[PATCH 1/2] tools/nolibc: define time_t in terms of __kernel_old_time_t

Thomas Weißschuh posted 2 patches 2 months, 3 weeks ago
[PATCH 1/2] tools/nolibc: define time_t in terms of __kernel_old_time_t
Posted by Thomas Weißschuh 2 months, 3 weeks ago
Nolibc assumes that the kernel ABI is using a time values that are as
large as a long integer. For most ABIs this holds true.
But for x32 this is not correct, as it uses 32bit longs but 64bit times.

Also the 'struct stat' implementation of nolibc relies on timespec::tv_sec
and time_t being the same type. While timespec::tv_sec comes from the
kernel and is of type __kernel_old_time_t, time_t is defined within nolibc.

Switch to the __kernel_old_time_t to always get the correct type.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 tools/include/nolibc/std.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/include/nolibc/std.h b/tools/include/nolibc/std.h
index adda7333d12e7d2c336938ede1aaf215b4b93165..ba950f0e7338438823b4ee8c68a067391c719823 100644
--- a/tools/include/nolibc/std.h
+++ b/tools/include/nolibc/std.h
@@ -16,6 +16,8 @@
 #include "stdint.h"
 #include "stddef.h"
 
+#include <linux/types.h>
+
 /* those are commonly provided by sys/types.h */
 typedef unsigned int          dev_t;
 typedef unsigned long         ino_t;
@@ -27,6 +29,6 @@ typedef unsigned long       nlink_t;
 typedef   signed long         off_t;
 typedef   signed long     blksize_t;
 typedef   signed long      blkcnt_t;
-typedef   signed long        time_t;
+typedef __kernel_old_time_t  time_t;
 
 #endif /* _NOLIBC_STD_H */

-- 
2.50.1

Re: [PATCH 1/2] tools/nolibc: define time_t in terms of __kernel_old_time_t
Posted by Willy Tarreau 2 months, 3 weeks ago
On Sat, Jul 12, 2025 at 11:00:55AM +0200, Thomas Weißschuh wrote:
> Nolibc assumes that the kernel ABI is using a time values that are as
> large as a long integer. For most ABIs this holds true.
> But for x32 this is not correct, as it uses 32bit longs but 64bit times.
> 
> Also the 'struct stat' implementation of nolibc relies on timespec::tv_sec
> and time_t being the same type. While timespec::tv_sec comes from the
> kernel and is of type __kernel_old_time_t, time_t is defined within nolibc.
> 
> Switch to the __kernel_old_time_t to always get the correct type.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

Great! I didn't know we could support x32 and thought it was phased out.
But if it works it can be convenient for those seeking smaller binaries.

Both patches look good to me, for the whole series:

Acked-by: Willy Tarreau <w@1wt.eu>

Thanks!
Willy