Small native code reorganization

native/jni/utils/include/stream.hpp

@@ -0,0 +1,84 @@
+#pragma once
+
+#include <stdio.h>
+#include <memory>
+
+#include "../files.hpp"
+
+class stream {
+public:
+	virtual int read(void *buf, size_t len);
+	virtual int write(const void *buf, size_t len);
+	virtual off_t seek(off_t off, int whence);
+	virtual ~stream() = default;
+};
+
+using stream_ptr = std::unique_ptr<stream>;
+
+// Delegates all operations to base stream
+class filter_stream : public stream {
+public:
+	filter_stream(stream_ptr &&base) : base(std::move(base)) {}
+
+	int read(void *buf, size_t len) override;
+	int write(const void *buf, size_t len) override;
+
+protected:
+	stream_ptr base;
+};
+
+// Byte stream that dynamically allocates memory
+class byte_stream : public stream {
+public:
+	byte_stream(uint8_t *&buf, size_t &len);
+	template <class byte>
+	byte_stream(byte *&buf, size_t &len) : byte_stream(reinterpret_cast<uint8_t *&>(buf), len) {}
+	int read(void *buf, size_t len) override;
+	int write(const void *buf, size_t len) override;
+	off_t seek(off_t off, int whence) override;
+
+private:
+	uint8_t *&_buf;
+	size_t &_len;
+	size_t _pos = 0;
+	size_t _cap = 0;
+
+	void resize(size_t new_pos, bool zero = false);
+};
+
+// File stream but does not close the file descriptor at any time
+class fd_stream : public stream {
+public:
+	fd_stream(int fd) : fd(fd) {}
+	int read(void *buf, size_t len) override;
+	int write(const void *buf, size_t len) override;
+	off_t seek(off_t off, int whence) override;
+
+private:
+	int fd;
+};
+
+/* ****************************************
+ * Bridge between stream class and C stdio
+ * ****************************************/
+
+// sFILE -> stream_ptr
+class fp_stream final : public stream {
+public:
+	fp_stream(FILE *fp = nullptr) : fp(fp, fclose) {}
+	fp_stream(sFILE &&fp) : fp(std::move(fp)) {}
+	int read(void *buf, size_t len) override;
+	int write(const void *buf, size_t len) override;
+	off_t seek(off_t off, int whence) override;
+
+private:
+	sFILE fp;
+};
+
+// stream_ptr -> sFILE
+sFILE make_stream_fp(stream_ptr &&strm);
+
+template <class T, class... Args>
+sFILE make_stream_fp(Args &&... args) {
+	return make_stream_fp(stream_ptr(new T(std::forward<Args>(args)...)));
+}