[PATCH] tftp: implement forward seeking

[Uwe Kleine-König]

Just abuse tftp_read to step forward.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
---
 fs/tftp.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/fs/tftp.c b/fs/tftp.c
index 56d4365d773a..272a7106eb51 100644
--- a/fs/tftp.c
+++ b/fs/tftp.c
@@ -591,8 +591,29 @@ static int tftp_read(struct device_d *dev, FILE *f, void *buf, size_t insize)
 
 static loff_t tftp_lseek(struct device_d *dev, FILE *f, loff_t pos)
 {
-	/* not implemented in tftp protocol */
-	return -ENOSYS;
+	if (pos >= f->pos) {
+		char buf[1024];
+		int ret;
+		while (pos > f->pos) {
+			size_t len = min(sizeof(buf), (size_t)(pos - f->pos));
+			ret = tftp_read(dev, f, buf, len);
+
+			if (ret < 0)
+				return ret;
+			else if (!ret)
+				return -EINVAL;
+			f->pos += ret;
+
+			memory_display(buf, f->pos - len, 0x10, 4, 0);
+		}
+		return pos;
+	} else {
+		/*
+		 * We cannot seek backwards without reloading or caching the
+		 * file
+		 */
+		return -ENOSYS;
+	}
 }
 
 static DIR* tftp_opendir(struct device_d *dev, const char *pathname)
-- 
2.11.0