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-rw-r--r--lib/if.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/lib/if.c b/lib/if.c
index 2e36eff3..d80e2347 100644
--- a/lib/if.c
+++ b/lib/if.c
@@ -46,7 +46,14 @@ struct if_master
int (*if_delete_hook) (struct interface *);
} if_master;
-/* Compare interface names */
+/* Compare interface names, returning an integer greater than, equal to, or
+ * less than 0, (following the strcmp convention), according to the
+ * relationship between ifp1 and ifp2. Interface names consist of an
+ * alphabetic prefix and a numeric suffix. The primary sort key is
+ * lexicographic by name, and then numeric by number. No number sorts
+ * before all numbers. Examples: de0 < de1, de100 < fxp0 < xl0, devpty <
+ * devpty0, de0 < del0
+ */
int
if_cmp_func (struct interface *ifp1, struct interface *ifp2)
{
@@ -67,6 +74,9 @@ if_cmp_func (struct interface *ifp1, struct interface *ifp2)
if (l1 != l2)
return (strcmp(p1, p2));
+ /* Note that this relies on all numbers being less than all letters, so
+ * that de0 < del0.
+ */
res = strncmp(p1, p2, l1);
/* names are different -> compare them */