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Simplify read error detection.

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This commit is contained in:
Daniel Patterson 2016-11-14 18:43:30 -08:00
parent 608044305d
commit d8b016b92a
1 changed files with 7 additions and 11 deletions
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18
include/storage/io.hpp
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@ -56,21 +56,17 @@ class FileReader
"bytewise reading requires trivially copyable type");
if (count == 0)
return;
input_stream.read(reinterpret_cast<char *>(dest), count * sizeof(T));
// safe to cast here, according to CPP docs, negative values for gcount
// are never used.
const unsigned long bytes_read = static_cast<unsigned long>(input_stream.gcount());
const auto expected_bytes = count * sizeof(T);
if (bytes_read == 0)
const auto &result = input_stream.read(reinterpret_cast<char *>(dest), count * sizeof(T));
if (!result)
{
if (result.eof())
{
throw util::exception("Error reading from " + filename +
": Unexpected end of file");
}
throw util::exception("Error reading from " + filename + ": " + std::strerror(errno));
}
else if (bytes_read < expected_bytes)
{
throw util::exception("Error reading from " + filename + ": Unexpected end of file");
}
}
template <typename T> void ReadInto(T &target) { ReadInto(&target, 1); }