学号20145220《信息安全系统设计基础》第11周学习总结

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

include

include

include

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

include

include

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

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

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

include <sys/types.h> //基本系统数据类型

include

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

include

include <sys/types.h>

include

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

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

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

include

include

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

include

include

include <sys/types.h>

include <sys/stat.h>

include

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

include

include

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

include

include

include

include

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, ¤t_record, reclen) == reclen )
show_info(¤t_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

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