1, learning tasks
Reference pseudo-code for the function ls submit the compiled code, the results shots, cloud codes link code
Open the catalog file
for the directory file
read directory entry
displays the file name
to close the file directory file
2, ls function
ls: Displays the file directory listing
- -a: Displays all files, including hidden files
- -l: List length data string showing data file attributes and permissions, etc. (common)
- -i: in conjunction with the -l option lists each file inode
- -d: list only the directory itself, rather than listing the contents of a directory list
3, Code
include <stdio.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/stat.h>
#include <pwd.h>
#include <grp.h>
#include <unistd.h>
#include <string.h>
#define LS_NONE 0
#define LS_L 101
#define LS_R 102
#define LS_D 103
#define LS_I 104
#define LS_A 200
#define LS_AL (LS_A+LS_L)
#define LS_AI (LS_A+LS_I)
// 展示单个文件的详细信息
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';
}
}
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;
}
}
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;
}
}
void do_ls(char dirname[],int mode)
{
DIR* dir_ptr;
struct dirent* direntp;
if ((dir_ptr = opendir(dirname)) == NULL)
{
fprintf(stderr, "ls2: cannot open %s \n", dirname);
}
else
{
if(mode==LS_D)
{
printf("%s\n", dirname);
}
else
{
char dirs[20][100];
int dir_count = 0;
while ((direntp = readdir(dir_ptr)) != NULL)
{
if(mode < 200 && direntp->d_name[0]=='.')
{
continue;
}
char complete_d_name[200]; // 文件的完整路径
strcpy (complete_d_name,dirname);
strcat (complete_d_name,"/");
strcat (complete_d_name,direntp->d_name);
struct stat info;
if (stat(complete_d_name, &info) == -1)
{
perror(complete_d_name);
}
else
{
if(mode == LS_L||mode == LS_AL)
{
show_file_info(direntp->d_name, &info);
}
else if(mode == LS_A||mode == LS_NONE||mode == LS_I||mode == LS_AI)
{
if(mode == LS_I||mode == LS_AI)
{
printf("%llu ", direntp->d_ino);
}
printf("%s\n", direntp->d_name);
}
else if(mode == LS_R)
{
if(S_ISDIR(info.st_mode))
{
printf("%s\n", direntp->d_name);
strcpy (dirs[dir_count],complete_d_name);
dir_count++;
}
else
{
printf("%s\n", direntp->d_name);
}
}
}
}
if(mode == LS_R)
{
int i=0;
printf("\n");
for(;i<dir_count;i++){
printf("%s:\n", dirs[i]);
do_ls(dirs[i],LS_R);
printf("\n");
}
}
}
closedir(dir_ptr);
}
}
// 解析一个单词参数，如-l，-i
int analyzeParam(char* input){
if(strlen(input)==2)
{
if(input[1]=='l') return LS_L;
if(input[1]=='a') return LS_A;
if(input[1]=='d') return LS_D;
if(input[1]=='R') return LS_R;
if(input[1]=='i') return LS_I;
}
else if(strlen(input)==3)
{
if(input[1]=='a'&& input[2]=='l') return LS_AL;
if(input[1]=='a'&& input[2]=='i') return LS_AI;
}
return -1;
}
int main(int ac,char* av[])
{
if(ac == 1)
{
do_ls(".",LS_NONE);
}
else
{
int mode = LS_NONE; // 默认为无参数ls
int have_file_param = 0; // 是否有输入文件参数
while(ac>1)
{
ac--;
av++;
int calMode = analyzeParam(*av);
if(calMode!=-1)
{
mode+=calMode;
}
else
{
have_file_param = 1;
do
{
printf("%s:\n", *av);
do_ls(*av,mode);
printf("\n");
ac--;
av++;
}while(ac>=1);
}
}
if (!have_file_param)
{
do_ls(".",mode);
}
}
} 4, test implementation mystat
