80 lines
2.3 KiB
C++
80 lines
2.3 KiB
C++
// Copyright 2019 Google LLC
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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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// https://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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#include "sandboxed_api/sandbox2/buffer.h"
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <cerrno>
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#include <cstddef>
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#include <cstdint>
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#include <memory>
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#include <utility>
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#include "absl/memory/memory.h"
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#include "absl/status/status.h"
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#include "absl/status/statusor.h"
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#include "sandboxed_api/sandbox2/util.h"
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namespace sandbox2 {
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// Creates a new Buffer that is backed by the specified file descriptor.
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absl::StatusOr<std::unique_ptr<Buffer>> Buffer::CreateFromFd(int fd) {
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// Using `new` to access a non-public constructor.
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auto buffer = absl::WrapUnique(new Buffer());
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struct stat stat_buf;
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if (fstat(fd, &stat_buf) != 0) {
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return absl::ErrnoToStatus(errno, "Could not stat buffer fd");
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}
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size_t size = stat_buf.st_size;
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int prot = PROT_READ | PROT_WRITE;
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int flags = MAP_SHARED;
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off_t offset = 0;
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buffer->buf_ =
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reinterpret_cast<uint8_t*>(mmap(nullptr, size, prot, flags, fd, offset));
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if (buffer->buf_ == MAP_FAILED) {
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return absl::ErrnoToStatus(errno, "Could not map buffer fd");
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}
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buffer->fd_ = fd;
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buffer->size_ = size;
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return std::move(buffer); // GCC 7 needs the move (C++ DR #1579)
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}
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// Creates a new Buffer of the specified size, backed by a temporary file that
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// will be immediately deleted.
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absl::StatusOr<std::unique_ptr<Buffer>> Buffer::CreateWithSize(size_t size) {
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int fd;
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if (!util::CreateMemFd(&fd)) {
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return absl::InternalError("Could not create buffer temp file");
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}
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if (ftruncate(fd, size) != 0) {
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return absl::ErrnoToStatus(errno, "Could not extend buffer fd");
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}
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return CreateFromFd(fd);
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}
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Buffer::~Buffer() {
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if (buf_ != nullptr) {
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munmap(buf_, size_);
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}
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if (fd_ != -1) {
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close(fd_);
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}
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}
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} // namespace sandbox2
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