20145209《信息安全系统设计基础》第11周学习总结

学号20145209《信息安全系统设计基础》第11周学习总结

教材学习内容总结

教材学习内容总结
代码运行情况
1、cp1.c

include <stdio.h> //标准输入输出头文件
include <stdlib.h> //标准库头文件
include <unistd.h> //unix类系统定义符号常量的头文件
include <fcntl.h> //定义了一组基于C的非缓冲的文件操作函数，可用于文件和设备（及socket等）的I/O操作
define BUFFERSIZE 4096 //缓冲区大小
define COPYMODE 0644 // 新文件的访问权限位
void oops(char , char ); //错误处理函数

int main(int argc, char argv[])
{
int in_fd, out_fd, n_chars;
char buf[BUFFERSIZE]; //定义缓冲区
if (argc != 3) //当输入参数不足时
{
fprintf(stderr, "usage: %s source destination\n", argv);
exit(1);
}

if ((in_fd = open(argv[1], O_RDONLY)) == -1) /打开文件失败
oops("Cannot open ", argv[1]);

if ((out_fd = creat(argv[2], COPYMODE)) == -1) //创建新文件失败
oops("Cannot creat", argv[2]);

while ((n_chars = read(in_fd, buf, BUFFERSIZE)) > 0) //缓冲区不空时，开始写文件
if (write(out_fd, buf, n_chars) != n_chars) //写文件出错
oops("Write error to ", argv[2]);
if (n_chars == -1) //从文件中读数据出错
oops("Read error from ", argv[1]);

if (close(in_fd) == -1 || close(out_fd) == -1) //关闭输入文件出错或关闭输出文件出错
oops("Error closing files", "");
}

void oops(char s1, char s2) //错误处理
{
fprintf(stderr, "Error: %s ", s1);
perror(s2);
exit(1);
}
首先，进入week10文件夹，用vim编辑器编辑cp1.c的代码并编译：

再次查看scncp1.c中的内容，发现和cp1.c中的内容完全一致：

说明此代码的功能是：复制文件或目录

2、echostate.c

include <stdio.h>
include <stdlib.h>
include <termios.h>
int main()
{
struct termios info;
int rv;

rv = tcgetattr( 0, &info );     /* read values from driver      */

if ( rv == -1 ){
        perror( "tcgetattr");
        exit(1);
}
if ( info.c_lflag & ECHO )
        printf(" echo is on , since its bit is 1\n");
else
        printf(" echo is OFF, since its bit is 0\n");

return 0;

}

功能：查看在命令行中输入命令时是否可见，可见返回1，否则返回0

3、fileinfo.c

include <stdio.h>
include
include
void show_stat_info(char , struct stat );
//显示文件属性函数
int main(int argc, char *argv[])
{
struct stat info;

if (argc>1) //运行时有参数
{

if( stat(argv[1], &info) != -1 )    //显示文件状态
{
    show_stat_info( argv[1], &info );
    return 0;
}
else
    perror(argv[1]);  //错误处理

}
return 1;
}
void show_stat_info(char fname, struct stat buf)
{
printf(" mode: %o\n", buf->st_mode);
printf(" links: %d\n", buf->st_nlink);
printf(" user: %d\n", buf->st_uid);
printf(" group: %d\n", buf->st_gid);
printf(" size: %d\n", (int)buf->st_size);
printf("modtime: %d\n", (int)buf->st_mtime);
printf(" name: %s\n", fname );
}

功能：查看文件信息

4、filesize.c

include <stdio.h>
include
int main()
{
struct stat infobuf;

if ( stat( "/etc/passwd", &infobuf) == -1 )
//查看文件属性函数
perror("/etc/passwd"); //错误处理
else
printf(" The size of /etc/passwd is %d\n", infobuf.st_size );
}

