[PATCH v2 4/5] qga/commands-posix: Log all net stats failures

[Andrew Deason]

guest_get_network_stats can silently fail in a couple of ways. Add
debug messages to these cases, so we're never completely silent on
failure.

Signed-off-by: Andrew Deason <adeason@sinenomine.net>
---
Changes since v1:
- new in v2

 qga/commands-posix.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index c0b00fc488..97e001e998 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -2789,20 +2789,22 @@ static int guest_get_network_stats(const char *name,
                        GuestNetworkInterfaceStat *stats)
 {
 #ifdef CONFIG_LINUX
     int name_len;
     char const *devinfo = "/proc/net/dev";
     FILE *fp;
     char *line = NULL, *colon;
     size_t n = 0;
     fp = fopen(devinfo, "r");
     if (!fp) {
+        g_debug("failed to open network stats %s: %s", devinfo,
+                g_strerror(errno));
         return -1;
     }
     name_len = strlen(name);
     while (getline(&line, &n, fp) != -1) {
         long long dummy;
         long long rx_bytes;
         long long rx_packets;
         long long rx_errs;
         long long rx_dropped;
         long long tx_bytes;
@@ -2837,21 +2839,23 @@ static int guest_get_network_stats(const char *name,
             stats->tx_errs = tx_errs;
             stats->tx_dropped = tx_dropped;
             fclose(fp);
             g_free(line);
             return 0;
         }
     }
     fclose(fp);
     g_free(line);
     g_debug("/proc/net/dev: Interface '%s' not found", name);
-#endif /* CONFIG_LINUX */
+#else /* !CONFIG_LINUX */
+    g_debug("Network stats reporting available only for Linux");
+#endif /* !CONFIG_LINUX */
     return -1;
 }
 
 /*
  * Build information about guest interfaces
  */
 GuestNetworkInterfaceList *qmp_guest_network_get_interfaces(Error **errp)
 {
     GuestNetworkInterfaceList *head = NULL, **tail = &head;
     struct ifaddrs *ifap, *ifa;
-- 
2.11.0