OffsetInputSource.cc
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#include <qpdf/OffsetInputSource.hh>
#include <qpdf/Util.hh>
#include <limits>
#include <sstream>
#include <stdexcept>
using namespace qpdf;
OffsetInputSource::OffsetInputSource(
std::shared_ptr<InputSource> proxied, qpdf_offset_t global_offset) :
proxied(proxied),
global_offset(global_offset)
{
util::assertion(global_offset >= 0, "OffsetInputSource constructed with negative offset");
max_safe_offset = std::numeric_limits<qpdf_offset_t>::max() - global_offset;
}
qpdf_offset_t
OffsetInputSource::findAndSkipNextEOL()
{
return proxied->findAndSkipNextEOL() - global_offset;
}
std::string const&
OffsetInputSource::getName() const
{
return proxied->getName();
}
qpdf_offset_t
OffsetInputSource::tell()
{
return proxied->tell() - global_offset;
}
void
OffsetInputSource::seek(qpdf_offset_t offset, int whence)
{
if (whence == SEEK_SET) {
if (offset > max_safe_offset) {
std::ostringstream msg;
msg.imbue(std::locale::classic());
msg << "seeking to " << offset << " offset by " << global_offset
<< " would cause an overflow of the offset type";
throw std::range_error(msg.str());
}
proxied->seek(offset + global_offset, whence);
} else {
proxied->seek(offset, whence);
}
util::no_ci_rt_error_if(tell() < 0, "offset input source: seek before beginning of file");
}
void
OffsetInputSource::rewind()
{
seek(0, SEEK_SET);
}
size_t
OffsetInputSource::read(char* buffer, size_t length)
{
size_t result = proxied->read(buffer, length);
setLastOffset(proxied->getLastOffset() - global_offset);
return result;
}
void
OffsetInputSource::unreadCh(char ch)
{
proxied->unreadCh(ch);
}