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/*
* Copyright (C) 2020 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 "common/libs/fs/shared_fd_stream.h"
#include <cstdio>
#include <streambuf>
#include "common/libs/fs/shared_buf.h"
namespace cuttlefish {
SharedFDStreambuf::SharedFDStreambuf(SharedFD shared_fd)
: shared_fd_(shared_fd) {}
int SharedFDStreambuf::underflow() {
if (gptr() < egptr()) {
return *gptr();
}
size_t unget_size = 0;
constexpr size_t bytes_to_read = kBufferSize - kUngetSize;
if (read_buffer_ == nullptr) {
read_buffer_ = std::make_unique<char[]>(kBufferSize);
} else {
unget_size = std::min(gptr() - eback(), kUngetSize);
std::memcpy(read_buffer_.get(),
read_buffer_.get() + kBufferSize - unget_size,
unget_size);
}
ssize_t bytes_read = ReadExact(shared_fd_,
read_buffer_.get() + unget_size,
bytes_to_read);
setg(read_buffer_.get(),
read_buffer_.get() + unget_size,
read_buffer_.get() + unget_size + bytes_read);
if (bytes_read <= 0 || in_avail() == 0) {
return EOF;
}
return static_cast<int>(*gptr());
}
std::streamsize SharedFDStreambuf::xsgetn(char* dst, std::streamsize count) {
std::streamsize bytes_read = 0;
while (bytes_read < count) {
if (in_avail() == 0) {
if (underflow() == EOF) {
break;
}
}
std::streamsize buffer_count =
std::min(static_cast<std::streamsize>(in_avail()), count - bytes_read);
std::memcpy(dst + bytes_read, gptr(), buffer_count);
gbump(buffer_count);
bytes_read += buffer_count;
}
return bytes_read;
}
int SharedFDStreambuf::overflow(int c) {
if (c != EOF) {
char z = c;
if (WriteAll(shared_fd_, &z, 1) != 1) {
return EOF;
}
}
return c;
}
std::streamsize SharedFDStreambuf::xsputn(const char* src,
std::streamsize count) {
return static_cast<std::streamsize>(
WriteAll(shared_fd_, src, static_cast<std::size_t>(count)));
}
int SharedFDStreambuf::pbackfail(int c) {
if (c != EOF) {
if (gptr() != eback()) {
gbump(-1);
*(gptr()) = c;
return c;
}
}
return EOF;
}
SharedFDOstream::SharedFDOstream(SharedFD shared_fd)
: std::ostream(nullptr), buf_(shared_fd) { rdbuf(&buf_); }
SharedFDIstream::SharedFDIstream(SharedFD shared_fd)
: std::istream(nullptr), buf_(shared_fd) { rdbuf(&buf_); }
} // namespace cuttlefish
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