功能:獲取文件元數據

#include <sys/types.h> #include <sys/stat.h> #include <unistd.h> int stat(const char *path, struct stat *buf); int fstat(int fd, struct stat *buf); int lstat(const char *path, struct stat *buf);

stat結構體

struct stat {dev_t st_dev; /* ID of device containing file */ino_t st_ino; /* inode number */mode_t st_mode; /* protection */nlink_t st_nlink; /* number of hard links */uid_t st_uid; /* user ID of owner */gid_t st_gid; /* group ID of owner */dev_t st_rdev; /* device ID (if special file) */off_t st_size; /* total size, in bytes */blksize_t st_blksize; /* blocksize for filesystem I/O */blkcnt_t st_blocks; /* number of 512B blocks allocated */time_t st_atime; /* time of last access */time_t st_mtime; /* time of last modification */time_t st_ctime; /* time of last status change */ }; //示例 - err_exit函數如前 // 其實可以通過Linux 系統調用major, minor來替換(如下) #define MAJOR(a) (int)((unsigned short)a >> 8) //主設備號: 獲取高8位 #define MINOR(a) (int)((unsigned short)a & 0xFF)//次設備號: 獲取低8位 bool fileType(const struct stat &fileStat); void filePerm(const struct stat &fileStat, char *perm);int main(int argc, char *argv[]) {if (argc != 2){cerr << "Usage: " << argv[0] << " <file-name>" << endl;exit(EXIT_FAILURE);}struct stat fileStat;if (lstat(argv[1], &fileStat) == -1)err_exit("stat error");cout << "file-name: " << argv[1] << endl;cout << "st_ino = " << fileStat.st_ino << endl;cout << "device major: " << major(fileStat.st_dev)<< ", minor: " << minor(fileStat.st_dev) << endl;if (fileType(fileStat)){cout << "----------------------------" << endl;cout << "major: " << MAJOR(fileStat.st_dev)<< ", minor: " << MINOR(fileStat.st_rdev) << endl; // cout << "major: " << major(fileStat.st_dev) // << ", minor: " << minor(fileStat.st_rdev) << endl;}//獲取文件的權限: 但要注意需要&上07777fprintf(stdout, "file permission: %o", fileStat.st_mode&07777);char perm[11];filePerm(fileStat, perm);cout << ", msg: " << perm << endl;cout << "st_nlink = " << fileStat.st_nlink << endl;cout << "st_uid = " << fileStat.st_uid << endl;cout << "st_gid = " << fileStat.st_gid << endl;cout << "st_size = " << fileStat.st_size << endl;cout << "st_blksize = " << fileStat.st_blksize << endl;cout << "st_blocks = " << fileStat.st_blocks << endl;cout << "st_atime = " << fileStat.st_atime << endl;cout << "st_ctime = " << fileStat.st_ctime << endl;cout << "st_mtime = " << fileStat.st_mtime << endl; }bool fileType(const struct stat &fileStat) {cout << "file-type: ";switch(fileStat.st_mode & S_IFMT){case S_IFSOCK:cout << "socket";break;case S_IFLNK:cout << "symbolic link";break;case S_IFREG:cout << "regular file";break;case S_IFBLK:cout << "block device" << endl;return true;break;case S_IFDIR:cout << "directory";break;case S_IFCHR:cout << "character device" << endl;return true;break;case S_IFIFO:cout << "FIFO" << endl;break;default:cout << "unknown?";break;}cout << endl;return false; }void filePerm(const struct stat &fileStat, char *perm) {strcpy(perm, "----------");switch(fileStat.st_mode & S_IFMT){case S_IFSOCK:perm[0] = 's';break;case S_IFLNK:perm[0] = 'l';break;case S_IFREG:perm[0] = '-';break;case S_IFBLK:perm[0] = 'b';break;case S_IFDIR:perm[0] = 'd';break;case S_IFCHR:perm[0] = 'c';break;case S_IFIFO:perm[0] = 'p';break;default:perm[0] = '?';break;}if (fileStat.st_mode & S_IRUSR)perm[1] = 'r';if (fileStat.st_mode & S_IWUSR)perm[2] = 'w';if (fileStat.st_mode & S_IXUSR)perm[3] = 'x';if (fileStat.st_mode & S_IRGRP)perm[4] = 'r';if (fileStat.st_mode & S_IWGRP)perm[5] = 'w';if (fileStat.st_mode & S_IXGRP)perm[6] = 'x';if (fileStat.st_mode & S_IROTH)perm[7] = 'r';if (fileStat.st_mode & S_IWOTH)perm[8] = 'w';if (fileStat.st_mode & S_IXOTH)perm[9] = 'x'; }

