Roll forward to cl/314549634

Change-Id: I4d1e7eacd5fa4078a094571ad6d5f51e422535ff

cpp/platform_v2/base/base_input_stream.cc

@@ -0,0 +1,85 @@
+#include "platform_v2/base/base_input_stream.h"
+
+namespace location {
+namespace nearby {
+
+ExceptionOr<ByteArray> BaseInputStream::Read(std::int64_t size) {
+  if (!IsAvailable(size)) {
+    return ExceptionOr<ByteArray>{Exception::kIo};
+  }
+
+  ByteArray read_bytes{static_cast<size_t>(size)};
+  if (read_bytes.CopyAt(/*offset=*/0, buffer_,
+                        /*source_offset=*/position_)) {
+    position_ += size;
+    return ExceptionOr<ByteArray>{read_bytes};
+  } else {
+    return ExceptionOr<ByteArray>{Exception::kIo};
+  }
+}
+
+std::uint8_t BaseInputStream::ReadUint8() {
+  constexpr int byte_size = sizeof(std::uint8_t);
+  ByteArray read_bytes = ReadBytes(byte_size);
+  if (read_bytes.Empty() || read_bytes.size() != byte_size) {
+    return -1;
+  }
+
+  return read_bytes.data()[0];
+}
+
+std::uint16_t BaseInputStream::ReadUint16() {
+  constexpr int byte_size = sizeof(std::uint16_t);
+  ByteArray read_bytes = ReadBytes(byte_size);
+  if (read_bytes.Empty() || read_bytes.size() != byte_size) {
+    return -1;
+  }
+
+  // Convert from network order.
+  const char *data = read_bytes.data();
+  return static_cast<uint16_t>(data[0]) << 8 | static_cast<uint16_t>(data[1]);
+}
+
+std::uint32_t BaseInputStream::ReadUint32() {
+  constexpr int byte_size = sizeof(std::uint32_t);
+  ByteArray read_bytes = ReadBytes(byte_size);
+  if (read_bytes.Empty() || read_bytes.size() != byte_size) {
+    return -1;
+  }
+
+  // Convert from network order.
+  const char *data = read_bytes.data();
+  return static_cast<uint32_t>(data[0]) << 24 |
+         static_cast<uint32_t>(data[1]) << 16 |
+         static_cast<uint32_t>(data[2]) << 8 | static_cast<uint32_t>(data[3]);
+}
+
+std::uint64_t BaseInputStream::ReadUint64() {
+  constexpr int byte_size = sizeof(std::uint64_t);
+  ByteArray read_bytes = ReadBytes(byte_size);
+  if (read_bytes.Empty() || read_bytes.size() != byte_size) {
+    return -1;
+  }
+
+  // Convert from network order.
+  const char *data = read_bytes.data();
+  return static_cast<uint64_t>(data[0]) << 56 |
+         static_cast<uint64_t>(data[1]) << 48 |
+         static_cast<uint64_t>(data[2]) << 40 |
+         static_cast<uint64_t>(data[3]) << 32 |
+         static_cast<uint64_t>(data[4]) << 24 |
+         static_cast<uint64_t>(data[5]) << 16 |
+         static_cast<uint64_t>(data[6]) << 8 | static_cast<uint64_t>(data[7]);
+}
+
+ByteArray BaseInputStream::ReadBytes(int size) {
+  ExceptionOr<ByteArray> read_bytes_result = Read(size);
+  if (!read_bytes_result.ok()) {
+    return ByteArray{};
+  }
+
+  return read_bytes_result.GetResult();
+}
+
+}  // namespace nearby
+}  // namespace location