Sample for reading a file asynchronously using libuv

uv_read_file.c

// Sample for reading a file asynchronously using libuv
// taken from https://www.snip2code.com/Snippet/247423/Sample-for-reading-a-file-asynchronously

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

static uv_fs_t openReq;
static uv_fs_t readReq;
static uv_fs_t closeReq;
static uv_buf_t uvBuf;
static char strBuf[65];
static char dataBuf[64];

static void onRead(uv_fs_t *req);

static void readData(void)
{
    memset(strBuf, 0, sizeof(strBuf));
    memcpy(strBuf, dataBuf, sizeof(dataBuf));
    fprintf(stdout, "got some data: %s\n", strBuf);
    memset(dataBuf, 0, sizeof(dataBuf));
    uv_fs_read(uv_default_loop(), &readReq, openReq.result, &uvBuf, 1, -1, onRead);
}

static void onRead(uv_fs_t *req)
{
    uv_fs_req_cleanup(req);
    if (req->result < 0) {
        fprintf(stderr, "error: %s\n", uv_strerror(req->result));
    } else if (req->result == 0) {
        uv_fs_close(uv_default_loop(), &closeReq, openReq.result, NULL);
    } else {
        readData();
    }
}

static void onOpen(uv_fs_t *req)
{
    if (req->result < 0) {
        fprintf(stderr, "error: %s\n", uv_strerror(req->result));
    } else {
        uvBuf = uv_buf_init(dataBuf, sizeof(dataBuf));
        uv_fs_read(uv_default_loop(), &readReq, req->result, &uvBuf, 1, -1, onRead);
    }
    uv_fs_req_cleanup(req);
}


int main (int argc, char* argv[])
{
    uv_fs_open(uv_default_loop(), &openReq, argv[1], O_RDONLY, 0, onOpen);
    return uv_run(uv_default_loop(), UV_RUN_DEFAULT);
}