C语言实现修改文本文件中特定行的实现代码

wireless.1.authmode=1
wireless.1.compression=0
wireless.1.current_ap=ssid12
wireless.1.current_state=1
wireless.1.devname=ath0
wireless.1.enable_slave1_status=disabled
wireless.1.enable_slave2_status=disabled
wireless.1.enable_slave3_status=disabled

wireless.1.current_state=0

/*
 * Author：DLUTBruceZhang
 * Date: 2013.06.24
 */
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
int main()
{
 /*
  *linebuffer：读取文件中的一行存入的缓冲
  *buffer1：一行中第一个字段的存入缓冲
  *buffer2：一行中第二个字段的存入缓冲
  */
 char linebuffer[512] = {0};
 char buffer1[512] = {0};
 char buffer2[512] = {0};

 int line_len = 0;
 int len = 0;
 int res;

 /*
  * cc.cfg是文件名，r+代表可以读写文件
  */
 FILE *fp = fopen("cc.cfg", "r+");
 if(fp == NULL)
 {
  printf("open error");
  return -1;
 }
 while(fgets(linebuffer, 512, fp))
 {
  line_len = strlen(linebuffer);
  len += line_len;
  /*
   * buffer1=wireless.1.current_state
   * buffer2=1
   */
  sscanf(linebuffer, "%[^=]=%[^=]", buffer1,buffer2);
  if(!strcmp("wireless.1.current_state", buffer1))
  {
   /*
    * 由于已经找到所需要写的位置，所以需要写位置的“头”
    */
   len -= strlen(linebuffer);
   /*
    * 实现文件位置的偏移，为写文件做准备
    */
   res = fseek(fp, len, SEEK_SET);
   if(res < 0)
   {
    perror("fseek");
    return -1;
   }
   strcpy(buffer2, "=0");
   /*strcat(buffer1, "=");*/
   strcat(buffer1, buffer2);
   printf("%d",strlen(buffer1));
   /*
    * 写文件，存入所需的内容
       */
   fprintf(fp, "%s", buffer1);
   fclose(fp);
   return;
  }
 }
return 0;
}

wireless.1.authmode=1
wireless.1.compression=0
wireless.1.current_ap=ssid12
wireless.1.current_state=0
wireless.1.enable_slave1_status=disabled
wireless.1.enable_slave2_status=disabled
wireless.1.enable_slave3_status=disabled