Check secondaries value before writing it as /proc could be read-only.

diff --git a/if-linux.c b/if-linux.c
index 553669ab3cd6e4563d6d0d3a3356af177ff7763d..866da57ec7e029b351ac22523b1f588e566a0b16 100644 (file)
--- a/if-linux.c
+++ b/if-linux.c
@@ -160,11 +160,39 @@ if_machinearch(char *str, size_t len)
        return -1;
 }
 
+static int
+check_proc_int(const char *path)
+{
+       FILE *fp;
+       int i;
+
+       fp = fopen(path, "r");
+       if (fp == NULL)
+               return -1;
+       if (fscanf(fp, "%d", &i) != 1)
+               i = -1;
+       fclose(fp);
+       return i;
+}
+
+static ssize_t
+write_path(const char *path, const char *val)
+{
+       FILE *fp;
+       ssize_t r;
+
+       fp = fopen(path, "w");
+       if (fp == NULL)
+               return -1;
+       r = fprintf(fp, "%s\n", val);
+       fclose(fp);
+       return r;
+}
+
 int
 if_init(struct interface *ifp)
 {
        char path[sizeof(PROC_PROMOTE) + IF_NAMESIZE];
-       FILE *fp;
        int n;
 
        /* We enable promote_secondaries so that we can do this
@@ -175,29 +203,27 @@ if_init(struct interface *ifp)
         * This matches the behaviour of BSD which makes coding dhcpcd
         * a little easier as there's just one behaviour. */
        snprintf(path, sizeof(path), PROC_PROMOTE, ifp->name);
-
-       fp = fopen(path, "w");
-       if (fp == NULL)
+       n = check_proc_int(path);
+       if (n == -1)
                return errno == ENOENT ? 0 : -1;
-       n = fprintf(fp, "1");
-       fclose(fp);
-       return n == -1 ? -1 : 0;
+       if (n == 1)
+               return 0;
+       return write_path(path, "1") == -1 ? -1 : 0;
 }
 
 int
 if_conf(struct interface *ifp)
 {
-       char path[sizeof(SYS_LAYER2) + IF_NAMESIZE], buf[1];
-       FILE *fp;
+       char path[sizeof(SYS_LAYER2) + IF_NAMESIZE];
+       int n;
 
        /* Some qeth setups require the use of the broadcast flag. */
        snprintf(path, sizeof(path), SYS_LAYER2, ifp->name);
-       fp = fopen(path, "r");
-       if (fp == NULL)
+       n = check_proc_int(path);
+       if (n == -1)
                return errno == ENOENT ? 0 : -1;
-       if (fgets(buf, sizeof(buf), fp) != NULL && buf[0] == '0')
+       if (n == 0)
                ifp->options->options |= DHCPCD_BROADCAST;
-       fclose(fp);
        return 0;
 }
 
@@ -1137,35 +1163,6 @@ if_addrflags6(const char *ifname, const struct in6_addr *addr)
        return -1;
 }
 
-static int
-check_proc_int(const char *path)
-{
-       FILE *fp;
-       int i;
-
-       fp = fopen(path, "r");
-       if (fp == NULL)
-               return -1;
-       if (fscanf(fp, "%d", &i) != 1)
-               i = -1;
-       fclose(fp);
-       return i;
-}
-
-static ssize_t
-write_path(const char *path, const char *val)
-{
-       FILE *fp;
-       ssize_t r;
-
-       fp = fopen(path, "w");
-       if (fp == NULL)
-               return -1;
-       r = fprintf(fp, "%s\n", val);
-       fclose(fp);
-       return r;
-}
-
 static const char *prefix = "/proc/sys/net/ipv6/conf";
 
 void