ifupdown: reread state file before rewriting it.

Fixes "ifup started another ifup" state corruption bug.
Patch by Natanael Copa <natanael.copa@gmail.com>.

diff --git a/networking/ifupdown.c b/networking/ifupdown.c
index 887c2ee..ff4f785 100644 (file)
--- a/networking/ifupdown.c
+++ b/networking/ifupdown.c
@@ -1083,15 +1083,33 @@ static llist_t *find_iface_state(llist_t *state_list, const char *iface)
        return NULL;
 }
 
+/* read the previous state from the state file */
+static llist_t *read_iface_state(void)
+{
+       llist_t *state_list = NULL;
+       FILE *state_fp = fopen("/var/run/ifstate", "r");
+
+       if (state_fp) {
+               char *start, *end_ptr;
+               while ((start = xmalloc_fgets(state_fp)) != NULL) {
+                       /* We should only need to check for a single character */
+                       end_ptr = start + strcspn(start, " \t\n");
+                       *end_ptr = '\0';
+                       llist_add_to(&state_list, start);
+               }
+               fclose(state_fp);
+       }
+       return state_list;
+}
+
+
 int ifupdown_main(int argc, char **argv);
 int ifupdown_main(int argc, char **argv)
 {
        int (*cmds)(struct interface_defn_t *) = NULL;
        struct interfaces_file_t *defn;
-       llist_t *state_list = NULL;
        llist_t *target_list = NULL;
        const char *interfaces = "/etc/network/interfaces";
-       FILE *state_fp;
        bool any_failures = 0;
 
        cmds = iface_down;
@@ -1118,32 +1136,9 @@ int ifupdown_main(int argc, char **argv)
        startup_PATH = getenv("PATH");
        if (!startup_PATH) startup_PATH = "";
 
-       /* Read the previous state from the state file */
-       state_fp = fopen("/var/run/ifstate", "r");
-       if (state_fp) {
-               char *start, *end_ptr;
-               while ((start = xmalloc_fgets(state_fp)) != NULL) {
-                       /* We should only need to check for a single character */
-                       end_ptr = start + strcspn(start, " \t\n");
-                       *end_ptr = '\0';
-                       llist_add_to(&state_list, start);
-               }
-               fclose(state_fp);
-       }
-
        /* Create a list of interfaces to work on */
        if (DO_ALL) {
-               if (cmds == iface_up) {
-                       target_list = defn->autointerfaces;
-               } else {
-                       /* iface_down */
-                       const llist_t *list = state_list;
-                       while (list) {
-                               llist_add_to_end(&target_list, xstrdup(list->data));
-                               list = list->link;
-                       }
-                       target_list = defn->autointerfaces;
-               }
+               target_list = defn->autointerfaces;
        } else {
                llist_add_to_end(&target_list, argv[optind]);
        }
@@ -1170,6 +1165,7 @@ int ifupdown_main(int argc, char **argv)
                }
 
                if (!FORCE) {
+                       llist_t *state_list = read_iface_state();
                        const llist_t *iface_state = find_iface_state(state_list, iface);
 
                        if (cmds == iface_up) {
@@ -1185,6 +1181,7 @@ int ifupdown_main(int argc, char **argv)
                                        continue;
                                }
                        }
+                       llist_free(state_list, free);
                }
 
 #if ENABLE_FEATURE_IFUPDOWN_MAPPING
@@ -1239,6 +1236,8 @@ int ifupdown_main(int argc, char **argv)
                        bb_error_msg("ignoring unknown interface %s", liface);
                        any_failures = 1;
                } else {
+                       /* update the state file */
+                       llist_t *state_list = read_iface_state();
                        llist_t *iface_state = find_iface_state(state_list, iface);
 
                        if (cmds == iface_up) {
@@ -1254,19 +1253,21 @@ int ifupdown_main(int argc, char **argv)
                                llist_unlink(&state_list, iface_state);
                                free(llist_pop(&iface_state));
                        }
-               }
-       }
 
-       /* Actually write the new state */
-       if (!NO_ACT) {
-               state_fp = xfopen("/var/run/ifstate", "w");
-               while (state_list) {
-                       if (state_list->data) {
-                               fprintf(state_fp, "%s\n", state_list->data);
+                       /* Actually write the new state */
+                       if (!NO_ACT) {
+                               FILE *state_fp = xfopen("/var/run/ifstate", "w");
+                               llist_t *state = state_list;
+                               while (state) {
+                                       if (state->data) {
+                                               fprintf(state_fp, "%s\n", state->data);
+                                       }
+                                       state = state->link;
+                               }
+                               fclose(state_fp);
                        }
-                       state_list = state_list->link;
+                       llist_free(state_list, free);
                }
-               fclose(state_fp);
        }
 
        return any_failures;