Author: markj
Date: Tue Apr 30 14:44:39 2019
New Revision: 346960
URL: https://svnweb.freebsd.org/changeset/base/346960
Log:
Retry upon NET_RT_IFLIST sysctl failure.
Port the logic used by getifaddrs(3) to handle the case where
NET_RT_IFLIST returns ENOMEM, which can occur if the list size changes
between the buffer allocation and sysctl read.
PR: 195191
Submitted by: Guy Yur <guy...@gmail.com> (original version)
MFC after: 1 week
Modified:
head/usr.sbin/rtadvd/if.c
Modified: head/usr.sbin/rtadvd/if.c
==============================================================================
--- head/usr.sbin/rtadvd/if.c Tue Apr 30 14:29:09 2019 (r346959)
+++ head/usr.sbin/rtadvd/if.c Tue Apr 30 14:44:39 2019 (r346960)
@@ -408,6 +408,8 @@ update_ifinfo_nd_flags(struct ifinfo *ifi)
return (0);
}
+#define MAX_SYSCTL_TRY 5
+
struct ifinfo *
update_ifinfo(struct ifilist_head_t *ifi_head, int ifindex)
{
@@ -419,26 +421,43 @@ update_ifinfo(struct ifilist_head_t *ifi_head, int ifi
size_t len;
char *lim;
int mib[] = { CTL_NET, PF_ROUTE, 0, AF_INET6, NET_RT_IFLIST, 0 };
- int error;
+ int error, ntry;
syslog(LOG_DEBUG, "<%s> enter", __func__);
- if (sysctl(mib, sizeof(mib)/sizeof(mib[0]), NULL, &len, NULL, 0) <
- 0) {
- syslog(LOG_ERR,
- "<%s> sysctl: NET_RT_IFLIST size get failed", __func__);
- exit(1);
- }
- if ((msg = malloc(len)) == NULL) {
- syslog(LOG_ERR, "<%s> malloc failed", __func__);
- exit(1);
- }
- if (sysctl(mib, sizeof(mib)/sizeof(mib[0]), msg, &len, NULL, 0) <
- 0) {
- syslog(LOG_ERR,
- "<%s> sysctl: NET_RT_IFLIST get failed", __func__);
- exit(1);
- }
+ ntry = 0;
+ do {
+ /*
+ * We'll try to get addresses several times in case that
+ * the number of addresses is unexpectedly increased during
+ * the two sysctl calls. This should rarely happen.
+ * Portability note: since FreeBSD does not add margin of
+ * memory at the first sysctl, the possibility of failure on
+ * the second sysctl call is a bit higher.
+ */
+
+ if (sysctl(mib, nitems(mib), NULL, &len, NULL, 0) < 0) {
+ syslog(LOG_ERR,
+ "<%s> sysctl: NET_RT_IFLIST size get failed",
+ __func__);
+ exit(1);
+ }
+ if ((msg = malloc(len)) == NULL) {
+ syslog(LOG_ERR, "<%s> malloc failed", __func__);
+ exit(1);
+ }
+ if (sysctl(mib, nitems(mib), msg, &len, NULL, 0) < 0) {
+ if (errno != ENOMEM || ++ntry >= MAX_SYSCTL_TRY) {
+ free(msg);
+ syslog(LOG_ERR,
+ "<%s> sysctl: NET_RT_IFLIST get failed",
+ __func__);
+ exit(1);
+ }
+ free(msg);
+ msg = NULL;
+ }
+ } while (msg == NULL);
lim = msg + len;
for (ifm = (struct if_msghdr *)msg;
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