转自:http://blog.csdn.net/echo_qiang/article/details/6233057
/********************************************************************* * * Filename: pfile.c * Version: 1.0 * Description: Demo for Linux LIST utility * Compilation: gcc –D__KERNEL__ -I/usr/src/linux/include pfile.c * Status: Stable * Author: Yang Shazhou<pubb@163.net> * Created at: Thu Jul 15 13:50:33 2004 * Modified at: Thu Jul 15 14:39:03 2004 * Modified by: Yang Shazhou<pubb@163.net> * * Copyright (c) 2004 Yang Shazhou, All Rights Reserved. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, * MA 02111-1307 USA * ********************************************************************/ #include <linux/list.h> #include <stdio.h> #include <strings.h> int main(int argc,char *argv[]) { LIST_HEAD(list); //定义存放文件内容的链表 FILE *fp; struct file_store { char c; struct list_head node; } *pstore; if(argc<2){ printf("usage: pfile <filename> <[r]>/n"); return -1; } if(!(fp=fopen(argv[1],"rb"))){ printf("fopen(%s) error/n",argv[1]); return -1; } /* 读文件到链表 */ while(1){ if(!(pstore=(struct file_store *)malloc(sizeof(struct file_store)))) break; pstore->c=fgetc(fp); if(feof(fp)){ free(pstore); break; } list_add_tail(&pstore->node,&list); //将本字符插入链表中 } fclose(fp); /* 遍历链表,输出链表中的节点个数,即文件字符数 */ int count=0; struct list_head *p; list_for_each(p,&list){ count++; } printf("%s has altogether %d character(s)/n",argv[1],count); /* 根据命令行参数正向/反向遍历链表,输出链表中存放的字符,同时释放各节点 */ if(argc>2 && !strcasecmp(argv[2],"r")){ struct list_head *p; list_for_each_entry_reverse(pstore,&list,node){ //反向遍历,没有保护 p=pstore->node.next; list_del(&pstore->node); putchar(pstore->c); free(pstore); /* 如果没有这一句,将报segmentation fault */ pstore=list_entry(p,struct file_store,node); //取数据项 } }else{ struct file_store *p; list_for_each_entry_safe(pstore,p,&list,node){ //正向遍历,有保护 list_del(&pstore->node); putchar(pstore->c); free(pstore); } } return 0; }
【作者】张昺华
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