实现Linux下的ls -l命令

基本实现了Linux下的ls -l命令,对于不同的文件显示不同的颜色和显示符号链接暂时没有实现:

/*************************************************************************
    > File Name: dirwalk.c
    > Author: 
    > Mail: 
    > Created Time: Tue 31 Mar 2015 11:56:38 AM CST
 ************************************************************************/

#include<stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>
#include <time.h>

#define MAX_PATH 1024
#define MODE_LEN 10
#define TIME_LEN 20
#define NAME_LEN 30

unsigned long  ugo_mode[9] = {S_IRUSR, S_IWUSR, S_IXUSR, S_IRGRP, S_IWGRP, S_IXGRP, S_IROTH, S_IWOTH, S_IXOTH};
char* rwx[3] = {"r", "w", "x"};
char* userpath = "/etc/passwd";
char* grouppath = "/etc/group";

/*dirwalk: apply fcn to all files in dir */
void dirwalk(char* dir, void(*fcn)(char*))
{
    struct dirent *dp;
    DIR* dfd;

    char name[MAX_PATH];
    if((dfd = opendir(dir)) == NULL)
    {
        fprintf(stderr, "dirwalk: can't open %s\n", dir);
        return;
    }

    while((dp = readdir(dfd)) != NULL)
    {
        if(strcmp(dp->d_name, ".") == 0 || strcmp(dp->d_name, "..") == 0)
        {
            continue;
        }

        if(strlen(dir) + strlen(dp->d_name) + 2 > sizeof(name))
        {
            fprintf(stderr, "%s/%s too long\n", dir, dp->d_name);
        }else
        {
            sprintf(name, "%s/%s", dir, dp->d_name);
            (*fcn)(name);
        }
    }
    closedir(dfd);
}

/*getname: get the name of the user and the name of the group name */
void getname(char* path, int id, char* name)
{   

    int fd, save_fd;
    if((fd = open(path, O_RDONLY)) < 0)
    {
        perror("open \n");
        exit(1);
    }
    
    save_fd = dup(STDIN_FILENO);
    dup2(fd, STDIN_FILENO);
    close(fd);
    char p[MAX_PATH];
    char usrid[20];
    sprintf(usrid, "%d", id);
    char* puid;
    while((scanf("%s", p)) != EOF)
    {
        if((puid = strstr(p, usrid)) != NULL)
        {
            char* pFlag;
            char* pResult;
            if((pFlag = strstr(p, ":")) != NULL)
            {
                pResult = pFlag;
                pFlag = strstr(pFlag + 1, ":");
            }
            if(pFlag != NULL)
            {
                if((memcmp(pFlag + 1, puid, strlen(usrid))) == 0)
                {
                    *pResult = '\0';
                    strcpy(name, p);
                }
            }
            //printf("%s\n", puid);
        }
    }

    dup2(save_fd, STDIN_FILENO);
    close(save_fd);
}

/*getmode: get the mode of a file in string format  by st_mode */
void getmode(unsigned long  st_mode, char* mode)
{
    switch(st_mode & S_IFMT)
    {
        case S_IFDIR:
            mode[0] = 'd';
            break;
        case S_IFIFO:
            mode[0] = 'p';
            break;
        case S_IFBLK:
            mode[0] = 'b';
            break;
        case S_IFCHR:
            mode[0] = 'c';
            break;
        case S_IFREG:
            mode[0] = '-';
            break;
        case S_IFLNK:
            mode[0] = 'l';
            break;
        case S_IFSOCK:
            mode[0] = 's';
            break;
        default:
            mode[0] = 'u';
            break;
    }

    int i;
    for(i = 0; i < 9; ++i)
    {
        if(st_mode & ugo_mode[i])
        {
            strcat(mode, rwx[i % 3]);
        }else
        {
            strcat(mode, "-");
        }
    }
}
 

/*gettime: get the time in string format */
void gettime(const time_t ct, char* time)
{
    char* tmp = ctime(&ct);
    time[0] = tmp[4];
    time[1] = tmp[5];
    time[2] = tmp[6];
    time[3] = ' ';

    struct tm* tm_buf = gmtime(&ct);
    char last[20];
    sprintf(last, "%02d %02d:%02d", tm_buf->tm_mday, tm_buf->tm_hour, tm_buf->tm_min);
    strcat(time, last);
}

/* print the file name and the size of the "name" */
void fsize(char* name)
{
    struct stat st_buf;
    if(stat(name, &st_buf) < 0)
    {
        fprintf(stderr, "fsize: can't access %s\n", name);
        return;
    }



    if((st_buf.st_mode & S_IFMT) == S_IFDIR)
    {
        dirwalk(name, fsize);
    }
    char* time = (char*)malloc(sizeof(char) * TIME_LEN);
    memset(time, 0, TIME_LEN);
    gettime(st_buf.st_atime, time);

    char* mode = (char*)malloc(sizeof(char) * MODE_LEN);
    memset(mode, 0, MODE_LEN);
    getmode(st_buf.st_mode, mode);


    char* username = (char*)malloc(sizeof(char) * NAME_LEN);
    memset(username, 0, NAME_LEN);
    getname(userpath, st_buf.st_uid, username);

    char* groupname = (char*)malloc(sizeof(char) *  NAME_LEN);
    memset(groupname, 0, NAME_LEN);
    getname(grouppath, st_buf.st_gid, groupname);

    printf("%s %d %s %s  %4ld %s %s\n", mode, (int)st_buf.st_nlink, username, groupname,  st_buf.st_size, time,  name);
    free(groupname);
    free(username);
    free(mode);
    free(time);
}

int main(int argc, char* argv[])
{
    if(argc == 1)
        fsize(".");
    while(--argc)
        fsize(*++argv);
    return 0;