passwd: do not set 0 as date of last password change, closes 11951

function                                             old     new   delta
update_passwd                                       1491    1505     +14

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/libbb/update_passwd.c b/libbb/update_passwd.c
index 95423d19b..dc967683a 100644
--- a/libbb/update_passwd.c
+++ b/libbb/update_passwd.c
@@ -270,10 +270,16 @@ int FAST_FUNC update_passwd(const char *filename,
                         if (shadow && *cp == ':') {
                                 /* /etc/shadow's field 3 (passwd change date) needs updating */
                                 /* move past old change date */
+                                unsigned time_days = (unsigned long)(time(NULL)) / (24*60*60);
+
+                                if (time_days == 0) {
+                                        /* 0 as change date has special meaning, avoid it */
+                                        time_days = 1;
+                                }
                                 cp = strchrnul(cp + 1, ':');
                                 /* "name:" + "new_passwd" + ":" + "change date" + ":rest of line" */
                                 fprintf(new_fp, "%s%s:%u%s\n", name_colon, new_passwd,
-                                        (unsigned)(time(NULL)) / (24*60*60), cp);
+                                        time_days, cp);
                         } else {
                                 /* "name:" + "new_passwd" + ":rest of line" */
                                 fprintf(new_fp, "%s%s%s\n", name_colon, new_passwd, cp);