Chen Gang <[email protected]> writes:
> When path is truncated by PATH_MAX limitation, it causes QEMU to access
> incorrect file. So use original full path instead of PATH_MAX within
> 9pfs (need check/process ENOMEM for related memory allocation).
>
> The related test:
[...]
> Signed-off-by: Chen Gang <[email protected]>
> ---
> hw/9pfs/cofs.c | 15 ++-
> hw/9pfs/virtio-9p-handle.c | 9 +-
> hw/9pfs/virtio-9p-local.c | 285
> +++++++++++++++++++++++++++--------------
> hw/9pfs/virtio-9p-posix-acl.c | 52 ++++++--
> hw/9pfs/virtio-9p-xattr-user.c | 27 +++-
> hw/9pfs/virtio-9p-xattr.c | 9 +-
> hw/9pfs/virtio-9p-xattr.h | 27 +++-
> hw/9pfs/virtio-9p.h | 6 +-
> 8 files changed, 292 insertions(+), 138 deletions(-)
>
> diff --git a/hw/9pfs/cofs.c b/hw/9pfs/cofs.c
> index 3891050..739bad0 100644
> --- a/hw/9pfs/cofs.c
> +++ b/hw/9pfs/cofs.c
> @@ -20,18 +20,24 @@
> int v9fs_co_readlink(V9fsPDU *pdu, V9fsPath *path, V9fsString *buf)
> {
> int err;
> - ssize_t len;
> + ssize_t len, maxlen = PATH_MAX;
> V9fsState *s = pdu->s;
>
> if (v9fs_request_cancelled(pdu)) {
> return -EINTR;
> }
> - buf->data = g_malloc(PATH_MAX);
> + buf->data = g_malloc(maxlen);
> v9fs_path_read_lock(s);
> v9fs_co_run_in_worker(
> - {
> + while (1) {
> len = s->ops->readlink(&s->ctx, path,
> - buf->data, PATH_MAX - 1);
> + buf->data, maxlen - 1);
> + if (len == maxlen - 1) {
> + g_free(buf->data);
> + maxlen *= 2;
> + buf->data = g_malloc(maxlen);
> + continue;
> + }
> if (len > -1) {
> buf->size = len;
> buf->data[len] = 0;
err = 0;
> } else {
> err = -errno;
> }
> + break;
> });
> v9fs_path_unlock(s);
> if (err) {
Harmless off-by-one: you double the buffer even when the link contents
plus terminating null fits the buffer exactly (len == maxlen - 1).
I prefer to have the exceptional stuff handled in conditionals, and not
the normal stuff, like this:
for (;;) {
len = s->ops->readlink(&s->ctx, path, buf->data, maxlen);
if (len < 0) {
err = -errno;
break;
}
if (len == maxlen) {
g_free(buf->data);
maxlen *= 2;
buf->data = g_malloc(maxlen);
continue;
}
buf->size = len;
buf->data[len] = 0;
err = 0;
break;
}
Matter of taste.
[...]
I skimmed a few more hunks, and they look good to me. Leaving full
review to Aneesh.
