Linux ls 命令实现(简化版)
时间:2014-05-07 11:32:19
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在学习linux系统编程的时候,实现了ls命令的简化版本。
实现的功能如下:
1. 每种文件类型有自己的颜色 (- 普通文件, d 目录文件, l 链接文件, c 字符设备文件, b 快设备文件, p 管道文件, s socket文件。共7种)
2. 支持的参数有 -hali (a: 显示隐藏文件, i: 显示inode节点号,l: 以列表形式显示文件的详细信息,h: 人类可读的文件大小显示)
3. 对于符号链接,显示出其指向的文件。
4. 设备文件,显示主设备号和次设备号,不显示文件大小(设备文件没有大小属性,对于设备号,不同的 *nix 存储方式可能不同)
5. 文件按照字典序排序显示。
程序说明:
1. 程序中大部分使用的都是linux系统调用和c标准库函数,只有文件排序用到了c++ stl 的vector和sort算法(好吧,我又偷懒了!)
2. stat(): 获取文件的详细信息,inode, 权限, 连接数, uid, gid, size, time 等
opendir(), readdir(), closedir(): 读取目录信息
程序编译运行(见下图)
程序源码:
#include <sys/types.h> #include <sys/stat.h> #include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <time.h> #include <errno.h> #include <dirent.h> #include <grp.h> #include <pwd.h> // c++ #include <vector> #include <algorithm> #include <string> using namespace std; #define BUF_SIZE 1024 #define COLOR_R (char*)"\33[0m" #define COLOR_D (char*)"\33[01m\33[34m" #define COLOR_L (char*)"\33[01m\33[36m" #define COLOR_P (char*)"\33[40m\33[33m" #define COLOR_B (char*)"\33[40m\33[33m" #define COLOR_C (char*)"\33[40m\33[33m" #define COLOR_S (char*)"\33[02m\33[35m" #define RESET_CLOLR (char*)"\33[0m" int get_option(const char *opt); int show_ls(); int show_ls_one_path(const char *path); int show_ls_file(const char *path, const char *name); int show_ll_part(struct stat *p_stat, int bHuman); void to_humen_size(char *buf, off_t size); char get_file_type(mode_t st_mode); void get_mode(char *buf, mode_t st_mode); // global var enum EOPT { E_a, E_i, E_l, E_h, E_num }; int g_opt[E_num] = {0}; // order: -ailh char *g_scolor; vector<string> gv_path; /* ls: ./a.out argv... */ int main(int argc, char const *argv[]) { int i; for (i = 1; i < argc; ++i) { if (‘-‘ == argv[i][0]) { if (-1 == get_option(argv[i]+1)) { fprintf(stderr, "bad option!\n"); return 1; } } else { gv_path.push_back(argv[i]); } } if (0 == gv_path.size()) { gv_path.push_back("."); } show_ls(); return 0; } /* -ailh */ int get_option(const char *opt) { while (*opt != ‘\0‘) { switch (*opt) { case ‘a‘: g_opt[E_a] = 1; break; case ‘i‘: g_opt[E_i] = 1; break; case ‘l‘: g_opt[E_l] = 1; break; case ‘h‘: g_opt[E_h] = 1; break; default: return -1; } opt++; } return 0; } int show_ls() { for (vector<string>::iterator it = gv_path.begin(); it != gv_path.end(); ++it) { show_ls_one_path(it->c_str()); } return 0; } int show_ls_one_path(const char *path) { DIR *dir; dir = opendir(path); if (NULL == dir) { // not a dir if (ENOTDIR == errno) { char *p = rindex((char *)path, ‘/‘); if (NULL == p) { show_ls_file("./", path); } else { char sdir[BUF_SIZE] = {‘\0‘}; strncpy(sdir, path, p-path); show_ls_file(sdir, p+1); } printf("\n"); return 0; } perror(path); return -1; } if (gv_path.size() > 1) { fprintf(stdout, "%s:\n", path); } struct dirent *entry; vector<string> v_name; while (1) { entry = readdir(dir); if (NULL == entry) { break; } // show conten depends on option(g_opt) if (g_opt[E_a] != 1) { if (‘.