libuv的调用例子

（来自文心一言）

Libuv 是一个多平台的异步 I/O 库，旨在提供事件驱动的编程模型，类似于 Node.js 的底层机制。以下是一个简单的例子，展示了如何使用 libuv 来创建一个 TCP 服务器和客户端。

首先，确保你已经安装了 libuv。你可以从 libuv 的 GitHub 页面下载并安装它。
简单的 TCP 服务器

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <uv.h>

void alloc_buffer(uv_handle_t* handle, size_t suggested_size, uv_buf_t* buf) {
    buf->base = (char*) malloc(suggested_size);
    buf->len = suggested_size;
}

void on_read(uv_stream_t* stream, ssize_t nread, const uv_buf_t* buf, const uv_stream_t* src) {
    if (nread < 0) {
        if (nread != UV_EOF)
            fprintf(stderr, "Read error %s\n", uv_strerror((int)nread));
        uv_close((uv_handle_t*) stream, NULL);
        free(buf->base);
        return;
    }

    if (nread == 0) {
        free(buf->base);
        return;
    }

    printf("Server received: %s\n", buf->base);

    uv_buf_t write_buf = uv_buf_init("Hello from server", strlen("Hello from server"));
    uv_write_t req;
    uv_write(&req, stream, &write_buf, 1, NULL);

    free(buf->base);
}

void on_new_connection(uv_stream_t* server, int status) {
    if (status < 0) {
        fprintf(stderr, "New connection error %s\n", uv_strerror(status));
        return;
    }

    uv_tcp_t* client = (uv_tcp_t*) malloc(sizeof(uv_tcp_t));
    uv_tcp_init(uv_default_loop(), client);
    uv_accept(server, (uv_stream_t*) client);

    uv_read_start((uv_stream_t*) client, alloc_buffer, on_read);
}

int main() {
    uv_loop_t* loop = uv_default_loop();
    uv_tcp_t server;

    uv_tcp_init(loop, &server);
    uv_ip4_addr("0.0.0.0", 7000, &server.addr);

    uv_listen((uv_stream_t*)&server, 128, on_new_connection);

    return uv_run(loop, UV_RUN_DEFAULT);

}

简单的 TCP 客户端

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <uv.h>

void alloc_buffer(uv_handle_t* handle, size_t suggested_size, uv_buf_t* buf) {
    buf->base = (char*) malloc(suggested_size);
    buf->len = suggested_size;
}

void on_read(uv_stream_t* stream, ssize_t nread, const uv_buf_t* buf, const uv_stream_t* src) {
    if (nread < 0) {
        if (nread != UV_EOF)
            fprintf(stderr, "Read error %s\n", uv_strerror((int)nread));
        uv_close((uv_handle_t*) stream, NULL);
        free(buf->base);
        return;
    }

    if (nread == 0) {
        free(buf->base);
        return;
    }

    printf("Client received: %s\n", buf->base);

    uv_close((uv_handle_t*) stream, NULL);
    free(buf->base);
}

void on_connect(uv_connect_t* req, int status) {
    if (status < 0) {
        fprintf(stderr, "Connect error %s\n", uv_strerror(status));
        return;
    }

    uv_buf_t write_buf = uv_buf_init("Hello from client", strlen("Hello from client"));
    uv_write_t write_req;
    uv_write(&write_req, req->handle, &write_buf, 1, NULL);

    uv_read_start((uv_stream_t*) req->handle, alloc_buffer, on_read);
}

int main() {
    uv_loop_t* loop = uv_default_loop();
    uv_tcp_t socket;
    uv_connect_t connect_req;

    uv_tcp_init(loop, &socket);

    struct sockaddr_in dest;
    uv_ip4_addr("127.0.0.1", 7000, &dest);

    uv_tcp_connect(&connect_req, &socket, (const struct sockaddr*)&dest, on_connect);

    return uv_run(loop, UV_RUN_DEFAULT);