initial commit; recreate bufio reader because learning

go.mod

@@ -0,0 +1,3 @@
+module gitea/bufio
+
+go 1.21.4

main.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"io"
+	"log"
+	"math/rand"
+)
+
+func main() {
+	reader := NewStreamOfStuff()
+	bufferedReader := NewBufferedReader(reader)
+	lenBits := make([]byte, 1)
+	for i := 0; i < 10; i++ {
+		if n, err := bufferedReader.Read(lenBits); err != nil || n != len(lenBits) {
+			panic(err)
+		}
+		payload := make([]byte, int(lenBits[0]))
+		if n, err := bufferedReader.Read(payload); err != nil || n != len(payload) {
+			panic(err)
+		}
+		log.Printf("[%d] (%d) %q", i, len(payload), payload)
+	}
+}
+
+type BufferedReader struct {
+	buffer []byte
+	reader io.Reader
+}
+
+func (r *BufferedReader) Read(b []byte) (int, error) {
+	for len(b) > len(r.buffer) {
+		more := make([]byte, 8)
+		n, err := r.reader.Read(more)
+		if err != nil {
+			return 0, err
+		}
+		r.buffer = append(r.buffer, more[:n]...)
+	}
+	n := len(b)
+	if copied := copy(b, r.buffer[:n]); copied != n {
+		panic(copied)
+	}
+	r.buffer = r.buffer[n:]
+	return n, nil
+}
+
+func NewBufferedReader(r io.Reader) io.Reader {
+	return &BufferedReader{
+		buffer: []byte{},
+		reader: r,
+	}
+}
+
+func NewStreamOfStuff() io.Reader {
+	return jitterReader{}
+}
+
+type jitterReader struct{}
+
+func (jitterReader jitterReader) Read(b []byte) (int, error) {
+	n := rand.Int()%len(b) + 1
+	for i := 0; i < n; i++ {
+		b[i] = 'a' + byte(rand.Int()%26)
+	}
+	return n, nil
+}