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refactored mapped_file to no longer be derived from std::istream

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This commit is contained in:
Bob Polis 2020-07-12 13:29:58 +02:00
parent fc264ed860
commit cf9836f2a2
2 changed files with 6 additions and 11 deletions
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8
libscio.hpp
View File

@ -16,7 +16,6 @@
#include <cstdint> #include <cstdint>
#include <cstdlib> #include <cstdlib>
#include <string> #include <string>
#include <sstream>
namespace sc { namespace sc {
@ -282,7 +281,7 @@ namespace sc {
byte_order _saved_byte_order {byte_order::undefined}; byte_order _saved_byte_order {byte_order::undefined};
}; };
class mapped_file : public std::istream { class mapped_file {
public: public:
mapped_file(); mapped_file();
mapped_file(const std::string& path); mapped_file(const std::string& path);
@ -295,20 +294,21 @@ namespace sc {
mapped_file(mapped_file&& other); mapped_file(mapped_file&& other);
mapped_file& operator=(mapped_file&& other); mapped_file& operator=(mapped_file&& other);
// cleanup: mapped_file is RAII class for memory mapping and file descriptor
~mapped_file(); ~mapped_file();
// it's an error to open an already opened mapped_file // it's an error to open an already opened mapped_file
// open() is meant to be used after default constructor
void open(const std::string& path); void open(const std::string& path);
// direct (read-only) access to mapped memory // direct (read-only) access to mapped memory
const char* mapping() const { return _mapping; } char* mapping() const { return _mapping; }
size_t size() const { return _length; } size_t size() const { return _length; }
private: private:
int _fd {-1}; int _fd {-1};
char* _mapping {nullptr}; char* _mapping {nullptr};
size_t _length {0}; size_t _length {0};
std::stringbuf _membuf;
}; };
} }

9
mapped_file.cpp
View File

@ -18,9 +18,7 @@
using namespace sc::io; using namespace sc::io;
mapped_file::mapped_file() : std::istream {&_membuf} {} mapped_file::mapped_file(const std::string& path) {
mapped_file::mapped_file(const std::string& path) : std::istream {&_membuf} {
open(path); open(path);
} }
@ -36,16 +34,14 @@ mapped_file::~mapped_file() {
} }
} }
mapped_file::mapped_file(mapped_file&& other) : std::istream {std::move(other)} { mapped_file::mapped_file(mapped_file&& other) {
_fd = other._fd; _fd = other._fd;
_mapping = other._mapping; _mapping = other._mapping;
_length = other._length; _length = other._length;
_membuf = std::move(other._membuf);
other._fd = -1; other._fd = -1;
other._mapping = nullptr; other._mapping = nullptr;
other._length = 0; other._length = 0;
other._membuf.pubsetbuf(nullptr, 0);
} }
mapped_file& mapped_file::operator=(mapped_file &&other) { mapped_file& mapped_file::operator=(mapped_file &&other) {
@ -65,5 +61,4 @@ void mapped_file::open(const std::string& path) {
_length = st.st_size; _length = st.st_size;
_mapping = reinterpret_cast<char*>(mmap(nullptr, _length, PROT_READ, MAP_PRIVATE, _fd, 0)); _mapping = reinterpret_cast<char*>(mmap(nullptr, _length, PROT_READ, MAP_PRIVATE, _fd, 0));
if (_mapping == MAP_FAILED) throw std::runtime_error("could not map file"); if (_mapping == MAP_FAILED) throw std::runtime_error("could not map file");
_membuf.pubsetbuf(_mapping, _length);
} }