From ff19d525a98418915e5e10e0e0bb6e40f7259b76 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Wed, 20 Oct 2010 15:14:32 +0200 Subject: add/remove-shell: use O_TRUNC instead of O_EXCL Signed-off-by: Denys Vlasenko --- loginutils/add-remove-shell.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'loginutils') diff --git a/loginutils/add-remove-shell.c b/loginutils/add-remove-shell.c index 986fe57c5..757e50503 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); */ -- cgit v1.2.3