Linux C下获取下载和上传的网速V2

/*
* 作者：杨志永
* 日期：2012-04-17 10:10 
* Email:ljy520zhiyong@163.com
* ＱＱ：929168233
* 
* 文件名: watch_network_speed.c
* 编译环境：Debian 6.0.4 Testing, GCC 4.6.3 X86_64
* 
* 功能：获取Linux系统下的下载和上传的网速
*
*/
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>

#define BUFFER 1024
#define SECOND 1
int get_net_work_download_speed(long int * download_speed, long int * upload_speed, char * download_type, char * upload_type);

int main(int argc, char * argv[])
{
    long int start_download_speed;
    long int end_download_speed;
    long int start_upload_speed;
    long int end_upload_speed;

    while (1)
    {
        get_net_work_download_speed(&start_download_speed, &start_upload_speed, "RX bytes:", "TX bytes:");
        sleep(SECOND);
        get_net_work_download_speed(&end_download_speed, &end_upload_speed, "RX bytes:", "TX bytes:");
        printf("下载速度: %.2lf KB/s\t", (float)(end_download_speed-start_download_speed)/(SECOND*1000));
        printf("上传速度: %.2lf KB/s\n", (float)(end_upload_speed-start_upload_speed)/(SECOND*1000));
    }
    exit(EXIT_SUCCESS);
}

int get_net_work_download_speed(long int * download_speed, long int * upload_speed, char * download_type, char * upload_type)
{
    FILE * pipo_stream;
    size_t bytes_read;

    char buffer[BUFFER];
    char * match;

    if ( (pipo_stream=popen("sudo ifconfig", "r")) == NULL )
    {
        printf("pipo error!\n");
        return -1;
    }

    bytes_read = fread(buffer, 1, sizeof(buffer), pipo_stream);

    if ( (fclose(pipo_stream)) != 0 )
    {
        printf("fclose error!\n");
        return -1;
    }

    if ( bytes_read == 0 )
    {
        printf("bytes_read == 0\n");
        return -1;
    }

    match = strstr(buffer, download_type);

    if (match == NULL)
    {
        printf("NO Keyword %s To Find!\n", download_type);
        return -1;
    }

    sscanf(match, "RX bytes:%ld", download_speed);

    match = strstr(buffer, upload_type);
    if (match == NULL)
    {
        printf("No Keyword %s To Find!\n", upload_type);
        return -1;
    }
    sscanf(match, "TX bytes:%ld", upload_speed);
    return 0;

}