On Tue, Mar 19, 2024 at 11:13:40AM +0100, Laurent
Vivier wrote:
In write_remainder() 'skip' is the
offset to start the operation from
in the iovec array.
In iov_skip_bytes(), 'skip' is also the offset in the iovec array but
'offset' is the first unskipped byte in the iovec entry.
As write_remainder() uses 'skip' for both, 'skip' is reset to the
first unskipped byte in the iovec entry rather to staying the first
unskipped byte in the iovec array.
Fix the problem by introducing a new variable not to overwrite 'skip'
on each loop.
Fixes: 8bdb0883b441 ("util: Add write_remainder() helper")
Cc: david(a)gibson.dropbear.id.au
Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>
Ouch. *dons paper bag*
I believe this is correct as it stands, but..
---
util.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/util.c b/util.c
index 3b2393d6bfa8..eee53aed811b 100644
--- a/util.c
+++ b/util.c
@@ -533,13 +533,14 @@ int do_clone(int (*fn)(void *), char *stack_area, size_t
stack_size, int flags,
int write_remainder(int fd, const struct iovec *iov, int iovcnt, size_t skip)
{
int i;
+ size_t offset;
- while ((i = iov_skip_bytes(iov, iovcnt, skip, &skip)) < iovcnt) {
+ while ((i = iov_skip_bytes(iov, iovcnt, skip, &offset)) < iovcnt) {
ssize_t rc;
if (skip) {
.. it would be more optimal if you checked for offset != 0 rather than
skip != 0 here. Otherwise even once we've written an entire buffer,
we'll continue to write the rest of the buffers one by one, rather
than writing them all with a writev().