added mapped_file class

libscio.hpp

@@ -16,6 +16,7 @@
 #include <cstdint>
 #include <cstdlib>
 #include <string>
+#include <sstream>
 
 namespace sc {
 
@@ -281,6 +282,30 @@ namespace sc {
 				byte_order _saved_byte_order {byte_order::undefined};
 		};
 
+		class mapped_file : std::istream {
+			public:
+				mapped_file() = default;
+				mapped_file(const std::string& path);
+
+				mapped_file(const mapped_file&) = delete;
+				mapped_file& operator=(const mapped_file&) = delete;
+
+				mapped_file(mapped_file&& other);
+				mapped_file& operator=(mapped_file&& other);
+
+				~mapped_file();
+
+				void open(const std::string& path);
+
+				size_t size() const { return _length; }
+
+			private:
+				int _fd {-1};
+				char* _mapping {nullptr};
+				size_t _length {0};
+				std::stringbuf _membuf;
+		};
+
 	}
 
 }

mapped_file.cpp

@@ -0,0 +1,62 @@
+//
+// mapped_file.cpp
+// conceal
+//
+// Created by Bob Polis at 2020-01-06
+// Copyright (c) 2020 SwiftCoder. All rights reserved.
+//
+
+#include "libscio.hpp"
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <utility>
+#include <stdexcept>
+#include <algorithm>
+#include <libscerror.hpp>
+
+mapped_file::mapped_file(const std::string& path) : std::istream {&_membuf} {
+    open(path);
+}
+
+mapped_file::~mapped_file() {
+    if (_mapping) {
+        munmap(_mapping, _length);
+        _mapping = nullptr;
+        _length = 0;
+    }
+    if (_fd != -1) {
+        close(_fd);
+        _fd = -1;
+    }
+}
+
+mapped_file::mapped_file(mapped_file&& other) {
+    _fd = other._fd;
+    _mapping = other._mapping;
+    _length = other._length;
+    _membuf = std::move(other._membuf);
+
+    other._fd = -1;
+    other._mapping = nullptr;
+    other._length = 0;
+    other._membuf.pubsetbuf(nullptr, 0);
+}
+
+mapped_file& mapped_file::operator=(mapped_file &&other) {
+    mapped_file mf {std::move(other)};
+    std::swap(mf, *this);
+    return *this;
+}
+
+void mapped_file::open(const std::string& path) {
+    _fd = ::open(path.c_str(), O_RDONLY);
+    throw_if_min1_msg(_fd, "could not open file");
+    struct stat st;
+    throw_if_min1_msg(fstat(_fd, &st), "could not stat file");
+    _length = st.st_size;
+    _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");
+    _membuf.pubsetbuf(_mapping, _length);
+}