功能：查看文件大小

5、ls1.c

include <stdio.h>
include
include <dirent.h>
void do_ls(char []);

int main(int argc, char argv[])
{
if ( argc == 1 ) //没有参数是，显示 当前万人当
do_ls( "." );
else
while ( --argc ){
printf("%s:\n", ++argv ); //显示参数
do_ls( *argv );
}

return 0;
}

void do_ls( char dirname[] )
{
DIR dir_ptr; //DIR表示目录类型
struct dirent direntp; //目录结构体

if ( ( dir_ptr = opendir( dirname ) ) == NULL )
fprintf(stderr,"ls1: cannot open %s\n", dirname);
else
{
while ( ( direntp = readdir( dir_ptr ) ) != NULL )
printf("%s\n", direntp->d_name );
closedir(dir_ptr);
}
}

功能：显示当前目录下的所有文件

6、ls2.c

include <stdio.h>
include <string.h>
include
include <dirent.h>
include
void do_ls(char[]); //显示指定目录下的文件
void dostat(char ); //显示文件属性
void show_file_info( char , struct stat ); //显示文件读取详细信息
void mode_to_letters( int , char [] ); //显示文件读取权限信息
char uid_to_name( uid_t );
char *gid_to_name( gid_t );

int main(int argc, char argv[])
{
if ( argc == 1 )
do_ls( "." );
else
while ( --argc ){
printf("%s:\n", ++argv );
do_ls( *argv );
}

return 0;
}

void do_ls( char dirname[] )
{
DIR dir_ptr;
struct dirent direntp;

if ( ( dir_ptr = opendir( dirname ) ) == NULL )
fprintf(stderr,"ls1: cannot open %s\n", dirname);
else
{
while ( ( direntp = readdir( dir_ptr ) ) != NULL )
dostat( direntp->d_name );
closedir(dir_ptr);
}
}

void dostat( char *filename )
{
struct stat info;

if ( stat(filename, &info) == -1 )
perror( filename );
else
show_file_info( filename, &info );
}

void show_file_info( char filename, struct stat info_p )
{
char uid_to_name(), ctime(), gid_to_name(), filemode();
void mode_to_letters();
char modestr[11];

mode_to_letters( info_p->st_mode, modestr );

printf( "%s" , modestr );
printf( "%4d " , (int) info_p->st_nlink);
printf( "%-8s " , uid_to_name(info_p->st_uid) );
printf( "%-8s " , gid_to_name(info_p->st_gid) );
printf( "%8ld " , (long)info_p->st_size);
printf( "%.12s ", 4+ctime(&info_p->st_mtime));
printf( "%s\n" , filename );
}

void mode_to_letters( int mode, char str[] )
{
strcpy( str, "----------" );

if ( S_ISDIR(mode) ) str[0] = 'd';
if ( S_ISCHR(mode) ) str[0] = 'c';
if ( S_ISBLK(mode) ) str[0] = 'b';

if ( mode & S_IRUSR ) str[1] = 'r';
if ( mode & S_IWUSR ) str[2] = 'w';
if ( mode & S_IXUSR ) str[3] = 'x';

if ( mode & S_IRGRP ) str[4] = 'r';
if ( mode & S_IWGRP ) str[5] = 'w';
if ( mode & S_IXGRP ) str[6] = 'x';

if ( mode & S_IROTH ) str[7] = 'r';
if ( mode & S_IWOTH ) str[8] = 'w';
if ( mode & S_IXOTH ) str[9] = 'x';
}

include <pwd.h> //定义口令结构体
char uid_to_name( uid_t uid )
{
struct passwd getpwuid(), *pw_ptr;
static char numstr[10];

if ( ( pw_ptr = getpwuid( uid ) ) == NULL ){
sprintf(numstr,"%d", uid);
return numstr;
}
else
return pw_ptr->pw_name ;
}

include <grp.h> //包含组结构的定义
char gid_to_name( gid_t gid )
{
struct group getgrgid(), *grp_ptr;
static char numstr[10];

if ( ( grp_ptr = getgrgid(gid) ) == NULL ){
sprintf(numstr,"%d", gid);
return numstr;
}
else
return grp_ptr->gr_name; //返回组名
}

