实现ls命令

实现ls命令，支持-l，-a，-r，-q等选项。

//ls命令#include <stdio.h>#include <dirent.h>#include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <stdlib.h>#include <string.h>#include <vector>#include <string>#include <algorithm>#include <assert.h>#include <pwd.h>#include <grp.h>#include <time.h>#include <fcntl.h>using namespace std;//optionsenum OPTION {OPT_l, OPT_A, OPT_r, OPT_q, OPT_i, OPT_R, OPT_NUM};//gobal variableint g_option[OPT_NUM];vector<string> g_dirPath;int dirFd;  //the file descriptor  associated with the directoryvoid get_option(const char* strOption);void get_path(const char* strPath);void do_ls(const char* path);void do_stat(const string& filename, struct stat* p);void show_info(const struct stat& filestat, const string& name);void mode_to_letter(mode_t mode, char* str);char* uid_to_name(uid_t uid);char* gid_to_name(gid_t gid);int main(int argc, char** argv){    memset(g_option, 0, sizeof(int) * OPT_NUM);    //process option    while(--argc != 0)    {        if('-' == argv[argc][0])        {            get_option(argv[argc]);         }        else        {            get_path(argv[argc]);        }    }    if(g_dirPath.empty())    {        do_ls(".");    }    else    {        for(auto it = g_dirPath.begin(); it != g_dirPath.end();)        {            printf("%s:\n", it->c_str());            do_ls(it->c_str());            if(++it != g_dirPath.end())            {                printf("\n");            }        }    }    return 0;}void get_option(const char* strOption){    assert(strOption);    while(*(++strOption) != '\0')    {        if(*strOption == 'a') g_option[OPT_A] = 1;        else if(*strOption == 'A') g_option[OPT_A] = 1;        else if(*strOption == 'l') g_option[OPT_l] = 1;        else if(*strOption == 'i') g_option[OPT_i] = 1;        else if(*strOption == 'r') g_option[OPT_r] = 1;        else if(*strOption == 'q') g_option[OPT_q] = 1;        else if(*strOption == 'R') g_option[OPT_R] = 1;        else fprintf(stderr, "option error\n");    }}void get_path(const char* strPath){    assert(strPath);    g_dirPath.push_back(strPath);}void do_ls(const char* path){    assert(path);    DIR* p_dir;    struct dirent* p_next;    vector<string> list;    if((p_dir = opendir(path)) == NULL)    {        perror("opendir error");        exit(1);    }    if((dirFd = dirfd(p_dir)) == -1)    {        perror("dirfd error");        exit(0);    }    while((p_next = readdir(p_dir)) != NULL)    {        //process option -a        if(strcmp(p_next->d_name, ".") == 0 || strcmp(p_next->d_name, "..") || (p_next->d_name[0] == '.') == 0)        {            if(g_option[OPT_A] == 0)                continue;        }        list.push_back(p_next->d_name);    }    if(g_option[OPT_r])    {        sort(list.rbegin(), list.rend());    }    else if(g_option[OPT_q] == 0)    {        sort(list.begin(), list.end());    }    for(auto w : list)    {        struct stat fsTemp;        do_stat(w, &fsTemp);        show_info(fsTemp, w);    }    if(closedir(p_dir) != 0)    {        perror("closedir error");        exit(1);    }}void do_stat(const string& filename, struct stat* p){    assert(p);    if(fstatat(dirFd, filename.c_str(), p, AT_SYMLINK_NOFOLLOW) == -1)    {        perror("fstatat error");        exit(0);    }}void show_info(const struct stat& filestat, const string& name){    if(g_option[OPT_I])    {        printf("%ld ", filestat.st_ino);    }    if(g_option[OPT_L])    {        char buf[11];        mode_to_letter(filestat.st_mode, buf);        printf("%s ", buf);        printf("%4ld ", filestat.st_nlink);        printf("%-8s ", uid_to_name(filestat.st_uid));        printf("%-8s ", gid_to_name(filestat.st_gid));        printf("%8ld ", filestat.st_size);        printf("%.12s ", 4 + ctime(&filestat.st_mtime)); //只打印前12个字符        printf("%s\n", name.c_str());    }    else    {        printf("%s\t", name.c_str());    }}void mode_to_letter(mode_t mode, char* str){    assert(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(S_ISFIFO(mode)) str[0] = 'p';    if(S_ISLNK(mode)) str[0] = 'l';    if(S_ISSOCK(mode)) str[0] = 's';    if(S_IRUSR & mode) str[1] = 'r';    if(S_IWUSR & mode) str[2] = 'w';    if(S_IXUSR & mode) str[3] = 'x';    if(S_IRGRP & mode) str[4] = 'r';    if(S_IWGRP & mode) str[5] = 'w';    if(S_IXGRP & mode) str[6] = 'x';    if(S_IROTH & mode) str[7] = 'r';    if(S_IWOTH & mode) str[8] = 'w';    if(S_IXOTH & mode) str[9] = 'x';}char* uid_to_name(uid_t uid){    struct passwd * 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* grp_ptr;    static char numstr[10];    if((grp_ptr = getgrgid(gid)) == NULL)    {        sprintf(numstr, "%d", gid);        return numstr;    }    else    {        return grp_ptr->gr_name;    }}