fs: Update FILE position in lseek()

Instead on relying on driver callbacks to update 'pos' in FILE, do it
as a part of lseek() code. This allows us to drop a bit of repeating
code as well as making lseek() implementation consistent with write()
and read().

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 13 insertions, 4 deletions

diff --git a/fs/tftp.c b/fs/tftp.c
index 1b50ba84f9..f9e204db59 100644
--- a/fs/tftp.c
+++ b/fs/tftp.c
@@ -576,12 +576,14 @@ 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)
 {
 	/* We cannot seek backwards without reloading or caching the file */
-	if (pos >= f->pos) {
+	loff_t f_pos = f->pos;
+
+	if (pos >= f_pos) {
 		loff_t ret;
 		char *buf = xmalloc(1024);
 
-		while (pos > f->pos) {
-			size_t len = min_t(size_t, 1024, pos - f->pos);
+		while (pos > f_pos) {
+			size_t len = min_t(size_t, 1024, pos - f_pos);
 
 			ret = tftp_read(dev, f, buf, len);
 
@@ -591,13 +593,20 @@ static loff_t tftp_lseek(struct device_d *dev, FILE *f, loff_t pos)
 			if (ret < 0)
 				goto out_free;
 
-			f->pos += ret;
+			f_pos += ret;
 		}
 
 		ret = pos;
 
 out_free:
 		free(buf);
+		if (ret < 0) {
+			/*
+			 * Update f->pos even if the overall request
+			 * failed since we can't move backwards
+			 */
+			f->pos = f_pos;
+		}
 		return ret;
 	}