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#ifndef MEM_OBJECT_HPP
#define MEM_OBJECT_HPP #include <exception> #include <sstream> #include <sys/mman.h> #include <unistd.h> class MemObject { public: class Exception: public std::exception {}; class InvalidMemObject : public Exception { public: virtual const char* what() const noexcept { return "invalid MemObject"; } }; class AccessViolation : public Exception { public: AccessViolation(off_t off, size_t size, size_t len) { std::ostringstream os; os << "access violation: [" << off << ", " << off+size << ") does not fit into [0, " << len << ")"; message = os.str(); } virtual const char* what() const noexcept { return message.c_str(); } private: std::string message; }; friend void swap(MemObject& lhs, MemObject& rhs) noexcept { using std::swap; swap(lhs.fd, rhs.fd); swap(lhs.addr, rhs.addr); swap(lhs.len, rhs.len); } MemObject() noexcept : fd{-1}, addr{MAP_FAILED}, len{0} { } MemObject(MemObject&& other) noexcept : MemObject() { swap(*this, other); } MemObject(int fd, off_t off, size_t len, int prot, int flags) noexcept : fd{fd}, addr{mmap(nullptr, len, prot, flags, fd, off)}, len{len} { std::cout << "addr = " << addr << std::endl; } ~MemObject() noexcept { if (addr != MAP_FAILED) { munmap(addr, len); } if (fd >= 0) { close(fd); } } MemObject& operator=(const MemObject&) = delete; MemObject& operator=(MemObject&& other) { swap(*this, other); return *this; } bool valid() const noexcept { return addr != MAP_FAILED; } template<typename T> const T& access(size_t off) const throw(AccessViolation, InvalidMemObject) { if (!valid()) { throw InvalidMemObject(); } if (off < 0 || off >= len || off + sizeof(T) > len) { throw AccessViolation(off, sizeof(T), len); } return *(T*)((char*) addr + off); } template<typename T> T& access(size_t off) throw(AccessViolation, InvalidMemObject) { if (!valid()) { throw InvalidMemObject(); } if (off < 0 || off >= len || off + sizeof(T) > len) { throw AccessViolation(off, sizeof(T), len); } return *(T*)((char*) addr + off); } private: int fd; void* addr; size_t len; }; #endif |