useradd reports spurious warning "failed to reset the lastlog entry"

[brown-midas]

I've noticed that useradd reports a spurious error if you create a system user, e.g.
useradd -r -u 111 testuser1
The user is still created correctly.

In the code for useradd (line 2044) I see:

	if (   (lseek (fd, offset_uid, SEEK_SET) != offset_uid)
	    || (write_full (fd, &ll, sizeof (ll)) != (ssize_t) sizeof (ll))
	    || (fsync (fd) != 0)) {

But write_full() returns zero on success, -1 on error, so it should be:

	if (   (lseek (fd, offset_uid, SEEK_SET) != offset_uid)
	    || (write_full (fd, &ll, sizeof (ll)) == -1)
	    || (fsync (fd) != 0)) {

[ikerexxe]

You are right. Let me prepare a patch to fix this issue.