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Extend to allow vending of only portions of files.

This commit is contained in:
Thomas Harte 2022-08-30 15:51:29 -04:00
parent cd7671e8fa
commit 3c954e76ed

View File

@ -17,12 +17,15 @@
namespace Storage { namespace Storage {
namespace MassStorage { namespace MassStorage {
template <size_t sector_size> class RawSectorDump: public MassStorageDevice { template <long sector_size> class RawSectorDump: public MassStorageDevice {
public: public:
RawSectorDump(const std::string &file_name) : file_(file_name) { RawSectorDump(const std::string &file_name, long offset = 0, long length = -1) :
file_(file_name),
file_size_((length == -1) ? long(file_.stats().st_size) : length),
file_start_(offset)
{
// Is the file a multiple of sector_size bytes in size? // Is the file a multiple of sector_size bytes in size?
const auto file_size = size_t(file_.stats().st_size); if(file_size_ % sector_size) throw std::exception();
if(file_size % sector_size) throw std::exception();
} }
/* MassStorageDevices overrides. */ /* MassStorageDevices overrides. */
@ -31,22 +34,23 @@ template <size_t sector_size> class RawSectorDump: public MassStorageDevice {
} }
size_t get_number_of_blocks() final { size_t get_number_of_blocks() final {
return size_t(file_.stats().st_size) / sector_size; return size_t(file_size_ / sector_size);
} }
std::vector<uint8_t> get_block(size_t address) final { std::vector<uint8_t> get_block(size_t address) final {
file_.seek(long(address * sector_size), SEEK_SET); file_.seek(file_start_ + long(address * sector_size), SEEK_SET);
return file_.read(sector_size); return file_.read(sector_size);
} }
void set_block(size_t address, const std::vector<uint8_t> &contents) final { void set_block(size_t address, const std::vector<uint8_t> &contents) final {
assert(contents.size() == sector_size); assert(contents.size() == sector_size);
file_.seek(long(address * sector_size), SEEK_SET); file_.seek(file_start_ + long(address * sector_size), SEEK_SET);
file_.write(contents); file_.write(contents);
} }
private: private:
FileHolder file_; FileHolder file_;
const long file_size_, file_start_;
}; };
} }