How to get file's owner name in Linux using C++?

Question

How can I get get the owner name and group name of a file on a Linux filesystem using C++? The stat() call only gives me owner ID and group ID but not the actua

Answer 1

Use getpwuid() and getgrgid().

#include <pwd.h>
#include <grp.h>
#include <sys/stat.h>

struct stat info;
stat(filename, &info);  // Error check omitted
struct passwd *pw = getpwuid(info.st_uid);
struct group  *gr = getgrgid(info.st_gid);

// If pw != 0, pw->pw_name contains the user name
// If gr != 0, gr->gr_name contains the group name

Answer 2

One way would be to use stat() to get the uid of a file and then getpwuid() to get the username as a string.