/// read portion of file into internal buffer
/// if a_crunch == true, crunch buffer before reading
bool read(bool a_crunch = true) {
if (!m_open || !m_file.is_open())
return false;
if (a_crunch)
m_buf.crunch();
while (true) {
BOOST_ASSERT(m_buf.capacity() > 0);
m_file.read(m_buf.wr_ptr(), m_buf.capacity());
int n = m_file.gcount();
if (n == 0) {
if (m_file.good()) continue;
if (m_file.eof()) return false;
// this should never happen since we have set badbit
throw io_error(errno, "Unexpected error reading ", m_fname);
}
m_buf.commit(n);
return true;
}
}
/// open file for reading
void open(const std::string& a_fname) {
if (m_open) return;
// make sure exception thrown in case of error
m_file.exceptions(std::ifstream::failbit | std::ifstream::badbit);
m_file.open(a_fname.c_str(), std::ios::in | std::ios::binary);
// further read can set failbit in case there is not enough data
// this case should not throw an exception in our class
m_file.exceptions(std::ifstream::badbit);
m_open = true;
m_fname = a_fname;
m_buf.reset();
BOOST_ASSERT(m_buf.capacity() > 0);
}
void open(const std::string& a_fname, bool a_append = false) {
using std::ios;
using std::ios_base;
if (m_open) return;
m_file.exceptions(ios::failbit | ios::badbit);
ios_base::openmode l_mode = ios::out | ios::binary;
if (a_append)
l_mode |= ios::app;
else
l_mode |= ios::trunc;
m_file.open(a_fname.c_str(), l_mode);
m_offset = m_file.tellp();
m_open = true;
m_fname = a_fname;
m_buf.reset();
BOOST_ASSERT(m_buf.capacity() > 0);
}
size_t capacity() const { return m_buf.capacity(); }