diff options
| -rw-r--r-- | loginutils/add-remove-shell.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/loginutils/add-remove-shell.c b/loginutils/add-remove-shell.c index 986fe57..757e505 100644 --- a/loginutils/add-remove-shell.c +++ b/loginutils/add-remove-shell.c @@ -63,11 +63,19 @@ int add_remove_shell_main(int argc UNUSED_PARAM, char **argv) orig_fp = fopen_for_read(orig_fn); new_fn = xasprintf("%s.tmp", orig_fn); - xmove_fd(xopen(new_fn, O_WRONLY | O_CREAT | O_EXCL), STDOUT_FILENO); + /* + * O_TRUNC or O_EXCL? At the first glance, O_EXCL looks better, + * since it prevents races. But: (1) it requires a retry loop, + * (2) if /etc/shells.tmp is *stale*, then retry loop + * with O_EXCL will never succeed - it should have a timeout, + * after which it should revert to O_TRUNC. + * For now, I settle for O_TRUNC instead. + */ + xmove_fd(xopen(new_fn, O_WRONLY | O_CREAT | O_TRUNC), STDOUT_FILENO); /* TODO: struct stat sb; - fstat(fileno(orig_fp), &sb); + xfstat(fileno(orig_fp), &sb); xfchown(STDOUT_FILENO, sb.st_uid, sb.st_gid); xfchmod(STDOUT_FILENO, sb.st_mode); */ |