‘ == entry->d_name[0]) { continue; } } v_name.push_back(entry->d_name); } // sort filename sort(v_name.begin(), v_name.end()); for (vector<string>::iterator it = v_name.begin(); it != v_name.end(); ++it) { show_ls_file(path, it->c_str()); } fprintf(stdout, "\n"); closedir(dir); } int show_ls_file(const char *path, const char *name) { // stat char full_path[BUF_SIZE]; int ret; struct stat st_stat; snprintf(full_path, BUF_SIZE, "%s/%s", path, name); ret = lstat(full_path, &st_stat); if (-1 == ret) { perror(full_path); return -1; } if (1 == g_opt[E_i]) { fprintf(stdout, "%7d ", (int)st_stat.st_ino); } if (1 == g_opt[E_l]) { show_ll_part(&st_stat, g_opt[E_h]); } else { get_file_type(st_stat.st_mode);//get file color actually } // show filename with color fprintf(stdout, "%s", g_scolor); fprintf(stdout, "%s ", name); fprintf(stdout, RESET_CLOLR); if (1 == g_opt[E_l] && ‘l‘ == get_file_type(st_stat.st_mode)) { // -> real file char real_file[BUF_SIZE]; int path_size = readlink(full_path, real_file, BUF_SIZE); real_file[path_size] = ‘\0‘; fprintf(stdout, "-> %s", real_file); } if (1 == g_opt[E_l]) { fprintf(stdout, "\n"); } return 0; } /* show ll: mode, link num, user, group, size, time */ int show_ll_part(struct stat *p_stat, int bHuman) { // mode char buf[BUF_SIZE]; get_mode(buf, p_stat->st_mode); char file_type = buf[0]; fprintf(stdout, "%s", buf); // link num fprintf(stdout, " %d", p_stat->st_nlink); // uid gid // get_id_name(buf, p_stat->st_uid, "/etc/passwd"); // fprintf(stdout, " %s", buf); // get_id_name(buf, p_stat->st_gid, "/etc/group"); // fprintf(stdout, " %s", buf); struct passwd * st_user = getpwuid(p_stat->st_uid); fprintf(stdout, " %s", st_user->pw_name); struct group * st_group = getgrgid(p_stat->st_gid); fprintf(stdout, " %s", st_group->gr_name); // show dev id if (‘c‘ == file_type || ‘b‘ == file_type/* || ‘p‘ == file_type*/) { // dev_id int major = 0xFF00 & p_stat->st_rdev; major >>= 8; int sub = 0x00FF & p_stat->st_rdev; fprintf(stdout, "\t%4d,%4d", major, sub); } else // show file size { // -h bHuman size off_t size = p_stat->st_size; if (bHuman) { char buf[BUF_SIZE]; to_humen_size(buf, size); fprintf(stdout, " %s", buf); } else { fprintf(stdout, " %9ld", size); } } // time char stime[BUF_SIZE] = {‘\0‘}; snprintf(stime, 13, "%s", 4+ctime(&p_stat->st_ctime)); fprintf(stdout, " %s ", stime); return 0; } // -h option void to_humen_size(char *buf, off_t size) { double tmp = size; if (size >= 1024*1024*1024) { tmp /= 1024*1024*1024; snprintf(buf, BUF_SIZE, "%5.1fG", tmp); } else if (size >= 1024*1024) { tmp /= 1024*1024; snprintf(buf, BUF_SIZE, "%5.1fM", tmp); } else if (size >= 1024) { tmp /= 1024; snprintf(buf, BUF_SIZE, "%5.1fK", tmp); } else { snprintf(buf, BUF_SIZE, "%6ld", size); } } char get_file_type(mode_t st_mode) { if (S_ISREG(st_mode)) { g_scolor = COLOR_R; return ‘-‘; } if (S_ISDIR(st_mode)) { g_scolor = COLOR_D; return ‘d‘; } if (S_ISCHR(st_mode)) { g_scolor = COLOR_C; return ‘c‘; } if (S_ISBLK(st_mode)) { g_scolor = COLOR_B; return ‘b‘; } if (S_ISFIFO(st_mode)) { g_scolor = COLOR_P; return ‘p‘; } if (S_ISLNK(st_mode)) { g_scolor = COLOR_L; return ‘l‘; } if (S_ISSOCK(st_mode)) { g_scolor = COLOR_S; return ‘s‘; } g_scolor = COLOR_R; return ‘-‘; } // -rwx---... void get_mode(char *buf, mode_t st_mode) { buf[0] = get_file_type(st_mode); int i; mode_t bit; for (i = 3; i > 0; --i) { bit = st_mode & 0x01; buf[i*3] = (1 == bit ? ‘x‘ : ‘-‘); st_mode >>= 1; bit = st_mode & 0x01; buf[i*3-1] = (1 == bit ? ‘w‘ : ‘-‘); st_mode >>= 1; bit = st_mode & 0x01; buf[i*3-2] = (1 == bit ? ‘r‘ : ‘-‘); st_mode >>= 1; } buf[10] = ‘\0‘; }
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