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