Create generic streams on top of stdio

WIP

native/jni/utils/stream.cpp

@@ -0,0 +1,122 @@
+#include <logging.h>
+#include <stream.h>
+
+static int strm_read(void *v, char *buf, int len) {
+	auto strm = reinterpret_cast<stream *>(v);
+	return strm->read(buf, len);
+}
+
+static int strm_write(void *v, const char *buf, int len) {
+	auto strm = reinterpret_cast<stream *>(v);
+	return strm->write(buf, len);
+}
+
+static fpos_t strm_seek(void *v, fpos_t off, int whence) {
+	auto strm = reinterpret_cast<stream *>(v);
+	return strm->seek(off, whence);
+}
+
+static int strm_close(void *v) {
+	auto strm = reinterpret_cast<stream *>(v);
+	int ret = strm->close();
+	delete strm;
+	return ret;
+}
+
+FILE *open_stream(stream *strm) {
+	FILE *fp = funopen(strm, strm_read, strm_write, strm_seek, strm_close);
+	// Disable buffering
+	setbuf(fp, nullptr);
+	return fp;
+}
+
+int stream::read(void *buf, size_t len)  {
+	LOGE("This stream does not support read");
+	return -1;
+}
+
+int stream::write(const void *buf, size_t len) {
+	LOGE("This stream does not support write");
+	return -1;
+}
+
+off_t stream::seek(off_t off, int whence) {
+	LOGE("This stream does not support seek");
+	return -1;
+}
+
+int stream::close() {
+	return 0;
+}
+
+off_t seekable_stream::new_pos(off_t off, int whence) {
+	off_t new_pos;
+	switch (whence) {
+		case SEEK_CUR:
+			new_pos = _pos + off;
+			break;
+		case SEEK_END:
+			new_pos = end_pos() + off;
+			break;
+		case SEEK_SET:
+			new_pos = off;
+			break;
+		default:
+			return -1;
+	}
+	return new_pos;
+}
+
+byte_stream::byte_stream(uint8_t *&buf, size_t &len) : _buf(buf), _len(len) {
+	buf = nullptr;
+	len = 0;
+}
+
+int byte_stream::read(void *buf, size_t len) {
+	len = std::min(len, _len - _pos);
+	memcpy(buf, _buf + _pos, len);
+	return len;
+}
+
+int byte_stream::write(const void *buf, size_t len) {
+	resize(_pos + len);
+	memcpy(_buf + _pos, buf, len);
+	_pos += len;
+	_len = std::max(_len, _pos);
+	return len;
+}
+
+off_t byte_stream::seek(off_t off, int whence) {
+	off_t np = new_pos(off, whence);
+	if (np < 0)
+		return -1;
+	resize(np, true);
+	_pos = np;
+	return np;
+}
+
+void byte_stream::resize(size_t new_pos, bool zero) {
+	bool resize = false;
+	size_t old_cap = _cap;
+	while (new_pos > _cap) {
+		_cap = _cap ? (_cap << 1) - (_cap >> 1) : 1 << 12;
+		resize = true;
+	}
+	if (resize) {
+		_buf = (uint8_t *) xrealloc(_buf, _cap);
+		if (zero)
+			memset(_buf + old_cap, 0, _cap - old_cap);
+	}
+}
+
+int fd_stream::read(void *buf, size_t len) {
+	return ::read(fd, buf, len);
+}
+
+int fd_stream::write(const void *buf, size_t len) {
+	return ::write(fd, buf, len);
+}
+
+off_t fd_stream::seek(off_t off, int whence) {
+	return lseek(fd, off, whence);
+}