[拓展]

1.getpwuid?

struct passwd *getpwuid(uid_t uid); //passwd結構體 struct passwd {char *pw_name; /* username */char *pw_passwd; /* user password */uid_t pw_uid; /* user ID */gid_t pw_gid; /* group ID */char *pw_gecos; /* user information */char *pw_dir; /* home directory */char *pw_shell; /* shell program */ };

2.getgrgid

struct group *getgrgid(gid_t gid); //group結構體 struct group {char *gr_name; /* group name */char *gr_passwd; /* group password */gid_t gr_gid; /* group ID */char **gr_mem; /* group members */ };

3.?readlink

ssize_t readlink(const char *path, char *buf, size_t bufsiz);

4.?localtime

struct tm *localtime(const time_t *timep); //tm結構體 struct tm {int tm_sec; /* seconds */int tm_min; /* minutes */int tm_hour; /* hours */int tm_mday; /* day of the month */int tm_mon; /* month */int tm_year; /* year */int tm_wday; /* day of the week */int tm_yday; /* day in the year */int tm_isdst; /* daylight saving time */ };
//示例: 實現簡單的ls -l功能 #include <iostream>#include <stdio.h> #include <stdlib.h> #include <string.h> #include <string.h>#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <grp.h> #include <pwd.h> #include <time.h>using namespace std;inline void err_exit(std::string message); bool isDevice(const struct stat &fileStat); bool isLink(const struct stat &fileStat); void filePerm(const struct stat &fileStat, char *perm);int main(int argc, char *argv[]) {if (argc != 2){cerr << "Usage: " << argv[0] << " <file-name>" << endl;exit(EXIT_FAILURE);}struct stat fileStat;if (lstat(argv[1], &fileStat) == -1)err_exit("lstat error");//獲取權限char perm[11];filePerm(fileStat, perm);cout << perm << ' ';//獲取文件鏈接數cout << fileStat.st_nlink << ' ';//獲取文件所有者struct passwd *ps = getpwuid(fileStat.st_uid);cout << ps->pw_name << ' ';//獲取文件所屬組struct group *gp = getgrgid(fileStat.st_gid);cout << gp->gr_name << ' ';if (isDevice(fileStat))cout << major(fileStat.st_dev) << ", "<< minor(fileStat.st_rdev) << ' ';elsecout << fileStat.st_size << ' ';// 打印最后一次修改時間time_t mtime = fileStat.st_mtime;struct tm *pTime = localtime(&mtime);cout << pTime->tm_mon+1 << "月 " << pTime->tm_mday << ' '<< pTime->tm_hour << ':' << pTime->tm_min << ' ';// 打印文件名cout << argv[1];if (isLink(fileStat)){cout << " -> ";char name[1024] = {0};if (readlink(argv[1], name, sizeof(name)) == -1)err_exit("readlink error");cout << name;}cout << endl;}inline void err_exit(std::string message) {perror(message.c_str());exit(EXIT_FAILURE); } bool isDevice(const struct stat &fileStat) {switch(fileStat.st_mode & S_IFMT){case S_IFBLK:case S_IFCHR:return true;break;default:return false;break;}return false; } bool isLink(const struct stat &fileStat) {if ((fileStat.st_mode & S_IFMT) == S_IFLNK)return true;return false; } void filePerm(const struct stat &fileStat, char *perm) {strcpy(perm, "----------");switch(fileStat.st_mode & S_IFMT){case S_IFSOCK:perm[0] = 's';break;case S_IFLNK:perm[0] = 'l';break;case S_IFREG:perm[0] = '-';break;case S_IFBLK:perm[0] = 'b';break;case S_IFDIR:perm[0] = 'd';break;case S_IFCHR:perm[0] = 'c';break;case S_IFIFO:perm[0] = 'p';break;default:perm[0] = '?';break;}if (fileStat.st_mode & S_IRUSR)perm[1] = 'r';if (fileStat.st_mode & S_IWUSR)perm[2] = 'w';if (fileStat.st_mode & S_IXUSR)perm[3] = 'x';if (fileStat.st_mode & S_IRGRP)perm[4] = 'r';if (fileStat.st_mode & S_IWGRP)perm[5] = 'w';if (fileStat.st_mode & S_IXGRP)perm[6] = 'x';if (fileStat.st_mode & S_IROTH)perm[7] = 'r';if (fileStat.st_mode & S_IWOTH)perm[8] = 'w';if (fileStat.st_mode & S_IXOTH)perm[9] = 'x'; }

總結

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