[PATCH] stat: fix negative %X/%Y/%Z timestamps after Y2038 on 32-bit builds

Introduce a utility function to always print `time_t` values using either
`long long` or `unsigned long long`, depending on whether `time_t` is
signed. This fixes the bug reported in [1].

Previously, `time_t` values were cast to `long`, which is a 32-bit value
on 32-bit builds.

[1]: https://lists.busybox.net/pipermail/busybox/2026-August/092413.html

Signed-off-by: Benjamin Robin <[email protected]>
---
 coreutils/stat.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/coreutils/stat.c b/coreutils/stat.c
index 2c2909e7e45b..e504ab1ab7f2 100644
--- a/coreutils/stat.c
+++ b/coreutils/stat.c
@@ -303,12 +303,25 @@ static void FAST_FUNC print_statfs(char *pformat, const char m,
 }
 #endif
 
+static void FAST_FUNC print_time_t(char *pformat, time_t val)
+{
+#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+
+	if (TYPE_SIGNED(time_t)) {
+		strcat(pformat, "lld");
+		printf(pformat, (long long) val);
+	}
+	else {
+		strcat(pformat, "llu");
+		printf(pformat, (unsigned long long) val);
+	}
+}
+
 /* print stat info */
 static void FAST_FUNC print_stat(char *pformat, const char m,
 		const char *const filename, const void *data
 		IF_SELINUX(, security_context_t scontext))
 {
-#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
 	struct stat *statbuf = (struct stat *) data;
 	struct passwd *pw_ent;
 	struct group *gw_ent;
@@ -382,20 +395,15 @@ static void FAST_FUNC print_stat(char *pformat, const char m,
 	} else if (m == 'x') {
 		printfs(pformat, human_time(&statbuf->st_atim));
 	} else if (m == 'X') {
-		strcat(pformat, TYPE_SIGNED(time_t) ? "ld" : "lu");
-		/* note: (unsigned long) would be wrong:
-		 * imagine (unsigned long64)int32 */
-		printf(pformat, (long) statbuf->st_atime);
+		print_time_t(pformat, statbuf->st_atime);
 	} else if (m == 'y') {
 		printfs(pformat, human_time(&statbuf->st_mtim));
 	} else if (m == 'Y') {
-		strcat(pformat, TYPE_SIGNED(time_t) ? "ld" : "lu");
-		printf(pformat, (long) statbuf->st_mtime);
+		print_time_t(pformat, statbuf->st_mtime);
 	} else if (m == 'z') {
 		printfs(pformat, human_time(&statbuf->st_ctim));
 	} else if (m == 'Z') {
-		strcat(pformat, TYPE_SIGNED(time_t) ? "ld" : "lu");
-		printf(pformat, (long) statbuf->st_ctime);
+		print_time_t(pformat, statbuf->st_ctime);
 # if ENABLE_SELINUX
 	} else if (m == 'C' && (option_mask32 & OPT_SELINUX)) {
 		printfs(pformat, scontext);

---
base-commit: 7473045ad3504db9b421427a452fd9b146346306
change-id: 20260822-fix-stat-seconds-since-epoch-b80c5eb17371

Best regards,
--  
Benjamin Robin <[email protected]>