dlang_fileonheap.d

import std.stdio;
import std.conv;
import core.stdc.stdio;
import core.stdc.stdlib;
import std.string;

struct fileData {
	void* data;
	size_t numData;
}

@trusted fileData readFile(string filename) {
	FILE* file;
	static int BUFFER_SIZE = 10;
	void* data = null;
	size_t currentSize = 0;
	size_t currentData;
	size_t offset = 0;
    file = fopen(filename.toStringz, "r");

	if(file == null) {
		throw new StringException("Failed to open file: " ~ filename);
	}

	do {
		data = realloc(data, currentSize + BUFFER_SIZE);

		if (data == null) {
			throw new StringException("Memory allocation failed for: " ~ to!string(currentSize + BUFFER_SIZE));
		}

		currentSize += BUFFER_SIZE;
		currentData = fread(&data[offset], 1, BUFFER_SIZE, file);
		offset += currentData;
	} while (currentData == BUFFER_SIZE);
	fclose(file);
	fileData fd = {data, offset};
	return fd;
}

@trusted char[] getStringFile(fileData file) {
    char* dataChar = cast(char*) file.data;
    return dataChar[0..file.numData];
}

@safe void main() {
	fileData file = readFile("/proc/version");
    writeln(getStringFile(file));
}