examples/vm_power: fix build on Ubuntu 20.04

When compiling on Ubuntu 20.04, a warning was issued about possible
truncation of the path string for the power management socket.

channel_manager.c: In function ‘add_all_channels’:
channel_manager.c:470:41: warning: ‘%s’ directive output may be
  truncated writing up to 255 bytes into a region of size 90
  [-Wformat-truncation=]
  470 |     sizeof(chan_info->channel_path), "%s%s",
      |                                         ^~

This can be fixed by adding in an explicit truncation check to the code
and handling it appropriately.

Fixes: e8ae9b662506 ("examples/vm_power: channel manager and monitor in host")
Cc: stable@dpdk.org
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: David Hunt <david.hunt@intel.com>

diff --git a/examples/vm_power_manager/channel_manager.c b/examples/vm_power_manager/channel_manager.c
index 74a2a67..a263150 100644 (file)
--- a/examples/vm_power_manager/channel_manager.c
+++ b/examples/vm_power_manager/channel_manager.c
@@ -467,9 +467,15 @@ add_all_channels(const char *vm_name)
                        continue;
                }
 
-               snprintf(chan_info->channel_path,
+               if ((size_t)snprintf(chan_info->channel_path,
                                sizeof(chan_info->channel_path), "%s%s",
-                               CHANNEL_MGR_SOCKET_PATH, dir->d_name);
+                               CHANNEL_MGR_SOCKET_PATH, dir->d_name)
+                                       >= sizeof(chan_info->channel_path)) {
+                       RTE_LOG(ERR, CHANNEL_MANAGER, "Pathname too long for channel '%s%s'\n",
+                                       CHANNEL_MGR_SOCKET_PATH, dir->d_name);
+                       rte_free(chan_info);
+                       continue;
+               }
 
                if (setup_channel_info(&vm_info, &chan_info, channel_num) < 0) {
                        rte_free(chan_info);