Just abuse tftp_read to step forward.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
---
Hello,
this is v2 which compared to (implicit) v1 uses xmalloc and no debugging
any more.
When tftp_lseek is entered with f->pos == pos, the only thing that the
function does is xmalloc, free, return. Is it worth to optimize that?
I thought it's not worth the additional (even if trivial) complication,
but want to at least point that out.
Best regards
Uwe
fs/tftp.c | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/fs/tftp.c b/fs/tftp.c
index 56d4365d773a..4bacd2ed7fcf 100644
--- a/fs/tftp.c
+++ b/fs/tftp.c
@@ -591,7 +591,32 @@ 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 */
+ /* We cannot seek backwards without reloading or caching the file */
+ 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);
+
+ ret = tftp_read(dev, f, buf, len);
+
+ if (!ret)
+ /* EOF, so the desired pos is invalid. */
+ ret = -EINVAL;
+ if (ret < 0)
+ goto out_free;
+
+ f->pos += ret;
+ }
+
+ ret = pos;
+
+out_free:
+ free(buf);
+ return ret;
+ }
+
return -ENOSYS;
}
--
2.11.0
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