Wenchao Xia <xiaw...@linux.vnet.ibm.com> writes:
> This patch simply remove "variable may be used uninitialized" warning.
>
> Signed-off-by: Wenchao Xia <xiaw...@linux.vnet.ibm.com>
> ---
> V2: Address Stefan and Peter's comments, use 0 in send_msg() instead of
> initialize mhHeader.
>
> libcacard/vscclient.c | 3 +--
> util/iov.c | 2 +-
> 2 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/libcacard/vscclient.c b/libcacard/vscclient.c
> index ac23647..7fbf1da 100644
> --- a/libcacard/vscclient.c
> +++ b/libcacard/vscclient.c
> @@ -641,7 +641,6 @@ main(
> GIOChannel *channel_stdin;
> char *qemu_host;
> char *qemu_port;
> - VSCMsgHeader mhHeader;
>
> VCardEmulOptions *command_line_options = NULL;
>
> @@ -750,7 +749,7 @@ main(
> .magic = VSCARD_MAGIC,
> .capabilities = {0}
> };
> - send_msg(VSC_Init, mhHeader.reader_id, &init, sizeof(init));
> + send_msg(VSC_Init, 0, &init, sizeof(init));
>
> g_main_loop_run(loop);
> g_main_loop_unref(loop);
This one's actually a bit more than just a warning suppression. The
uninitialized value gets passed to send_msg(), which prints it if
verbose > 10.
Makes no sense to me. Comes from commit 2ac85b9; cc'ing its author for
advice.
> diff --git a/util/iov.c b/util/iov.c
> index cc6e837..b91cfb9 100644
> --- a/util/iov.c
> +++ b/util/iov.c
> @@ -146,7 +146,7 @@ ssize_t iov_send_recv(int sockfd, struct iovec *iov,
> unsigned iov_cnt,
> {
> ssize_t total = 0;
> ssize_t ret;
> - size_t orig_len, tail;
> + size_t orig_len = 0, tail;
> unsigned niov;
>
> while (bytes > 0) {
Here are the uses of orig_len:
if (tail) {
/* second, fixup the last element, and remember the original
* length */
assert(niov < iov_cnt);
assert(iov[niov].iov_len > tail);
orig_len = iov[niov].iov_len;
iov[niov++].iov_len = tail;
}
ret = do_send_recv(sockfd, iov, niov, do_send);
/* Undo the changes above before checking for errors */
if (tail) {
iov[niov-1].iov_len = orig_len;
}
gcc is too stupid to understand the control flow. The initialization
shuts it up.
Personally, I dislike "shut up" initializations, because when you
mistakenly adds a new uninitialized use, you get the arbitrary "shut up"
value without warning.
Possible alternative:
if (tail) {
/* second, fixup the last element, and remember the original
* length */
assert(niov < iov_cnt);
assert(iov[niov].iov_len > tail);
orig_len = iov[niov].iov_len;
iov[niov++].iov_len = tail;
ret = do_send_recv(sockfd, iov, niov, do_send);
/* Undo the changes above before checking for errors */
iov[niov-1].iov_len = orig_len;
} else {
ret = do_send_recv(sockfd, iov, niov, do_send);
}
