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Tools: hv: update buffer handling in hv_fcopy_daemon

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Currently this warning is triggered when compiling hv_fcopy_daemon:

hv_fcopy_daemon.c:216:4: warning: dereferencing type-punned pointer will break
strict-aliasing rules [-Wstrict-aliasing]
    kernel_modver = *(__u32 *)buffer;

Convert the send/receive buffer to a union and pass individual members as
needed. This also gives the correct size for the buffer.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Olaf Hering 2017-08-10 15:45:16 -07:00 committed by Greg Kroah-Hartman
parent 3619350cf0
commit 3f2baa8a7d
1 changed files with 17 additions and 15 deletions
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32
tools/hv/hv_fcopy_daemon.c
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@ -138,14 +138,17 @@ void print_usage(char *argv[])
int main(int argc, char *argv[])
{
int fcopy_fd, len;
int fcopy_fd;
int error;
int daemonize = 1, long_index = 0, opt;
int version = FCOPY_CURRENT_VERSION;
char *buffer[4096 * 2];
struct hv_fcopy_hdr *in_msg;
union {
struct hv_fcopy_hdr hdr;
struct hv_start_fcopy start;
struct hv_do_fcopy copy;
__u32 kernel_modver;
} buffer = { };
int in_handshake = 1;
__u32 kernel_modver;
static struct option long_options[] = {
{"help", no_argument, 0, 'h' },
@ -195,32 +198,31 @@ int main(int argc, char *argv[])
* In this loop we process fcopy messages after the
* handshake is complete.
*/
len = pread(fcopy_fd, buffer, (4096 * 2), 0);
ssize_t len;
len = pread(fcopy_fd, &buffer, sizeof(buffer), 0);
if (len < 0) {
syslog(LOG_ERR, "pread failed: %s", strerror(errno));
exit(EXIT_FAILURE);
}
if (in_handshake) {
if (len != sizeof(kernel_modver)) {
if (len != sizeof(buffer.kernel_modver)) {
syslog(LOG_ERR, "invalid version negotiation");
exit(EXIT_FAILURE);
}
kernel_modver = *(__u32 *)buffer;
in_handshake = 0;
syslog(LOG_INFO, "kernel module version: %d",
kernel_modver);
syslog(LOG_INFO, "kernel module version: %u",
buffer.kernel_modver);
continue;
}
in_msg = (struct hv_fcopy_hdr *)buffer;
switch (in_msg->operation) {
switch (buffer.hdr.operation) {
case START_FILE_COPY:
error = hv_start_fcopy((struct hv_start_fcopy *)in_msg);
error = hv_start_fcopy(&buffer.start);
break;
case WRITE_TO_FILE:
error = hv_copy_data((struct hv_do_fcopy *)in_msg);
error = hv_copy_data(&buffer.copy);
break;
case COMPLETE_FCOPY:
error = hv_copy_finished();
@ -231,7 +233,7 @@ int main(int argc, char *argv[])
default:
syslog(LOG_ERR, "Unknown operation: %d",
in_msg->operation);
buffer.hdr.operation);
}