
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};
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// Split up the remote read across page boundaries.
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// From the manpage:
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// A partial read/write may result if one of the remote_iov elements points to an invalid
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// memory region in the remote process.
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//
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// Partial transfers apply at the granularity of iovec elements. These system calls won't
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// perform a partial transfer that splits a single iovec element.
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constexpr size_t kMaxIovecs = 64;
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struct iovec src_iovs[kMaxIovecs];
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size_t iovecs_used = 0;
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const char* cur = static_cast<const char*>(src);
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while (len > 0) {
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if (iovecs_used == kMaxIovecs) {
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errno = EINVAL;
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return -1;
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}
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src_iovs[iovecs_used].iov_base = const_cast<char*>(cur);
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if (!IsAlignedParam(cur, PAGE_SIZE)) {
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src_iovs[iovecs_used].iov_len = AlignUp(cur, PAGE_SIZE) - cur;
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} else {
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src_iovs[iovecs_used].iov_len = PAGE_SIZE;
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}
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src_iovs[iovecs_used].iov_len = std::min(src_iovs[iovecs_used].iov_len, len);
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len -= src_iovs[iovecs_used].iov_len;
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cur += src_iovs[iovecs_used].iov_len;
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++iovecs_used;
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}
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ssize_t rc = process_vm_readv(getpid(), &dst_iov, 1, src_iovs, iovecs_used, 0);
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if (rc == -1) {
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return 0;
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}
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return rc;
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#else
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UNUSED(dst, src, len);
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return -1;
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#endif
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}
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} // namespace art
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