feat(c/libuv/demo): Add libuv demo echo_server

refactor(c/libuv): Adjust comments and file names to accommodate merge

c/libuv/_demo/echo_server/echo_server.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/c/libuv"
+	"github.com/goplus/llgo/c/net"
+	"unsafe"
+)
+
+var DEFAULT_PORT c.Int = 8080
+var DEFAULT_BACKLOG c.Int = 128
+
+var loop *libuv.Loop
+
+type WriteReq struct {
+	req libuv.Write
+	buf libuv.Buf
+}
+
+func FreeWriteReq(req *libuv.Write) {
+	wr := (*WriteReq)(c.Pointer(req))
+	c.Free(c.Pointer(wr.buf.Base))
+	c.Free(c.Pointer(wr))
+}
+
+func AllocBuffer(handle *libuv.Handle, suggestedSize uintptr, buf *libuv.Buf) {
+	buf.Base = (*c.Char)(c.Malloc(suggestedSize))
+	buf.Len = suggestedSize
+}
+
+func EchoWrite(req *libuv.Write, status c.Int) {
+	if status != 0 {
+		c.Fprintf(c.Stderr, c.Str("write error: %s\n"), libuv.Strerror(status))
+	}
+	defer FreeWriteReq(req)
+}
+
+func EchoRead(client *libuv.Stream, nread c.Long, buf *libuv.Buf) {
+	if nread > 0 {
+		req := (*WriteReq)(c.Malloc(unsafe.Sizeof(WriteReq{})))
+		if req == nil {
+			c.Fprintf(c.Stderr, c.Str("Failed to allocate memory for write request\n"))
+			defer c.Free(c.Pointer(buf.Base))
+			return
+		}
+		req.buf = libuv.InitBuf(buf.Base, c.Uint(nread))
+		(*libuv.Write)(c.Pointer(req)).Write(client, []libuv.Buf{req.buf}, 1, EchoWrite)
+		return
+	}
+	if nread < 0 {
+		if (libuv.Errno)(nread) != libuv.EOF {
+			c.Fprintf(c.Stderr, c.Str("Read error: %s\n"), libuv.Strerror(c.Int(nread)))
+		}
+		(*libuv.Handle)(client).Close(nil)
+	}
+	if buf.Base != nil {
+		c.Free(c.Pointer(buf.Base))
+	}
+}
+
+func OnNewConnection(server *libuv.Stream, status c.Int) {
+	if status < 0 {
+		c.Fprintf(c.Stderr, c.Str("New connection error: %s\n"), libuv.Strerror(status))
+		return
+	}
+
+	client := (*libuv.Tcp)(c.Malloc(unsafe.Sizeof(libuv.Tcp{})))
+
+	if client == nil {
+		c.Fprintf(c.Stderr, c.Str("Failed to allocate memory for client\n"))
+		return
+	}
+
+	if libuv.InitTcp(loop, client) < 0 {
+		c.Fprintf(c.Stderr, c.Str("Failed to initialize client\n"))
+		c.Free(c.Pointer(client))
+		return
+	}
+
+	if server.Accept((*libuv.Stream)(client)) == 0 {
+		(*libuv.Stream)(client).StartRead(AllocBuffer, EchoRead)
+	} else {
+		(*libuv.Handle)(client).Close(nil)
+	}
+}
+
+func main() {
+	// Initialize the default event loop
+	loop = libuv.DefaultLoop()
+
+	// Initialize a TCP server
+	var server libuv.Tcp
+	libuv.InitTcp(loop, &server)
+
+	// Set up the address to bind the server to
+	var addr net.SockaddrIn
+	libuv.Ip4Addr(c.Str("0.0.0.0"), DEFAULT_PORT, &addr)
+
+	// Bind the server to the specified address and port
+	(&server).Bind((*net.SockAddr)(c.Pointer(&addr)), 0)
+	res := (*libuv.Stream)(&server).Listen(DEFAULT_BACKLOG, OnNewConnection)
+	if res != 0 {
+		c.Fprintf(c.Stderr, c.Str("Listen error: %s\n"), libuv.Strerror(res))
+		return
+	}
+
+	// Start listening for incoming connections
+	loop.Run(libuv.RUN_DEFAULT)
+}