[RFC PATCH v2 4/4] y2038: convert ppdev to 2038 safe

[Bamvor Zhang Jian]

Convert ppdev use 64bit time_t internally by replacing timeval to
timeval64.

In order to migrate to y2038 safe, split ioctl command PP[SG]ETTIME
to PP[SG]ETTIME64(y2038 safe) and PP[SG]ETTIME32 (the legacy
behavior in 32bit application). The 32bit application should make
use of PP[SG]ETTIME64 and __kernel_timeval to migrate to time64_t.

Signed-off-by: Bamvor Zhang Jian <bamvor.zhangjian@xxxxxxxxxx>
---
 drivers/char/ppdev.c       | 32 +++++++++++++++++++++++++-------
 include/uapi/linux/ppdev.h | 14 ++++++++++++--
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c
index 9207658..a103d3d 100644
--- a/drivers/char/ppdev.c
+++ b/drivers/char/ppdev.c
@@ -497,8 +497,9 @@ static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		unsigned char mask;
 		int mode;
 		int ret;
-		struct timeval par_timeout;
+		struct timeval64 par_timeout;
 		long to_jiffies;
+		int is_not_compat_timeval = 0;
 
 	case PPRSTATUS:
 		reg = parport_read_status (port);
@@ -593,9 +594,17 @@ static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		atomic_sub (ret, &pp->irqc);
 		return 0;
 
-	case PPSETTIME:
-		if (copy_from_user (&par_timeout, argp, sizeof(struct timeval))) {
-			return -EFAULT;
+	case PPSETTIME64:
+		is_not_compat_timeval = 1;
+	case PPSETTIME32:
+		if (is_not_compat_timeval) {
+			if (get_timeval64(&par_timeout, argp)) {
+				return -EFAULT;
+			}
+		} else {
+			if (compat_get_timeval64(&par_timeout, argp)) {
+				return -EFAULT;
+			}
 		}
 		/* Convert to jiffies, place in pp->pdev->timeout */
 		if ((par_timeout.tv_sec < 0) || (par_timeout.tv_usec < 0)) {
@@ -609,13 +618,22 @@ static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		pp->pdev->timeout = to_jiffies;
 		return 0;
 
-	case PPGETTIME:
+	case PPGETTIME64:
+		is_not_compat_timeval = 1;
+	case PPGETTIME32:
 		to_jiffies = pp->pdev->timeout;
 		memset(&par_timeout, 0, sizeof(par_timeout));
 		par_timeout.tv_sec = to_jiffies / HZ;
 		par_timeout.tv_usec = (to_jiffies % (long)HZ) * (1000000/HZ);
-		if (copy_to_user (argp, &par_timeout, sizeof(struct timeval)))
-			return -EFAULT;
+		if (is_not_compat_timeval) {
+			if (put_timeval64(&par_timeout, argp)) {
+				return -EFAULT;
+			}
+		} else {
+			if (compat_put_timeval64(&par_timeout, argp)) {
+				return -EFAULT;
+			}
+		}
 		return 0;
 
 	default:
diff --git a/include/uapi/linux/ppdev.h b/include/uapi/linux/ppdev.h
index dc18c5d..d62a47d 100644
--- a/include/uapi/linux/ppdev.h
+++ b/include/uapi/linux/ppdev.h
@@ -74,8 +74,18 @@ struct ppdev_frob_struct {
 #define PPSETPHASE	_IOW(PP_IOCTL, 0x94, int)
 
 /* Set and get port timeout (struct timeval's) */
-#define PPGETTIME	_IOR(PP_IOCTL, 0x95, struct timeval)
-#define PPSETTIME	_IOW(PP_IOCTL, 0x96, struct timeval)
+/* Force application use 64 time_t ioctl */
+/* TODO: It is an open question about we should use a __xxx_timeval or an
+ * implicit array.
+ * replace struct __kernel_timeval with __s32[4]
+ * replace struct compat_timeval with __s32[2]
+ */
+#define PPGETTIME	PPGETTIME64
+#define PPSETTIME	PPSETTIME64
+#define PPGETTIME64	_IOR(PP_IOCTL, 0x95, struct __kernel_timeval)
+#define PPSETTIME64	_IOW(PP_IOCTL, 0x96, struct __kernel_timeval)
+#define PPGETTIME32	_IOR(PP_IOCTL, 0x9c, struct __kernel_compat_timeval)
+#define PPSETTIME32	_IOW(PP_IOCTL, 0x9d, struct __kernel_compat_timeval)
 
 /* Get available modes (what the hardware can do) */
 #define PPGETMODES	_IOR(PP_IOCTL, 0x97, unsigned int)
-- 
2.1.4

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