学号20145220《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

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 <sys/types.h> //基本系统数据类型

include <sys/stat.h> //文件属性结构体

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 <sys/stat.h> //文件属性结构体

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 <sys/types.h> //基本系统数据类型

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 <sys/types.h>

include <dirent.h>

include <sys/stat.h>

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)

//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 <sys/types.h>

include <sys/stat.h>

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 <sys/ioctl.h>

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