功能：显示指定目录下的文件详细信息

7、setcho.c

include <stdio.h>
include <stdlib.h>
include <termios.h> //串口配置中，终端的工作模式，是一个结构体
define oops(s,x) { perror(s); exit(x); }
//用于错误处理的宏

int main(int argc, char *argv[])
{
struct termios info;

if ( argc == 1 ) 
exit(0);

if ( tcgetattr(0,&info) == -1 )          /* 获取文件属性   */
    oops("tcgettattr", 1);

if ( argv[1][0] == 'y' )
        info.c_lflag |= ECHO ;          /* 设置打开标志位    */
else
        info.c_lflag &= ~ECHO ;         /* 设置关闭标志位   */

if ( tcsetattr(0,TCSANOW,&info) == -1 ) /* 设置文件属性    */
       oops("tcsetattr",2);

return 0;

}

功能：设置echo的状态

8、spwd.c

include <stdio.h>
include <stdlib.h>
include <string.h>
include
include
include <dirent.h>
ino_t get_inode(char ); // 获取i-node节点号
void printpathto(ino_t); // 打印当前目录路径
void inum_to_name(ino_t , char , int ); //根据i-node节点找到对应文件名

int main()
{
printpathto( get_inode( "." ) );
putchar('\n');
return 0;
}

void printpathto( ino_t this_inode )
{
ino_t my_inode ;
char its_name[BUFSIZ];

if ( get_inode("..") != this_inode )
{
chdir( ".." );

inum_to_name(this_inode,its_name,BUFSIZ);

my_inode = get_inode( "." );        
printpathto( my_inode );        
printf("/%s", its_name );       

}
}

void inum_to_name(ino_t inode_to_find , char namebuf, int buflen)
{
DIR dir_ptr;
struct dirent *direntp;

dir_ptr = opendir( "." );
if ( dir_ptr == NULL ){
perror( "." );
exit(1);
}

while ( ( direntp = readdir( dir_ptr ) ) != NULL )
if ( direntp->d_ino == inode_to_find )
{
strncpy( namebuf, direntp->d_name, buflen);
namebuf[buflen-1] = '\0';
closedir( dir_ptr );
return;
}
fprintf(stderr, "error looking for inum %d\n", (int) inode_to_find);
exit(1);
}

ino_t get_inode( char *fname )
{
struct stat info;

if ( stat( fname , &info ) == -1 ){
fprintf(stderr, "Cannot stat ");
perror(fname);
exit(1);
}
return info.st_ino; //返回i-node节点号
}

功能：显示当前目录路径

9、testioctl.c

include <stdio.h>
include <stdlib.h>
include <unistd.h>
include
int main()
{
struct winsize size;
if( isatty(STDOUT_FILENO) == 0) //判断一个文件描述符是否指向一个终端
exit(1);
if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &size) < 0) //控制驱动器
{
perror("ioctl TIOCGWINSZ error");
exit(1);
}

printf("%d rows %d columns\n", size.ws_row, size.ws_col);
return 0;
}

功能：查看窗体大小信息

9、who1.c

include <stdio.h>
include <stdlib.h>
include <utmp.h> // 定义用户信息结构体
include <fcntl.h>
include <unistd.h> //对 POSIX 操作系统 API 的访问功能的头文件
define SHOWHOST
int show_info( struct utmp *utbufp )
{
printf("%-8.8s", utbufp->ut_name);
printf(" ");
printf("%-8.8s", utbufp->ut_line);
printf(" ");
printf("%10ld", utbufp->ut_time);
printf(" ");

ifdef SHOWHOST
printf("(%s)", utbufp->ut_host);
endif
printf("\n");

return 0;
}
int main()
{
struct utmp current_record;
int utmpfd;
int reclen = sizeof(current_record);

if ( (utmpfd = open(UTMP_FILE, O_RDONLY)) == -1 ){
perror( UTMP_FILE );
exit(1);
}
while ( read(utmpfd, &current_record, reclen) == reclen )
show_info(&current_record);
close(utmpfd);
return 0;

学习进度条

	代码行数（新增/累积）	博客量（新增/累积）	学习时间（新增/累积）	重要成长
目标	5000行	30篇	400小时
第一周	200/200	2/2	20/20
第二周	300/500	2/4	18/38
第三周	500/1000	3/7	22/60
第四周	300/1300	2/9	30/90

参考资料

• 《深入理解计算机系统V2》学习指导
• ...